Energy simulation programs commonly define construction assemblies by listing a sequence of material layers that make up the construction assembly. Appendix 5.5A has a list of standard materials that may be referenced by construction assemblies. Additional materials not 'listed in Appendix 5.5A may be defined as described below. Alternate methods may be used to define construction assemblies such as specifying the U-factor and optionally, a metric describing thermal mass such as heat capacity (HC). These alternate methods may not require identification of materials. When a material is defined, all of the properties listed below must be defined. Some materials listed in Appendix 5.5A are non-homogeneous, for instance, framing members with insulation in the cavity. Typical construction assemblies and their respective material layers are defined in Reference Appendix JA4. Additionally, the properties of the each material layer can be found in ACM Appendix 5.5A.
Material Name
Applicability
Opaque constructions
Definition
The name of a construction material used in the exterior envelope of the building
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
Density
Applicability
Opaque constructions
Definition
The density (or mass per unit of 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
Specific Heat
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
Thermal Conductivity
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/h·ft·°F
Input Restrictions
Prescribed from Appendix 5.5A
Standard Design
Not applicable
Thickness
Applicability
All non-standard materials
Definition
The thickness of a material
Units
ft or in.
Input Restrictions
Prescribed from Appendix 5.5A
Standard Design
Not applicable
For California Compliance and Reach, construction assemblies for the proposed design shall be created by selecting from a library of building construction layers in ACM Appendix 5.5A. The compliance software shall all specify composite layers that consist of both framing and insulation and shall use established methods defined in the ASHRAE Handbook of Fundamentals for calculating effective R-values of composite layers.
Geometry
The geometry of roofs, walls, floors, doors and fenestration should match the construction documents or as-built drawings as accurately as possible. Unusual curved surfaces such as a dome or semi-circular wall may be approximated by a series of constructions.
Mass Walls
For mass walls, the user first chooses the mass layer from Appendix 5.5A. After that, the user may select an insulating layer from Appendix 5.5A for outside and/or inside the mass wall.
Ballasted Roofs, Vegetated Roofs, Concrete Pavers, and Other Mass Roofs
An additional layer may be added to the roof construction assembly when thermal mass is used above the roof membrane. This exception is intended to allow ballasted roofs, concrete pavers and other massive elements to be explicitly modeled. To qualify, the weight of the stone ballast, the concrete pavers or other elements must exceed 15 lb/ft². The thickness, heat capacity, conductance and density of the additional mass layer shall be based on the measured physical properties of the material. If the surface properties of the additional mass material have been verified through the Cool Roof Rating Council (CRRC), the CRRC reported properties may be used for the proposed design; otherwise, the mass layer shall be modeled with an aged reflectance of 0.10 and an emittance of 0.85.
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: unique
Input Restrictions
Construction name is a required input.
Standard Design
Not applicable
Specification Method
Applicability
All projects
Definition
The method of describing a construction assembly. The more simple method is to describe the U-factor of the construction assembly which can account for thermal bridging and other factors. However with this method, the time delay of heat transfer through the construction assembly is not accounted for. Generally, with the U-factor method, heat transfer is assumed to occur instantly. The more complex method is to describe the construction assembly as a series of layers, each layer representing a material. With this method, heat transfer is delayed in accord with the thermal mass and other properties of the assembly. For below-grade constructions, a C-factor can be specified; for slab-on-grade constructions, an F-factor is specified.
Units
List: layers, U-factor, C-factor, 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.
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.
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: unique
Input Restrictions
None
Standard Design
None
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 baseline building are modeled as “insulation entirely above deck.” Metal building.
Standard Design, Existing Buildings
For existing buildings, the standard design roof type is the same as that for the proposed design.
Roof Geometry
Applicability
All roofs, required input
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.)
Roof Solar Reflectance
Applicability
All opaque exterior surfaces exposed to ambient conditions
Definition
The solar reflectance of a material. For roofing materials, the 3-year aged reflectance value from CRRC testing should be used if available.
Units
Unitless fraction between 0 and 1
Input Restrictions
For roofs that are part of new construction, if asphalt shingles or composition shingles are not rated by the Cool Roof Rating Council (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 have been tested by the (CRRC) 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:
ƿaged = 0.2 + β · (ƿinit – 0.2)
Where,
ƿaged = the calculated aged reflectance
β = 0.65 for field-applied coatings, 0.7 for all other roof surfaces
ƿinit = the initial CRRC reflectance
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% 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.
Roof Thermal Emittance
Applicability
All opaque exterior surfaces exposed to ambient conditions; this is prescribed for exterior walls at 0.85 and is the as-designed value entered for roofs, with some restrictions.
Definition
The thermal emittance of a material. For roofing materials, the 3-year aged emittance value from CRRC testing should be used if available.
