Workflow Inputs

Introduction

OpenStudio-ERI requires a building description in an HPXML file format. HPXML is an open data standard for collecting and transferring home energy data. Using HPXML files reduces the complexity and effort for software developers to leverage the EnergyPlus simulation engine.

HPXML Inputs

HPXML is an flexible and extensible format, where nearly all elements in the schema are optional and custom elements can be included. Because of this, a stricter set of requirements for the HPXML file have been developed for purposes of running an Energy Rating Index calculation.

HPXML files submitted to OpenStudio-ERI undergo a two step validation process:

1. Validation against the HPXML Schema

The HPXML XSD Schema can be found at hpxml-measures/HPXMLtoOpenStudio/resources/hpxml_schema/HPXML.xsd. XSD Schemas are used to validate what elements/attributes/enumerations are available, data types for elements/attributes, the number/order of children elements, etc.

2. Validation using Schematron

The Schematron document for the ERI use case can be found at rulesets/resources/301validator.xml. Schematron is a rule-based validation language, expressed in XML using XPath expressions, for validating the presence or absence of inputs in XML files. As opposed to an XSD Schema, a Schematron document validates constraints and requirements based on conditionals and other logical statements. For example, if an element is specified with a particular value, the applicable enumerations of another element may change.

Important

Usage of both validation approaches (XSD and Schematron) is recommended for developers actively working on creating HPXML files for Energy Rating Index calculations:

• Validation against XSD for general correctness and usage of HPXML

• Validation against Schematron for understanding XML document requirements specific to running ERI calculations

HPXML Software Info

High-level software inputs are entered in /HPXML/SoftwareInfo.

HPXML Calculations

The OpenStudio-ERI calculation(s) to be performed are entered in /HPXML/SoftwareInfo/extension.

Element	Type	Units	Constraints	Required	Default	Description
ERICalculation/Version	string		See [1]	No	<none>	Version to perform ERI calculation
CO2IndexCalculation/Version	string		See [2]	No	<none>	Version to perform CO2e Index calculation
IECCERICalculation/Version	string		See [3]	No	<none>	Version to perform IECC ERI calculation
EnergyStarCalculation/Version	string		See [4]	No	<none>	Version to perform ENERGY STAR ERI calculation
ZERHCalculation/Version	string		See [5]	No	<none>	Version to perform DOE ZERH ERI calculation

[1]

ERICalculation/Version choices are “latest”, “2019ABCD”, “2019ABC”, “2019AB”, “2019A”, “2019”, “2014AEG”, “2014AE”, “2014A”, or “2014”. For example, a value of “2019AB” tells the workflow to use ANSI/RESNET/ICC© 301-2019 with both Addendum A and Addendum B included. A value of “latest” can be used to always point to the latest version available.

[2]

CO2IndexCalculation/Version choices are “latest” and “2019ABCD”. A value of “latest” can be used to always point to the latest version available. If both CO2IndexCalculation/Version and ERICalculation/Version are provided, they must use the same version.

[3]

IECCERICalculation/Version choices are “2021”, “2018”, or “2015”.

[4]

EnergyStarCalculation/Version choices are “SF_National_3.2”, “SF_National_3.1”, “SF_National_3.0”, “SF_Pacific_3.0”, “SF_Florida_3.1”, “SF_OregonWashington_3.2”, “MF_National_1.2”, “MF_National_1.1”, “MF_National_1.0”, or “MF_OregonWashington_1.2”.

[5]

ZERHCalculation/Version choices are “SF_2.0”, “MF_2.0” or “1.0”.

Warning

For the IECC ERI compliance calculation, OpenStudio-ERI does not perform additional compliance checks beyond calculating the ERI. For example, it does not check the building thermal envelope (2021 IECC, Section R406.3). It is the software tool’s responsibility to perform these additional steps. It does impose renewable energy limits (2021 IECC, Section R406.4), as applicable.

Warning

For the ENERGY STAR and Zero Energy Ready Home ERI calculation, OpenStudio-ERI does not perform additional compliance checks beyond comparing the ERI to the ENERGY STAR and Zero Energy Ready Home ERI Target. For example, it does not check that the home meets all ENERGY STAR and Zero Energy Ready Home Mandatory Requirements. It is the software tool’s responsibility to perform these additional steps.

HPXML Building Site

Site information is entered in /HPXML/Building/Site.

Element	Type	Units	Constraints	Required	Default	Description
Address/StateCode	string		See [6]	Yes		State/territory where the home is located
Address/ZipCode	string		See [7]	Yes		ZIP Code where the home is located [8]

[6]

For ENERGY STAR calculations, allowed StateCode choices depend on the ENERGY STAR version:

- National: <anything>

- Pacific: HI, GU, MP

- Florida: FL

- OregonWashington: OR, WA

[7]

ZipCode can be defined as the standard 5 number postal code, or it can have the additional 4 number code separated by a hyphen.

[8]

ZipCode is only currently used to look up the eGrid subregion (see rulesets/data/egrid/ZIP_mappings.csv) and Cambium region (see rulesets/data/cambium/ZIP_mappings.csv) for emissions calculations and the CO2e Index.

HPXML Building Summary

High-level building summary information is entered in /HPXML/Building/BuildingDetails/BuildingSummary.

HPXML Building Fuels

Each fuel type available to the building is entered in /HPXML/Building/BuildingDetails/BuildingSummary/Site/FuelTypesAvailable.

Element	Type	Units	Constraints	Required	Default	Description
Fuel	string		See [9]	Yes		Fuel name

[9]

Fuel choices can be found at the HPXML Toolbox website.

Note

The provided fuels are used to determine whether the home has access to natural gas or fossil fuel delivery (specified by any value other than “electricity”). This information may be used for determining the heating system, as specified by the ERI 301 Standard.

HPXML Building Construction

Building construction is entered in /HPXML/Building/BuildingDetails/BuildingSummary/BuildingConstruction.

Element	Type	Units	Constraints	Required	Default	Notes
ResidentialFacilityType	string		See [10]	Yes		Type of dwelling unit
NumberofConditionedFloors	double		> 0	Yes		Number of conditioned floors (including a basement)
NumberofConditionedFloorsAboveGrade	double		> 0, <= NumberofConditionedFloors	Yes		Number of conditioned floors above grade (including a walkout basement)
NumberofBedrooms	integer		> 0	Yes		Number of bedrooms
ConditionedFloorArea	double	ft2	> 0	Yes		Floor area within conditioned space boundary

[10]

ResidentialFacilityType choices are “single-family detached”, “single-family attached”, or “apartment unit”. For ENERGY STAR, “single-family detached” may only be used for SF versions and “apartment unit” may only be used for MF versions; “single-family attached” may be used for all versions.

HPXML Weather Station

Weather information is entered in /HPXML/Building/BuildingDetails/ClimateandRiskZones/WeatherStation.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
Name	string			Yes		Name of weather station
extension/EPWFilePath	string			Yes		Path to the EnergyPlus weather file (EPW) [11]

[11]

A full set of U.S. TMY3 weather files can be downloaded here.

HPXML Climate Zones

One or more IECC climate zones are each entered as a /HPXML/Building/BuildingDetails/ClimateandRiskZones/ClimateZoneIECC.

Element	Type	Units	Constraints	Required	Default	Description
Year	integer		See [12]	Yes [13]		IECC year
ClimateZone	string		See [14]	Yes		IECC zone

[12]

Year choices are 2003, 2006, 2009, 2012, 2015, 2018, or 2021.

[13]

The IECC climate zone for 2006 is always required. Additional climate zones of other years may be required based on the programs selected for calculation:

- IECC ERI 2015: 2015

- IECC ERI 2018: 2018

- IECC ERI 2021: 2021

- ENERGY STAR SFNH National v3.2: 2021

- ENERGY STAR MFNC National v1.2: 2021

- ZERH 1.0: 2015

- ZERH SF/MF 2.0: 2021

[14]

ClimateZone choices are “1A”, “1B”, “1C”, “2A”, “2B”, “2C”, “3A”, “3B”, “3C”, “4A”, “4B”, “4C”, “5A”, “5B”, “5C”, “6A”, “6B”, “6C”, “7”, or “8”.

HPXML Enclosure

The dwelling unit’s enclosure is entered in /HPXML/Building/BuildingDetails/Enclosure.

All surfaces that bound different space types of the dwelling unit (i.e., not just thermal boundary surfaces) must be specified in the HPXML file. For example, an attached garage would generally be defined by walls adjacent to conditioned space, walls adjacent to outdoors, a slab, and a roof or ceiling. For software tools that do not collect sufficient inputs for every required surface, the software developers will need to make assumptions about these surfaces or collect additional input.

Interior partition surfaces (e.g., walls between rooms inside conditioned space, or the floor between two conditioned stories) can be excluded.

For single-family attached (SFA) or multifamily (MF) buildings, surfaces between unconditioned space and the neighboring unit’s same unconditioned space should set InteriorAdjacentTo and ExteriorAdjacentTo to the same value. For example, a foundation wall between the unit’s vented crawlspace and the neighboring unit’s vented crawlspace would use InteriorAdjacentTo="crawlspace - vented" and ExteriorAdjacentTo="crawlspace - vented".

Warning

It is the software tool’s responsibility to provide the appropriate building surfaces. While some error-checking is in place, it is not possible to know whether some surfaces are incorrectly missing.

Also note that wall and roof surfaces do not require an azimuth to be specified. Rather, only the windows/skylights themselves require an azimuth. Thus, software tools can choose to use a single wall (or roof) surface to represent multiple wall (or roof) surfaces for the entire building if all their other properties (construction type, interior/exterior adjacency, etc.) are identical.

HPXML Air Infiltration

Building air leakage is entered in /HPXML/Building/BuildingDetails/Enclosure/AirInfiltration/AirInfiltrationMeasurement.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
InfiltrationVolume	double	ft3	> 0	Yes		Volume associated with infiltration measurement
InfiltrationHeight	double	ft	> 0	No	See [15]	Height associated with infiltration measurement [16]

[15]

If InfiltrationHeight not provided, it is inferred from other inputs (e.g., conditioned floor area, number of conditioned floors above-grade, above-grade foundation wall height, etc.).

[16]

InfiltrationHeight is defined as the vertical distance between the lowest and highest above-grade points within the pressure boundary, per ASHRAE 62.2.

In addition, one of the following air leakage types must also be defined:

• ACH or CFM

• Natural ACH or CFM

• Effective Leakage Area

ACH or CFM

If entering air leakage as ACH or CFM at a user-specific pressure, additional information is entered in /HPXML/Building/BuildingDetails/Enclosure/AirInfiltration/AirInfiltrationMeasurement. For example, ACH50 (ACH at 50 Pascals) is a commonly obtained value from a blower door measurement.

Element	Type	Units	Constraints	Required	Default	Notes
BuildingAirLeakage/UnitofMeasure	string		See [17]	Yes		Units for air leakage
HousePressure	double	Pa	> 0	Yes		House pressure with respect to outside [18]
BuildingAirLeakage/AirLeakage	double		> 0	Yes		Value for air leakage [19]

[17]

UnitofMeasure choices are “ACH” or “CFM”.

[18]

HousePressure typical value is 50 Pa.

[19]

For attached dwelling units, BuildingAirLeakage/AirLeakage should be a compartmentalization test value and not adjusted by the Aext reduction factor specified in ANSI/RESNET/ICC 301. OpenStudio-ERI will automatically calculate and apply the Aext adjustment (and the Aext value can be found in, e.g., the ERIRatedHome.xml output file). Note that all attached surfaces, even adiabatic surfaces, must be defined in the HPXML file.

Natural ACH or CFM

If entering air leakage as natural ACH or CFM, additional information is entered in /HPXML/Building/BuildingDetails/Enclosure/AirInfiltration/AirInfiltrationMeasurement. Natural ACH or CFM represents the annual average infiltration that a building will see.

Element	Type	Units	Constraints	Required	Default	Notes
BuildingAirLeakage/UnitofMeasure	string		See [20]	Yes		Units for air leakage
BuildingAirLeakage/AirLeakage	double		> 0	Yes		Value for air leakage [21]

[20]

UnitofMeasure choices are “ACHnatural” or “CFMnatural”.

[21]

For attached dwelling units, BuildingAirLeakage/AirLeakage should not be adjusted by the Aext reduction factor specified in ANSI/RESNET/ICC 301. OpenStudio-ERI will automatically calculate and apply the Aext adjustment (and the Aext value can be found in, e.g., the ERIRatedHome.xml output file).

Effective Leakage Area

If entering air leakage as Effective Leakage Area (ELA), additional information is entered in /HPXML/Building/BuildingDetails/Enclosure/AirInfiltration/AirInfiltrationMeasurement. Effective Leakage Area is defined as the area of a special nozzle-shaped hole (similar to the inlet of a blower door fan) that would leak the same amount of air as the building does at a pressure difference of 4 Pascals. Note that ELA is different than Equivalent Leakage Area (EqLA), which involves a sharp-edged hole at a pressure difference of 10 Pascals.

Element	Type	Units	Constraints	Required	Default	Notes
EffectiveLeakageArea	double	sq. in.	>= 0	Yes		Effective leakage area value [22]

[22]

For attached dwelling units, BuildingAirLeakage/AirLeakage should not be adjusted by the Aext reduction factor specified in ANSI/RESNET/ICC 301. OpenStudio-ERI will automatically calculate and apply the Aext adjustment (and the Aext value can be found in, e.g., the ERIRatedHome.xml output file).

HPXML Attics

If the dwelling unit has an unvented attic, whether it is within the infiltration volume is entered in /HPXML/Building/BuildingDetails/Enclosure/Attics/Attic[AtticType/Attic[Vented="false"]].

