Proposed Design
The building is defined through entries for zones, surfaces, and equipment. Zone types include attic, conditioned space, crawl space, basements, and garages. The roof (such as asphalt shingles or tile) is defined as either part of the attic or part of a cathedral ceiling (also called a rafter roof). The compliance software models surfaces separating conditioned space from exterior or unconditioned spaces (such as a garage or storage) as interior surfaces adjacent to the unconditioned zone. Exterior surfaces of an attached garage or storage space are modeled as part of the unconditioned zone.
The input file will include entries for floor areas, wall, door, roof and ceiling areas, and fenestration and skylight areas, as well as the water-heating, space-conditioning, ventilation, and distribution systems.
Each surface area is entered along with performance characteristics, including building materials, U-factor, and SHGC. The orientation and tilt (Figure 13: Surface Definitions) are required for envelope elements.
Building elements are to be consistent with the actual building design and configuration.
Standard Design
To determine the standard design, the compliance software creates a building with the same general characteristics (number of stories, attached garage, climate zone). Energy features are set to be equal to §170.2, Table 170.2-A and Table 170.2-K for multifamily buildings. For additions and alterations, the standard design for existing features in the existing building shall have the same wall and fenestration areas and orientations as the proposed building. The details are below.
Verification and Reporting
All inputs that are used to establish compliance requirements are reported on the LMCC or NRCC.
Figure 13: Surface Definitions
Source: California Energy Commission
Internal gains and IAQ ventilation calculations depend on the conditioned floor area and number of bedrooms. For multifamily buildings with individual IAQ ventilation systems, each combination of bedrooms and conditioned floor area has a different minimum ventilation CFM that must be verified. In buildings with multiple dwelling units, a dwelling unit type has the same floor area, number of bedrooms, and appliances (washer/dryer in the dwelling unit).
PROPOSED DESIGN
For each dwelling unit type the user inputs the following information:
Unit name
Quantity of this unit type in building
Conditioned floor area (CFA) in square feet per dwelling unit
Number of bedrooms
STANDARD DESIGN
The standard design shall have the same conditioned floor area and number of bedrooms and type of dwelling units as the proposed design.
VERIFICATION AND REPORTING
The number of units of each type and minimum IAQ ventilation for each unit is reported on the LMCC or NRCC for field verification.
Multifamily projects have multiple dwelling units within the project. The dwelling units per space represents the number of residential living units within a single compliance model space and is shown as a positive integer.
Proposed Design
The proposed design represents the building as designed.
Standard Design
The standard design assumes 1 dwelling unit per space. This applies for both newly constructed buildings projects and existing building projects.
Multifamily projects can have multiple bedrooms within a dwelling unit. The user will provide the number of bedrooms per dwelling unit as an integer with a minimum of 0 and a maximum of 5.
Proposed Design
The proposed design represents the number of bedrooms per dwelling unit as designed.
Standard Design
The standard design assumes the same number of bedrooms per dwelling unit as identified in the proposed design. This applies for both newly constructed buildings projects and existing building projects.
Applicability: Multifamily projects will need to specify the number of people in a space. The number of people is modified by an hourly schedule, which approaches but does not exceed 1.0. Therefore, the number of people specified by the building descriptor is similar to design conditions as opposed to average occupancy.
The number of people may be specified in ft²/person or people/1000 ft².
Proposed Design
The number of occupants is prescribed, and the values are given by Space Type in Appendix 5.4A for nonresidential buildings. For multifamily buildings, the rules established in Chapter 6 Multifamily Building Descriptors Reference of the Nonresidential ACM Reference Manual apply., For multifamily spaces, the number of occupants is defined as: Max (number of bedrooms +1, 2).
Standard Design:
The number of occupants must be identical for both the proposed and standard design cases. This applies for both newly constructed buildings and existing building projects.
For multifamily common areas in the building the indoor lighting power is specified. Indoor lighting power can be specified using the area category method or the tailored method.