Units
Unitless fraction between 0 and 1
Input Restrictions
For roofs, new construction: as designed, from CRRC values. If CRRC rating information is not available, the default thermal emittance shall be 0.75.
Standard Design
For roofs, new construction, the standard design thermal emittance shall be 0.85.
For alterations to more than 50% 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.
SPECIAL NOTE: A simplified version of the compliance software will be developed to be used for envelope tradeoffs, and for roof alterations in particular. This option will constrain almost all inputs not related to roof performance and will provide a way to determine insulation tradeoffs allowed with roof reflectance.
Roof Construction
Applicability
All roofs, 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 roof construction type.
Units
List: layers
Input Restrictions
The construction assembly, 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
Metal Building U – 0.098
Wood Framed and Others U – 0.075
Additions and Alterations
Roof / Ceiling Insulation See 141.0(b)2Biii of the Standards
Appropriate R-values for insulation can be calculated using the formula below.
Rinsulation = (1/U-factor) – Rlayer(1) – Rlayer(2) – Rlayer(3) – Rlayer(n)
Rinsulation = Rins.continuous + Rins.framing
Ceilings that form the boundary between the modeled building of an additions and alterations project and the existing, unmodeled portion of the building may be modeled as adiabatic roofs (no heat transfer).
Standard Design
Roofs in the baseline building are of the type “insulation entirely above deck.” The insulation requirement is determined by climate zone and baseline standard. The baseline 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:
Layer 1 Metal Standing Seam 1/16 in. R - 0.00
Layer 2 Continuous Insulation R - Based on Climate Zone
Layer 3 Open Framing + No Insulation R – 0.00
The value of the Continuous Insulation layer entirely above framing shall be set to achieve the following R-values:
Nonresidential Buildings – Continuous Ins.
Climate Zones 2, 3, 4, 9- 16 R – 24.86
Climate Zones 1, 5: R - 19.62
Climate Zones 7, 8: R – 14.15
Climate Zones 6: R – 12.55
High-Rise Residential Buildings and Hotel / Motel Guestrooms – Continuous Ins.
Climate Zones 2, 4, 8- 16 R – 34.93
Climate Zone 1 R – 28.63
Climate Zones 3, 5, 7 R – 24.86
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 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. Also, the standard design roof that serves as the boundary between the modeled additions and alterations building and the existing, unmodeled portion of the building is modeled as an adiabatic roof, to match the proposed design. 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.
The Reference Appendix JA4 reference and U-factor are provided for reference only. The U-factor does not need to exactly match the JA4 value, but the layer shall match the layer described below.
Alterations Roof Standard Design
|
Nonres |
CZ 1,3-9 |
CZ 2,10-16 |
|
HRR |
n/a |
All Climate Zones |
|
JA4 U-factor* |
0.082 |
0.055 |
|
Roof Type |
Wood-framed roof |
Wood-framed roof |
|
Layer 1 |
2x8, 24” o.c., No Insulation JA4 4.2.2-F25 |
2x8, 24” o.c., No Insulation JA4 4.2.2-H25 |
|
Layer 2 |
R-8 continuous insulation |
R-14 continuous insulation |
*U-factor and JA4 assembly table and cell reference is provided for reference only. The compliance software shall only require that the layers in the construction match those in this table.
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, optional input
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: unique
Input Restrictions
None
Standard Design
None
Applicability
All wall surfaces, optional
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:
a) Mass Light,
b) Mass Heavy
c) Metal building,
d) Metal framing, and
e) 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-F. 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
The existing building standard design Wall Type shall be the same as the proposed.
Wall Geometry
Applicability
All walls, required input
Definition
Wall geometry defines the position, orientation, azimuth, and tilt of the wall surface. The details of how the coordinate system is implemented may vary between simulation engines. The data structure for surfaces is described in the reference section of this chapter.
Units
Data structure: surface
Input Restrictions
As designed
Standard Design
Wall geometry in the standard design building is identical to the proposed design.
Wall Solar Reflectance
Applicability
All opaque exterior surfaces exposed to ambient conditions
Definition
The solar reflectance of a material. For roofing materials, the 3-year aged reflectance value from CRRC testing should be used if available.
Units
Unitless fraction between 0 and 1
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.
For new construction, the standard design reflectance shall meet the requirements stated in Section 140.3 of the Standards.
For alterations to more than 50% 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.
Wall Thermal Emittance
Applicability
All opaque exterior surfaces exposed to ambient conditions; this is prescribed for exterior walls at 0.85 and is the as-designed value entered for roofs, with some restrictions.
Definition
The thermal emittance of a material. For roofing materials, the 3-year aged emittance value from CRRC testing should be used if available.
Units
Unitless fraction between 0 and 1
Input Restrictions
For walls and other non-roof surfaces: The value is prescribed to be 0.9.
For roofs, new construction: as designed, from CRRC values. If CRRC rating information is not available, the default thermal emittance shall be 0.75.
