Additions may comply using the performance approach for an addition alone. With only two exceptions, the energy budget is the same as is required for new construction. The two exceptions are: (1) For additions that are 300 ft2 or less no cool roof requirements apply, and (2) if Package A requires a whole house fan, the requirement does not apply to additions that are 1,000 ft2 or less.
1. Performance compliance may not be used for tradeoffs for an alteration alone unless there are at least two or more altered components listed in §150.2 and Table 150.2-C.
2. Existing roofs/ceilings removed as part of an addition or alteration--and all existing skylights being removed as part of the removed roofs/ceilings--are excluded (not modeled) in the Existing + Addition + Alterations (E+A+A) performance calculations.
3. Existing exterior walls removed as part of an addition or alterations--and all existing vertical fenestration (windows, clerestories, glazed doors) being removed as part of the removed walls--are excluded (not modeled) in the E+A+A performance calculations.
4. Only “Existing,” “Altered,” and “New” building components and/or systems are included and modeled in the E+A+A performance calculations.
5. Existing fenestration not being removed as part of an alteration can now be improved with window films and can be modeled in the E+A+A performance calculations.
6. Without third party verification of the building’s existing (pre-alteration) conditions, the E+A+A approach no longer provides energy credits based on altered components which upgrade (improve) the existing conditions until a fairly high threshold is met. See §150.2(b)2B and Table 150.2-C of the Energy Standards.
7. With third party verification of the building’s existing (i.e., pre-alteration) conditions, the E+A+A approach still provides energy credits based on altered components which upgrade (improve) the existing conditions. See §150.2(b)2B and Table 150.2-C of the Energy Standards.
Additions may comply using the performance approach with one of the following compliance paths summarized in Section 9.3, Table 9-1:
1. E + A + A Without Third Party Verification;
2. E + A + A With Third Party Verification;
3. E + A + A as New Construction.
Energy Commission-approved compliance software is used to model the building as explained in Chapter 8. Whichever compliance path is selected, the Certificate of Compliance (CF1R) generated by the software must be submitted for permit. If the CF1R includes energy measures that require HERS testing or verification, the CF1R must also be registered online with a HERS provider. See Chapter 2 of this manual.
To learn more about using the Existing + Addition + Alterations performance approach, see Table 9-4.
9.7.3.1 Existing + Addition + Alterations Without Third Party Verification
The existing building with all alterations is modeled together with the addition and existing conditions are not verified by a third party HERS Rater. The Standard Design that sets the energy budget for this approach is automatically based only on the type of each altered component and not on the existing conditions. Under this performance path the building is modeled as follows:
1. Addition: All new components at the addition and all new systems serving the addition are modeled including roof/ceilings, skylights, exterior walls, glazing (fenestration), raised floors and slab floors, HVAC equipment, ducts, and water heating. All of these components are tagged within the compliance software as “New.”
2. Existing Components to Remain Unchanged: Existing components and systems to remain as is (untouched) are modeled and tagged within the compliance software as “Existing.”
3. Existing Components to be Altered or Replaced: Each altered component (i.e., a new component which replaces an existing component) is modeled and tagged within the performance compliance program as "Altered." For example, a new water heater that replaces an existing water heater would be labeled "altered” whereas a new water heater that is added to supplement an existing water heater would be labeled "new." Also, new mechanical equipment that does not replace existing mechanical equipment would be tagged as "new." Verification of existing conditions is not required for this compliance path; therefore, no “existing” (pre-alteration) conditions are specified.
4. Existing to be Removed: Existing roof/ceilings to be removed as part of the permitted work, plus any skylights within those removed roof/ceilings, are excluded from the model (i.e., they are completely omitted from the calculations); exterior walls to be removed and all fenestration areas in those walls are not modeled; raised floors and slab-on-grade floors to be removed are also omitted.
Note: Portions of new fenestration including skylights that will occur in the existing opening of fenestration to be replaced are tagged "altered." Portions of new fenestration that will occur where there is no existing fenestration opening are labeled "new."
