Material Name

Applicability

Opaque constructions

Definition

The name of a construction material used.

Units

Text: unique

Input Restrictions

Material name is a required input for materials not available from the standard list in ACM Appendix 5.5A. The user may not modify entries for predefined materials.

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Applicability

Opaque constructions

Definition

The density, mass per unit volume, of the construction material as documented in Appendix 5.5A.

Units

lb/ft³

Input Restrictions

Prescribed from Appendix 5.5A

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Applicability

Opaque constructions

Definition

The specific heat capacity of a material is numerically equal to the quantity of heat that must be supplied to a unit mass of the material to increase its temperature by 1°F

Units

Btu/lb·°F

Input Restrictions

Prescribed from Appendix 5.5A

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Applicability

All non-standard materials

Definition

The thermal conductivity of a material of unit thickness is numerically equal to the quantity of heat that will flow through a unit area of the material when the temperature difference through the material is 1°F.

Units

Btu/lb·°F

Input Restrictions

Prescribed from Appendix 5.5A

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Thickness

Applicability

All non-standard materials

Definition

The thickness of a material

Units

Inches

Input Restrictions

Prescribed from Appendix 5.5A

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Assembly Name

Applicability

All projects

Definition

The name of a construction assembly that describes a roof, wall, or floor assembly. The name generally needs to be unique so it can be referenced precisely by surfaces.

Units

Text

Input Restrictions

Required input and name must be unique.

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Specification Method

Applicability

All projects

Definition

The method of describing a construction assembly. The common method is to describe the construction assembly as a series of layers, each layer representing a material. For slab-on-grade constructions, exterior insulation levels are specified, and the compliance software determines the corresponding F-factor from Reference Joint Appendix IV tables.

Units

List: layers, F-factor

Input Restrictions

The layers method shall be used for all above-grade constructions

Standard Design

For each construction, the proposed design specification method shall be used.

Standard Design:

Existing Buildings

Same as new construction

Layers

Applicability

All construction assemblies that use the layers method of specification

Definition

A structured list of material names that describe a construction assembly, beginning with the exterior finish and progressing through the assembly to the interior finish. Material names must be from the standard list (Appendix E) or defined (see above) ACM Appendix 5.5A.

Units

List: layers of construction assembly

Input Restrictions

The user is required to describe all layers in the actual assembly and model the proposed design based the layer descriptions.

Standard Design

See building descriptors for roofs, exterior walls, exterior floors, doors, fenestration, and below-grade walls.

Standard Design:

Existing Buildings

Same as new construction

Roof Name

Applicability

All roof surfaces

Definition

A unique name or code that identifies the roof and ties it to the construction documents submitted for energy code review. It is not mandatory to name roofs.

Units

Text

Input Restrictions

Name must be unique

Standard Design

N/A

Standard Design:

Existing Buildings

N/A

Roof Type

Applicability

All roof surfaces

Definition

A roof classification defined in the standards. This descriptor can be derived from other building descriptors and it may not be necessary for the software user to specify it directly.

Units

List: attic and other roofs; metal building roofs; and roofs with insulation entirely above deck metal building, wood framed or other

Input Restrictions

Not applicable for new construction; as designed for existing buildings

Standard Design

All roofs in the standard design are modeled as wood-framed and other.

Standard Design:

Existing Buildings

Same as proposed

Roof Geometry

Applicability

All roofs

Definition

Roof geometry defines the position, orientation, azimuth, tilt, and dimensions of the roof surface. The details of how the coordinate system is implemented may vary between software programs. The data structure for surfaces is described in the reference section of this chapter.

Units

Data structure: surface

Input Restrictions

There are no restrictions other than that the surfaces defined must agree with the building being modeled, as represented on the construction drawings or as-built drawings.

Standard Design

Roof geometry will be identical in the proposed and standard design building designs.

For alterations, roof geometry will be fixed, based on one of the building prototypes (office, retail, etc.)

Standard Design:

Existing Buildings

Same as new construction

Roof Solar Reflectance

Applicability

All opaque exterior roof surfaces exposed to ambient conditions

Definition

The solar reflectance of a material. For roofing materials, the three-year aged reflectance value from CRRC testing should be used if available.

Units

Input Restrictions

For roofs that are part of new construction, if asphalt shingles or composition shingles are not rated by the CRRC, the default aged solar reflectance shall be equal to 0.08 for asphalt roofs and 0.10 for all other roof types. The default value may be overridden when roof materials are used that the CRRC has tested and are called for in the construction documents. In cases where the default value is overridden, the user is required to submit documentation identifying the test procedure that was used to establish the non-default values. If the aged CRRC reflectance is not known, the aged CRRC reflectance may be calculated from the initial CRRC reflectance using the following equation:

ƿ_aged = 0.2 + β · (ƿ_init – 0.2)

Where,

ƿ_aged = the calculated aged reflectance

β = 0.65 for field-applied coatings, 0.7 for all other roof surfaces

ƿ_init = the initial CRRC reflectance

As a compliance option, low-sloped roofs that use aggregate may specify an aged reflectance of 0.50 if the product meets the following criteria:

1. Conforms to material standard ASTM D1863.

2. Conforms to ASTM D448, size number equal between No.6 and No.7.

3. Has a CRRC‐tested initial solar reflectance that meets or exceeds 0.55 using the ASTM E1918 test procedure with aggregate passing a No. 4 sieve and is retained by a No. 8 sieve that conforms to ASTM D448, conducted by a CRRC-accredited independent laboratory meeting the requirement of Section 10‐113(d)4 of the Building Energy Efficiency Standards. 

4. Has a label on bags or containers of aggregate stating that the materials conform to ASTM D1863 and ASTM D448.

Standard Design

For new construction, the standard design reflectance is defined in Table 140.3-B for nonresidential buildings, Table 140.3-C for high-rise residential buildings and hotel-motel buildings containing guestrooms, and Table 140.3-D for relocatable classroom buildings.