Element	Type	Units	Constraints	Required	Default	Notes
WithinInfiltrationVolume	boolean			Yes		In accordance with ANSI/RESNET/ICC Standard 380

If the dwelling unit has a vented attic, attic ventilation information can be optionally entered in /HPXML/Building/BuildingDetails/Enclosure/Attics/Attic[AtticType/Attic[Vented="true"]]/VentilationRate.

Element	Type	Units	Constraints	Required	Default	Notes
UnitofMeasure	string		See [23]	No	SLA	Units for ventilation rate
Value	double		> 0	No	1/300	Value for ventilation rate

[23]

UnitofMeasure choices are “SLA” (specific leakage area) or “ACHnatural” (natural air changes per hour).

HPXML Foundations

If the dwelling unit has an unconditioned basement, whether it is within the infiltration volume is entered in Enclosure/Foundations/Foundation/FoundationType/Basement[Conditioned='false'].

Element	Type	Units	Constraints	Required	Default	Notes
WithinInfiltrationVolume	boolean			Yes		In accordance with ANSI/RESNET/ICC Standard 380

If the dwelling unit has an unvented crawlspace, whether it is within the infiltration volume is entered in Enclosure/Foundations/Foundation/FoundationType/Crawlspace[Vented='false'].

Element	Type	Units	Constraints	Required	Default	Notes
WithinInfiltrationVolume	boolean			Yes		In accordance with ANSI/RESNET/ICC Standard 380

If the dwelling unit has a vented crawlspace, crawlspace ventilation information can be optionally entered in /HPXML/Building/BuildingDetails/Enclosure/Foundations/Foundation[FoundationType/Crawlspace[Vented="true"]]/VentilationRate.

Element	Type	Units	Constraints	Required	Default	Notes
UnitofMeasure	string		See [24]	No	SLA	Units for ventilation rate
Value	double		> 0	No	1/150	Value for ventilation rate

[24]

UnitofMeasure only choice is “SLA” (specific leakage area).

HPXML Roofs

Each pitched or flat roof surface that is exposed to ambient conditions is entered as an /HPXML/Building/BuildingDetails/Enclosure/Roofs/Roof.

For a multifamily building where the dwelling unit has another dwelling unit above it, the surface between the two dwelling units should be considered a Floor and not a Roof.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
InteriorAdjacentTo	string		See [25]	Yes		Interior adjacent space type
Area	double	ft2	> 0	Yes		Gross area (including skylights)
Azimuth	integer	deg	0 - 359	No	See [26]	Azimuth (clockwise from North)
SolarAbsorptance	double		0 - 1	Yes		Solar absorptance
Emittance	double		0 - 1	Yes		Emittance
Pitch	integer	?:12	>= 0	Yes		Pitch
RadiantBarrier	boolean			Yes		Presence of radiant barrier
RadiantBarrierGrade	integer		1 - 3	See [27]		Radiant barrier installation grade
Insulation/SystemIdentifier	id			Yes		Unique identifier
Insulation/AssemblyEffectiveRValue	double	F-ft2-hr/Btu	> 0	Yes		Assembly R-value [28]

[25]

InteriorAdjacentTo choices are “attic - vented”, “attic - unvented”, “conditioned space”, or “garage”. See HPXML Locations for descriptions.

[26]

If Azimuth not provided, and it’s a pitched roof, modeled as four surfaces of equal area facing every direction. Azimuth is irrelevant for flat roofs.

[27]

RadiantBarrierGrade only required if RadiantBarrier is provided.

[28]

AssemblyEffectiveRValue includes all material layers, interior/exterior air films, and insulation installation grade.

HPXML Rim Joists

Each rim joist surface (i.e., the perimeter of floor joists typically found between stories of a building or on top of a foundation wall) is entered as an /HPXML/Building/BuildingDetails/Enclosure/RimJoists/RimJoist.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
ExteriorAdjacentTo	string		See [29]	Yes		Exterior adjacent space type
InteriorAdjacentTo	string		See [30]	Yes		Interior adjacent space type
Area	double	ft2	> 0	Yes		Gross area
Azimuth	integer	deg	0 - 359	No	See [31]	Azimuth (clockwise from North)
SolarAbsorptance	double		0 - 1	See [32]		Solar absorptance
Emittance	double		0 - 1	See [33]		Emittance
Insulation/SystemIdentifier	id			Yes		Unique identifier
Insulation/AssemblyEffectiveRValue	double	F-ft2-hr/Btu	> 0	Yes		Assembly R-value [34]

[29]

ExteriorAdjacentTo choices are “outside”, “attic - vented”, “attic - unvented”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[30]

InteriorAdjacentTo choices are “conditioned space”, “attic - vented”, “attic - unvented”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, or “garage”. See HPXML Locations for descriptions.

[31]

If Azimuth not provided, and it’s an exterior rim joist, modeled as four surfaces of equal area facing every direction. Azimuth is irrelevant for interior rim joists.

[32]

SolarAbsorptance only required for exterior rim joists (i.e., ExteriorAdjacentTo=outside).

[33]

Emittance only required for exterior rim joists (i.e., ExteriorAdjacentTo=outside).

[34]

AssemblyEffectiveRValue includes all material layers, interior/exterior air films, and insulation installation grade.

HPXML Walls

Each wall surface is entered as an /HPXML/Building/BuildingDetails/Enclosure/Walls/Wall.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
ExteriorAdjacentTo	string		See [35]	Yes		Exterior adjacent space type
InteriorAdjacentTo	string		See [36]	Yes		Interior adjacent space type
WallType	element		1 [37]	Yes		Wall type (for thermal mass)
Area	double	ft2	> 0	Yes		Gross area (including doors/windows)
Azimuth	integer	deg	0 - 359	No	See [38]	Azimuth (clockwise from North)
SolarAbsorptance	double		0 - 1	See [39]		Solar absorptance
Emittance	double		0 - 1	See [40]		Emittance
Insulation/SystemIdentifier	id			Yes		Unique identifier
Insulation/AssemblyEffectiveRValue	double	F-ft2-hr/Btu	> 0	Yes		Assembly R-value [41]

[35]

ExteriorAdjacentTo choices are “outside”, “attic - vented”, “attic - unvented”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[36]

InteriorAdjacentTo choices are “conditioned space”, “attic - vented”, “attic - unvented”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, or “garage”. See HPXML Locations for descriptions.

[37]

WallType child element choices are WoodStud, DoubleWoodStud, ConcreteMasonryUnit, StructuralInsulatedPanel, InsulatedConcreteForms, SteelFrame, SolidConcrete, StructuralBrick, StrawBale, Stone, LogWall, or Adobe.

[38]

If Azimuth not provided, and it’s an exterior wall, modeled as four surfaces of equal area facing every direction. Azimuth is irrelevant for interior walls (e.g., between conditioned space and garage).

[39]

SolarAbsorptance only required for exterior walls (i.e., ExteriorAdjacentTo=outside).

[40]

Emittance only required for exterior walls (i.e., ExteriorAdjacentTo=outside).

[41]

AssemblyEffectiveRValue includes all material layers, interior/exterior air films, and insulation installation grade.

HPXML Foundation Walls

Each foundation wall surface is entered as an /HPXML/Building/BuildingDetails/Enclosure/FoundationWalls/FoundationWall. Any wall surface in contact with the ground is considered a foundation wall.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
ExteriorAdjacentTo	string		See [42]	Yes		Exterior adjacent space type [43]
InteriorAdjacentTo	string		See [44]	Yes		Interior adjacent space type
Type	string		See [45]	No	solid concrete	Type of material
Height	double	ft	> 0	Yes		Total height
Area	double	ft2	> 0	Yes		Gross area (including doors/windows)
Azimuth	integer	deg	0 - 359	No	See [46]	Azimuth (clockwise from North)
Thickness	double	in	> 0	Yes		Thickness excluding interior framing
DepthBelowGrade	double	ft	0 - Height	Yes		Depth below grade [47]
Insulation/SystemIdentifier	id			Yes		Unique identifier
Insulation/Layer[InstallationType="continuous - interior"]	element		0 - 1	See [48]		Interior insulation layer
Insulation/Layer[InstallationType="continuous - exterior"]	element		0 - 1	See [49]		Exterior insulation layer
Insulation/AssemblyEffectiveRValue	double	F-ft2-hr/Btu	> 0	See [50]		Assembly R-value [51]

[42]

ExteriorAdjacentTo choices are “ground”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[43]

InteriorAdjacentTo choices are “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, or “garage”. See HPXML Locations for descriptions.

[44]

Interior foundation walls (e.g., between basement and crawlspace) should not use “ground” even if the foundation wall has some contact with the ground due to the difference in below-grade depths of the two adjacent spaces.

[45]

Type choices are “solid concrete”, “concrete block”, “concrete block foam core”, “concrete block vermiculite core”, “concrete block perlite core”, “concrete block solid core”, “double brick”, or “wood”.

[46]

If Azimuth not provided, and it’s an exterior foundation wall, modeled as four surfaces of equal area facing every direction. Azimuth is irrelevant for interior foundation walls (e.g., between basement and garage).

[47]

For exterior foundation walls, depth below grade is relative to the ground plane. For interior foundation walls, depth below grade is the vertical span of foundation wall in contact with the ground. For example, an interior foundation wall between an 8 ft conditioned basement and a 3 ft crawlspace has a height of 8 ft and a depth below grade of 5 ft. Alternatively, an interior foundation wall between an 8 ft conditioned basement and an 8 ft unconditioned basement has a height of 8 ft and a depth below grade of 0 ft.

[48]

Layer[InstallationType=”continuous - interior”] only required if AssemblyEffectiveRValue is not provided.

[49]

Layer[InstallationType=”continuous - exterior”] only required if AssemblyEffectiveRValue is not provided.

[50]

AssemblyEffectiveRValue only required if Layer elements are not provided.

[51]

AssemblyEffectiveRValue includes all material layers, interior air film, and insulation installation grade. R-value should not include exterior air film (for any above-grade exposure) or any soil thermal resistance.

If insulation layers are provided, additional information is entered in each FoundationWall/Insulation/Layer.

Element	Type	Units	Constraints	Required	Default	Notes
NominalRValue	double	F-ft2-hr/Btu	>= 0	Yes		R-value of the foundation wall insulation; use zero if no insulation
DistanceToTopOfInsulation	double	ft	>= 0	Yes		Vertical distance from top of foundation wall to top of insulation
DistanceToBottomOfInsulation	double	ft	See [52]	Yes		Vertical distance from top of foundation wall to bottom of insulation

[52]

When NominalRValue is non-zero, DistanceToBottomOfInsulation must be greater than DistanceToTopOfInsulation and less than or equal to FoundationWall/Height.

HPXML Floors

Each floor/ceiling surface that is not in contact with the ground (Slab) nor adjacent to ambient conditions above (Roof) is entered as an /HPXML/Building/BuildingDetails/Enclosure/Floors/Floor.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
ExteriorAdjacentTo	string		See [53]	Yes		Exterior adjacent space type
InteriorAdjacentTo	string		See [54]	Yes		Interior adjacent space type
FloorType	element		1 [55]	Yes		Floor type (for thermal mass)
Area	double	ft2	> 0	Yes		Gross area
Insulation/SystemIdentifier	id			Yes		Unique identifier
Insulation/AssemblyEffectiveRValue	double	F-ft2-hr/Btu	> 0	Yes		Assembly R-value [56]

[53]

ExteriorAdjacentTo choices are “outside”, “attic - vented”, “attic - unvented”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[54]

InteriorAdjacentTo choices are “conditioned space”, “attic - vented”, “attic - unvented”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, or “garage”. See HPXML Locations for descriptions.

[55]

FloorType child element choices are WoodFrame, StructuralInsulatedPanel, SteelFrame, or SolidConcrete.

[56]

AssemblyEffectiveRValue includes all material layers, interior/exterior air films, and insulation installation grade.

For floors adjacent to “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”, additional information is entered in Floor.

Element	Type	Units	Constraints	Required	Default	Notes
FloorOrCeiling	string		See [57]	Yes		Specifies whether a floor or ceiling from the perspective of the conditioned space

[57]

FloorOrCeiling choices are “floor” or “ceiling”.

HPXML Slabs

Each space type that borders the ground (i.e., basement, crawlspace, garage, and slab-on-grade foundation) should have a slab entered as an /HPXML/Building/BuildingDetails/Enclosure/Slabs/Slab.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
InteriorAdjacentTo	string		See [58]	Yes		Interior adjacent space type
Area	double	ft2	> 0	Yes		Gross area
Thickness	double	in	>= 0	Yes		Thickness [59]
ExposedPerimeter	double	ft	>= 0	Yes		Perimeter exposed to ambient conditions [60]
DepthBelowGrade	double	ft	>= 0	No	See [61]	Depth from the top of the slab surface to grade
PerimeterInsulation/SystemIdentifier	id			Yes		Unique identifier
PerimeterInsulation/Layer/NominalRValue	double	F-ft2-hr/Btu	>= 0	Yes		R-value of vertical insulation
PerimeterInsulation/Layer/InsulationDepth	double	ft	>= 0	Yes		Depth from top of slab to bottom of vertical insulation
UnderSlabInsulation/SystemIdentifier	id			Yes		Unique identifier
UnderSlabInsulation/Layer/NominalRValue	double	F-ft2-hr/Btu	>= 0	Yes		R-value of horizontal insulation
UnderSlabInsulation/Layer/InsulationWidth	double	ft	>= 0	See [62]		Width from slab edge inward of horizontal insulation
UnderSlabInsulation/Layer/InsulationSpansEntireSlab	boolean			See [63]		Whether horizontal insulation spans entire slab
extension/CarpetFraction	double	frac	0 - 1	Yes		Fraction of slab covered by carpet
extension/CarpetRValue	double	F-ft2-hr/Btu	>= 0	Yes		Carpet R-value

[58]

InteriorAdjacentTo choices are “conditioned space”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - vented”, “crawlspace - unvented”, or “garage”. See HPXML Locations for descriptions.