•Advantages: Energy improvements to the existing building that go beyond the Standard Design levels are an energy credit that can be “traded” against features of the addition that are less energy efficient than required by the prescriptive levels that set the Standard Design for the addition alone. For example, an addition with a large glazing area may comply by replacing the existing HVAC system with high-efficiency equipment.
•Disadvantages: Detailed plans and other information on the existing building may be difficult to document and obtain. The E+A+A analysis may be relatively complex and time-consuming.
9.7.3.2 Existing + Addition + Alterations With Third Party Verification
The existing building with alterations is modeled together with the addition(s); and existing conditions of the components being altered must be verified by a third party HERS Rater before construction begins. The Standard Design that sets the energy budget may, depending on the energy efficiency of the altered component or system, be based on the pre-altered existing conditions. In those instances, energy credit is calculated as a function of the difference between pre-altered existing conditions and post-alteration energy measures. Under this approach the building is modeled as follows:
1. Addition: All new components for the addition and all new systems serving the addition are modeled including roof/ceilings and skylights, exterior walls and glazing (fenestration), raised floors and slab floors, HVAC equipment, ducts, and water heating. All these elements are tagged within the compliance software as “new.”
2. Existing Components to Remain Unchanged: Existing components and systems to remain as is (untouched) are modeled and tagged within the compliance software as “Existing.”
3. Existing Components to be Altered or Replaced: First, select “HERS verification of existing conditions” in the compliance software. This unlocks software inputs for both “existing” and “altered” characteristics for those particular building features. The compliance software will not give the option to enter pre-altered existing conditions, if you do not specify that the existing conditions will be HERS-verified.
Each altered component (i.e., a new component that replaces an existing component) is modeled and tagged within the performance compliance program as "Altered." The corresponding HERS verified existing component or system to be changed is modeled and tagged within the same entry in the compliance software as “existing.” For example, if existing HERS-verified single pane metal frame window are replaced with NFRC-rated super-efficient windows, to receive the maximum energy credit one must identify the existing windows to be HERS-verified. Then, each altered window input would include both “existing” and “altered” window types.
Note: Any window area in addition to that being replaced would be labeled “new” not “altered.”
5. Removed Surfaces: Existing roof/ceilings to be removed as part of the permitted work, plus any skylights within those removed roof/ceilings, are excluded from the model (i.e., they are completely omitted from the calculations). Exterior walls to be removed and all fenestration areas to be removed in those walls are not modeled; raised floors and slab-on-grade floors to be removed are also omitted.
•Advantages: Energy improvements meeting certain threshold values are credited based on the difference between existing conditions and the altered component or system. These energy credits can be “traded” against features of the addition that are less energy efficient than required by the prescriptive levels that set the Standard Design for the addition alone. For example, an addition with a large glazing area may comply by upgrading insulation levels in the existing house.
•Disadvantages: Detailed plans and other information on the existing building may be difficult to document and obtain. The E+A+A analysis may be relatively complex and time-consuming. A third party verification must be conducted of selected existing conditions to be altered prior to construction, and verification must be registered online with a HERS provider prior to permit submittal.
9.7.3.3 Existing + Addition + Alterations as New Construction
A compliance approach rarely used, but available within the Energy Standards, is to model Existing + Addition + Alterations as all “new” components and systems and the compliance software sets the energy budget as if the project were an entirely new building.
•Advantages: Modeling the existing building with alterations and additions as all new makes the performance analysis relatively simple and less time-consuming. This method will provide the owner and designer with energy efficiency compliance relative to requirements for new construction. Any owner who wants to bring their building up to new construction efficiency levels should have their project modeled as “new.”
•Disadvantages: The energy budget with this approach is very stringent. Unless a building is going through a complete retrofit of all its envelope components, as well as replacing all mechanical and water heating systems, it is unlikely that the building will meet the Energy Standards with this approach.
9.7.3.4 8Summary of Modeling Rules
Table 9-4 summarizes the basic rules for compliance software users analyzing a residential addition or alteration using the Existing + Addition + Alterations approach. For further information, see the specific compliance software user's manual for details on how to input data correctly.