For alterations to more than 50 percent of the roof area or roof areas above 2,000 ft², the standard design shall be modeled as the more efficient of either the existing conditions or the values required for cool roofs under Section 141.0 of the standards.

Standard Design:

Existing Buildings

Same as new construction

Roof Thermal Emittance

Applicability

All opaque exterior roof surfaces exposed to ambient conditions

Definition

The thermal emittance of a material. For roofing materials, the three-year aged emittance value from CRRC testing should be used if available.

Units

Input Restrictions

For roofs, new construction: as designed, from CRRC values. If CRRC rating information is not available, the default thermal emittance shall be 0.85. Aggregate that meets the following criteria may specify a thermal emittance of 0.85:

1. Conforms to material standard ASTM D1863.

2. Conforms to ASTM D448, size number equal between No.6 and No.7.

3. Has a CRRC‐tested initial solar reflectance that meets or exceeds 0.55 using the ASTM E1918 test procedure with aggregate passing a No. 4 sieve and is retained by a No. 8 sieve that conforms to ASTM D448, conducted by a CRRC accredited independent laboratory meeting the requirement of Section 10‐113(d)4 of the Building Energy Efficiency Standards.

4. Has a label on bags or containers of aggregate stating that the materials conform to ASTM D1863 and ASTM D448.

Standard Design

For roofs, new construction, the standard design thermal emittance shall be 0.85.

For alterations to more than 50 percent of the roof area or roof areas above 2,000 ft², the standard design shall be modeled as the more efficient of either the existing conditions or a thermal emittance of 0.85.

Standard Design:

Existing Buildings

If the existing roof is unaltered, same as proposed. For alterations, the standard design is 0.85.

Roof Construction

Applicability

All roofs

Definition

A specification containing a series of layers that result in a construction assembly for the proposed design. The first layer in the series represents the outside (or exterior) layer and the last layer represents the inside (or interior) layer. See the building descriptors above for roof construction type.

Units

List: layers

Input Restrictions

The area-weighted average of the roof construction assembly U-factors, defined by a series of layers, must be equal to or more efficient than the mandatory U-factor requirements of Section 120.7 of the standards for new construction, and Section 141.0 of the standards for alterations. Note that these U-Factor requirements assume an exterior air film of R-0.17 and an interior air film of R-0.61. Each layer specified must be listed in the materials database in the ACM Appendix 5.5A.

New Construction

Additions and Alterations

Appropriate R-values for insulation can be calculated using the formula below.

Ceilings that form the boundary between the modeled building of an additions and alterations project and the existing, un-modeled portion of the building may be modeled as adiabatic roofs (no heat transfer).

Standard Design

Roofs in the standard design are of the type “insulation entirely above deck.” The insulation requirement is determined by climate zone. The standard design building roof construction shall be modeled as layers as defined. See Appendix 5.5B for details.

For new construction, the standard design roof type is wood framed and other, and the roof is a standing seam metal roof, with the R-value of continuous insulation adjusted to match the prescriptive standards for wood-framed and other roofs. The U-factor required for roof construction is defined in Table 140.3-B, C or D of the standards. Programs that model a U-factor shall include an exterior and interior air film resistance. The standard design construction is based on JA4-10 Table 4.2.7 and assumes an exterior air film of R-0.17 and an interior air film of R-0.61.

The standard design construction shall include the following layers:

The value of the continuous insulation layer entirely above framing shall be set to achieve the following R-values:

Nonresidential Buildings: Continuous Insulation

High-Rise Residential Buildings and Hotel/Motel Guestrooms: Continuous Insulation

For mixed-use buildings, the roof standard design requirements shall be determined by which space type (nonresidential or residential) is the majority of the floor area of the adjoining conditioned spaces.

For re-locatable classroom buildings, the standard design shall use the construction assembly corresponding to the most stringent of requirements in any climate zone, or R-28.63 continuous insulation.

For alterations, any approved roof type may be used. The U-factor in the standard design shall be modeled as the more efficient of either the existing conditions or the values stated in Section 141.0 of the standards. Where applicable, selection shall be based on building type, assembly, and climate zone. A construction of layers shall be defined to yield an equivalent U-factor.

Standard Design:

Existing Buildings

For existing buildings, if the roof component is not altered, the standard design roof construction shall match the proposed design roof construction of the existing building. If the roof is altered, the roof component shall meet the prescriptive requirements for new construction for the roof type of the existing building.

The roof type of the existing building is either a metal building roof or a wood-framed or other roof. The standard design roof assemblies for altered roofs are shown below for the appropriate climate zones.

Alterations Roof Standard Design:

For alterations, any approved roof type may be used. The U-factor in the standard design shall be modeled as the more efficient of either the existing conditions or the values stated in Section 141.0 of the standards. Where applicable, selection shall be based on building type, assembly, and climate zone. A construction of layers shall be defined to yield an equivalent U-factor.

Wall Name

Applicability

All walls

Definition

A unique name or code that relates the exterior wall to the design documents. This is an optional input since there are other acceptable ways to key surfaces to the construction documents.

Units

Text

Input Restrictions

Must be unique

Standard Design

None

Standard Design:

Existing Buildings

None

Applicability

All walls

Definition

One of four categories of above-grade wall assemblies used to determine minimum insulation requirements for walls. The five wall type categories are as follows:

1.   Mass Light

2.   Mass Heavy

3.   Metal building

4.   Metal framing

5.   Wood framing and other walls

A mass light wall is defined as a wall with total heat capacity greater than 7 but less than 15 Btu/ft²-. A mass heavy wall is defined as a wall with a total heat capacity of 15 Btu/ft²-°F or greater. (Heat capacity is defined as the product of the specific heat in Btu/lb-°F, the thickness in ft, and the density in lb/ft³.)