[59]

For a crawlspace with a dirt floor, enter a thickness of zero.

[60]

ExposedPerimeter includes any slab length that falls along the perimeter of the building’s footprint (i.e., is exposed to ambient conditions). So a basement slab edge adjacent to a garage or crawlspace, for example, should not be included.

[61]

If DepthBelowGrade not provided, defaults to zero for foundation types without walls. For foundation types with walls, DepthBelowGrade is ignored as the slab’s position relative to grade is determined by the FoundationWall/DepthBelowGrade value(s).

[62]

InsulationWidth only required if InsulationSpansEntireSlab=true is not provided.

[63]

InsulationSpansEntireSlab=true only required if InsulationWidth is not provided.

HPXML Windows

Each window or glass door area is entered as an /HPXML/Building/BuildingDetails/Enclosure/Windows/Window.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
Area	double	ft2	> 0	Yes		Total area
Azimuth	integer	deg	0 - 359	Yes		Azimuth (clockwise from North)
UFactor	double	Btu/F-ft2-hr	> 0	Yes		Full-assembly NFRC U-factor
SHGC	double		0 - 1	Yes		Full-assembly NFRC solar heat gain coefficient
Overhangs	element		0 - 1	No	<none>	Presence of overhangs (including roof eaves)
FractionOperable	double	frac	0 - 1	Yes		Operable fraction [64]
PerformanceClass	string		See [65]	No	residential	Performance class
AttachedToWall	idref		See [66]	Yes		ID of attached wall

[64]

FractionOperable reflects whether the windows are operable (can be opened), not how they are used by the occupants. If a Window represents a single window, the value should be 0 or 1. If a Window represents multiple windows, the value is calculated as the total window area for any operable windows divided by the total window area.

[65]

PerformanceClass choices are “residential” (e.g., Class R) or “architectural” (e.g., Class AW).

[66]

AttachedToWall must reference a Wall or FoundationWall.

If overhangs are specified, additional information is entered in Overhangs.

Element	Type	Units	Constraints	Required	Default	Notes
Depth	double	ft	>= 0	Yes		Depth of overhang
DistanceToTopOfWindow	double	ft	>= 0	Yes		Vertical distance from overhang to top of window
DistanceToBottomOfWindow	double	ft	See [67]	Yes		Vertical distance from overhang to bottom of window [68]

[67]

The difference between DistanceToBottomOfWindow and DistanceToTopOfWindow defines the height of the window.

[68]

When Depth is non-zero, DistanceToBottomOfWindow must be greater than DistanceToTopOfWindow.

HPXML Skylights

Each skylight is entered as an /HPXML/Building/BuildingDetails/Enclosure/Skylights/Skylight.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
Area	double	ft2	> 0	Yes		Total area
Azimuth	integer	deg	0 - 359	Yes		Azimuth (clockwise from North)
UFactor	double	Btu/F-ft2-hr	> 0	Yes		Full-assembly NFRC U-factor
SHGC	double		0 - 1	Yes		Full-assembly NFRC solar heat gain coefficient
AttachedToRoof	idref		See [69]	Yes		ID of attached roof

[69]

AttachedToRoof must reference a Roof.

HPXML Doors

Each opaque door is entered as an /HPXML/Building/BuildingDetails/Enclosure/Doors/Door.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
AttachedToWall	idref		See [70]	Yes		ID of attached wall
Area	double	ft2	> 0	Yes		Total area
Azimuth	integer	deg	0 - 359	Yes		Azimuth (clockwise from North)
RValue	double	F-ft2-hr/Btu	> 0	Yes		R-value

[70]

AttachedToWall must reference a Wall or FoundationWall.

HPXML Systems

The dwelling unit’s systems are entered in /HPXML/Building/BuildingDetails/Systems.

HPXML Heating Systems

Each heating system (other than a heat pump) is entered as an /HPXML/Building/BuildingDetails/Systems/HVAC/HVACPlant/HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
HeatingSystemType	element		1 [71]	Yes		Type of heating system
HeatingSystemFuel	string		See [72]	Yes		Fuel type
HeatingCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity
FractionHeatLoadServed	double	frac	0 - 1 [73]	Yes		Fraction of heating load served

[71]

HeatingSystemType child element choices are ElectricResistance, Furnace, WallFurnace, FloorFurnace, Boiler, Stove, SpaceHeater, or Fireplace.

[72]

HeatingSystemFuel choices are “natural gas”, “fuel oil”, “propane”, “electricity”, “wood”, or “wood pellets”. For ElectricResistance, “electricity” is required.

[73]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

Electric Resistance

If electric resistance heating is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
AnnualHeatingEfficiency[Units="Percent"]/Value	double	frac	0 - 1	Yes		Efficiency

Furnace

If a furnace is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [74]	Yes		ID of attached distribution system
AnnualHeatingEfficiency[Units="AFUE"]/Value	double	frac	0 - 1	Yes		Rated efficiency
extension/FanPowerWattsPerCFM	double	W/cfm	>= 0 [75]	Yes		Blower fan efficiency at maximum fan speed [76]
extension/AirflowDefectRatio	double	frac	-0.9 - 9	Yes		Deviation between design/installed airflows [77]

[74]

HVACDistribution type must be AirDistribution (type: “regular velocity” or “gravity”) or DSE.

[75]

If there is a cooling system attached to the DistributionSystem, the heating and cooling systems cannot have different values for FanPowerWattsPerCFM.

[76]

If the fan power is not measured, a value of 0.58 W/cfm should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[77]

AirflowDefectRatio is defined as (InstalledAirflow - DesignAirflow) / DesignAirflow; a value of zero means no airflow defect. A non-zero airflow defect can only be applied for systems attached to a distribution system. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the airflow rate is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

Warning

HVAC installation quality should be provided per the conditions specified in ANSI/RESNET/ACCA 310. OS-ERI does not check that, for example, the total duct leakage requirement has been met or that a Grade I/II input is appropriate per the ANSI 310 process flow; that is currently the responsibility of the software developer.

Wall/Floor Furnace

If a wall furnace or floor furnace is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
AnnualHeatingEfficiency[Units="AFUE"]/Value	double	frac	0 - 1	Yes		Rated efficiency
extension/FanPowerWatts	double	W	>= 0	No	0	Fan power

Boiler

If a boiler is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
IsSharedSystem	boolean			Yes		Whether it serves multiple dwelling units
DistributionSystem	idref		See [78]	Yes		ID of attached distribution system
AnnualHeatingEfficiency[Units="AFUE"]/Value	double	frac	0 - 1	Yes		Rated efficiency

[78]

For in-unit boilers, HVACDistribution type must be HydronicDistribution (type: “radiator”, “baseboard”, “radiant floor”, or “radiant ceiling”) or DSE. For shared boilers, HVACDistribution type must be HydronicDistribution (type: “radiator”, “baseboard”, “radiant floor”, “radiant ceiling”, or “water loop”) or AirDistribution (type: “fan coil”). If the shared boiler has “water loop” distribution, a Water-Loop-to-Air Heat Pump must also be specified.

Note

The choice of hydronic distribution type (radiator vs baseboard vs radiant panels) does not affect simulation results; it is currently only used to know if there’s an attached water loop heat pump or not.

If an in-unit boiler if specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
ElectricAuxiliaryEnergy	double	kWh/yr	>= 0	No	See [79]	Electric auxiliary energy

[79]

If ElectricAuxiliaryEnergy not provided, defaults as follows:

- Oil boiler: 330 kWh/yr

- Gas boiler: 170 kWh/yr

If instead a shared boiler is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
NumberofUnitsServed	integer		> 1	Yes		Number of dwelling units served
extension/SharedLoopWatts	double	W	>= 0	Yes		Shared loop power
extension/SharedLoopMotorEfficiency	double	frac	0 - 1	No	0.85	Shared loop motor efficiency
extension/FanCoilWatts	double	W	>= 0	See [80]		Fan coil power

[80]

FanCoilWatts only required if boiler connected to fan coil.

Stove

If a stove is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
AnnualHeatingEfficiency[Units="Percent"]/Value	double	frac	0 - 1	Yes		Efficiency
extension/FanPowerWatts	double	W	>= 0	No	40	Fan power

Space Heater

If a space heater (portable or fixed) is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
AnnualHeatingEfficiency[Units="Percent"]/Value	double	frac	0 - 1	Yes		Efficiency
extension/FanPowerWatts	double	W	>= 0	No	0	Fan power

Fireplace

If a fireplace is specified, additional information is entered in HeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
AnnualHeatingEfficiency[Units="Percent"]/Value	double	frac	0 - 1	Yes		Efficiency
extension/FanPowerWatts	double	W	>= 0	No	0	Fan power

HPXML Cooling Systems

Each cooling system (other than a heat pump) is entered as an /HPXML/Building/BuildingDetails/Systems/HVAC/HVACPlant/CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
CoolingSystemType	string		See [81]	Yes		Type of cooling system
CoolingSystemFuel	string		See [82]	Yes		Fuel type
FractionCoolLoadServed	double	frac	0 - 1 [83]	Yes		Fraction of cooling load served

[81]

CoolingSystemType choices are “central air conditioner”, “room air conditioner”, “evaporative cooler”, “mini-split”, “chiller”, “cooling tower”, or “packaged terminal air conditioner”.

[82]

CoolingSystemFuel only choice is “electricity”.

[83]

The sum of all FractionCoolLoadServed (across all HVAC systems) must be less than or equal to 1.

Central Air Conditioner

If a central air conditioner is specified, additional information is entered in CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [84]	Yes		ID of attached distribution system
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
CompressorType	string		See [85]	No	See [86]	Type of compressor
AnnualCoolingEfficiency[Units="SEER" or Units="SEER2"]/Value	double	Btu/Wh	> 0	Yes		Rated efficiency [87]
SensibleHeatFraction	double	frac	0 - 1	No	See [88]	Sensible heat fraction
extension/FanPowerWattsPerCFM	double	W/cfm	>= 0 [89]	Yes		Blower fan efficiency at maximum fan speed [90]
extension/AirflowDefectRatio	double	frac	-0.9 - 9	Yes		Deviation between design/installed airflows [91]
extension/ChargeDefectRatio	double	frac	-0.25, 0, 0.25	Yes		Deviation between design/installed refrigerant charges [92]

[84]

HVACDistribution type must be AirDistribution (type: “regular velocity”) or DSE.

[85]

CompressorType choices are “single stage”, “two stage”, or “variable speed”.

[86]

If CompressorType not provided, defaults to “single stage” if SEER <= 15, else “two stage” if SEER <= 21, else “variable speed”.

[87]

If SEER2 provided, converted to SEER using ANSI/RESNET/ICC 301-2022 Addendum C, where SEER = SEER2 / 0.95 (assumed to be a split system). If not a split system, provide SEER using the appropriate conversion factor.

[88]

If SensibleHeatFraction not provided, defaults to 0.73 for single/two stage and 0.78 for variable speed.

[89]

If there is a heating system attached to the DistributionSystem, the heating and cooling systems cannot have different values for FanPowerWattsPerCFM.

[90]

If the fan power is not measured, a value of 0.58 W/cfm should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[91]

AirflowDefectRatio is defined as (InstalledAirflow - DesignAirflow) / DesignAirflow; a value of zero means no airflow defect. A non-zero airflow defect can only be applied for systems attached to a distribution system. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the airflow rate is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[92]

ChargeDefectRatio is defined as (InstalledCharge - DesignCharge) / DesignCharge; a value of zero means no refrigerant charge defect. A non-zero charge defect should typically only be applied for systems that are charged on site, not for systems that have pre-charged line sets. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the charge is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

Warning

HVAC installation quality should be provided per the conditions specified in ANSI/RESNET/ACCA 310. OS-ERI does not check that, for example, the total duct leakage requirement has been met or that a Grade I/II input is appropriate per the ANSI 310 process flow; that is currently the responsibility of the software developer.

Room Air Conditioner

If a room air conditioner is specified, additional information is entered in CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
AnnualCoolingEfficiency[Units="EER" or Units="CEER"]/Value	double	Btu/Wh	> 0	Yes		Rated efficiency
SensibleHeatFraction	double	frac	0 - 1	No	0.65	Sensible heat fraction
IntegratedHeatingSystemFuel	string		See [93]	No	<none>	Fuel type of integrated heater

[93]

IntegratedHeatingSystemFuel choices are “electricity”, “natural gas”, “fuel oil”, “propane”, “wood”, or “wood pellets”.

If the room air conditioner has integrated heating, additional information is entered in CoolingSystem. Note that a room air conditioner with reverse cycle heating should be entered as a heat pump; see Room Air Conditioner w/ Reverse Cycle.

Element	Type	Units	Constraints	Required	Default	Notes
IntegratedHeatingSystemCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity of integrated heater
IntegratedHeatingSystemAnnualEfficiency[Units="Percent"]/Value	double	frac	0 - 1	Yes		Efficiency of integrated heater
IntegratedHeatingSystemFractionHeatLoadServed	double	frac	0 - 1 [94]	Yes		Fraction of heating load served

[94]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

Packaged Terminal Air Conditioner

If a PTAC is specified, additional information is entered in CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
AnnualCoolingEfficiency[Units="EER" or Units="CEER"]/Value	double	Btu/Wh	> 0	Yes		Rated cooling efficiency
SensibleHeatFraction	double	frac	0 - 1	No	0.65	Sensible heat fraction
IntegratedHeatingSystemFuel	string		See [95]	No	<none>	Fuel type of integrated heater

[95]

IntegratedHeatingSystemFuel choices are “electricity”, “natural gas”, “fuel oil”, “propane”, “wood”, or “wood pellets”.