Standard Design
For walls and other non-roof surfaces, the thermal emittance is 0.90.
For roofs, new construction, the standard design thermal emittance shall be 0.85.
For alterations to more than 50% 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.
SPECIAL NOTE: A simplified version of the compliance software will be developed to be used for envelope tradeoffs, and for roof alterations in particular. This option will constrain almost all inputs not related to roof performance and will provide a way to determine insulation tradeoffs allowed with roof reflectance.
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 construction assembly, 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.
New Construction
Metal Building U – 0.113
Metal Framed U – 0.105
Light Mass Walls U – 0.440
Heavy Mass Walls U – 0.690
Wood Framed and Others U – 0.110
Spandrel Panels / Glass Curtain Walls U – 0.280
Additions and Alterations
Metal Building U – 0.113
Metal Framed U – 0.217
Wood Framed and Others U – 0.110
Spandrel Panels / Glass Curtain Walls U – 0.280
Appropriate R-values for insulation can be calculated using the formula below.
Rinsulation = (1/U-factor) – Rlayer(1) – Rlayer(2) – Rlayer(3) – Rlayer(n)
Rinsulation = Rins.continuous + Rins.framing
Walls that form the boundary between the modeled building of an additions and alterations project and the existing, unmodeled portion of the building may be modeled as adiabatic walls (no heat transfer).
Standard Design
For new construction, the standard design wall type is metal framed with continuous insulation. 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:
Layer 1 Stucco – 7/8 in. R - 0.18
Layer 2 Building Paper R – 0.06
Layer 3 Continuous Insulation R - Based on Climate Zone
Layer 4 Closed Framing and No Ins. R – 0.65
Layer 5 Gypsum Board – 1/2 in. R – 0.45
The value of the Continuous Insulation layer entirely outside framing shall be set to achieve the following R-values:
Nonresidential Buildings – Continuous Ins.
Climate Zones 1, 6, and 7 R – 8.01
Climate Zones 2, 4, 5, and 8 – 16 R – 13.94
Climate Zones 3 R – 10.01
High-Rise Residential Buildings and Hotel / Motel Guestrooms – Continuous Ins.
Climate Zones 1 and 5 R – 7.33
Climate Zones 2 – 4, and 6 – 16 R – 9.52
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.
Standard Design, Existing Buildings
For existing buildings, the standard design wall for unaltered components is the same as the proposed design. Also, the standard design wall that serves as the boundary between the modeled additions and alterations building and the existing, unmodeled portion of the building is modeled as an adiabatic wall, to match the proposed design. For altered exterior walls, the baseline assembly shall be as follows:
Step 1. Determine the existing wall type: metal building wall, metal framed wall, mass wall, medium; mass wall, heavy; wood-framed wall. The standard design wall type for alterations in existing building shall be the same as the proposed design wall type.
Step 2. Use the tables below to determine the standard design construction assembly, (The JA4 U-factors and cell references are provided as a reference only; the assembly U-factor need not match exactly the U-factor in Reference Appendix JA4, but the assembly shall include the layers defined below.)
Metal Framed Wall – same as new construction assembly above
Mass Wall, Light (Heat Capacity > 7 Btu/ft2-F and <15 Btu/ft2-F
|
|
CZ2,10-16 |
CZ 1 |
CZ 4 |
CZ 3 |
CZ 5-9 |
|
0.170 |
0.196 |
0.227 |
0.278 |
0.440 | |
|
Layer 1 |
4 in MW CMU, 115 lb/sf 4.3.6-B5 |
4 in MW CMU, 115 lb/sf 4.3.6-B5 |
4 in MW CMU, 115 lb/sf 4.3.6-B5 |
4 in MW CMU, 115 lb/sf 4.3.6-B5 |
8 in NW CMU, 125 lb/ft2, partly grouted, reinforced with insulated cells 4.3.6-C10 |
|
Layer 2* |
3” furring space with R-21 insulation and metal clips 4.3.14-V15 (equiv R-4.8 c.i.) |
2.5” furring space with R-13 insulation and metal clips 4.3.14-R13 (equiv R-3.8 c.i.) |
2” furring space with R-13 insulation and metal clips 4.3.14-N11 (equiv R-3.3 c.i.) |
1.5” furring space with R-9 insulation and metal clips 4.3.14-J9 (equiv R-2.5 c.i.) |
|
|
Layer 3 |
|
|
|
|
|
|
Layer n |
|
|
|
|
|
Heavy Mass Wall (Heat Capacity >= 15 Btu/ft2-F):
|
|
CZ2,10-16 |
CZ 1 |
CZ 4 |
CZ 3 |
CZ 5-9 |
|
|
0.160 |
0.184 |
0.211 |
0.253 |
0.650 |
0.690 | |
|
Layer 1 |