Units

List: mass light, mass heavy, metal building walls, metal framing walls, and wood framing and other walls

Input Restrictions

This input is required for existing buildings when any wall is altered. This input is not required for new construction.

Standard Design

All walls in the standard design building are modeled as “metal framed.”

Standard Design:

Existing Buildings

Same as proposed

Wall Geometry

Applicability

All walls

Definition

Wall geometry defines the position, orientation, azimuth, and tilt of the wall surface. The data structure for surfaces is described in the reference section of this chapter.

Units

Data structure: surface

Input Restrictions

As designed

Standard Design

Same as proposed

Standard Design:

Existing Buildings

Same as proposed

Wall Solar Reflectance

Applicability

All opaque exterior walls exposed to ambient conditions

Definition

The solar reflectance of a material.

Units

Unitless ratio

Input Restrictions

For walls and other non-roof surfaces, the value is prescribed to be 0.3.

Standard Design

For walls and other non-roof surfaces, the value is prescribed to be 0.3.

Standard Design:

Existing Buildings

0.3

Wall Thermal Emittance

Applicability

All opaque exterior walls exposed to ambient conditions

Definition

The thermal emittance of a material.

Units

Unitless ratio

Input Restrictions

For walls and other non-roof surfaces, the value is prescribed to be 0.9

Standard Design

For walls and other non-roof surfaces, the thermal emittance is 0.9

Standard Design:

Existing Buildings

For walls and other non-roof surfaces, the thermal emittance is 0.9

Wall Construction

Applicability

All walls that use the layers method

Definition

A specification containing a series of layers that result in a construction assembly for the proposed design. The first layer in the series represents the outside (or exterior) layer and the last layer represents the inside (or interior) layer. See the building descriptors above for wall construction type.

Units

List: Layers

Input Restrictions

The area weighted-average of the construction assembly U-factors, defined by a series of layers, must be equal to or more efficient than the mandatory U-factor requirements of Section 120.7 of the standards for new construction. Note that these U-Factor requirements assume an exterior air film of R-0.17 and an interior air film of R-0.68. Each layer specified, with the exception of composite layers, must be listed in the materials database in the ACM Appendix 5.5A.

Newly Constructed

Additions and Alterations          

Appropriate R-values for insulation can be calculated using the formula below.

Walls that form the boundary between the modeled building of an additions and alterations project and the existing, un-modeled portion of the building may be modeled as adiabatic walls (no heat transfer).

Standard Design

The U-factor required for wall construction of the standard design building is defined in Table 140.3-B, C or D of the standards. Programs that model a U-factor shall use an exterior and interior air film resistance. The standard design construction is based on JA4-10 Table 4.3.3 and assumes an exterior air film of R-0.17 and an interior air film of R-0.68.

For metal framed walls, the standard design construction shall include the following layers:

Standard Design:

Existing Buildings

The value of the continuous insulation layer entirely outside framing shall be set to achieve the following R-values:

Nonresidential Buildings: Continuous Insulation

High-Rise Residential Buildings and Hotel/Motel Guestrooms: Continuous Insulation

For mixed-use buildings that contain both nonresidential and residential spaces, walls adjacent to nonresidential spaces shall use the Nonresidential Buildings standard design construction, and walls adjacent to residential and high-rise residential spaces shall use the high-rise residential standard design construction.

For relocatable classroom buildings, the standard design shall use the construction assembly corresponding to the most stringent of requirements in any climate zone, or R-13.94 continuous insulation.

Floor Name

Applicability

All floor surfaces

Definition

A unique name or code that relates the exposed floor to the design documents.

Exposed floors include floors exposed to the outdoors and floors over unconditioned spaces, but do not include slab-on-grade floors, below grade floors, or interior floors.

Units

Text

Input Restrictions

Must be unique

Standard Design

None

Standard Design:

Existing Buildings

None

Floor Type

Applicability

All exterior floor surfaces, optional

Definition

The category that defines the standard design prescriptive floor requirements

Units

List: mass or other

Input Restrictions

Standard Design

The standard design building floors shall be of type “other” 

Standard Design:

Existing Buildings

Same as proposed

Floor Geometry

Applicability

All exterior floors

Definition

Floor geometry defines the position, orientation, azimuth, and tilt of the floor surface. The details of how the coordinate system is implemented may vary between software programs. The data structure for surfaces is described in the reference section of this chapter.

Units

Data structure: surface

Input Restrictions

As designed. Required input.

Standard Design

Standard design building floor geometry is identical to the proposed design.

Standard Design:

Existing Buildings

Same as proposed.

Floor Construction

Applicability

All floors

Definition

A specification containing a series of layers that result in a construction assembly for the proposed design. The first layer in the series represents the outside (or exterior) layer and the last layer represents the inside (or interior) layer. See the building descriptors above for floor construction type.

Units

List: Layers

Input Restrictions

The area weighted-average of the floor construction assembly U-factors, defined by a series of layers, must be equal to or more efficient than the mandatory U-factor requirements of Section 120.7 of the standards for new construction, and Section 141.0 of the standards for alterations. Note that these U-factor requirements assume an exterior air film of R-0.17 and an interior air film of R-0.92. Each layer specified must be listed in the materials database in the ACM Appendix 5.5A.

New Construction

Additions and Alterations          

Appropriate R-values for insulation can be calculated using the formula below.

Floors that form the boundary between the modeled building of an addition and alteration project and the existing, un-modeled portion of the building may be modeled as adiabatic floors (no heat transfer).

Standard Design

The U-factor required for floor construction is defined in Table 140.3-B, C or D of the standards. Programs that model a U-factor shall use an exterior and interior air film resistance. The standard design construction is based on JA4-10 Table 4.4.5 and assumes an exterior air film of R-0.17 and an interior air film of R-0.92.