Proposed Design
Area category method can be used for all areas of the building with space types listed in Appendix 5.4A. This method can be used by itself or with the tailored lighting method.
Tailored lighting method can be used for spaces with primary function listed in Table 170.2-N of the Energy Code. The tailored lighting method is intended to accommodate special lighting applications. The tailored lighting method can be used by itself for all areas of the building or with the area category method. For a given area only one classification type can be used.
Only area category or tailored lighting are allowed.
The area category method can be used for multifamily general lighting power and multifamily additional lighting power. The tailored lighting method can be used for multifamily general lighting power, multifamily wall display lighting power, multifamily task lighting power and multifamily decorative/special effect lighting power.
Standard Design
The standard design lighting power shall be modeled as described for nonresidential spaces except as noted below.
• Area category method lighting power allowances, as well as additional lighting power qualified systems and allowances are defined by Table 170.2-M
• Available function types for tailored method lighting power allowances and related adjustment factors are defined by Tables 170.2-N, 170.2-O, 170.2-P and 170.2-Q.
All common area spaces in multifamily buildings may have multifamily general lighting power. General lighting power is the power used by installed electric lighting that provides a uniform level of illumination throughout an area, exclusive of any provision for special visual tasks or decorative effect, and also known as ambient lighting.
Proposed Design
For spaces without special task lighting, wall display lighting or similar requirements, this input will be the same as the regulated lighting power.
Trade-offs in general lighting power are allowed between spaces all using the area category method, between spaces all using the tailored lighting method and between spaces that use area category and tailored methods.
Standard Design
With the area category method, general lighting power is the product of the lighting power densities for the space type from Appendix 5.4A and the floor areas for the corresponding conditioned spaces.
With the tailored lighting method, general lighting power is the product of the lighting power density for the primary function type in Table 170.2-N of the Energy Code and the floor area of the space. The lighting power density is given as a function of room cavity ratio (RCR) and interior illumination level in Table 170.2-Q. No interpolation is allowed for this table.
The general lighting power in the tailored method is calculated by the following steps:
Step 1. Determine illumination level from Table 170.2-N by matching the primary function area in Table 170.2-N with the space type in Appendix 5.4A.
Step 2. Calculate the room cavity ratio (RCR) by using the applicable equation in Table 170.2-P.
Step 3. Determine the general lighting in the space(s) using the tailored method by a look-up in Table 170.2-Q, where the general lighting LPD is a function of illuminance level and RCR. No interpolation is allowed for this table. A space between two illuminance levels (for example, 150 lux) uses the applicable LPD from the next lower illuminance level (100 lux).
The standard design uses the irregular room RCR equation for both simplified and detailed geometry models.
The standard design lighting power is modified by a factor of 1/1.20 (0.833) if the simplified geometry approach is used and if the visible transmittance of any fenestration in the space does not meet the prescriptive requirements established in §170.2(b) of the Energy Code.
When the lighting status is “existing” (and unaltered) for the space, the standard design is the same as the existing, proposed design.
When the lighting status is “altered” for the space, and at least 10 percent of existing luminaires have been altered:
Ø If the lighting status is “existing”, then the standard design LPD is the same as the proposed design.
Ø If the lighting status is “new”, then the standard design LPD is same as newly constructed buildings.
Ø If the lighting status is “altered”, then the standard design LPD is the same as newly constructed buildings.
Common areas spaces in multifamily buildings that use area category method can identify multifamily additional lighting power task area.
Proposed Design
The area associated with each of the additional lighting allowances in the ALP building descriptor. This area is based on the proposed designed but cannot exceed the floor area of the space.
Standard Design
The standard design multifamily additional lighting power task area is the same as the proposed. This applies for both newly constructed buildings and existing building projects.
Multifamily spaces or projects that use the tailored lighting method can identify multifamily building custom lighting power.