If the PTAC has integrated heating, additional information is entered in CoolingSystem. Note that a packaged terminal heat pump should be entered as a heat pump; see Packaged Terminal Heat Pump.

Element	Type	Units	Constraints	Required	Default	Notes
IntegratedHeatingSystemCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity of integrated heater
IntegratedHeatingSystemAnnualEfficiency[Units="Percent"]/Value	double	frac	0 - 1	Yes		Efficiency of integrated heater
IntegratedHeatingSystemFractionHeatLoadServed	double	frac	0 - 1 [96]	Yes		Fraction of heating load served

[96]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

Evaporative Cooler

If an evaporative cooler is specified, additional information is entered in CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [97]	No		ID of attached distribution system
CoolingCapacity	double	Btu/hr	>= 0	No	autosized	Cooling output capacity

[97]

If DistributionSystem provided, HVACDistribution type must be AirDistribution (type: “regular velocity”) or DSE.

Mini-Split Air Conditioner

If a mini-split air conditioner is specified, additional information is entered in CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [98]	No		ID of attached distribution system
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
CompressorType	string		See [99]	No	variable speed	Type of compressor
AnnualCoolingEfficiency[Units="SEER" or Units="SEER2"]/Value	double	Btu/Wh	> 0	Yes		Rated cooling efficiency [100]
SensibleHeatFraction	double	frac	0 - 1	No	0.73	Sensible heat fraction
extension/FanPowerWattsPerCFM	double	W/cfm	>= 0	Yes		Blower fan efficiency at maximum fan speed [101]
extension/AirflowDefectRatio	double	frac	-0.9 - 9	Yes		Deviation between design/installed airflows [102]
extension/ChargeDefectRatio	double	frac	-0.25, 0, 0.25	Yes		Deviation between design/installed refrigerant charges [103]

[98]

If provided, HVACDistribution type must be AirDistribution (type: “regular velocity”) or DSE.

[99]

CompressorType only choices is “variable speed” (i.e., they are assumed to be inverter driven).

[100]

If SEER2 provided, converted to SEER using ANSI/RESNET/ICC 301-2022 Addendum C, where SEER = SEER2 / 0.95 if ducted and SEER = SEER2 if ductless.

[101]

If the fan power is not measured, a value of 0.58 W/cfm should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[102]

AirflowDefectRatio is defined as (InstalledAirflow - DesignAirflow) / DesignAirflow; a value of zero means no airflow defect. A non-zero airflow defect can only be applied for systems attached to a distribution system. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the airflow rate is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[103]

ChargeDefectRatio is defined as (InstalledCharge - DesignCharge) / DesignCharge; a value of zero means no refrigerant charge defect. A non-zero charge defect should typically only be applied for systems that are charged on site, not for systems that have pre-charged line sets. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the charge is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

Warning

HVAC installation quality should be provided per the conditions specified in ANSI/RESNET/ACCA 310. OS-ERI does not check that, for example, the total duct leakage requirement has been met or that a Grade I/II input is appropriate per the ANSI 310 process flow; that is currently the responsibility of the software developer.

Chiller

If a chiller is specified, additional information is entered in CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [104]	Yes		ID of attached distribution system
IsSharedSystem	boolean		true	Yes		Whether it serves multiple dwelling units
NumberofUnitsServed	integer		> 1	Yes		Number of dwelling units served
CoolingCapacity	double	Btu/hr	>= 0	Yes		Total cooling output capacity
AnnualCoolingEfficiency[Units="kW/ton"]/Value	double	kW/ton	> 0	Yes		Rated efficiency
extension/SharedLoopWatts	double	W	>= 0	Yes		Pumping and fan power serving the system
extension/SharedLoopMotorEfficiency	double	frac	0 - 1	No	0.85	Shared loop motor efficiency
extension/FanCoilWatts	double	W	>= 0	See [105]		Fan coil power

[104]

HVACDistribution type must be HydronicDistribution (type: “radiator”, “baseboard”, “radiant floor”, “radiant ceiling”, or “water loop”) or AirDistribution (type: “fan coil”). If the chiller has “water loop” distribution, a Water-Loop-to-Air Heat Pump must also be specified.

[105]

FanCoilWatts only required if chiller connected to fan coil.

Cooling Tower

If a cooling tower is specified, additional information is entered in CoolingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [106]	Yes		ID of attached distribution system
IsSharedSystem	boolean		true	Yes		Whether it serves multiple dwelling units
NumberofUnitsServed	integer		> 1	Yes		Number of dwelling units served
extension/SharedLoopWatts	double	W	>= 0	Yes		Pumping and fan power serving the system
extension/SharedLoopMotorEfficiency	double	frac	0 - 1	No	0.85	Shared loop motor efficiency

[106]

HVACDistribution type must be HydronicDistribution (type: “water loop”). A Water-Loop-to-Air Heat Pump must also be specified.

HPXML Heat Pumps

Each heat pump is entered as an /HPXML/Building/BuildingDetails/Systems/HVAC/HVACPlant/HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
HeatPumpType	string		See [107]	Yes		Type of heat pump
HeatPumpFuel	string		See [108]	Yes		Fuel type
BackupType	string		See [109]	No	<none>	Type of backup heating

[107]

HeatPumpType choices are “air-to-air”, “mini-split”, “ground-to-air”, “water-loop-to-air”, “packaged terminal heat pump”, or “room air conditioner with reverse cycle”.

[108]

HeatPumpFuel only choice is “electricity”.

[109]

BackupType only choice is “integrated”.

Air-to-Air Heat Pump

If an air-to-air heat pump is specified, additional information is entered in HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [110]	Yes		ID of attached distribution system
HeatingCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity (excluding any backup heating)
HeatingCapacity17F	double	Btu/hr	>= 0, <= HeatingCapacity	No		Heating output capacity at 17F, if available
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
CompressorType	string		See [111]	No	See [112]	Type of compressor
CompressorLockoutTemperature	double	F		No	See [113]	Minimum outdoor temperature for compressor operation
CoolingSensibleHeatFraction	double	frac	0 - 1	No	See [114]	Sensible heat fraction
FractionHeatLoadServed	double	frac	0 - 1 [115]	Yes		Fraction of heating load served
FractionCoolLoadServed	double	frac	0 - 1 [116]	Yes		Fraction of cooling load served
AnnualCoolingEfficiency[Units="SEER" or Units="SEER2"]/Value	double	Btu/Wh	> 0	Yes		Rated cooling efficiency [117]
AnnualHeatingEfficiency[Units="HSPF" or Units="HSPF2"]/Value	double	Btu/Wh	> 0	Yes		Rated heating efficiency [118]
extension/HeatingCapacityRetention[Fraction | Temperature]	double	frac | F	>= 0, < 1 | <= 17	No	See [119]	Heating output capacity retention at cold temperature [120]
extension/FanPowerWattsPerCFM	double	W/cfm	>= 0	Yes		Blower fan efficiency at maximum fan speed [121]
extension/AirflowDefectRatio	double	frac	-0.9 - 9	Yes		Deviation between design/installed airflows [122]
extension/ChargeDefectRatio	double	frac	-0.25, 0, 0.25	Yes		Deviation between design/installed refrigerant charges [123]

[110]

HVACDistribution type must be AirDistribution (type: “regular velocity”) or DSE.

[111]

CompressorType choices are “single stage”, “two stage”, or “variable speed”.

[112]

If CompressorType not provided, defaults to “single stage” if SEER <= 15, else “two stage” if SEER <= 21, else “variable speed”.

[113]

If neither CompressorLockoutTemperature nor BackupHeatingSwitchoverTemperature provided, CompressorLockoutTemperature defaults to 25F if fossil fuel backup otherwise 0F.

[114]

If not provided, defaults to 0.73 for single/two stage and 0.78 for variable speed.

[115]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

[116]

The sum of all FractionCoolLoadServed (across all HVAC systems) must be less than or equal to 1.

[117]

If SEER2 provided, converted to SEER using ANSI/RESNET/ICC 301-2022 Addendum C, where SEER = SEER2 / 0.95 (assumed to be a split system). If not a split system, provide SEER using the appropriate conversion factor.

[118]

If HSPF2 provided, converted to HSPF using ANSI/RESNET/ICC 301-2022 Addendum C, where HSPF = HSPF2 / 0.85 (assumed to be a split system). If not a split system, provide SEER using the appropriate conversion factor.

[119]

If neither extension/HeatingCapacityRetention nor HeatingCapacity17F provided, heating capacity retention defaults based on CompressorType:

- single/two stage: 0.425 (at 5F)

- variable speed: 0.0461 * HSPF + 0.1594 (at 5F)

[120]

The extension/HeatingCapacityRetention input is a more flexible alternative to HeatingCapacity17F. Either input approach can be used, but not both.

[121]

If the fan power is not measured, a value of 0.58 W/cfm should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[122]

AirflowDefectRatio is defined as (InstalledAirflow - DesignAirflow) / DesignAirflow; a value of zero means no airflow defect. A non-zero airflow defect can only be applied for systems attached to a distribution system. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the airflow rate is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[123]

ChargeDefectRatio is defined as (InstalledCharge - DesignCharge) / DesignCharge; a value of zero means no refrigerant charge defect. A non-zero charge defect should typically only be applied for systems that are charged on site, not for systems that have pre-charged line sets. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the charge is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

Warning

HVAC installation quality should be provided per the conditions specified in ANSI/RESNET/ACCA 310. OS-ERI does not check that, for example, the total duct leakage requirement has been met or that a Grade I/II input is appropriate per the ANSI 310 process flow; that is currently the responsibility of the software developer.

Mini-Split Heat Pump

If a mini-split heat pump is specified, additional information is entered in HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [124]	No		ID of attached distribution system, if present
HeatingCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity (excluding any backup heating)
HeatingCapacity17F	double	Btu/hr	>= 0, <= HeatingCapacity	No		Heating output capacity at 17F, if available
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
CompressorType	string		See [125]	No	variable speed	Type of compressor
CompressorLockoutTemperature	double	F		No	See [126]	Minimum outdoor temperature for compressor operation
CoolingSensibleHeatFraction	double	frac	0 - 1	No	0.73	Sensible heat fraction
FractionHeatLoadServed	double	frac	0 - 1 [127]	Yes		Fraction of heating load served
FractionCoolLoadServed	double	frac	0 - 1 [128]	Yes		Fraction of cooling load served
AnnualCoolingEfficiency[Units="SEER" or Units="SEER2"]/Value	double	Btu/Wh	> 0	Yes		Rated cooling efficiency [129]
AnnualHeatingEfficiency[Units="HSPF" or Units="HSPF2"]/Value	double	Btu/Wh	> 0	Yes		Rated heating efficiency [130]
extension/HeatingCapacityRetention[Fraction | Temperature]	double	frac | F	>= 0, < 1 | <= 17	No	See [131]	Heating output capacity retention at cold temperature [132]
extension/FanPowerWattsPerCFM	double	W/cfm	>= 0	Yes		Blower fan efficiency at maximum fan speed [133]
extension/AirflowDefectRatio	double	frac	-0.9 - 9	Yes		Deviation between design/installed airflows [134]
extension/ChargeDefectRatio	double	frac	-0.25, 0, 0.25	Yes		Deviation between design/installed refrigerant charges [135]

[124]

If DistributionSystem provided, HVACDistribution type must be AirDistribution (type: “regular velocity”) or DSE.

[125]

CompressorType only choice is “variable speed” (i.e., they are assumed to be inverter driven).

[126]

If neither CompressorLockoutTemperature nor BackupHeatingSwitchoverTemperature provided, CompressorLockoutTemperature defaults to 25F if fossil fuel backup otherwise -20F.

[127]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

[128]

The sum of all FractionCoolLoadServed (across all HVAC systems) must be less than or equal to 1.

[129]

If SEER2 provided, converted to SEER using ANSI/RESNET/ICC 301-2022 Addendum C, where SEER = SEER2 / 0.95 if ducted and SEER = SEER2 if ductless.

[130]

If HSPF2 provided, converted to HSPF using ANSI/RESNET/ICC 301-2022 Addendum C, where HSPF = HSPF2 / 0.85 if ducted and HSPF = HSPF2 / 0.90 if ductless.

[131]

If neither extension/HeatingCapacityRetention nor HeatingCapacity17F provided, heating capacity retention defaults to 0.0461 * HSPF + 0.1594 (at 5F).

[132]

The extension/HeatingCapacityRetention input is a more flexible alternative to HeatingCapacity17F. Either input approach can be used, but not both.

[133]

If the fan power is not measured, a value of 0.58 W/cfm should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[134]

AirflowDefectRatio is defined as (InstalledAirflow - DesignAirflow) / DesignAirflow; a value of zero means no airflow defect. A non-zero airflow defect can only be applied for systems attached to a distribution system. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the airflow rate is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[135]

ChargeDefectRatio is defined as (InstalledCharge - DesignCharge) / DesignCharge; a value of zero means no refrigerant charge defect. A non-zero charge defect should typically only be applied for systems that are charged on site, not for systems that have pre-charged line sets. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the charge is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

Warning

HVAC installation quality should be provided per the conditions specified in ANSI/RESNET/ACCA 310. OS-ERI does not check that, for example, the total duct leakage requirement has been met or that a Grade I/II input is appropriate per the ANSI 310 process flow; that is currently the responsibility of the software developer.