For metal framed floors, the standard design construction shall include the following layers:

Standard Design:

Existing Buildings

The value of the continuous insulation layer entirely above or below framing shall be set to achieve the following R-values:

Nonresidential Buildings: Continuous Insulation

High-Rise Residential Buildings and Hotel/Motel Guestrooms: Continuous Insulation

Door Name

Applicability

All exterior doors, optional input

Definition

A unique name or code that relates the door to the design documents submitted. Doors that are more than 50 percent glass are treated as windows and must be determined and entered by using the Fenestration building descriptors.

Units

Text: unique

Input Restrictions

None

Standard Design

None

Standard Design:

Existing Buildings

None

Door Type

Applicability

All exterior doors, required input

Definition

One of two door classifications of either: swinging or non-swinging. Non-swinging are generally roll-up doors. The prescriptive U-factor requirements depend on door type and climate. This building descriptor may be derived from other building descriptors, in which case a specific input is not necessary.

Units

List: swinging or non-swinging

Input Restrictions

The door type shall be consistent with the type of door represented on the construction documents or as-built drawings.

Standard Design

The standard design building door type shall be the same as the proposed design.

Standard Design:

Existing Buildings

Same as new construction

Door Geometry

Applicability

All exterior doors

Definition

Door geometry defines the position and dimensions of the door surface relative to its parent wall surface. The azimuth and tilt (if any) of the door is inherited from the parent surface. The position of the door within the parent surface is specified through (X, Y) coordinates. The size is specified as a height and width (all doors are generally assumed to be rectangular in shape). The details of how the geometry of doors is specified may vary for each energy simulation program.

Units

Data structure: opening

Input Restrictions

As designed

Standard Design

Door geometry in the standard design building is identical to the proposed design.

Standard Design:

Existing Buildings

Same as new construction

Door Construction

Applicability

All exterior doors

Definition

The thermal transmittance of the door, including the frame.

Units

Btu/h·ft²·°F

Input Restrictions

The construction assembly must be equal to or more efficient than the mandatory U-factor requirements of Section 110.6 of the standards for new construction. There are no restrictions for alterations.

Standard Design

For new construction, the U-factor required for door construction is defined in Table 140.3-B, C or D of the standards.

Nonresidential Buildings – U Factor:

High-Rise Residential Buildings and Hotel/Motel Guestrooms – U Factor:

Standard Design:

Existing Buildings

For alterations, the U-factor in the standard design is either the same standard design as the new construction standard design if the door is replaced, or the equal to the existing door construction, if the door is unaltered. Where applicable, selection shall be based on building type, assembly, and climate zone.

Operable Door Opening Type

Applicability

All exterior doors

Definition

The opening type that determines whether interlocks with mechanical cooling and heating are required, per Section 140.4(n). If manual, then interlocks are required when operable windows are present in any nonresidential space, excluding high-rise residential and healthcare spaces and buildings. If self-closing or a glazed door, interlocks are not required and are not present in the standard design.

Units

Btu/h·ft²·°F

Input Restrictions

List: Self-Closing, Manual, Glazed Door

Standard Design

Same as Proposed

Standard Design:

Existing Buildings

Fenestration Name

Applicability

All fenestration, optional input

Definition

A unique name or code that relates the fenestration to the design documents and a parent surface.

Units

Text: unique

Input Restrictions

None

Standard Design

None

Standard Design:

Existing Buildings

None

Fenestration Type (Vertical Fenestration)

Applicability

All vertical fenestration

Definition

This is a classification of vertical fenestration that determines the thermal performance and solar performance requirement for vertical fenestration

Units

List: Fixed, Operable, Curtain Wall, or Glazed Doors

Input Restrictions

As designed

Standard Design

Same as the proposed design

Standard Design:

Existing Buildings

Same as new construction

Fenestration Type (Skylights)

Applicability

All skylights

Definition

This is a classification of skylights that determines the thermal performance and solar performance requirement for vertical fenestration

Units

List: Glass, Curb-mounted, Glass, Deck-mounted, Plastic, or Tubular Daylighting Devices (TDD)

Input Restrictions

As designed

Standard Design

Same as the proposed design

Standard Design:

Existing Buildings

Same as new construction

Default Fenestration Type

Applicability

All fenestration that uses default thermal performance factors

Definition

This is a classification of fenestration that determines the thermal performance for fenestration using defaults from standards Section 110.6, Table 110.6-A. This is used for fenestration without National Fenestration Rating Council (NFRC) ratings or for fenestration for altered buildings that includes window films.

Units

List: fixed, operable, greenhouse/garden, doors, or skylight

Input Restrictions

As designed

Standard Design

Not applicable

Standard Design:

Existing Buildings

Default Glazing Type

Applicability

All fenestration that uses default thermal performance factors

Definition

This is a classification of fenestration that determines the thermal performance for fenestration using defaults from standards Section 110.6, Table 110.6-A. This is used for fenestration without NFRC ratings or for fenestration for altered buildings that includes window films.

Units

List: single pane, double pane, glass block

Input Restrictions

As designed

Glass block is only allowed if the default fenestration type is operable or fixed.

Standard Design

Not applicable

Standard Design:

Existing Buildings

Default Framing Type

Applicability

All fenestration that uses default thermal performance factors and window films for altered fenestration

Definition

This is a classification of fenestration that determines the thermal performance for fenestration using defaults from standards Section 110.6, Table 110.6-A. This is used for fenestration without NFRC ratings or for fenestration for altered buildings that includes window films.

Units

List: metal, metal with thermal break, or nonmetal

Input Restrictions

As designed

Standard Design

Not applicable

Standard Design:

Existing Buildings

Fenestration Geometry

Applicability

All fenestration

Definition

Fenestration geometry defines the position and dimensions of the fenestration surface within its parent surface and the identification of the parent surface. The orientation and tilt is inherited from the parent surface. The details of how the coordinate system is implemented may vary between compliance software programs.