8 in. NW CMU, 125 lb/ft2, solid grout, reinforced 4.3.5-A10 |
8 in. NW CMU, 125 lb/ft2, solid grout, reinforced 4.3.5-A10 |
8 in. NW CMU, 125 lb/ft2, solid grout, reinforced 4.3.5-A10 |
8 in. NW CMU, 125 lb/ft2, solid grout, reinforced 4.3.5-A10 |
8 in NW CMU, 125 lb/ft2, solid grout, reinforced 4.3.5-A9 |
8 in. NW CMU, 125 lb/ft2, solid grout, reinforced 4.3.5-A10 |
|
Layer 2* |
3” furring space with R-21 insulation and metal clips 4.3.14-V15 (equiv R-4.8 c.i.) |
2.5” furring space with R-13 insulation and metal clips 4.3.14-R13 (equiv R-3.8 c.i.) |
2” furring space with R-13 insulation and metal clips 4.3.14-N11 (equiv R-3.3 c.i.) |
1.5” furring space with R-9 insulation and metal clips 4.3.14-J9 (equiv R-2.5 c.i.) |
|
|
|
Layer 3 |
|
|
|
|
|
|
|
Layer n |
|
|
|
|
|
|
Metal Building Walls
|
CZ15 |
CZ 2,4,5,8,9,10-14,16 |
CZ 1,3,6,7 | |
|
0.057 |
0.061 |
0.113 | |
|
Layer 1 |
R-13 batt insulation draped over purlins and compressed
|
R-13 batt insulation draped over purlins and compressed
|
R-13 batt insulation draped over purlins and compressed Rlayer=8.85 |
|
Layer 2* |
Second layer R-13 batt insulation |
Second layer R-10 batt insulation |
|
|
Layer 3 |
|
|
|
|
Layer n |
|
|
|
Wood-Framed Walls
|
CZ15 |
CZ 2,4,9-14,16 |
CZ 4 |
CZ 3 | |
|
0.042 |
0.059 |
0.102 |
0.110 | |
|
Layer 1 |
2x4, 16” o.c, with R-13 batt ins |
2x4, 16” o.c., with R-11 batt ins |
2x4, 16” o.c. with R-13 batt ins |
2x4, 16” o.c. with R-11 batt ins |
|
Layer 2* |
R-14 continuous insulation |
R-8 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: unique
Input Restrictions
None
Standard Design
None
Floor Type
Applicability
All exterior floor surfaces, optional
Definition
The category that defines the standard design prescriptive floor requirements.
Units
List: mass, other
Input Restrictions
Not applicable for new construction; either
Standard Design
The standard design building floors shall be of type “other”
Standard Design, Existing Buildings
The standard design building floor type for existing buildings shall be same as proposed.
Floor Geometry
Applicability
All exterior floors, required input
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
Standard Design
Standard design building floor geometry is identical to the proposed design.
Floor Construction
Applicability
All floors, 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 floor construction type.
Units
List: Layers
Input Restrictions
The construction assembly, 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
Raised Mass Floors U – 0.269
Other Floors U – 0.071
Heated Slab Floors Climate Zone (see Section 120.7)
Additions and Alterations
Raised Framed Floors U – 0.071
Raised Mass Floors in High-rise Res and Hotel Motel U – 0.111
Raised Mass Floors in Other Occupancies No Requirement
Appropriate R-values for insulation can be calculated using the formula below.
Rinsulation = (1/U-factor) – Rlayer(1) – Rlayer(2) – Rlayer(3) – Rlayer(n)
Rinsulation = Rins.continuous + Rins.framing
Floors that form the boundary between the modeled building of an additions and alterations project and the existing, unmodeled portion of the building may be modeled as adiabatic floors (no heat transfer).
Standard Design
For new construction, the floor type for the standard design building is metal framed. 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:
Layer 1 Open Framing + No Ins. R – 0.00
Layer 2 Continuous Insulation R – Based on Climate Zone
Layer 3 Plywood – 5/8 in. R – 0.78
Layer 4 Carpet and Pad – 3/4 in. R – 1.30
The value of the Continuous Insulation layer entirely above or below framing shall be set to achieve the following R-values:
Nonresidential Buildings – Continuous Ins.
Climate Zones 1 R – 17.66
Climate Zones 2, 11, and 14 -16 R – 22.47
Climate Zones 3 – 10, 12, and 13 R – 10.91
High-Rise Residential Buildings and Hotel / Motel Guestrooms – Continuous Ins.
Climate Zones 1, 2, 14, and 16 R – 26.24
Climate Zones 3 – 6, 8 – 13, and 15 R – 22.47
Climate Zones 7 R – 10.91
Standard Design, Existing Buildings
The standard design floor that serves as the boundary between the modeled additions and alterations building and the existing, unmodeled portion of the building is modeled as an adiabatic floor, to match the proposed design. The standard design floor construction for existing buildings depends on the floor type.