Packaged Terminal Heat Pump

If a packaged terminal heat pump is specified, additional information is entered in HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
HeatingCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity (excluding any backup heating)
HeatingCapacity17F	double	Btu/hr	>= 0, <= HeatingCapacity	No		Heating output capacity at 17F, if available
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
CompressorLockoutTemperature	double	F		No	See [136]	Minimum outdoor temperature for compressor operation
CoolingSensibleHeatFraction	double	frac	0 - 1	No	0.65	Sensible heat fraction
FractionHeatLoadServed	double	frac	0 - 1 [137]	Yes		Fraction of heating load served
FractionCoolLoadServed	double	frac	0 - 1 [138]	Yes		Fraction of cooling load served
AnnualCoolingEfficiency[Units="EER" or Units="CEER"]/Value	double	Btu/Wh	> 0	Yes		Rated cooling efficiency
AnnualHeatingEfficiency[Units="COP"]/Value	double	W/W	> 0	Yes		Rated heating efficiency
extension/HeatingCapacityRetention[Fraction | Temperature]	double	frac | F	>= 0, < 1 | <= 17	No	0.425 | 5	Heating output capacity retention at cold temperature [139]

[136]

If neither CompressorLockoutTemperature nor BackupHeatingSwitchoverTemperature provided, CompressorLockoutTemperature defaults to 25F if fossil fuel backup otherwise 0F.

[137]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

[138]

The sum of all FractionCoolLoadServed (across all HVAC systems) must be less than or equal to 1.

[139]

The extension/HeatingCapacityRetention input is a more flexible alternative to HeatingCapacity17F. Either input approach can be used, but not both.

Room Air Conditioner w/ Reverse Cycle

If a room air conditioner with reverse cycle is specified, additional information is entered in HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
HeatingCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity (excluding any backup heating)
HeatingCapacity17F	double	Btu/hr	>= 0, <= HeatingCapacity	No		Heating output capacity at 17F, if available
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
CompressorLockoutTemperature	double	F		No	See [140]	Minimum outdoor temperature for compressor operation
CoolingSensibleHeatFraction	double	frac	0 - 1	No	0.65	Sensible heat fraction
FractionHeatLoadServed	double	frac	0 - 1 [141]	Yes		Fraction of heating load served
FractionCoolLoadServed	double	frac	0 - 1 [142]	Yes		Fraction of cooling load served
AnnualCoolingEfficiency[Units="EER" or Units="CEER"]/Value	double	Btu/Wh	> 0	Yes		Rated cooling efficiency
AnnualHeatingEfficiency[Units="COP"]/Value	double	W/W	> 0	Yes		Rated heating efficiency
extension/HeatingCapacityRetention[Fraction | Temperature]	double	frac | F	>= 0, < 1 | <= 17	No	0.425 | 5	Heating output capacity retention at cold temperature [143]

[140]

If neither CompressorLockoutTemperature nor BackupHeatingSwitchoverTemperature provided, CompressorLockoutTemperature defaults to 25F if fossil fuel backup otherwise 0F.

[141]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

[142]

The sum of all FractionCoolLoadServed (across all HVAC systems) must be less than or equal to 1.

[143]

The extension/HeatingCapacityRetention input is a more flexible alternative to HeatingCapacity17F. Either input approach can be used, but not both.

Ground-to-Air Heat Pump

If a ground-to-air heat pump is specified, additional information is entered in HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
IsSharedSystem	boolean			Yes		Whether it has a shared hydronic circulation loop [144]
DistributionSystem	idref		See [145]	Yes		ID of attached distribution system
HeatingCapacity	double	Btu/hr	>= 0	Yes		Heating output capacity (excluding any backup heating)
CoolingCapacity	double	Btu/hr	>= 0	Yes		Cooling output capacity
CoolingSensibleHeatFraction	double	frac	0 - 1	No	0.73	Sensible heat fraction
FractionHeatLoadServed	double	frac	0 - 1 [146]	Yes		Fraction of heating load served
FractionCoolLoadServed	double	frac	0 - 1 [147]	Yes		Fraction of cooling load served
AnnualCoolingEfficiency[Units="EER"]/Value	double	Btu/Wh	> 0	Yes		Rated cooling efficiency
AnnualHeatingEfficiency[Units="COP"]/Value	double	W/W	> 0	Yes		Rated heating efficiency
NumberofUnitsServed	integer		> 0	See [148]		Number of dwelling units served
extension/PumpPowerWattsPerTon	double	W/ton	>= 0	Yes		Pump power [149]
extension/SharedLoopWatts	double	W	>= 0	See [150]		Shared pump power [151]
extension/SharedLoopMotorEfficiency	double	frac	0 - 1	No	0.85 [152]	Shared loop motor efficiency
extension/FanPowerWattsPerCFM	double	W/cfm	>= 0	Yes		Blower fan efficiency at maximum fan speed [153]
extension/AirflowDefectRatio	double	frac	-0.9 - 9	Yes		Deviation between design/installed airflows [154]
extension/ChargeDefectRatio	double	frac	-0.25, 0, 0.25	Yes		Deviation between design/installed refrigerant charges [155]

[144]

IsSharedSystem should be true if the SFA/MF building has multiple ground source heat pumps connected to a shared hydronic circulation loop.

[145]

HVACDistribution type must be AirDistribution (type: “regular velocity”) or DSE.

[146]

The sum of all FractionHeatLoadServed (across all HVAC systems) must be less than or equal to 1.

[147]

The sum of all FractionCoolLoadServed (across all HVAC systems) must be less than or equal to 1.

[148]

NumberofUnitsServed only required if IsSharedSystem is true, in which case it must be > 1.

[149]

Pump power is calculated using PumpPowerWattsPerTon and the cooling capacity in tons, unless the system only provides heating, in which case the heating capacity in tons is used instead. Any pump power that is shared by multiple dwelling units should be included in SharedLoopWatts, not PumpPowerWattsPerTon, so that shared loop pump power attributed to the dwelling unit is calculated.

[150]

SharedLoopWatts only required if IsSharedSystem is true.

[151]

Shared loop pump power attributed to the dwelling unit is calculated as SharedLoopWatts / NumberofUnitsServed.

[152]

SharedLoopMotorEfficiency only used if IsSharedSystem is true.

[153]

If the fan power is not measured, a value of 0.58 W/cfm should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[154]

AirflowDefectRatio is defined as (InstalledAirflow - DesignAirflow) / DesignAirflow; a value of zero means no airflow defect. A non-zero airflow defect can only be applied for systems attached to a distribution system. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the airflow rate is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

[155]

ChargeDefectRatio is defined as (InstalledCharge - DesignCharge) / DesignCharge; a value of zero means no refrigerant charge defect. A non-zero charge defect should typically only be applied for systems that are charged on site, not for systems that have pre-charged line sets. See ANSI/RESNET/ACCA 310-2020 Standard for Grading the Installation of HVAC Systems for more information. If the charge is not measured and the measurement is not exempted, a value of -0.25 should be used according to ANSI/RESNET/ICC© 301-2019 Addendum B.

Warning

HVAC installation quality should be provided per the conditions specified in ANSI/RESNET/ACCA 310. OS-ERI does not check that, for example, the total duct leakage requirement has been met or that a Grade I/II input is appropriate per the ANSI 310 process flow; that is currently the responsibility of the software developer.

Water-Loop-to-Air Heat Pump

If a water-loop-to-air heat pump is specified, additional information is entered in HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
DistributionSystem	idref		See [156]	Yes		ID of attached distribution system
HeatingCapacity	double	Btu/hr	> 0	See [157]		Heating output capacity
CoolingCapacity	double	Btu/hr	> 0	See [158]		Cooling output capacity
AnnualCoolingEfficiency[Units="EER"]/Value	double	Btu/Wh	> 0	See [159]		Rated cooling efficiency
AnnualHeatingEfficiency[Units="COP"]/Value	double	W/W	> 0	See [160]		Rated heating efficiency

[156]

HVACDistribution type must be AirDistribution (type: “regular velocity”) or DSE.

[157]

HeatingCapacity required if there is a shared boiler with water loop distribution.

[158]

CoolingCapacity required if there is a shared chiller or cooling tower with water loop distribution.

[159]

AnnualCoolingEfficiency required if there is a shared chiller or cooling tower with water loop distribution.

[160]

AnnualHeatingEfficiency required if there is a shared boiler with water loop distribution.

Note

If a water loop heat pump is specified, there must be at least one shared heating system (i.e., Boiler) and/or one shared cooling system (i.e., Chiller or Cooling Tower) specified with water loop distribution.

Backup

If a backup type of “integrated” is provided, additional information is entered in HeatPump.

Element	Type	Units	Constraints	Required	Default	Notes
BackupSystemFuel	string		See [161]	Yes		Integrated backup heating fuel type
BackupAnnualHeatingEfficiency[Units="Percent" or Units="AFUE"]/Value	double	frac	0 - 1	Yes		Integrated backup heating efficiency
BackupHeatingCapacity	double	Btu/hr	>= 0	Yes		Integrated backup heating output capacity
BackupHeatingSwitchoverTemperature or CompressorLockoutTemperature	double	F		No	See [162]	Minimum outdoor temperature for compressor operation
BackupHeatingSwitchoverTemperature or BackupHeatingLockoutTemperature	double	F	See [163]	No	See [164]	Maximum outdoor temperature for backup operation

[161]

BackupSystemFuel choices are “electricity”, “natural gas”, “fuel oil”, “propane”, “wood”, or “wood pellets”.

[162]

If neither BackupHeatingSwitchoverTemperature nor CompressorLockoutTemperature provided, CompressorLockoutTemperature defaults as described above for individual heat pump types.

[163]

If both BackupHeatingLockoutTemperature and CompressorLockoutTemperature provided, BackupHeatingLockoutTemperature must be greater than or equal to CompressorLockoutTemperature.

[164]

If neither BackupHeatingSwitchoverTemperature nor BackupHeatingLockoutTemperature provided, BackupHeatingLockoutTemperature defaults to 40F for electric backup and 50F for fossil fuel backup.

Note

Provide BackupHeatingSwitchoverTemperature for a situation where there is a discrete outdoor temperature below which the heat pump stops operating and above which the backup heating system stops operating.

Alternatively, provide A) CompressorLockoutTemperature to specify the outdoor temperature below which the heat pump stops operating and/or B) BackupHeatingLockoutTemperature to specify the outdoor temperature above which the heat pump backup system stops operating. If both are provided, the compressor and backup system can both operate between the two temperatures (e.g., simultaneous operation or cycling). If both are provided using the same temperature, it is equivalent to using BackupHeatingSwitchoverTemperature.

HPXML HVAC Control

If any HVAC systems are specified, a single thermostat is entered as a /HPXML/Building/BuildingDetails/Systems/HVAC/HVACControl.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
ControlType	string		See [165]	Yes		Type of thermostat

[165]

ControlType choices are “manual thermostat” or “programmable thermostat”.

HPXML HVAC Distribution

Each separate HVAC distribution system is entered as a /HPXML/Building/BuildingDetails/Systems/HVAC/HVACDistribution.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
DistributionSystemType	element		1 [166]	Yes		Type of distribution system
ConditionedFloorAreaServed	double	ft2	> 0	See [167]		Conditioned floor area served

[166]

DistributionSystemType child element choices are AirDistribution, HydronicDistribution, or Other=DSE.

[167]

ConditionedFloorAreaServed required only when DistributionSystemType is AirDistribution and AirDistribution/Ducts are present.

Note

There should be at most one heating system and one cooling system attached to a distribution system. See HPXML Heating Systems, HPXML Cooling Systems, and HPXML Heat Pumps for information on which DistributionSystemType is allowed for which HVAC system. Also note that some HVAC systems (e.g., room air conditioners) are not allowed to be attached to a distribution system.

Air Distribution

To define an air distribution system, additional information is entered in HVACDistribution/DistributionSystemType/AirDistribution.

Element	Type	Units	Constraints	Required	Default	Notes
AirDistributionType	string		See [168]	Yes		Type of air distribution
NumberofReturnRegisters	integer		>= 0	See [169]		Number of return registers

[168]

AirDistributionType choices are “regular velocity”, “gravity”, or “fan coil” and are further restricted based on attached HVAC system type (e.g., only “regular velocity” or “gravity” for a furnace, only “fan coil” for a shared boiler, etc.).

[169]

NumberofReturnRegisters required only if AirDistribution/Ducts are present.

For the air distribution system, duct leakage inputs are required if AirDistributionType is “regular velocity” or “gravity” and optional if AirDistributionType is “fan coil”.

When provided, supply and return leakage to the outside are each entered as a HVACDistribution/DistributionSystemType/AirDistribution/DuctLeakageMeasurement:

Element	Type	Units	Constraints	Required	Default	Notes
DuctType	string		See [170]	Yes		Supply or return ducts
DuctLeakage/Units	string		See [171]	Yes		Duct leakage units
DuctLeakage/Value	double		>= 0	Yes		Duct leakage value [172]
DuctLeakage/TotalOrToOutside	string		to outside	Yes		Type of duct leakage (outside conditioned space vs total)

[170]

DuctType choices are “supply” or “return”.

[171]

Units choices are “CFM25” or “CFM50”.

[172]

If the HVAC system has no return ducts (e.g., a ducted evaporative cooler), use zero for the Value.

Note

ANSI/RESNET/ICC 301 allows for various duct leakage exemptions, including not testing a distribution system or measuring total duct leakage in lieu of leakage to the outside. OS-ERI does not automatically handle these exemptions. Any software tool that offers these options to their end users must incorporate the necessary logic and pass the appropriate inputs to OS-ERI (i.e., leakage to the outside or distribution system efficiency (DSE)).