Display Perimeter:

Display perimeter is the length of an exterior wall in a B-2 occupancy that immediately abuts a public sidewalk, measured at the sidewalk level for each story that abuts a public sidewalk. The compliance software shall allow the user to specify a value for the length of display perimeter, in feet, for each floor or story of the building. The user entry for display perimeter shall have a default value of zero. Note: Any non-zero input for display perimeter is an exceptional condition that shall be reported on the PRF-1 exceptional condition list and shall be reported on the ENV forms. The value for display perimeter is used as an alternate means of establishing maximum wall fenestration area in the standard design (§140.3 of the standards).

The display perimeter shall be calculated separately for west-facing fenestration, and for non-west facing fenestration.

Floor Number:

The compliance software shall also allow the user to specify the display perimeter associated with each floor (story) of the building.

Units

Data structure: opening                                 

Geometry is defined relative to the parent surface and can include setbacks.

Inputs include:

Geometry of opening (window or skylight), parent surface, display perimeter (optional), percent of roof area exempt from skylight requirements §140.3 of the standards.

Input Restrictions

As designed

Specification of the fenestration position within its parent surface is required for the following conditions:

1) Exterior shading is modeled from buildings, vegetation, or other objects; or

2) If daylighting is modeled within the adjacent space.

Standard Design

The standard design calculates the window wall ratio (WWR) for each orientation and the overall window wall ratio for the building. The window wall ratio is the total fenestration area (including framing) divided by the gross exterior wall area (excluding wall area that is underground). Note that exterior wall area that is below grade, but has exposure to ambient conditions, and any associated fenestration, is included in the WWR calculation.

The standard design vertical fenestration area and horizontal fenestration area for spaces that are specified as computer rooms or data centers (a server process load of 20W/ft² or higher) shall be zero.

For all other buildings, the geometry of the fenestration in the standard design shall be identical to the proposed design with the following exceptions:

Exception 1: Either the whole building window wall ratio or west window wall ratio exceeds 40 percent.

Exception 2: If display perimeter is entered, the fenestration area exceeds the greater of 40 percent of the gross wall area (excluding adiabatic walls) and six times the display perimeter.

Exception 1: The fenestration is adjusted based on the following conditions:

            Case 1. WWR_o > 0.40, WWR_w ≤0.40

In this case, the fenestration area of all windows is reduced by multiplying the fenestration area by the ratio 0.40/WWR_o. The dimensions of each window are reduced by increasing the sill height so that the window height is modified by the multiplier (0.40/WWR_o) so that the same window width is maintained.

            Case 2:  WWR_o < 0.40. WWR_w > 0.40

In this case, the fenestration area of all windows on the west orientation is reduced by multiplying the fenestration area by the ratio 0.40/WWR_o. The dimensions of each window are reduced by multiplying the proposed window dimension by increasing the sill height so that the window height is modified by the multiplier (0.40/WWR_o), so that the window width is maintained.

            Case 3:  WWR_o > 0.40. WWR_w > 0.40

If both the west window wall ratio and the overall window wall ratio exceed the prescriptive limit of 0.40, the fenestration areas must be reduced by:

1) Adjust the west window area multiplying the west window area by the ratio 0.4/WWR_w.

2) Calculate the WWR of the north, east and south facades:

WWR_nes = Window Area_nes / Gross Wall Area_nes

3) Adjust the window area of the windows on the north, east and south facades by the following ratio:

WindowArea_N,std = WindowArea_N,prop × 0.4 / WWR_nes

WindowArea_E,std = WindowArea_E,prop × 0.4 / WWR_nes

WindowArea_S,std = WindowArea_S,prop × 0.4 / WWR_nes

4) Adjust each window geometry for the west façade by multiplying the window height by (0.4/WWR_w) by adjusting the sill height and by maintaining the same window width.

5) Adjust each window geometry for the north, east and south façade by multiplying the window height by (0.4/WWR_nes) by adjusting the sill height and by maintaining the same window width.

Exception 2: If the display perimeter is entered and the window area exceeds the prescriptive limit, the window area for the standard design is calculated by multiplying the proposed window area by the following ratio:

WindowArea_std = 6 x DisplayPerimeter

The geometry of each window is modified by the following, and by modifying the sill height but not the head height position relative to the floor:

WindowHeight_std = WindowHeight_prop x (WindowArea_std/WindowArea_prop)

WindowWidth_std = WindowWidth_prop

The following rules apply for calculating geometry of skylights. For the calculation of the standard design skylight area, the gross roof area is defined as the total roof area, including skylights, that is directly over conditioned space.

The skylight area of the standard design is set:

1) For buildings without atria or with atria having a height less than 55 feet over conditioned space, the smaller of the proposed skylight area and 5 percent of the gross roof area that is over conditioned space.

2) For buildings with atria at a height of 55 ft or greater over conditioned spaces, the smaller of the proposed skylight area and 10 percent of the gross roof area that is over conditioned space.

3) For buildings with atria or other roof area directly over unconditioned spaces, the smaller of the proposed skylight area or 5 percent of the roof area excluding the atria area and excluding any adiabatic walls, if present in the modeled building. The skylight area of the atria or roof area directly over unconditioned space is not included in the skylight area limit in this case.

The skylight area for atria over unconditioned space is not included in determining the skylight to roof ratio (SRR) for the building.

