11.4 Application Scenarios

The performance approach may be used for whole building permit applications; or for permit applications that involve combination of either building envelope and indoor lighting or the mechanical system or for lighting and mechanical together. The performance method may be used to demonstrate compliance with the envelope alone or the mechanical system alone, but cannot be used to show lighting compliance alone. When less than a whole building is being considered, this is called a permit phase, e.g. the building envelope would be constructed in one permit phase, the mechanical system in another, etc.

11.4.1 Whole Building Compliance

Whole buildings are projects involving buildings where the applicant is applying for a permits and is submitting plans and specifications for all the major components of the building (envelope, mechanical, indoor lighting and service water heating). This could be a first-time tenant improvement that involves envelope, mechanical and lighting compliance; or a complete building, where plans and specifications for the entire building are being submitted for permit.

When a whole building is modeled using the performance approach, trade-offs can be made between the envelope, space conditioning, service water heating, and indoor lighting systems that are included in the permit application.

11.4.2 Compliance by Permit Stage

Compliance with only one or more building permit stages can be done using the performance approach except that indoor electrical lighting cannot be done alone. A permit stage is a portion of a whole building permit: either envelope, mechanical, or electrical. This means that trade-offs in energy use are limited to include only those features, or single feature in the case of envelop or mechanical, included in the building permit application.

There are two basic scenarios that occur when performing compliance by permit stage: modeling future construction features that are not included in the permit application, and modeling existing construction that has complied with the Standards.

When a feature of a building is not included in the permit application, it is required to default to a feature automatically determined in the computer program. The defaults vary for envelope, mechanical, and indoor lighting. The Nonresidential ACM Reference Manual and the program vendor’s compliance supplement contain additional information on the default values.

The default envelope features do not apply when modeling future construction. Usually, this is the first permit requested and at a minimum this feature must be modeled. The proposed building's envelope features are input and an energy budget is automatically generated based on the proposed building's envelope, and/or space conditioning and indoor lighting system.

The default space conditioning system features are fixed if no space conditioning system exists in the building. A standard package gas/electric unit is assumed for each thermal zone in the proposed design. The package system is sized based on the envelope design and whether it meets the prescriptive requirements. If a space conditioning system is included in the permit application, the default space conditioning system is based on the standard design as determined in the Nonresidential ACM Reference Manual.

The default lighting system features depend on whether or not the occupancy of the building is known. If the building occupancy is known, the allowed lighting power density is determined using the Complete Building Approach for each zone that the occupancy is known. If the building occupancy is not known, 0.6 W/ft² is assumed for both the proposed energy use and the energy budget

The default service water heating system features are fixed based on building occupancy. Default service water heating systems are specified for each occupancy type. For nonresidential occupancies other than high rise residential, hotel and motels the default can be gas or electric fired.

When existing indoor lighting or an existing mechanical system is not included in the permit application, the compliance software may use default values for certain inputs. The Nonresidential ACM Reference Manual contains additional information on the default values.

The envelope features are based on the program user's inputs to the compliance software. The user inputs the proposed building's conditioned floor area, glazing, wall, floor/soffit, roof/ceiling, and display perimeter features. The compliance software then applies the proposed building's features to the standard design in order to calculate the energy budget. If an application for an envelope permit is not being sought, the compliance software will automatically default the features of the standard design to be the same as the features of the proposed design. Only the EXISTING-ENV will be printed to document the existing building.

Default space conditioning system features are fixed based on the building's existing space conditioning system. The program user inputs the existing space conditioning system, including actual sizes and types of equipment. The compliance software then applies the proposed building's space conditioning features to create a standard design mechanical system used to calculate the energy budget. This means that if an application is not being sought for a mechanical permit, the computer program will automatically default the features of the standard design to be the same as the features of the proposed design. No mechanical forms will be printed.

Default service water heating system features are fixed based on building occupancy. Default service water heating systems are specified for each occupancy type. Water heating information will only be listed as "Existing".

Default lighting system features are based on the known occupancy of the building. The allowed lighting power density (LPD) is determined based on the Complete Building LPD for the proposed design, or an Existing Modeled LPD from field data. The compliance software then applies the proposed building's indoor lighting LPD the standard design in order to calculate the energy budget. This means that if an application for a lighting permit is not being sought, the compliance software will automatically default the lighting features of the standard design to be the same as the lighting features of the proposed design. No LTG form will be printed. All modeled indoor lighting will be reported on the PERF-1 Performance Certificate of Compliance.