Raised Floors, Floor Type = Other (framed floors)
|
All Climate Zones, Nonres | |
|
0.071, JA4 4.4.2-A2 | |
|
Layer 1 |
2x6 Wood-Framed, 16” o.c., R-11 batt |
|
Layer 2 |
|
Raised Floors, Floor Type= Mass
|
All Climate Zones, Nonres |
All Climate Zones, High-Rise Res. | |
|
U=0.269 |
U=0.111, JA4 4.4.2-A2 | |
|
Layer 1 |
Metal Deck, R-0 |
Metal Deck, R-0 |
|
Layer 2 |
4” Lightweight Concrete |
4” Lightweight Concrete |
|
Layer 3 |
|
R-6 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% 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
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.
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.
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. For alterations there are no restrictions.
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
Non-Swinging Doors
Climate Zones 1, and 16 U – 0.50
Climate Zones 2 – 15 U – 1.45
Swinging Doors
Climate Zones 1 – 16 U – 0.70
High-Rise Residential Buildings and Hotel / Motel Guestrooms – U Factor
Non-Swinging Doors
Climate Zones 1, and 16 U – 0.50
Climate Zones 2 – 15 U – 1.45
Swinging Doors
Climate Zones 1 – 16 U – 0.70
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.
Note that fenestration includes windows, doors that have more than 50% glazed area, and skylights. A skylight is fenestration that has a tilt of less than 60° from horizontal.
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
No restrictions
Standard Design
Not applicable
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
Fixed
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, or Plastic
Input Restrictions
As designed.
Standard Design
Glass, curb-mounted
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 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
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
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, Nonmetal
Input Restrictions
As designed
Standard Design
Not applicable
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 PERF-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, 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.
The standard design vertical fenestration area and horizontal fenestration area for data center buildings shall be zero (0).
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%.
Exception 2. If display perimeter is entered, the fenestration area exceeds the greater of 40% 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. WWRo > 0.40, WWRw <=0.40
In this case, the fenestration area of all windows is reduced by multiplying the fenestration area by the ratio 0.40/WWRo. The dimensions of each window is reduced by multiplying the proposed window dimension by (0.40/WWRo)1/2, so that the same window aspect ratio is maintained.
Case 2: WWRo < 0.40. WWRw > 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/WWRo. The dimensions of each window is reduced by multiplying the proposed window dimension by (0.40/WWRo)1/2, so that the same window aspect ratio is maintained.
Case 3: WWRo > 0.40. WWRw > 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/WWRw.
2) Calculate the WWR of the north, east and south facades:
WWRnes = 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:
WindowAreaN,std = WindowAreaN,prop x 0.4 / WWRnes
WindowAreaE,std = WindowAreaE,prop x 0.4 / WWRnes
WindowAreaS,std = WindowAreaS,prop x 0.4 / WWRnes
4) Adjust each window geometry for the west façade by multiplying each dimension by (0.4/WWRw)1/2
5) Adjust each window geometry for the north, east and south façade by multiplying each dimension by (0.4/WWRnes)1/2
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:
WindowAreastd = 6 x DisplayPerimeter
The geometry of each window is modified by the following:
WindowHeightstd = WindowHeightprop x (WindowAreastd/WindowAreaprop)1/2
WindowWidthstd = WindowWidthprop x (WindowAreastd/WindowAreaprop)1/2
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.
1) The skylight area of the standard design is set to:
2) 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% of the gross roof area that is over conditioned space
3) For buildings with atria at a height of 55ft or greater over conditioned spaces, the smaller of the proposed skylight area and 10% of the gross roof area that is over conditioned space
For buildings with atria or other roof area directly over unconditioned spaces, the smaller of the proposed skylight area or 5% 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 below 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, - building Floor area x 0.75 = Total primary daylit area+ Total skylit daylit area. See 5.4.5|topic=5.4.5 Daylighting Control 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 baseline 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 is done after adjustments to WWR, if any is completed.
Standard Design, Existing Buildings, Additions and Alterations
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% window to wall ratio (WWR) for the building, 40% WWR for the west orientation of the building, 5% skylight to roof ratio (SRR) for existing buildings without atria 55 feet or higher, or 10% 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
This is 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 feet, with exterior surfaces having a tilt angle less than 60 degrees (roofs) and no more than 3 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 0 %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 feet.
5. Plans or documents show that space is an auditorium, religious building of worship, movie theater, museum, or refrigerated warehouses.
Units:
Data Structure:
Unitless fraction between 0 and 1
List: Four 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
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 CEC default tables (110.6-A and B).