Depending on the following condition, adjustments to the SRR as described shall be made.

     i.      For open spaces other than auditoriums, churches, movie theaters, museums and refrigerated warehouses, for buildings in climate zones 2 through 15, and when spaces have ceiling heights greater than 15 ft and floor areas greater than 5000 ft², the skylight area shall be the greater of 3 percent or the area required to provide daylight coverage through skylights or primary side lighting to 75 percent of the floor area in the space. See 5.4.5 for detail description on primary daylit area and skylit daylit area.

     ii.     If the above condition is met and SRR ≤ 0.05, no adjustments are needed.

     iii.    If the condition is met and SRR > 0.05, skylight dimensions = Existing Dimension x [1- √ (0.05/SRR of Proposed Building)]

     iv.    If the condition is not met triggering the need for additional skylights, the standard design case shall be modeled with new skylights irrespective of the skylight location of the proposed case. The new skylights shall be distributed uniformly such that there is no overlapping of primary daylit areas from skylights or sidelights. The dimension of the new skylights shall be the same as the proposed design if calculated new SRR ≤ 0.05. If SRR > 0.05, skylight dimensions = existing dimension x [1- √ (0.05/SRR of proposed building)].

Note that the adjustments to SRR are done after adjustments to WWR, if any are completed.

Standard Design:

Existing Buildings

For alterations of existing vertical fenestration or skylights, where no fenestration area is added, the fenestration geometry of the standard design shall be the same as the proposed for the existing building.

For additions of vertical fenestration or skylights, where the additional fenestration causes the fenestration area to exceed the limit of 40 percent window to wall ratio (WWR) for the building, 40 percent WWR for the west orientation of the building, 5 percent skylight to roof ratio (SRR) for existing buildings without atria 55 feet or higher, or 10 percent SRR for existing buildings with atria 55 feet or higher, the fenestration geometry for the standard design shall be adjusted from the proposed design according to the rules set forth under the standard design rules.

For additions of vertical fenestration and/or skylights that do not cause the fenestration area to exceed any of these limits, the fenestration geometry of the standard design shall be the same as the proposed design.

Skylight Requirement Exception Fraction

Applicability

All buildings with interior ceiling heights greater than 15 feet

Definition

The fraction of floor area that is exempt from the minimum skylight area requirement for spaces with high ceilings.

Identifying areas subject to §140.3 of the standards:

When a proposed space has ceiling heights greater than 15 ft, with exterior surfaces having a tilt angle less than 60 degrees (roofs) and no more than three stories above grade, the user shall enter the fraction of the modeled space that is exempt from requirements of §140.3 of the standards. If the proposed design has skylights, the user shall also indicate the area of the proposed design daylight area under skylights in this space. When the user enters a value greater than zero percent for the fraction of the space area exempt to §140.3 of the standards, the compliance software shall require that the user indicate at least one of the following exceptions:

1.   The building is not located in climate zone 1 or climate zone 16

2.   Designed general lighting is less than 0.5 W/ft²

3.   Existing walls on plans result in enclosed spaces less than 5,000 ft²

4.   Future walls or ceilings on plans result in enclosed spaces less than 5,000 ft² or ceiling heights less than 15 ft

5.   Plans or documents show that space is an auditorium, religious building of worship, movie theater, museum, or refrigerated warehouses

Units

List five exceptions listed above (specified if fraction > 0)

Input Restrictions

No restrictions, other than that the vertical fenestration type must agree with the type specified on the construction documents or the as-built drawings

Standard Design

Same as the proposed design

Standard Design:

Existing Buildings

Not applicable

Fenestration Construction

Applicability

All fenestration

Definition

A collection of values that together describe the performance of a fenestration system.

The values that are used to specify the criteria are U-factor, SHGC, and VT. U-factor and SHGC inputs are whole-window values.

Units

Data structure: shall include at a minimum the following properties as specified by NFRC ratings:

U-factor: whole window U-factor

SHGC: whole window solar heat gain coefficient

VT: visible transmittance

Input Restrictions

For new construction, performance information for fenestration shall be obtained from NFRC test results or shall be developed from procedures outlined in Section 110.6 of the standards, as specified below. Values entered shall be consistent with the specifications and the construction documents.

For manufactured products:

•   U-factor, SHGC, and VT shall be equivalent to NFRC rated values.

•   For products not rated by NFRC, U-factor, SHGC and VT shall be determined from Energy Commission default tables (110.6-A and 110.6-B).

For site built products:

•   U-factor, SHGC, and VT shall be equivalent to NFRC rated values.

•   For products not rated by NFRC, up to 200 ft² of fenestration (total of new and altered) may use center of glass properties and Reference Appendix NA6 equations to calculate U-factor, SHGC, and VT. Any site-built fenestration in excess of 200 ft² must use the default values in Table 110.6-A and 110.6-B.

For buildings with fenestration area that meets requirements for use of center-of-glass U-factor and SHGC, the fenestration overall U-factor, SHGC, and VT shall be determined by the following equations from the Reference Appendix NA6:

U_T = C₁ + (C₂ · U_c)

SHGC_T = 0.08 + (0.86 · SHGC_c)

VT_T = VT_F · VT_C

Where,

U_T = U-factor is the total performance of the fenestration including glass and frame

C₁ = Coefficient selected from Table NA6-5 in Reference Appendix NA6

C₂ = Coefficient selected from Table NA6-5 in Reference Appendix NA6

U_C = Center of glass U-factor calculated in accordance with NFRC 100 Section 4.5.3.1

SHGC_T = Total SHGC performance including glass and frame SHGC_C = Center of glass SHGC calculated in accordance with NFRC 200 Section 4.5.1.1

VT_T = Is the total performance of the fenestration including glass and frame

VT_F = 0.53 for projecting windows, such as casement and awning windows

VT_F = 0.67 for operable or sliding windows

VT_F = 0.77 for fixed or non-operable windows

VT_F = 0.88 for curtain wall/storefront, site-built and manufactured non-curb mounted skylights

VT_F = 1.0 for curb mounted manufactured skylights

VT_C = Center of glass VT is calculated in accordance with NFRC 200 Section 4.5.1.1 or NFRC 202 for Translucent Products or NFRC 203 for Tubular Daylighting Devices and Hybrid Tubular Daylighting Devices or ASTM E972

For skylights, the default values shall be the alternate default U-factor and SHGC using default calculations specified above and in Reference Appendix NA6 or the U-factor and SHGC listed in Table 110.6-A and Table 110.6-B in the standards.