Proposed Design
Custom lighting power covers lighting sources that are not included as general lighting, including qualified lighting system designated in the two rightmost columns of Table 170.2-M and lighting systems in Table 170.2-N of the Energy Code. This lighting must be entered separately from the general lighting because it is not subject to tradeoffs.
Compliance software shall allow the user to input a custom lighting input for the allowed lighting system. If area category method is used, custom lighting power cannot be used if the tailored method is used for any area of the building.
Standard Design
Same as proposed but subject to the maximum limits specified in the two rightmost columns of Table 170.2-M and lighting systems in Table 170.2-N of the Energy Code. For spaces using the tailored method, the maximum allowed custom power is defined by the following procedure:
The standard design custom lighting power is calculated by the sum of the following four terms:
1) The product of the standard design wall display power and the standard design wall display length.
2) The product of the standard design floor and task lighting power and the standard design floor and task lighting area.
3) The product of the standard design decorative and special effect lighting power, and the standard design ornamental and special effect lighting area; and
4) The product of the standard design very valuable display case power and the standard design very valuable display case area, subject to prescriptive limits in Table 170.2-N.
For alterations where less than 10 percent of existing luminaires have been modified, the standard design is the existing lighting condition before the alteration. If 10 percent or more luminaires have been altered, the custom lighting power for the standard design is the same as proposed, but subject to the limits specified in the two rightmost columns of Table 170.2-M of the Energy Code.
All common use area spaces in multifamily buildings that use the tailored method can identify multifamily wall display power.
Proposed Design
The lighting power allowed for wall display, as specified in Table 170.2-N, column 3 of the Energy Code.
Standard Design
The standard design lighting power is the lesser of the proposed design wall display power or the limit specified in Table 170.2-N for the applicable space type.
For existing buildings, the multifamily wall display power standard design is the same as the proposed design.
All common use area spaces in multifamily buildings that use the tailored method can identify multifamily wall display length.
Proposed Design
The horizontal length of the wall display lighting area using the tailored method for the space. The length is based on the proposed design but this value cannot exceed the floor area of the space.
Standard Design
The standard design multifamily wall display length is the same as the proposed design. This applies for both newly constructed buildings and existing building projects.
All common use area spaces in multifamily buildings that use the tailored method can identify multifamily task lighting power.
Proposed Design
The lighting power allowed for task lighting, as specified in Table 170.2-N, column 4 of the Energy Code.
Standard Design
The standard design task lighting power is the lesser of the proposed design task lighting power or the limit specified in Table 170.2-N, column 4, for the applicable space type.
For existing buildings, the multifamily task lighting power allowed is the same as proposed design.
All common use area spaces in multifamily buildings that use the tailored method can identify multifamily task lighting area.
Proposed Design
The lighting area that is served by the task lighting defined using the tailored method for the space. The area is based on the proposed design but this value cannot exceed the floor area of the space.
Standard Design
The standard design multifamily task lighting area is the same as the proposed design. This applies for both newly constructed buildings and existing building projects.
All common use area spaces in multifamily buildings that use the tailored method can identify multifamily decorative and special effect lighting power.
Proposed Design
The lighting power allowed for decorative and special effect lighting, as specified in Table 170.2-N, column 5 of the Energy Code.
Standard Design
The standard design decorative and special effect lighting power is the lesser of the proposed design ornamental and special effect lighting power or the limit specified in Table 170.2-N, column 5, for the applicable space type.
For existing buildings, the multifamily decorative and special effect lighting power for the standard design is the same as the proposed design.
All common use area spaces in multifamily buildings that use the tailored method can identify multifamily decorative and special effect lighting area.
Proposed Design
The lighting area that is served by the decorative and special effect lighting defined using the tailored method for the space.
The multifamily decorative and special effect lighting area is based on the proposed design but this value cannot exceed the floor area of the space.
Standard Design
The multifamily decorative and special effect lighting area for the standard design is the same as the proposed design. This applies for both newly constructed buildings and existing building projects.