Example 9-37
Question
A 1,600 ft² house built in 1980 in climate zone 12 is being renovated as follows:
1. A 500 ft² room will be added, including 120 ft² of new windows.
2. A 200 ft² wall and 100 ft² of old window will be removed.
3. Attic insulation in the existing house will be upgraded to R-38.
4. The addition will be connected to the existing HVAC and duct system.
If the performance approach is used to demonstrate compliance, how does the compliance software establish the standard and proposed designs?
Answer
Table 9-4 summarizes the Modeling Rules for Existing + Addition + Alterations which must be followed to have the compliance software accurately set the standard design and model the proposed design. Under the 2016 Standards performance rules, the 200 ft² wall removed and the 100 ft² of old window within it are not included in the energy model and will have no impact on the standard design. The standard design for the addition portion is set using the prescriptive requirements of §150.1(c). If the existing duct system is extended by 40 linear feet or more, the standard design assumes the duct alterations requirements summarized in Table 9-5.
The standard design assumptions for the existing house follow the rules summarized in §150.2(b)2 and Table 150.2-B based on whether there is a third party verification of the existing conditions. Without third party verification, upgraded energy components in the existing house are modeled as fixed assumptions in the standard design that represent levels of efficiency reasonably expected for each altered component. If the energy analyst using the compliance software selects third party verification of energy components in the existing house to be upgraded, the standard design assumes the existing conditions for those components to be as part of the alterations.
If the proposed design including Existing + Addition + Alterations does not pass, other energy components of the existing building and/or the addition may have to achieve compliance. For example, the water heater or the HVAC equipment in the existing portion of the house may be upgraded to achieve additional credits towards compliance. In the addition, higher performing windows and higher levels of roof and wall insulation may also be used to achieve compliance.
Example 9-38
Question
For the 1980 house in the examples above, an operable single pane metal window is replaced with a 0.55 U-factor window. Does this alteration result in a compliance credit? How about the case where the existing window is replaced with a window that has a U-factor of 0.35?
Answer
As explained in Example 9-36, altered components that receive compliance credit must exceed the requirements of Table 150.2-B. Windows in the addition must have a U-factor of < 0.32 and SHGC < 0.25 to receive credit. Replacement windows in the existing house must have a U-factor of < 0.40 and SHGC < 0.35 to receive credit.
A window replacement with a 0.55 U-factor will receive a penalty as compared with a 0.40 U-factor standard design assumption for that window. Without third party verification of existing conditions, a 0.35 U-factor window replacement will receive a credit as compared with a 0.40 U-factor standard design assumption for that window. With third party verification of existing conditions, a 0.35 U-factor window replacement will receive a credit as compared with a 1.28 U-factor standard design assumption for an operable single pane metal existing window.
Although this example describes a window alteration, the same principles apply to other building systems, such as other building envelope components as well as HVAC and water heating equipment.
Example 9-39
Question
An addition of 590 ft² is being added to a 2,389 ft² single family house. How do you demonstrate compliance using the Existing + Addition + Alterations method?
Answer
The first step is to determine whether alterations to the existing building include at least two components (e.g., upgrading attic insulation and replacing the water heater, or more than one window.) If so, use the E+A+A approach. If not, do not use the performance approach.
Assuming the E+A+A calculation is permissible, the next steps are:
1. Collect accurate envelope and mechanical information about the existing building from scaled drawings (plans, sections, and elevations); determine what components, (HVAC, ducts, water heating, etc.) are being altered as part of the permitted scope of work.
2. Enter the information about the addition and the existing building into the compliance software program, identifying each modeled feature as “existing,” “altered,” or “new” as summarized in Table 9-4. Proper tagging of each of these inputs is critical to correctly and accurately determine compliance.
3. Run the compliance software to determine if the proposed building TDV energy is equal or less than the standard design TDV energy.
4. If it is not, modify the energy features of the addition and/or the existing building until compliance is achieved; print out the compliance report for permit submittal.
5. All projects that include energy measures requiring HERS field verification and diagnostic testing which represent almost all buildings under the 2016 Energy Standards--must be registered online with a HERS provider as explained in Section 2.3.