11.4.3 Additions Performance Compliance

An addition consists of both new conditioned floor area and added volume, and it is treated similar to a new building in the performance approach. All systems serving the addition will require compliance to be demonstrated; and either the prescriptive or performance approach can be used for each stage of the construction of the addition.

Note: When existing space conditioning or water heating is extended from the existing building to serve the addition, those systems do not need to comply with new construction energy efficiency requirements; however, all applicable mandatory measures must be met for new components and controls. .

Additions that show compliance with the performance approach independent of the existing building must meet the requirements for new buildings. §140.1 states that the envelope and indoor lighting in the conditioned space of the addition, and any newly installed space conditioning or service water heating system serving the addition, must meet mandatory measures and the applicable energy budget:

• If the permit is done in stages, the rules for each permit stage apply to the addition performance run.

• If the whole addition (envelope, lighting and mechanical) is included in the permit application, the rules for whole buildings apply.

• Demonstrating that efficiency improvements to the envelope component of the existing building, as well as certain indoor lighting and mechanical improvements, offset substandard addition performance (see §141.0(a)2Bii); or,

• That the existing building combined with the addition together meet the requirements of §141.0(b) as all new construction.

§141.0(a)2 states that the envelope and indoor lighting in the conditioned space of the addition, and any newly installed space conditioning or service water heating system serving the addition, must meet the mandatory measures as if it were an addition only. The energy use of the combination of the altered existing building plus the proposed addition shall be equal to or less than the energy use of the existing building with all alterations meeting the requirements of §141.0(b)2 plus the standard energy budget of an addition that complies with §140.1.

For a full description of when and how altered components in the existing building are counted as a credit or penalty in the performance calculation, as well as basic energy modeling rules for alterations, see section 11.4.4.2, Alterations in Existing Buildings Without an Addition.

This approach allows the applicant to improve the energy efficiency of the existing building so that the entire building meets the energy budget that would apply, if the existing building were unchanged, and the addition complied on its own. Changes to features in the existing building are considered alterations.

Example 11-2

Question

3,000 ft² of conditioned space is being added to an existing office building. 25 percent of the lighting fixtures in the existing office space are being replaced with more efficient fixtures. Can credit be taken for the improved lights in the existing building to comply through the existing-plus-addition performance approach?

Answer

Credit can only be taken for lighting efficiency improvements resulting in a lower lighting power density than is required to meet §140.6. Otherwise, credit may be taken for improvement(s) to the envelope components only. Lighting in the existing building must meet all prescriptive requirements in this case (more than 10 percent of the lighting fixtures are replaced or the connected load is increased).

11.4.4 Alterations Performance Compliance

Using the performance approach for an alteration is similar to demonstrating compliance with an addition.

Altered spaces can show compliance with the performance approach independent of the remainder of the existing building, but must still meet the requirements for the altered components of the building as specified in §141.0(b)2B and C. §141(b) states that envelope and lighting alterations, as well as and any new or replacement space conditioning or service water heating system serving the alteration, must meet the mandatory measures. The permitted space alone may comply with the energy budget determined using Energy Commission-approved compliance software.

If the permit is done in stages, the rules for each permit stage apply to the alteration performance run.

Alterations may also show compliance by demonstrating that the energy use of the proposed design -- including all energy efficiency improvements to the existing building -- is equal to or less than the standard design energy budget which is based on the alterations meeting the requirements of §141.0(b)2 and Table 141.0-D. Note that §141.0(a)1 also requires that envelope, lighting, space conditioning and service water heating system alterations meet the applicable mandatory measures.

This approach allows the applicant to improve the energy efficiency of the existing building so that it meets the energy budget that would apply to the entire building if the existing building other than the portion being altered was unchanged. Changes to features in the existing building are considered alterations.

An energy penalty is assigned to any altered component that does not meet or exceed the requirements of §141.0(b)2B. A credit is assigned to an alteration (improvement) that exceeds the requirements in §141(b)2B as summarized in Table 141.0-D and further detailed in the Nonresidential ACM Reference Manual. The compliance software sets the standard design for the type altered component as listed in Table 141.0-D.

Fenestration is the only type of altered component where the difference between the existing glazing type and the altered glazing type can be used as a credit in the Existing-Plus-Addition-Plus-Alteration performance calculation. In order to obtain this credit, a third party inspector must:

(a) Site verify all existing fenestration type(s) to be altered as shown on the PERF-1 form; and

(b) Sign a Verification of Existing Fenestration (Form VEF) to submit to the local enforcement agency as part of the Title 24 compliance report.