For site built 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 CEC default tables (110.6 A and B) when total site built fenestration > 1000 ft2
•be determined from methods outlined in NA-6 Procedure to Calculate Thermal Performance when total site built fenestration <=1000 ft2
For field fabricated products:
•U-factor, SHGC and VT shall be determined from CEC default tables (110.6 A and 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:
UT = C1 + (C2 · Uc)
SHGCT = 0.08 + (0.86 · SHGCc)
VTT = VTF · VTC
Where,
UT = 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
UC = Center of glass U-factor calculated in accordance with NFRC 100 Section 4.5.3.1
SHGCT = SHGC Is
SHGCC = Center of glass SHGC calculated in accordance with NFRC 200 Section 4.5.1.1
VTT = Is the Total Performance of the fenestration including glass and frame
VTF = 0.53 for projecting windows, such as casement and awning windows
VTF = 0.67 for operable or sliding windows
VTF = 0.77 for fixed or non-operable windows
VTF = 0.88 for curtain wall/storefront, Site-built and manufactured non-curb mounted skylights
VTF = 1.0 for Curb Mounted manufactured Skylights
VTC = 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.
For alterations of existing fenestration using window films, the thermal performance for solar heat gain coefficient shall be calculated from two user inputs:
1) Default Glazing Reference: unique identifier for the glazing without film, that determines the CEC default value (column 3 in table below) and the SHGC ratio multiplier (column 4), and
2) NFRC window film SHGC: the solar heat gain coefficient multiplier for the window film, from NFRC ratings.
The adjusted SHGC for the glazing with the window film is:
SHGCadj = DefaultSHGCValue x SHGCRatio x NFRCfilm
Where
DefaultSHGCValue = the CEC default value from 110.6, given in column 3 in the table below
SHGCRatio = multiplier based on the default glazing reference, given in column 4 in the table below
NFRCfilm – the NFRC SHGC rating of the window film
|
1 |
2 |
3 |
|
4 |
|
5 |
|
6 | ||||||||
|
Operator Type |
Default Glazing Reference |
CEC Default SHGC Value X |
|
SHGC Ratio Xy |
|
NFRC Window Film SHGC1,2,3 Z |
|
New Adjusted Total Value T | ||||||||
|
Residential or Commercial | ||||||||||||||||
|
Fixed |
3 mm (1/8in.) clear (Single Pane) |
0.83 |
x |
1.1528 |
x |
|
= |
| ||||||||
|
Fixed |
3 mm (1/8in.) clear 3 mm (1/8in.) clear (Double Pane - Clear) |
0.73 |
x |
1.1406 |
x |
|
= |
| ||||||||
|
|
1 |
2 |
3 |
|
4 |
|
5 |
|
6 | |||||||
|
|
Operator Type |
Default Glazing Reference |
CEC Default SHGC Value X |
|
SHGC Ratio Xy |
|
NFRC Window Film SHGC1,2,3 Z |
|
New Adjusted Total Value T | |||||||
|
|
Residential or Commercial | |||||||||||||||
|
|
Fixed |
3 mm (1/8in.) clear (Single Pane) |
0.83 |
x |
1.1528 |
x |
|
= |
| |||||||
|
|
Fixed |
3 mm (1/8in.) clear 3 mm (1/8in.) clear (Double Pane - Clear) |
0.73 |
x |
1.1406 |
x |
|
= |
| |||||||
Standard Design
For new construction, the requirements for vertical fenestration U factor, Solar Heat Gain Coefficient, and Visible light transmission by window type and framing type are specified in Table 140.3-B, C or D of the Standards.
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. Objects that shade the building but are not part of the building and parts of the building that cause the building to shade itself are also modeled, but are not a part of this building descriptor. See Shading of the Building Site. 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: opening shade
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.
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
Data structure: Indicates the type of control, or blind schedule if applicable
Input Restrictions
Internal shading shall not be modeled in the proposed design, unless it is automatically controlled, based on input from an astronomical timeclock, an exterior pyronometer, or other sensors. The control algorithm shall be documented on the construction documents. Interior shades without automatic controls shall not be modeled Interior shades shall only be modeled when automatic controls are present.
Standard Design
The baseline building shall be modeled without interior shades. None (not applicable)
SHGC Dim Fraction
Applicability
Fenestration with switchable glazing
Definition
For switchable glazing, this is the fraction of the solar heat gain coefficient when darkened to the solar heat gain coefficient during normal operation. This can be applied when the solar heat gain exceeds a specified threshold, or controlled by an electrical signal.
Units
Unitless
Input Restrictions
Between 0 and 1Internal shading shall not be modeled in the proposed design, unless it is automatically controlled, based on input from an astronomical timeclock, an exterior pyronometer, or other sensors. The control algorithm shall be documented on the construction documents. Interior shades without automatic controls shall not be modeled
Standard Design
Not applicable
VT Dim Fraction
Applicability
Fenestration with switchable glazing
Definition
For switchable glazing, this is the fraction of the visible transmittance when darkened to the visible transmittance during normal operation. This can be applied when the solar heat gain exceeds a specified threshold, or controlled by an electrical signal.