Additionally, each supply/return duct present is entered in a HVACDistribution/DistributionSystemType/AirDistribution/Ducts.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
DuctType	string		See [173]	Yes		Supply or return ducts
DuctInsulationRValue	double	F-ft2-hr/Btu	>= 0	Yes		R-value of duct insulation [174]
DuctBuriedInsulationLevel	string		See [175]	No	not buried	Duct buried insulation level [176]
DuctLocation	string		See [177]	Yes		Duct location
DuctSurfaceArea	double	ft2	>= 0	Yes		Duct surface area

[173]

DuctType choices are “supply” or “return”.

[174]

DuctInsulationRValue should not include the exterior air film (i.e., use 0 for an uninsulated duct). For ducts buried in insulation (using DuctBuriedInsulationLevel), DuctInsulationRValue should only represent any surrounding insulation duct wrap and not the entire attic insulation R-value.

[175]

DuctBuriedInsulationLevel choices are “not buried”, “partially buried”, “fully buried”, or “deeply buried”.

[176]

Whether the ducts are buried in, e.g., attic loose-fill insulation. Partially buried ducts have insulation that does not cover the top of the ducts. Fully buried ducts have insulation that just covers the top of the ducts. Deeply buried ducts have insulation that continues above the top of the ducts. See the Building America Solution Center for more information.

[177]

DuctLocation choices are “conditioned space”, “basement - conditioned”, “basement - unconditioned”, “crawlspace - unvented”, “crawlspace - vented”, “attic - unvented”, “attic - vented”, “garage”, “outside”, “exterior wall”, “under slab”, “roof deck”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

Hydronic Distribution

To define a hydronic distribution system, additional information is entered in HVACDistribution/DistributionSystemType/HydronicDistribution.

Element	Type	Units	Constraints	Required	Default	Notes
HydronicDistributionType	string		See [178]	Yes		Type of hydronic distribution system

[178]

HydronicDistributionType choices are “radiator”, “baseboard”, “radiant floor”, “radiant ceiling”, or “water loop”.

Distribution System Efficiency (DSE)

Warning

A simplified DSE model is provided for flexibility, but it is strongly recommended to use one of the other detailed distribution system types for better accuracy.

To define a DSE system, additional information is entered in HVACDistribution.

Element	Type	Units	Constraints	Required	Default	Notes
AnnualHeatingDistributionSystemEfficiency	double	frac	0 - 1	Yes		Seasonal distribution system efficiency for heating
AnnualCoolingDistributionSystemEfficiency	double	frac	0 - 1	Yes		Seasonal distribution system efficiency for cooling

DSE values can be calculated from ASHRAE Standard 152.

HPXML Ventilation Fan

Each ventilation fan system is entered as a /HPXML/Building/BuildingDetails/Systems/MechanicalVentilation/VentilationFans/VentilationFan.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
UsedForWholeBuildingVentilation or UsedForLocalVentilation or UsedForSeasonalCoolingLoadReduction or UsedForGarageVentilation	boolean		See [179]	See [180]		Ventilation fan use case

[179]

One (and only one) of the UsedFor... elements must have a value of true. If UsedForWholeBuildingVentilation is true, see Whole Ventilation Fan. If UsedForLocalVentilation is true, local ventilation is ignored. If UsedForSeasonalCoolingLoadReduction is true, see HPXML Whole House Fan. If UsedForGarageVentilation is true, garage ventilation is ignored.

[180]

Only the UsedFor... element that is true is required.

Whole Ventilation Fan

Each mechanical ventilation system that provides ventilation to the whole dwelling unit is entered as a /HPXML/Building/BuildingDetails/Systems/MechanicalVentilation/VentilationFans/VentilationFan[UsedForWholeBuildingVentilation=true].

Element	Type	Units	Constraints	Required	Default	Notes
IsSharedSystem	boolean		See [181]	Yes		Whether it serves multiple dwelling units
FanType	string		See [182]	Yes		Type of ventilation system
HoursInOperation	double	hrs/day	0 - 24	See [183]		Hours per day of operation [184]
FanPower or extension/FanPowerDefaulted=true	double or boolean	W	>= 0 or true	Yes		Fan power or whether fan power is unknown

[181]

For central fan integrated supply systems, IsSharedSystem must be false.

[182]

FanType choices are “energy recovery ventilator”, “heat recovery ventilator”, “exhaust only”, “supply only”, “balanced”, or “central fan integrated supply”.

[183]

HoursInOperation required unless the VentilationFan refers to the supplemental fan of a CFIS system, in which case it is not allowed.

[184]

For a CFIS system, the HoursInOperation and the flow rate are combined to form the expected/required hourly ventilation rate (e.g., 90 cfm and 8 hrs/day produce an hourly ventilation rate of 30 cfm). For a CFIS system with a supplemental fan, the supplemental fan’s runtime is automatically calculated for each hour (based on the air handler runtime) to maintain the hourly ventilation rate.

Exhaust/Supply Only

If a supply only or exhaust only system is specified, no additional information is entered.

Balanced

If a balanced system is specified, no additional information is entered.

Heat Recovery Ventilator

If a heat recovery ventilator system is specified, additional information is entered in VentilationFan.

Element	Type	Units	Constraints	Required	Default	Notes
SensibleRecoveryEfficiency or AdjustedSensibleRecoveryEfficiency	double	frac	0 - 1	Yes		(Adjusted) Sensible recovery efficiency

Energy Recovery Ventilator

If an energy recovery ventilator system is specified, additional information is entered in VentilationFan.

Element	Type	Units	Constraints	Required	Default	Notes
TotalRecoveryEfficiency or AdjustedTotalRecoveryEfficiency	double	frac	0 - 1	Yes		(Adjusted) Total recovery efficiency
SensibleRecoveryEfficiency or AdjustedSensibleRecoveryEfficiency	double	frac	0 - 1	Yes		(Adjusted) Sensible recovery efficiency

Central Fan Integrated Supply

If a central fan integrated supply (CFIS) system is specified, additional information is entered in VentilationFan.

Element	Type	Units	Constraints	Required	Default	Notes
CFISControls/AdditionalRuntimeOperatingMode	string		See [185]	Yes		How additional ventilation is provided (beyond when the HVAC system is running)
CFISControls/SupplementalFan	idref		See [186]	See [187]		The supplemental fan providing additional ventilation
AttachedToHVACDistributionSystem	idref		See [188]	Yes		ID of attached distribution system
extension/VentilationOnlyModeAirflowFraction	double		0 - 1	Yes		Blower airflow rate fraction during ventilation only mode [189]

[185]

AdditionalRuntimeOperatingMode choices are “air handler fan” or “supplemental fan”.

[186]

SupplementalFan must reference another VentilationFan where UsedForWholeBuildingVentilation=true, IsSharedSystem=false, and FanType=”exhaust only” or “supply only”.

[187]

SupplementalFan only required if AdditionalRuntimeOperatingMode is “supplemental fan”.

[188]

HVACDistribution type cannot be HydronicDistribution.

[189]

Blower airflow rate when operating in ventilation only mode (i.e., not heating or cooling mode), as a fraction of the maximum blower airflow rate. This value will depend on whether the blower fan can operate at reduced airflow rates during ventilation only operation. It is used to determine how much conditioned air is recirculated through ducts during ventilation only operation, resulting in additional duct losses. A value of zero will result in no conditioned air recirculation, and thus no additional duct losses.

Note

CFIS systems are automated controllers that use the HVAC system’s air handler fan to draw in outdoor air to meet an hourly ventilation target. CFIS systems are modeled as assuming they A) maximize the use of normal heating/cooling runtime operation to meet the hourly ventilation target, B) block the flow of outdoor air when the hourly ventilation target has been met, and C) provide additional runtime operation (via air handler fan or supplemental fan) to meet the remainder of the hourly ventilation target when space heating/cooling runtime alone is not sufficient.

In-Unit System

If the specified system is not a shared system (i.e., not serving multiple dwelling units), additional information is entered in VentilationFan.

Element	Type	Units	Constraints	Required	Default	Notes
TestedFlowRate or extension/FlowRateNotTested=true	double or boolean	cfm	>= 0 or true	Yes		Flow rate [190] or whether flow rate unmeasured

[190]

For a central fan integrated supply system, TestedFlowRate should equal the amount of outdoor air provided to the distribution system, not the total airflow through the distribution system.

Shared System

If the specified system is a shared system (i.e., serving multiple dwelling units), additional information is entered in VentilationFan.

Element	Type	Units	Constraints	Required	Default	Notes
RatedFlowRate	double	cfm	>= 0	Yes		Total flow rate of shared system
FractionRecirculation	double	frac	0 - 1	Yes		Fraction of supply air that is recirculated [191]
extension/InUnitFlowRate or extension/FlowRateNotTested=true	double or boolean	cfm	>= 0 [192] or true	Yes		Flow rate delivered to the dwelling unit or whether flow rate unmeasured
extension/PreHeating	element		0 - 1	No	<none>	Supply air preconditioned by heating equipment? [193]
extension/PreCooling	element		0 - 1	No	<none>	Supply air preconditioned by cooling equipment? [194]

[191]

1-FractionRecirculation is assumed to be the fraction of supply air that is provided from outside. The value must be 0 for exhaust only systems.

[192]

InUnitFlowRate must also be < RatedFlowRate.

[193]

PreHeating not allowed for exhaust only systems.

[194]

PreCooling not allowed for exhaust only systems.

If pre-heating is specified for the shared system, additional information is entered in extension/PreHeating.

Element	Type	Units	Constraints	Required	Default	Notes
Fuel	string		See [195]	Yes		Pre-heating equipment fuel type
AnnualHeatingEfficiency[Units="COP"]/Value	double	W/W	> 0	Yes		Pre-heating equipment annual COP
FractionVentilationHeatLoadServed	double	frac	0 - 1	Yes		Fraction of ventilation heating load served by pre-heating equipment

[195]

Fuel choices are “natural gas”, “fuel oil”, “propane”, “electricity”, “wood”, or “wood pellets”.

If pre-cooling is specified for the shared system, additional information is entered in extension/PreCooling.

Element	Type	Units	Constraints	Required	Default	Notes
Fuel	string		See [196]	Yes		Pre-cooling equipment fuel type
AnnualCoolingEfficiency[Units="COP"]/Value	double	W/W	> 0	Yes		Pre-cooling equipment annual COP
FractionVentilationCoolLoadServed	double	frac	0 - 1	Yes		Fraction of ventilation cooling load served by pre-cooling equipment

[196]

Fuel only choice is “electricity”.

HPXML Whole House Fan

Each whole house fan that provides cooling load reduction is entered as a /HPXML/Building/BuildingDetails/Systems/MechanicalVentilation/VentilationFans/VentilationFan[UsedForSeasonalCoolingLoadReduction=true].

Element	Type	Units	Constraints	Required	Default	Notes
RatedFlowRate	double	cfm	>= 0	Yes		Flow rate
FanPower	double	W	>= 0	Yes		Fan power

Note

The whole house fan is assumed to operate during hours of favorable outdoor conditions and will take priority over operable windows (natural ventilation).

HPXML Water Heating Systems

Each water heater is entered as a /HPXML/Building/BuildingDetails/Systems/WaterHeating/WaterHeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
IsSharedSystem	boolean			Yes		Whether it serves multiple dwelling units or shared laundry room
WaterHeaterType	string		See [197]	Yes		Type of water heater
Location	string		See [198]	Yes		Water heater location
FractionDHWLoadServed	double	frac	0 - 1 [199]	Yes		Fraction of hot water load served [200]
UsesDesuperheater	boolean			No	false	Presence of desuperheater?
NumberofUnitsServed	integer		> 0	See [201]		Number of dwelling units served directly or indirectly

[197]

WaterHeaterType choices are “storage water heater”, “instantaneous water heater”, “heat pump water heater”, “space-heating boiler with storage tank”, or “space-heating boiler with tankless coil”.

[198]

Location choices are “conditioned space”, “basement - unconditioned”, “basement - conditioned”, “attic - unvented”, “attic - vented”, “garage”, “crawlspace - unvented”, “crawlspace - vented”, “other exterior”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[199]

The sum of all FractionDHWLoadServed (across all WaterHeatingSystems) must equal to 1.

[200]

FractionDHWLoadServed represents only the fraction of the hot water load associated with the hot water fixtures. Additional hot water load from clothes washers/dishwashers will be automatically assigned to the appropriate water heater(s).

[201]

NumberofUnitsServed only required if IsSharedSystem is true, in which case it must be > 1.

Conventional Storage

If a conventional storage water heater is specified, additional information is entered in WaterHeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
FuelType	string		See [202]	Yes		Fuel type
TankVolume	double	gal	> 0	Yes		Nominal tank volume
HeatingCapacity	double	Btu/hr	> 0	No	See [203]	Heating output capacity
UniformEnergyFactor or EnergyFactor	double	frac	< 1	Yes		EnergyGuide label rated efficiency
FirstHourRating	double	gal/hr	> 0	See [204]		EnergyGuide label first hour rating
RecoveryEfficiency	double	frac	0 - 1 [205]	No	See [206]	Recovery efficiency
WaterHeaterInsulation/Jacket/JacketRValue	double	F-ft2-hr/Btu	>= 0	No	0	R-value of additional tank insulation wrap

[202]

FuelType choices are “natural gas”, “fuel oil”, “propane”, “electricity”, “wood”, or “wood pellets”.

[203]

If HeatingCapacity not provided, defaults based on Table 8 in the 2014 BAHSP.

[204]

FirstHourRating only required if UniformEnergyFactor provided.

[205]

RecoveryEfficiency must also be greater than the EnergyFactor (or UniformEnergyFactor).