Example 9-40
Question
When using the existing-plus-addition performance approach, do the refrigerant charge, access holes (MAH and STMS) or FID, see §150.1(c)7,, airflow, watt draw measurement, and static pressure probe (HSPP), or a permanently installed static pressure probe (PSPP) as specified in §150.0(m)13 and need to be met for central split system air conditioners serving an addition?
Answer
If existing equipment is extended to serve the addition, these space conditioning requirements do not need to be met as specified by Exception 4 to §150.2(a). However, Exception 5 to §150.2(a) indicates that the duct system that is to be extended must be sealed, tested, and HERS verified according to §150.2(b)1D.
For performance compliance in climate zones that require a refrigerant charge and airflow measurement in Package A, a hypothetical standard design SEER split system with this credit would be modeled in both the standard and the proposed designs (for example, values from the vintage table, or minimally complying equipment), resulting in neither credit nor penalty related to this feature.
If a new central split system is installed to serve the addition, it must meet the requirements of §150.2(b)1C where installation of a new air conditioner to serve both the existing house and the addition is considered an alteration, and must meet the requirements for diagnostically tested refrigerant charge measurement fan airflow, watt draw, and other requirements described. The duct sealing, testing, and verification requirements of §150.2(b)1E must also be met.
Example 9-41
Question
When using the E+A+A performance method, can compliance credit be gained by sealing the existing ducts when it was not required for prescriptive compliance?
Answer
Yes. Credit can be obtained from sealing, testing, and HERS verification of duct sealing.
However, as shown in Table 150.2-B “Standard Design for an Altered Component,” the base case duct leakage will be the requirements in §150.2(b)1D (i.e., with 15 percent duct leakage or 10 percent leakage to the outside). Sealing below 15 percent can be difficult if the ducts are not readily accessible and large holes are present in the ducts. An alternative approach is to replace the ducted system with a ductless system such as a mini-split.
Example 9-42
Question
When using the existing plus addition performance compliance method, can credit be gained by installing a radiant barrier in the existing house attic? If so, where does the radiant barrier need to be installed?
Answer
Yes, installing a radiant barrier in the existing building will result in a credit relative to the standard design for existing buildings permitted (or constructed) prior to June 1, 2001. The radiant barrier must be installed over the entire attic/roof area including gable walls. If there are roof/ceiling assemblies where it is not possible to reach the underside of the roof, such as roof/ceiling assemblies using enclosed rafters which are not proposed to be exposed as part of the project, the radiant barrier cannot be properly installed and compliance credit is not possible.
Example 9-43
Question
I am adding a room to and altering an existing building in climate zone 12. I am upgrading a single-pane clear glass window with a U-factor of 1.2 and SHGC of 1.0 to a dual-pane window with a U-factor of 0.50 and SHGC of 0.45. Do I receive credit toward the addition compliance for installing this window?
Answer
No. There will be a penalty toward achieving compliance since the window is not as efficient as required by Table 150.2-B for climate zone 12 which requires a U-factor of 0.40 and an SHGC of 0.35. The penalty for the U-factor is based on the difference between 0.40 and 0.50 and for the SHGC is based on the difference between 0.35 and 0.45. If fenestration is installed which exceeds the performance of the values in Table 150.2-B, then credit is available.
Example 9-44
Question
I am planning on installing R-19 insulation in the attic of an existing house built in 1970. Can I use this added insulation as a credit for trading with the energy features of an addition?
Answer
No. When insulation is added to an attic, it must comply with §150.0.) which sets a mandatory minimum for attic insulation of R-22. No credit is allowed until the mandatory minimum R-22 is reached.
Example 9-45
Question
I am planning on installing R-25 insulation in an un-insulated vaulted ceiling without an attic space in an existing house built in 1970. Can I use this added insulation as a credit for trading with the energy features of an addition?
Answer
Yes. Since there is no attic space, the requirements of §150.0(a) require only R-19 or the equivalent between roof rafters. When you install R-25 you are allowed to take credit for the difference between R-25 and R-19 without third party verification of existing conditions. With third party site verification of the existing un-insulated vaulted ceiling prior to construction, you may take credit for the difference between the R-25 and R-0 (no insulation) in the vaulted ceiling