Standard Design

For new construction, the requirements for vertical fenestration U factor, SHGC, and visible light transmission by window or skylight type and framing type are specified in Table 140.3-B, C, or D of the standards. For plastic skylights, SHGC of 0.50 is assumed.

Standard Design:

Existing Buildings

The U-factor, SHGC, and VT in the standard design shall be modeled as design if unchanged, as the values stated in Table 141.0-A of the standards when the existing window area is unchanged (different than the new construction performance requirement), or Table 140.3-B, C, or D of the standards for all other cases.

The standard design does not include window films.

External Shading Devices

Applicability

All fenestration

Definition

Devices or building features that are documented in the construction documents and shade the glazing, such as overhangs, fins, shading screens, and setbacks of windows from the exterior face of the wall.

The Title 24 compliance software shall be capable of modeling vertical fins and overhangs. Recessed windows may also be modeled with side fins and overhangs.

Units

Data structure: surface

Input Restrictions

No restrictions other than that the inputs must match the construction documents

Standard Design

The standard design building is modeled without external shading devices.

Standard Design:

Existing Buildings

No shading devices

Internal Shading Devices

Applicability

All fenestration

Definition

Curtains, blinds, louvers, or other devices that are applied on the room side of the glazing material

Glazing systems that use blinds between the glazing layers are also considered internal shading devices. Glass coatings, components, or treatments of the glazing materials are addressed through the fenestration construction building descriptor.

Units

Not applicable – not modeled for compliance

Input Restrictions

Not applicable – interior shading is not modeled for compliance

Standard Design

Not applicable – interior shading is not modeled for compliance

Standard Design:

Existing Buildings

No interior shades

Dynamic Glazing Present

Applicability

All fenestration that has dynamic glazing

Definition

This is a flag used for reporting purposes only. Dynamic glazing is not modeled directly in compliance software.

Units

Boolean

Input Restrictions

None

Standard Design

False (not present)

Standard Design:

Existing Buildings

Not Applicable

Below-Grade Wall Name

Applicability

All projects, optional input

Definition

A unique name that keys the below-grade wall to the construction documents

Units

Text: unique

Input Restrictions

None

Standard Design

Not applicable

Standard Design:

Existing Buildings

Same as proposed

Below-Grade Wall Geometry

Applicability

All projects

Definition

A geometric construct that describes the dimensions and placement of walls located below grade. Below-grade walls have soil or crushed rock on one side and interior space on the other side. Some simulation models take the depth below grade into account when estimating heat transfer so the geometry may include height and width.

Units

Data structure: below-grade wall geometry

Input Restrictions

As designed

Standard Design

The geometry of below-grade walls in the standard design building is identical to the below-grade walls in the proposed design.

Standard Design:

Existing Buildings

Same as proposed

Below-Grade Wall Construction

Applicability

All projects, required input

Definition

A specification containing a series of layers that result in a construction assembly for the proposed design. The first layer in the series represents the outside (or exterior) layer and the last layer represents the inside (or interior) layer. See the building descriptors above for below-grade wall construction type.

Units

Data structure: construction assembly

The construction can be described as a C-factor which is similar to a U-factor, except that the outside air film is excluded, or the construction can be represented as a series of layers, like exterior constructions.

Input Restrictions

The construction assembly, defined by a series of layers, must be equal to or more efficient than the mandatory R-value and C-factor requirements of Section 120.7 of the standards for new construction, and Section 141.0 of the standards for alterations. Note that these requirements only apply when the slab floor connected to the below-grade wall is heated.

For new construction, the inputs shall be in agreement with the construction documents. Values for the C-factor shall be taken from Table 4.3.5, 4.3.6, or 4.3.7 of Reference Appendix JA4.

For alterations there are no restrictions.

Standard Design

For new construction, see Table 13. The standard design building shall use default values for C-factor. The height shall be the same as specified in the proposed design.

For below-grade walls, the standard design construction shall include the layers described in Appendix 5.7 and in the table below.

For alterations, the C-factor in the standard design shall be modeled as the more efficient of either the existing conditions, or the values stated above for new construction standard design.

For below-grade walls, the alteration standard design assembly shall include the appropriate existing layers.

Standard Design:

Existing Buildings

Same as proposed

Slab Floor Name

Applicability

All slab floors, optional

Definition

A unique name or code that relates the exposed floor to the construction documents

Units

Text: unique

Input Restrictions

None

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Slab Floor Type

Applicability

All slab floors, required

Definition

One of two types and two subtypes of floors in contact with ground:

1) Heated slab-on-grade floors,

2) Unheated slab-on-grade floors

3) Heated below-grade floors

4) Unheated below-grade floors.

Heated slab-on-grade floors include all floors that are heated directly in order to provide heating to the space. Unheated slab-on-grade floors are all other floors in contact with ground.

Units

List:  restricted to the four selections listed above

Input Restrictions

None

Standard Design

The slab for type is unheated (either unheated slab-on-grade for slab-on-grade floors or unheated below-grade for below-grade floors).

Standard Design:

Existing Buildings

Same as proposed

Slab Floor Geometry

Applicability

All slab floors, required

Definition

A geometric construct representing a slab floor in contact with the earth.

The geometric representation can vary depending on how the energy simulation software models slabs-on-grade. Some models require that only the perimeter of the slab be entered. Other models divide the slab into a perimeter band within 2 ft of the edge and the interior portion or core area, such that the perimeter area and the core area sum to the total area of the slab.