[206]

If RecoveryEfficiency not provided, defaults as follows based on a regression analysis of AHRI certified water heaters:

- Electric: 0.98

- Non-electric, EnergyFactor < 0.75: 0.252 * EnergyFactor + 0.608

- Non-electric, EnergyFactor >= 0.75: 0.561 * EnergyFactor + 0.439

Tankless

If an instantaneous tankless water heater is specified, additional information is entered in WaterHeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
FuelType	string		See [207]	Yes		Fuel type
UniformEnergyFactor or EnergyFactor	double	frac	< 1	Yes		EnergyGuide label rated efficiency

[207]

FuelType choices are “natural gas”, “fuel oil”, “propane”, “electricity”, “wood”, or “wood pellets”.

Heat Pump

If a heat pump water heater is specified, additional information is entered in WaterHeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
FuelType	string		See [208]	Yes		Fuel type
TankVolume	double	gal	> 0	Yes		Nominal tank volume
UniformEnergyFactor or EnergyFactor	double	frac	> 1, <= 5	Yes		EnergyGuide label rated efficiency
FirstHourRating	double	gal/hr	> 0	See [209]		EnergyGuide label first hour rating
WaterHeaterInsulation/Jacket/JacketRValue	double	F-ft2-hr/Btu	>= 0	No	0	R-value of additional tank insulation wrap

[208]

FuelType only choice is “electricity”.

[209]

FirstHourRating only required if UniformEnergyFactor provided.

Combi Boiler w/ Storage

If a combination boiler w/ storage tank (sometimes referred to as an indirect water heater) is specified, additional information is entered in WaterHeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
RelatedHVACSystem	idref		See [210]	Yes		ID of boiler
TankVolume	double	gal	> 0	Yes		Nominal volume of the storage tank
WaterHeaterInsulation/Jacket/JacketRValue	double	F-ft2-hr/Btu	>= 0	No	0	R-value of additional storage tank insulation wrap
StandbyLoss[Units="F/hr"]/Value	double	F/hr	> 0	No	See [211]	Storage tank standby losses

[210]

RelatedHVACSystem must reference a HeatingSystem of type Boiler.

[211]

If StandbyLoss not provided, defaults based on a regression analysis of AHRI Directory of Certified Product Performance.

Combi Boiler w/ Tankless Coil

If a combination boiler w/ tankless coil is specified, additional information is entered in WaterHeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
RelatedHVACSystem	idref		See [212]	Yes		ID of boiler

[212]

RelatedHVACSystem must reference a HeatingSystem (Boiler).

Desuperheater

If the water heater uses a desuperheater, additional information is entered in WaterHeatingSystem.

Element	Type	Units	Constraints	Required	Default	Notes
RelatedHVACSystem	idref		See [213]	Yes		ID of heat pump or air conditioner

[213]

RelatedHVACSystem must reference a HeatPump (air-to-air, mini-split, or ground-to-air) or CoolingSystem (central air conditioner).

HPXML Hot Water Distribution

If any water heating systems are provided, a single hot water distribution system is entered as a /HPXML/Building/BuildingDetails/Systems/WaterHeating/HotWaterDistribution.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
SystemType	element		1 [214]	Yes		Type of in-unit distribution system serving the dwelling unit
PipeInsulation/PipeRValue	double	F-ft2-hr/Btu	>= 0	Yes		Pipe insulation R-value
DrainWaterHeatRecovery	element		0 - 1	No	<none>	Presence of drain water heat recovery device
extension/SharedRecirculation	element		0 - 1 [215]	No	<none>	Presence of shared recirculation system serving multiple dwelling units

[214]

SystemType child element choices are Standard and Recirculation.

[215]

If SharedRecirculation is provided, SystemType must be Standard. This is because a stacked recirculation system (i.e., shared recirculation loop plus an additional in-unit recirculation system) is more likely to indicate input errors than reflect an actual real-world scenario.

Note

In attached/multifamily buildings, only the hot water distribution system serving the dwelling unit should be defined. The hot water distribution associated with, e.g., a shared laundry room should not be defined.

Standard

If the in-unit distribution system is specified as standard, additional information is entered in SystemType/Standard.

Element	Type	Units	Constraints	Required	Default	Notes
PipingLength	double	ft	> 0	Yes		Length of piping [216]

[216]

PipingLength is the length of hot water piping from the hot water heater (or from a shared recirculation loop serving multiple dwelling units) to the farthest hot water fixture, measured longitudinally from plans, assuming the hot water piping does not run diagonally, plus 10 feet of piping for each floor level, plus 5 feet of piping for unconditioned basements (if any).

Recirculation

If the in-unit distribution system is specified as recirculation, additional information is entered in SystemType/Recirculation.

Element	Type	Units	Constraints	Required	Default	Notes
ControlType	string		See [217]	Yes		Recirculation control type
RecirculationPipingLoopLength	double	ft	> 0	Yes		Recirculation piping loop length [218]
BranchPipingLength	double	ft	> 0	Yes		Branch piping length [219]
PumpPower	double	W	>= 0	Yes		Recirculation pump power

[217]

ControlType choices are “manual demand control”, “presence sensor demand control”, “temperature”, “timer”, or “no control”.

- manual demand control: The pump only runs when a user presses a button indicating they are about to use hot water.

- presence sensor demand control: The pump only runs when a sensor detects someone is present at the faucet.

- temperature: The pump runs based on monitoring temperature at some point in the system.

- timer: The pump is controlled by a timer.

- no control: The pump runs continuously.

[218]

RecirculationPipingLoopLength is the recirculation loop length including both supply and return sides, measured longitudinally from plans, assuming the hot water piping does not run diagonally, plus 20 feet of piping for each floor level greater than one plus 10 feet of piping for unconditioned basements.

[219]

BranchPipingLength is the length of the branch hot water piping from the recirculation loop to the farthest hot water fixture from the recirculation loop, measured longitudinally from plans, assuming the branch hot water piping does not run diagonally.

Shared Recirculation

If a shared recirculation system is specified, additional information is entered in extension/SharedRecirculation.

Element	Type	Units	Constraints	Required	Default	Notes
NumberofUnitsServed	integer		> 1	Yes		Number of dwelling units served
PumpPower	double	W	>= 0	Yes		Shared recirculation pump power
MotorEfficiency	double	frac	0 - 1	No	0.85	Shared recirculation motor efficiency
ControlType	string		See [220]	Yes		Shared recirculation control type

[220]

ControlType choices are “manual demand control”, “presence sensor demand control”, “temperature”, “timer”, or “no control”.

Drain Water Heat Recovery

If a drain water heat recovery (DWHR) device is specified, additional information is entered in DrainWaterHeatRecovery.

Element	Type	Units	Constraints	Required	Default	Notes
FacilitiesConnected	string		See [221]	Yes		Specifies which facilities are connected
EqualFlow	boolean			Yes		Specifies how the DHWR is configured [222]
Efficiency	double	frac	0 - 1	Yes		Efficiency according to CSA 55.1

[221]

FacilitiesConnected choices are “one” or “all”. Use “one” if there are multiple showers and only one of them is connected to the DWHR. Use “all” if there is one shower and it’s connected to the DWHR or there are two or more showers connected to the DWHR.

[222]

EqualFlow should be true if the DWHR supplies pre-heated water to both the fixture cold water piping and the hot water heater potable supply piping.

HPXML Water Fixtures

Each water fixture is entered as a /HPXML/Building/BuildingDetails/Systems/WaterHeating/WaterFixture.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
WaterFixtureType	string		See [223]	Yes		Bathroom faucet or shower
LowFlow	boolean			Yes		Whether the fixture is considered low-flow [224]

[223]

WaterFixtureType choices are “shower head” or “faucet”. If the shower stall has multiple shower heads that operate simultaneously, combine them as a single entry.

[224]

LowFlow should be true if the fixture’s flow rate (gpm) is <= 2.0. Where a shower stall has multiple shower heads that operate simultaneously, the sum of their flows must be <= 2.0.

HPXML Solar Thermal

A single solar hot water system can be entered as a /HPXML/Building/BuildingDetails/Systems/SolarThermal/SolarThermalSystem.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
SystemType	string		See [225]	Yes		Type of solar thermal system

[225]

SystemType only choice is “hot water”.

Solar hot water systems can be described with either simple or detailed inputs. It is recommended to use detailed inputs and allow EnergyPlus to calculate the solar contribution to the hot water load; the simple inputs are provided if equivalent calculations are performed in another software tool.

Simple Inputs

To define a simple solar hot water system, additional information is entered in SolarThermalSystem.

Element	Type	Units	Constraints	Required	Default	Notes
SolarFraction	double	frac	0 - 1	Yes		Solar fraction [226]
ConnectedTo	idref		See [227]	No [228]	<none>	Connected water heater

[226]

Portion of total conventional hot water heating load (delivered energy plus tank standby losses). Can be obtained from Directory of SRCC OG-300 Solar Water Heating System Ratings or NREL’s System Advisor Model or equivalent.

[227]

ConnectedTo must reference a WaterHeatingSystem. The referenced water heater cannot be a space-heating boiler nor attached to a desuperheater.

[228]

If ConnectedTo not provided, solar fraction will apply to all water heaters in the building.

Warning

The solar fraction will reduce the hot water load equally for every EnergyPlus timestep (even during nights and cloudy events).

Detailed Inputs

To define a detailed solar hot water system, additional information is entered in SolarThermalSystem.

Element	Type	Units	Constraints	Required	Default	Notes
CollectorArea	double	ft2	> 0	Yes		Area
CollectorLoopType	string		See [229]	Yes		Loop type
CollectorType	string		See [230]	Yes		System type
CollectorAzimuth	integer	deg	0 - 359	Yes		Azimuth (clockwise from North)
CollectorTilt	double	deg	0 - 90	Yes		Tilt relative to horizontal
CollectorRatedOpticalEfficiency	double	frac	0 - 1	Yes		Rated optical efficiency [231]
CollectorRatedThermalLosses	double	Btu/hr-ft2-R	> 0	Yes		Rated thermal losses [232]
StorageVolume	double	gal	> 0	Yes		Hot water storage volume
ConnectedTo	idref		See [233]	Yes		Connected water heater

[229]

CollectorLoopType choices are “liquid indirect”, “liquid direct”, or “passive thermosyphon”.

[230]

CollectorType choices are “single glazing black”, “double glazing black”, “evacuated tube”, or “integrated collector storage”.

[231]

CollectorRatedOpticalEfficiency is FRTA (y-intercept) from the Directory of SRCC OG-100 Certified Solar Collector Ratings.

[232]

CollectorRatedThermalLosses is FRUL (slope) from the Directory of SRCC OG-100 Certified Solar Collector Ratings.

[233]

ConnectedTo must reference a WaterHeatingSystem that is not of type space-heating boiler nor connected to a desuperheater.

HPXML Photovoltaics

Each solar electric photovoltaic (PV) system is entered as a /HPXML/Building/BuildingDetails/Systems/Photovoltaics/PVSystem.

Many of the inputs are adopted from the PVWatts model.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
IsSharedSystem	boolean			Yes		Whether it serves multiple dwelling units
Location	string		See [234]	Yes		Mounting location
ModuleType	string		See [235]	Yes		Type of module
Tracking	string		See [236]	Yes		Type of tracking
ArrayAzimuth	integer	deg	0 - 359	Yes		Direction panels face (clockwise from North)
ArrayTilt	double	deg	0 - 90	Yes		Tilt relative to horizontal
MaxPowerOutput	double	W	>= 0	Yes		Peak power
SystemLossesFraction	double	frac	0 - 1	Yes		System losses [237]
AttachedToInverter	idref		See [238]	Yes		ID of attached inverter
extension/NumberofBedroomsServed	integer		> 1	See [239]		Number of bedrooms served

[234]

Location choices are “ground” or “roof” mounted.

[235]

ModuleType choices are “standard”, “premium”, or “thin film”.

[236]

Tracking choices are “fixed”, “1-axis”, “1-axis backtracked”, or “2-axis”.

[237]

System losses due to soiling, shading, snow, mismatch, wiring, degradation, etc. Default from the PVWatts documentation is 0.14, which breaks down as follows. Note that the total loss (14%) is not the sum of the individual losses but is calculated by multiplying the reduction due to each loss.

- Soiling: 2%

- Shading: 3%

- Snow: 0%

- Mismatch: 2%

- Wiring: 2%

- Connections: 0.5%

- Light-induced degradation: 1.5%

- Nameplate rating: 1%

- Age: 0%

- Availability: 3%

[238]

AttachedToInverter must reference an Inverter.

[239]

NumberofBedroomsServed only required if IsSharedSystem is true, in which case it must be > NumberofBedrooms. PV generation will be apportioned to the dwelling unit using its number of bedrooms divided by the total number of bedrooms served by the PV system.

In addition, an inverter must be entered as a /HPXML/Building/BuildingDetails/Systems/Photovoltaics/Inverter.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
InverterEfficiency	double	frac	0 - 1 [240]	Yes		Inverter efficiency [241]

[240]

For homes with multiple inverters, all InverterEfficiency elements must have the same value.

[241]

Default from PVWatts is 0.96.

HPXML Generators

Each generator that provides on-site power is entered as a /HPXML/Building/BuildingDetails/Systems/extension/Generators/Generator.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
IsSharedSystem	boolean			Yes		Whether it serves multiple dwelling units
FuelType	string		See [242]	Yes		Fuel type
AnnualConsumptionkBtu	double	kBtu/yr	> 0	Yes		Annual fuel consumed
AnnualOutputkWh	double	kWh/yr	> 0 [243]	Yes		Annual electricity produced
NumberofBedroomsServed	integer		> 1	See [244]		Number of bedrooms served

[242]

FuelType choices are “natural gas”, “fuel oil”, “propane”, “wood”, or “wood pellets”.