Units
Unitless
Input Restrictions
Between 0 and 1Internal shading shall not be modeled in the proposed design, unless it is automatically controlled, based on input from an astronomical timeclock, an exterior pyronometer, or other sensors. The control algorithm shall be documented on the construction documents. Interior shades without automatic controls shall not be modeled
Standard Design
Not applicable
Switchable Solar Heat Gain Threshold
Applicability
Fenestration with automatically controlled switchable glazing.
Definition
For switchable glazing, this is the solar heat gain threshold above which the dynamic glazing is active (darkened). When the solar heat gain drops below this threshold, the glazing is switched back to being inactive (clearest setting). Indoor and outdoor air temperatures are the setpoints required for controlling the Switchable Solar Heat Gain Threshold. A flag may be used to indicate that this control is not used. During both occupied and unoccupied hours, the recommendation for the control of solar heat gain coefficient (SHGC) is to have the switchable glazing set to inactive (clearest setting) when the outdoor air temperature is below the heating setpoint, and active (darkened) when the outdoor air temperature is equal to or above the heating setpoint. The heating setpoint value shall be based on building type from ACM Appendix 5.4B.
Units
Incident solar threshold (Btu/h-ft2)
Input Restrictions
As designed. During both occupied and unoccupied hours, the recommendation for the control of solar heat gain coefficient (SHGC) is to have the switchable glazing set to inactive (clearest setting) when the outdoor air temperature is below the heating setpoint, and active (darkened) when the outdoor air temperature is equal to or above the heating setpoint. The heating setpoint value shall be based on building type from ACM Appendix 5.4B.
Standard Design
Not applicable
Switchable Space Temperature Threshold
Applicability
Fenestration with automatically controlled switchable glazing.
Definition
For switchable glazing, this is the space temperature above which the dynamic glazing is active (darkened). When the solar heat gain drops below this threshold, the glazing is switched back to being inactive (clearest setting). Indoor and outdoor air temperatures are the setpoints required for controlling the Switchable Solar Heat Gain Threshold. This may be used in combination with the solar heat gain and illuminance thresholds for control. A flag may be used to indicate that this control is not used. During both occupied and unoccupied hours, the recommendation for the control of solar heat gain coefficient (SHGC) is to have the switchable glazing set to inactive (clearest setting) when the outdoor air temperature is below the heating setpoint, and active (darkened) when the outdoor air temperature is equal to or above the heating setpoint. The heating setpoint value shall be based on building type from ACM Appendix 5.4B.
Units
°F
Input Restrictions
The space heating and cooling setpoints are prescribed from Appendix 5.4B. A flag may be used to indicate that this control is not used. During both occupied and unoccupied hours, the recommendation for the control of solar heat gain coefficient (SHGC) is to have the switchable glazing set to inactive (clearest setting) when the outdoor air temperature is below the heating setpoint, and active (darkened) when the outdoor air temperature is equal to or above the heating setpoint. The heating setpoint value shall be based on building type from ACM Appendix 5.4B.
Standard Design
Not applicable
Switchable Illuminance Threshold
Applicability
Fenestration with automatically controlled switchable glazing.
Definition
For switchable glazing, this is the illuminance threshold above which the dynamic glazing is regulated between active (darkened) and inactive (clearest setting). With a single illuminance setpoint the switchable glazing will adjust between the clearest and darkest setting to allow the desired illuminance level. A flag may be used to indicate that this control is not used. During both occupied and unoccupied hours, the recommendation for the control of solar heat gain coefficient (SHGC) is to have the switchable glazing set to inactive (clearest setting) when the outdoor air temperature is below the heating setpoint, and active (darkened) when the outdoor air temperature is equal to or above the heating setpoint. The heating setpoint value shall be based on building type from ACM Appendix 5.4B.
Units
Lux
Input Restrictions
As designed
During occupied hours, the recommendation for the illuminance threshold setpoint is to match a point within the recommended illumination levels, based on space type, from Appendix 5.4A. Values below this recommended range may require special documentation.
During unoccupied hours, the recommendation is to have the Switchable Solar Heat Gain Threshold descriptor in control of the switchable glass. If this descriptor is used in conjunction with the Switchable Solar Heat Gain Threshold descriptor, glare will need to be an additional parameter to control which threshold is used during occupied hours.
Standard Design
Not Applicable
Switchable Glazing Schedule
Applicability
Fenestration with switchable glazing controlled by an electrical signal
Definition
For switchable glazing, this is an hourly schedule for the when the switchable glazing is darkened, when controlled by an electrical signal.
Units
Boolean: 1 if switchable glazing is active (darkened); 0 if not active
Input Restrictions
0 or 1 for schedule values
Standard Design
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
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.