For further details of this process, see section 11.4.4.2, Alterations in Existing Buildings.

This compliance approach includes the entire building which means the ensemble of all enclosed space in a building, including the space for which a permit is sought, plus all conditioned and unconditioned space within the structure. However, the inclusion of the unconditioned spaces do not affect the overall performance budget of the building since indoor lighting allowances cannot be traded off between the conditioned and unconditioned spaces, and the installed indoor lighting in the unconditioned portion of the building does not affect the heating and cooling budget of the building.

When using this compliance approach it is important to take into account all changes in the building's features that are:

Note that surfaces which are being completely removed from the existing building – roofs/ceilings, exterior walls and floors, and all glazing removed within those surfaces – are not modeled (as was the case under the 2008 and earlier Standards).

Except for replacement fenestration with third party verification of the existing glazing type, the allowed for trade-off by improving the existing building is limited to the amount a particular improvement exceeds the applicable prescriptive requirements of §141.0(b)2.

To show compliance with this approach you need to follow the instructions in the compliance software user’s manual. Documentation of the existing building’s glazing areas is required to be submitted with the permit application if this method is used for replacement fenestration credit.

Example 11-3

Question

Alterations to an existing office building in Climate Zone 12 includes replacing all single clear metal frame operable windows with new NFRC-rated windows (U-factor =0.45, SHGC=0.31.) What standard design values will the compliance software use for the replacement fenestration area?

Answer

If the software user does not select Third Party Verification of the existing fenestration type, the standard design will use the values in Table 141.0-A (U=0.47 and SHGC=0.31) regardless of whether the replacement windows exceed those Table 141.0-A values.

If Third Party Verification of existing fenestration is selected, the standard design will use the applicable values in Table 110.6A and 110.6-B for the existing windows (U=1.28 and SHGC=0.83) because the replacement windows meet or exceed the Table 141.0-A values.
In this case, the compliance software will show a larger compliance credit for improving the existing windows.

For additions, the most flexible compliance method is to consider the entire existing building along with the addition (Existing + Addition + Alteration). The combination of additions and alterations to the existing building may be shown to comply by demonstrating that the proposed design energy use is equal or less than the standard design energy budget based on the alterations meeting the requirements of §141.0(b)2 summarized in Table 141.0-D and additions meeting the requirements of §141.0(a)2.

For a full description of when and how altered components in the existing building are counted as a credit or penalty in the performance calculation, see section 11.4.4.2, Alterations in Existing Buildings without an Addition.

When using this compliance method, all building components and systems input must be identified (tagged) as one of the following

• EXISTING. An existing component or system in the building that remains unchanged.

• ALTERED. An existing component or system that is being altered, changed, or replaced within the permitted scope of work.

• NEW. A newly installed component or system that was not a part of and/or did not previously serve the existing building.

Using this compliance method, credit may be taken for energy efficiency features added to the existing building. When the prescriptive approach is used, compliance can be demonstrated if the altered component meets or exceeds the requirements of §141.0(b)1 for that component. When the performance approach is used, the altered component must meet or exceed the requirements in §141.0(b)2, or another alteration(s) must be made to the existing building, which exceeds the requirements of §141.0(b)2 that saves the additional energy necessary to at least make up for the alteration(s). Alternatively, when there is an addition, the addition can be designed to exceed prescriptive requirements to offset proposed existing building alterations that do not meet prescriptive requirements.

Alterations may include previous fenestration improvements that were made to the building after original permit (when the existing building was first constructed). The upgraded efficiency values of the current fenestration must be documented as the proposed design; and the standard design is based on the current Standards. The permit applicant must provide evidence that the previous glazing improvements were made subsequent to the original construction of the building, and documentation to confirm the glazing type of previously existing fenestration. Such evidence may involve a receipt, a signed statement from previous owners, or in case where previous owners are not available, a signed statement of the current owner or other record. Note that previous fenestration improvements that have been used to achieve compliance for previous additions and alterations cannot be considered for compliance for subsequent additions and alterations.

11.4.5 Alternate Performance Compliance Approach

Any addition, alteration or repair may demonstrate compliance by meeting the requirements applicable to new buildings for the entire building. Using this method, the entire building could be shown to comply in permit stages or as a whole building. The rules for new buildings permit stage compliance, and whole building compliance would apply.

Documentation of the existing building’s features is required to be submitted with the permit application if this method is used.