Units

Data structure: surface

This may include: area, perimeter exposed

Input Restrictions

None

Standard Design

The geometry of the slab floor in the standard design building is identical to the slab floor in the proposed design.

Standard Design:

Existing Buildings

Same as proposed

Slab Floor Construction

Applicability

All slab floors, required

Definition

A specification containing a series of layers that result in a construction assembly for the proposed design.

The first layer in the series represents the outside (or exterior) layer and the last layer represents the inside (or interior) layer. See the building descriptors above for slab floor construction type.

A description of how the slab is insulated (or not)

How the construction is described will depend on the energy simulation model. The construction can be represented by an F-factor that represents the entire construction (floor and insulation).

Simple models may include just an F-factor, representing an instantaneous heat loss/gain to outside air. The F-factor could be related to the configuration of insulation in the proposed design. Other slab loss models may require that the surface area of the slab floor be divided between the perimeter and the interior. The insulation conditions then define heat transfer between both outside air and ground temperature.

The insulation condition for slabs includes the R-value of the insulation and the distance it extends into the earth at the slab edge and how far it extends underneath the slab.

Units

F-factor from Reference Appendix JA4; this is one selection from list 1 and one selection from list 2. Note that some combinations from list 1 and list 2 are not allowed, see Reference Appendix JA4 Table 4.4.8 and Table 4.4.7 for details.

List 1: 

List 2:

The software shall also provide the following slab insulation options:

1) Horizontal+Vertical, R-5 vertical down to the horizontal insulation and R-5 horizontal insulation extending 4 feet inwards from the perimeter

2) Horizontal+Vertical, R-10 vertical down to the horizontal insulation and R-7 horizontal insulation extending 4 feet inwards from the perimeter

These two combinations of slab insulation are mapped to an F-factor in Appendix 5.4B.

Input Restrictions

The construction assembly, defined by an F-factor, must be equal to or more efficient than the mandatory F-factor requirements of Section 120.7 of the standards for new construction, and Section 141.0 of the standards for alterations.

For new construction, F-factors shall be taken from Table 4.4.8 of Reference Appendix JA4 for heated slab floors and Table 4.4.7 for unheated slab floors. For all methods, inputs shall be consistent with the construction documents. For heated slab floors, the F-factor shall be determined by the mandatory R-value and installation requirements in Section 110.8 of the standards. That information is used in Table 4.4.8 of Reference Appendix JA4 to determine the required F-factor. The same requirements apply for alterations.

Standard Design

Slab loss shall be modeled with the simple method (F-factor).

The standard design construction shall include the following layer:

Layer 1: Concrete 140lb/ft³ – 6 in. (R - 0.44)

The standard design shall include no insulation, equivalent to an F-factor of 0.73.

For alterations, the F-factor in the standard design shall be modeled as the more efficient of either the existing conditions, or the values stated above for new construction standard design.

Standard Design:

Existing Buildings

Same as proposed

Partition Name

Applicability

All partitions, optional

Definition

A unique name or code that relates the partition to the construction documents

Units

Text: unique

Input Restrictions

The text should provide a key to the construction documents.

Standard Design

Not applicable

Standard Design:

Existing Buildings

Not applicable

Partition Geometry

Applicability

All partitions

Definition

A geometric construct that defines the position and size of partitions that separate one thermal zone from another.

The construct shall identify the thermal zones on each side of the partition. Since solar gains are not generally significant for interior partitions, the geometry of partitions is sometimes specified as an area along with identification of the thermal zones on each side.

Units

Data structure: surface with additional information identifying the two thermal zones that the partition separates

Input Restrictions

No restrictions other than agreement with the construction documents

Standard Design

The geometry of partitions in the standard design building shall be identical to the proposed design.

Standard Design:

Existing Buildings

Same as proposed

Partition Construction

Applicability

All partitions

Definition

A description of the construction assembly for the partition

Units

Data structure: construction assembly

Input Restrictions

As designed

Standard Design

Partitions in the standard design shall be steel framed walls with 5/8-inch gypsum board on each side. For walls, partitions in the standard design building shall be steel-framed walls with 5/8-inch gypsum board on each side. For interior floors and ceilings, standard design construction shall be 5/8-inch gypsum board, 4 inches of heavyweight concrete, and 5/8-inch gypsum board.

Standard Design:

Existing Buildings

Same as proposed

Demising Partition Construction

Applicability

All demising walls and demising partitions (ceilings, floors) that separate conditioned spaces from unconditioned spaces

Definition

A description of the construction assembly for the partition

Units

Data structure: construction assembly

Input Restrictions

As designed

Standard Design

For walls, when the proposed design demising partition is metal-framed or other, the standard design shall be a metal-framed wall meeting the mandatory U-factor requirements of section 120.7 (b) of the Standards.

For walls, when the proposed design demising partition is wood-framed, the standard design shall be a wood-framed wall with the opaque portions of the wall meeting the mandatory U-factor requirements of section 120.7 (b) of the Standards.

For windows in demising walls, the fenestration area shall equal the fenestration area of the proposed design.  The window U-factor for fenestration in demising walls shall equal the fixed window prescriptive U-factor requirement of 5.5.7. Neither solar heat gain nor daylighting through interior demising windows will be modeled.

Demising ceiling partitions, separating conditioned space from unconditioned space and attics, shall be insulated to the same levels as exterior roofs in section 5.5.3. Demising floor partitions shall be insulated to the same levels as exterior floors in section 5.5.5.

Standard Design:

Existing Buildings

Demising ceiling partitions, separating conditioned space from unconditioned space and attics shall be insulated to the same levels as exterior roofs in section 5.5.3. Demising floor partitions shall be insulated to the same levels as exterior floors in section 5.5.5.