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 following layers:
Layer 1 CMU Solid Grout 115lb/ft3 – 8 in. R – 0.87 C – 1.14
|
Construction |
Layer |
Thickness (inch) |
Conductivity (Btu/h ft F) |
Density (lb/ft² ) |
Specific Heat (Btu/lb F) |
R-value (ft²·°F·h/Btu) |
C-factor (Btu/ft²·°F·h) |
|
NR |
115 lb/ft3 CMU, solid grout |
8 |
0.45 |
115 |
0.20 |
0.87 |
1.140 |
|
R-7.5 c.i. |
115 lb/ft3 CMU, solid grout |
8 |
0.45 |
115 |
0.20 |
0.87 |
|
|
|
1.8 |
0.02 |
1.8 |
0.29 |
7.50 |
| |
|
|
Total assembly |
|
|
|
|
8.37 |
0.119 |
|
R-10 c.i. |
115 lb/ft3 CMU, solid grout |
8 |
0.45 |
115 |
0.20 |
0.87 |
|
|
|
R-10 continuous insulation |
0.02 |
1.8 |
0.29 |
10.00 |
| |
|
|
Total assembly |
|
|
|
|
10.87 |
0.092 |
|
R-12.5 c.i. |
115 lb/ft3 CMU, solid grout |
8 |
0.45 |
115 |
0.20 |
0.87 |
|
|
|
R-10 continuous insulation |
3.0 |
0.02 |
1.8 |
0.29 |
12.50 |
|
|
|
Total assembly |
|
|
|
|
13.37 |
0.075 |
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.
These building descriptors apply to slab-on-grade or below-grade floors that are in direct contact with the ground.
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
Slab Floor Type
Applicability
All slab floors, required
Definition
One of two classes for floors in contact with ground. The classes are:
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.
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: as appropriate for the simulation tool
This may include: Area, Perimeter Exposed
Input Restrictions
No restrictions
Standard Design
The geometry of the slab floor in the standard design building is identical to the slab floor in the proposed design.
Slab Floor Construction
Applicability
All slab floors, 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 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
List
F-factor from Reference Appendix JA4|topic=Appendix JA4 – U-factor\, C-factor\, and Thermal Mass Data; this is one selection from list 1 and one selection from list 2. Note that some combinations from list 1 and list3 are not allowed – see Reference Appendix JA4 Table 4.4.8 and Table 4.4.7 for details.
List 1: None, 12 in horizontal, 24 in horizontal, 36 in horizontal, 48 in horizontal, 12 in vertical, 24 in vertical, 36 in vertical, 48 in vertical, Fully insulated slab
List 2: R-0, R-5, R-7.5, R-10, R-15, R-20, R-25, R-30, R-35, R-40, R-45, R-50, R-55
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, and then that information is used in Table 4.4.8 of Reference Appendix JA4 to determine the required F-factor. For alterations the same requirements apply.
Standard Design
Slab loss shall be modeled with the simple method (F-factor).
The standard design construction shall include the following layers:
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.
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
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 just 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.
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 baseline building shall be steel framed walls with 5/8 in. gypsum board on each side. For walls, partitions in the standard design building shall be steel framed walls with 5/8 in. gypsum board on each side. For interior floors and ceilings, baseline construction shall be 5/8 in. gypsum board, an air space of 4” or more, and 5/8” gypsum board.
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
Partitions in the baseline building shall be steel framed walls with 5/8 in. gypsum board on each side. For walls, partitions in the standard design building shall be steel framed walls with 5/8 in. gypsum board on each side and R-13 fiberglass batt insulation between the studs
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.
The compliance software may have an option to model a building with simplified (two-dimensional geometry). This is an optional capability as an alternative to modeling the three-dimensional geometry of a building. If the compliance software only provides a two-dimensional building model, the following features cannot be modeled:
•Daylighting controls and dimming
•Exterior shading or self-shading
All mandatory and prescriptive daylight controls must be present when submitting a compliance project using software that only models a building with two-dimensional geometry.
The compliance software must pass all reference method tests corresponding to two-dimensional geometry to meet certification requirements as compliance software. Consult Appendix 3B of the ACM Reference Manual for additional information. The software must pass the ruleset implementation tests, and for the sensitivity tests that verify simulation accuracy, there are 2D tests specified for building envelope, but for other building components (lighting, HVAC), the software is compared against the results of the reference method, which uses a three-dimensional geometry model.
The compliance software must have sufficient information to specify each exterior surface when modeling a building with two-dimensional geometry. At a minimum, building surface azimuth, elevation, area are required and the tilt, azimuth and area is specified for roof components. The model must use only vertical walls for the analysis. The model follows all other ACM requirements for space and zone definitions, lighting and HVAC specifications, and follows the same rules for the standard design and proposed design constraints.
The model also requires the following explicit inputs from the user:
•Total Building Story Count – the total number of stories
•Total Above Grade Stories – the total number of stories above grade, used in determination of high-rise residential classification