[243]

AnnualOutputkWh must also be < AnnualConsumptionkBtu*3.412 (i.e., the generator must consume more energy than it produces).

[244]

NumberofBedroomsServed only required if IsSharedSystem is true, in which case it must be > NumberofBedrooms. Annual consumption and annual production will be apportioned to the dwelling unit using its number of bedrooms divided by the total number of bedrooms served by the generator.

Note

Generators will be modeled as operating continuously (24/7).

HPXML Appliances

Appliances entered in /HPXML/Building/BuildingDetails/Appliances.

HPXML Clothes Washer

A single clothes washer can be entered as a /HPXML/Building/BuildingDetails/Appliances/ClothesWasher.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
IsSharedAppliance	boolean			Yes		Whether it serves multiple dwelling units [245]
Location	string		See [246]	Yes		Location
IntegratedModifiedEnergyFactor or ModifiedEnergyFactor	double	ft3/kWh/cyc	> 0	Yes		Efficiency [247]
RatedAnnualkWh	double	kWh/yr	> 0	Yes		EnergyGuide label annual consumption
LabelElectricRate	double	$/kWh	> 0	Yes		EnergyGuide label electricity rate
LabelGasRate	double	$/therm	> 0	Yes		EnergyGuide label natural gas rate
LabelAnnualGasCost	double	$	> 0	Yes		EnergyGuide label annual gas cost
LabelUsage	double	cyc/wk	> 0	Yes		EnergyGuide label number of cycles (not used if 301 version < 2019A)
Capacity	double	ft3	> 0	Yes		Clothes washer volume

[245]

For example, a clothes washer in a shared laundry room of a MF building.

[246]

Location choices are “conditioned space”, “basement - conditioned”, “basement - unconditioned”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[247]

If ModifiedEnergyFactor (MEF) provided instead of IntegratedModifiedEnergyFactor (IMEF), it will be converted using the Interpretation on ANSI/RESNET 301-2014 Clothes Washer IMEF: IMEF = (MEF - 0.503) / 0.95. IMEF may be found using the manufacturer’s data sheet, the California Energy Commission Appliance Database, the EPA ENERGY STAR website, or another reputable source.

If the clothes washer is shared, additional information is entered in /HPXML/Building/BuildingDetails/Appliances/ClothesWasher.

Element	Type	Units	Constraints	Required	Default	Notes
AttachedToWaterHeatingSystem or AttachedToHotWaterDistribution	idref		See [248]	Yes		ID of attached water heater or distribution system
Count	integer			Yes		Number of clothes washers in the shared laundry room
NumberofUnitsServed	integer			Yes		Number of dwelling units served by the shared laundry room

[248]

AttachedToWaterHeatingSystem must reference a WaterHeatingSystem; AttachedToHotWaterDistribution must reference a HotWaterDistribution.

Note

If no clothes washer is located within the Rated Home, a clothes washer in the nearest shared laundry room on the project site shall be used if available for daily use by the occupants of the Rated Home. If there are multiple clothes washers, the clothes washer with the highest Label Energy Rating (kWh/yr) shall be used.

HPXML Clothes Dryer

A single clothes dryer can be entered as a /HPXML/Building/BuildingDetails/Appliances/ClothesDryer.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
IsSharedAppliance	boolean			Yes		Whether it serves multiple dwelling units [249]
Location	string		See [250]	Yes		Location
FuelType	string		See [251]	Yes		Fuel type
CombinedEnergyFactor or EnergyFactor	double	lb/kWh	> 0	Yes		EnergyGuide label efficiency [252]
ControlType	string		See [253]	See [254]		Type of controls

[249]

For example, a clothes dryer in a shared laundry room of a MF building.

[250]

Location choices are “conditioned space”, “basement - conditioned”, “basement - unconditioned”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[251]

FuelType choices are “natural gas”, “fuel oil”, “propane”, “electricity”, “wood”, or “wood pellets”.

[252]

If EnergyFactor (EF) provided instead of CombinedEnergyFactor (CEF), it will be converted using the following equation based on the Interpretation on ANSI/RESNET/ICC 301-2014 Clothes Dryer CEF: CEF = EF / 1.15.

[253]

ControlType choices are “timer” or “moisture”.

[254]

ControlType only required if ERI Version < 2019A.

If the clothes dryer is shared, additional information is entered in /HPXML/Building/BuildingDetails/Appliances/ClothesDryer.

Element	Type	Units	Constraints	Required	Default	Notes
Count	integer			Yes		Number of clothes dryers in the shared laundry room
NumberofUnitsServed	integer			Yes		Number of dwelling units served by the shared laundry room

Note

If no clothes dryer is located within the Rated Home, a clothes dryer in the nearest shared laundry room on the project site shall be used if available for daily use by the occupants of the Rated Home. If there are multiple clothes dryers, the clothes dryer with the lowest Energy Factor or Combined Energy Factor shall be used.

HPXML Dishwasher

A single dishwasher can be entered as a /HPXML/Building/BuildingDetails/Appliances/Dishwasher.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
IsSharedAppliance	boolean			Yes		Whether it serves multiple dwelling units [255]
Location	string		See [256]	Yes		Location
RatedAnnualkWh or EnergyFactor	double	kWh/yr or #	> 0	Yes		EnergyGuide label consumption/efficiency [257]
LabelElectricRate	double	$/kWh	> 0	Yes		EnergyGuide label electricity rate (not used if 301 version < 2019A)
LabelGasRate	double	$/therm	> 0	Yes		EnergyGuide label natural gas rate (not used if 301 version < 2019A)
LabelAnnualGasCost	double	$	> 0	Yes		EnergyGuide label annual gas cost (not used if 301 version < 2019A)
LabelUsage	double	cyc/wk	> 0	Yes		EnergyGuide label number of cycles (not used if 301 version < 2019A)
PlaceSettingCapacity	integer	#	> 0	Yes		Number of place settings

[255]

For example, a dishwasher in a shared mechanical room of a MF building.

[256]

Location choices are “conditioned space”, “basement - conditioned”, “basement - unconditioned”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[257]

If EnergyFactor (EF) provided instead of RatedAnnualkWh, it will be converted using the following equation based on ANSI/RESNET/ICC 301-2014: RatedAnnualkWh = 215.0 / EF.

If the dishwasher is shared, additional information is entered in /HPXML/Building/BuildingDetails/Appliances/Dishwasher.

Element	Type	Units	Constraints	Required	Default	Notes
AttachedToWaterHeatingSystem or AttachedToHotWaterDistribution	idref		See [258]	Yes		ID of attached water heater or distribution system

[258]

AttachedToWaterHeatingSystem must reference a WaterHeatingSystem; AttachedToHotWaterDistribution must reference a HotWaterDistribution.

Note

If no dishwasher is located within the Rated Home, a dishwasher in the nearest shared kitchen in the building shall be used only if available for daily use by the occupants of the Rated Home. If there are multiple dishwashers, the dishwasher with the lowest Energy Factor (highest kWh/yr) shall be used.

HPXML Refrigerators

A single refrigerator can be entered as a /HPXML/Building/BuildingDetails/Appliances/Refrigerator.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
Location	string		See [259]	Yes		Location
RatedAnnualkWh	double	kWh/yr	> 0	Yes		Annual consumption

[259]

Location choices are “conditioned space”, “basement - conditioned”, “basement - unconditioned”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

Note

If there are multiple refrigerators, the total energy consumption of all refrigerators/freezers shall be used along with the location that represents the majority of power consumption.

HPXML Dehumidifier

Each dehumidifier can be entered as a /HPXML/Building/BuildingDetails/Appliances/Dehumidifier.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
Type	string		See [260]	Yes		Type of dehumidifier
Location	string		See [261]	Yes		Location of dehumidifier
Capacity	double	pints/day	> 0	Yes		Dehumidification capacity
IntegratedEnergyFactor or EnergyFactor	double	liters/kWh	> 0	Yes		Rated efficiency
FractionDehumidificationLoadServed	double	frac	0 - 1 [262]	Yes		Fraction of dehumidification load served

[260]

Type choices are “portable” or “whole-home”.

[261]

Location only choice is “conditioned space”.

[262]

The sum of all FractionDehumidificationLoadServed (across all Dehumidifiers) must be less than or equal to 1.

Note

Dehumidifiers only affect ERI scores if Version 2019AB or newer is used, as dehumidifiers were incorporated into the ERI calculation as of 301-2019 Addendum B.

Note

Dehumidifiers are currently modeled as located within conditioned space; the model is not suited for a dehumidifier in, e.g., a wet unconditioned basement or crawlspace. Therefore the dehumidifier Location is currently restricted to “conditioned space”.

HPXML Cooking Range/Oven

A single cooking range can be entered as a /HPXML/Building/BuildingDetails/Appliances/CookingRange.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
Location	string		See [263]	Yes		Location
FuelType	string		See [264]	Yes		Fuel type
IsInduction	boolean			Yes		Induction range?

[263]

Location choices are “conditioned space”, “basement - conditioned”, “basement - unconditioned”, “garage”, “other housing unit”, “other heated space”, “other multifamily buffer space”, or “other non-freezing space”. See HPXML Locations for descriptions.

[264]

FuelType choices are “natural gas”, “fuel oil”, “propane”, “electricity”, “wood”, or “wood pellets”.

If a cooking range is specified, a single oven is also entered as a /HPXML/Building/BuildingDetails/Appliances/Oven.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
IsConvection	boolean			Yes		Convection oven?

HPXML Lighting & Ceiling Fans

Lighting and ceiling fans are entered in /HPXML/Building/BuildingDetails/Lighting.

HPXML Lighting

Multiple /HPXML/Building/BuildingDetails/Lighting/LightingGroup elements must be provided, each of which is the combination of:

• LightingType: ‘LightEmittingDiode’, ‘CompactFluorescent’, and ‘FluorescentTube’

• Location: ‘interior’, ‘exterior’, and ‘garage’ (garage lighting groups only required if a garage is present)

Use LightEmittingDiode for Tier II qualifying light fixtures; use CompactFluorescent and/or FluorescentTube for Tier I qualifying light fixtures.

Information is entered in each LightingGroup.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
LightingType	element		1 [265]	Yes		Lighting type
Location	string		See [266]	Yes		Lighting location [267]
FractionofUnitsInLocation	double	frac	0 - 1 [268]	Yes		Fraction of light fixtures in the location with the specified lighting type

[265]

LightingType child element choices are LightEmittingDiode, CompactFluorescent, or FluorescentTube.

[266]

Location choices are “interior”, “garage”, or “exterior”.

[267]

Garage lighting location is ignored if the HPXML file has no garage specified elsewhere.

[268]

The sum of FractionofUnitsInLocation for a given Location (e.g., interior) must be less than or equal to 1. If the fractions sum to less than 1, the remainder is assumed to be incandescent lighting.

HPXML Ceiling Fans

Each ceiling fan is entered as a /HPXML/Building/BuildingDetails/Lighting/CeilingFan.

Element	Type	Units	Constraints	Required	Default	Notes
SystemIdentifier	id			Yes		Unique identifier
Airflow[FanSpeed="medium"]/Efficiency	double	cfm/W	> 0	Yes		Efficiency at medium speed
Count	integer		> 0	Yes		Number of similar ceiling fans

HPXML Locations

The various locations used in an HPXML file are defined as follows:

Value	Description	Temperature	Building Type
outside	Ambient environment	Weather data	Any
ground		EnergyPlus calculation	Any
conditioned space	Above-grade conditioned floor area	EnergyPlus calculation	Any
attic - vented		EnergyPlus calculation	Any
attic - unvented		EnergyPlus calculation	Any
basement - conditioned	Below-grade conditioned floor area	EnergyPlus calculation	Any
basement - unconditioned		EnergyPlus calculation	Any
crawlspace - vented		EnergyPlus calculation	Any
crawlspace - unvented		EnergyPlus calculation	Any
garage	Single-family (not shared parking)	EnergyPlus calculation	Any
other housing unit	Unrated Conditioned Space	Same as conditioned space	SFA/MF only
other heated space	Unrated Heated Space	Avg of conditioned space/outside; min of 68F	SFA/MF only
other multifamily buffer space	Multifamily Buffer Boundary	Avg of conditioned space/outside; min of 50F	SFA/MF only
other non-freezing space	Non-Freezing Space	Floats with outside; minimum of 40F	SFA/MF only
other exterior	Water heater outside	Weather data	Any
exterior wall	Ducts in exterior wall	Avg of conditioned space/outside	Any
under slab	Ducts under slab (ground)	EnergyPlus calculation	Any
roof deck	Ducts on roof deck (outside)	Weather data	Any

Validating & Debugging Errors

When running HPXML files, errors may occur because:

1. An HPXML file provided is invalid (either relative to the HPXML schema or the ERI Use Case).

2. An unexpected error occurred in the workflow (e.g., applying the ERI 301 ruleset).

3. An unexpected EnergyPlus simulation error occurred.

If, for example, the Rated Home is unsuccessful, first look in the ERIRatedHome/run.log for details. If there are no errors in that log file, then the error may be in the EnergyPlus simulation – see ERIRatedHome/eplusout.err.

Contact us if you can’t figure out the cause of an error.

Sample Files

Dozens of sample HPXML files are included in the workflow/sample_files directory. The sample files help to illustrate how different building components are described in HPXML.

Each sample file generally makes one isolated change relative to the base HPXML (base.xml) building. For example, the base-dhw-dwhr.xml file adds a DrainWaterHeatRecovery element to the building.

You may find it useful to search through the files for certain HPXML elements or compare (diff) a sample file to the base.xml file.