For a definition of an addition in the Energy Standards and several useful examples of additions, see Section 9.1 of this chapter.
For a summary of compliance alternatives for additions, see Section 9.3.1 of this chapter.
This section provides more specific information, descriptions, and guidelines on how to meet the Energy Standards using each of the available compliance paths. Copies of compliance forms referenced here are included in the Compliance Forms Summary, Appendix A of this manual.
In general, the prescriptive requirements apply to additions in the same way they apply to entirely new buildings and must be documented on the CF1R-ADD Form. However, there are a few exceptions as noted below and summarized in Table 9-3A.
There are three prescriptive paths available for additions based on the total conditioned floor area (CFA) of the addition. The total CFA of the addition may include floor areas representing several physically separate additions to the building under the same permit.
Table 9-3A summarizes the key features of the prescriptive envelope requirements for the three prescriptive addition options in §150.2(a)1. Envelope requirements unique to that type of prescriptive addition are shown in bold face on white background. Table 9-3E shows that all prescriptive additions have the same mechanical system and water heating system requirements as the Package A prescriptive measures for new construction listed in §150.1(c) and explained in Chapters 4 and 5. For more details on the residential envelope requirements and compliance options, refer to Chapter 3|topic=3 Building Envelope Requirements.
A. Additions ≤ 400 ft2
All prescriptive Package A requirements must be met except:
1. Total glazing area may be up to 75 ft2 or 30 percent of conditioned floor area, whichever is greater.
2. West-facing glazing area may be up to 60 ft2.
3. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and require the following cavity insulation:
a. In 2x4 wood-framed walls, insulation shall be R-15.
b. In 2x6 or greater wood-framed walls, insulation shall be R-19.
4. No requirement for a whole-house fan (WHF) to provide ventilation cooling.
5. Mandatory roof and ceiling insulation requirements (§150.0a).
6. For additions ≤ 300 ft2, cool roof compliance is not required.
B. Additions > 400 ft2 and ≤ 700 ft2 :
All prescriptive Package A requirements must be met except:
1. Total glazing area may be up to 120 ft2 or 25 percent of conditioned floor area, whichever is greater.
2. West-facing glazing area may be up to 60 ft2.
3. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and require the following cavity insulation:
a. In 2x4 wood-framed walls, insulation shall be R-15.
b. In 2x6 or greater wood-framed walls, insulation shall be R-19.
4. No requirement for a whole-house fan (WHF) to provide ventilation cooling.
5. Mandatory roof and ceiling insulation requirements (§150.0(a)).
C. Additions > 700 ft2
All prescriptive Package A requirements must be met except:
1. Total glazing area may be up to 175 ft2 or 20 percent of conditioned floor area, whichever is greater.
2. West-facing glazing area may be up to 70 ft2 or 5 percent of conditioned floor area, whichever is greater.
3. If the total proposed fenestration area exceeds the standard maximum glazing area of 20 percent, then the performance compliance approach must be used. Likewise, if the proposed west-facing fenestration area in Climate Zones 2, 4, and 6-16 exceeds 5 percent of the conditioned floor area, then the performance compliance approach must be used.
4. To provide consistency with existing wall alignment, extensions of existing wood-framed walls may retain the dimensions of the existing walls and require the following cavity insulation:
a. In 2x4 wood-framed walls, insulation shall be R-15.
b. In 2x6 or greater wood-framed walls, insulation shall be R-19.
5. Whole-house fan (WHF) requirement:
a. If the addition is 1,000 ft2 or less, there is no requirement for WHF to provide ventilation cooling.
b. Additions greater than 1,000 ft2 must include provide ventilation cooling with a WHF, as indicated in §150.1(c)12 in climate zones 8-14.
The permit applicant must submit a completed version of the Certificate of Compliance,CF1R-ADD form for prescriptive additions when less than 1000 ft2.
All projects that require third-party diagnostic testing and/or field verification by a HERS Rater must also have the CF1R-ADD form uploaded and registered online with a HERS Provider. (See Chapter 2.)
Use the CF1R-ADD form to document fenestration by orientation. The total percentage of fenestration should be no greater than the amount summarized above and in Table 9-3A. West-facing area includes skylights tilted to the west or tilted in any direction when the pitch is less than 1:12 (9.5 degrees from the horizontal) and must not exceed 5 percent of the conditioned floor area (CFA) in Climate Zones 2, 4, and 6-16.
Plan checkers will verify on the CF1R-ADD form that the total proposed glazing area is less than or equal to the standard maximum glazing area, and that the proposed west-facing glazing area is less than or equal to the standard west-facing glazing area.
New fenestration in prescriptive additions must meet the area-weighted average U-factor and SHGC requirements in §150.1(c)3A, with the following exceptions particularly relevant to additions:
1. EXCEPTION 1: For each dwelling unit, up to 3 ft2 of new glazing in doors and up to 3 ft2 of tubular skylights with dual-pane diffusers are exempt.
2. EXCEPTION 2: For each dwelling unit, up to 16 ft2 of skylights with a maximum U-factor of 0.55 and a maximum SHGC of 0.30 is exempt.
See Section 3.5 for further information on fenestration that meets or is exempt from §150.1(c)3A in new construction.
Other Prescriptive Addition Envelope Measures
For further information on prescriptive envelope measures which are not specific to additions and not mentioned above, see Chapter 3.
Prescriptive Mechanical Measures
For a summary and discussion of prescriptive mechanical requirements when installing new or replacement space-conditioning equipment and/or ducts, see Section 9.6.2.
Example 9 8
Question:
When using the performance approach for the addition alone, do the refrigerant charge requirements in §150.1(c)7A|topic=(c) Prescriptive Standards/Component Package. and fan airflow and watt draw measurements in §150.0(m)13|topic=(m) Air-Distribution and Ventilation System Ducts\, Plenums\, and Fans. need to be met for existing central split-system air conditioners serving an addition?
Answer:
If existing equipment is used to serve the addition, the refrigerant charge, airflow, and watt draw requirements do not need to be met as specified by Exception 5 to §150.2(a)|topic=(a) Additions.. However, if added ducts to serve the addition are more than 40 linear feet and they are in unconditioned space, then the ducts must be tested and verified by a HERS Rater as described in §150.2(b)1D|. All installed ducts regardless of length and location shall be sealed and meet insulation levels as described in §150.0(m) Items 1 through 6.
If a new central split system is installed to serve the addition, it must meet all of the requirements for air conditioners in a new residence.
|
Component |
Requirements of |
Requirements of Additions > 400 ft2 |
Requirements of |
|
Roof/Ceiling |
Mandatory requirements |
Mandatory requirements |
Option A, B, or C (see Table 9-3B below). |
|
Roof Products (Cool Roof): |
Package A: Steep-Sloped (> 2:12): CZ10-15: Reflect.=0.20 and Emittance=0.75; or SRI=16 |
Package A: Steep-Sloped (> 2:12): CZ10-15: Reflect.=0.20 and Emittance=0.75; or SRI=16 |
Package A: Steep-Sloped (> 2:12): |
|
Package A: Low-Sloped (< 2:12) CZ13 & 15: Reflect.=0.63 and Emittance=0.75; or SRI=75 |
Package A: Low-Sloped (< 2:12): |
Package A: Low-Sloped (< 2:12): | |
|
Exception: Additions < 300 ft2 exempt from all cool roof requirements. | |||
|
Radiant Barrier Above Attic: |
Package A: CZ2-15: Radiant Barrier above Attic Spaces |
Package A: CZ2-15: Radiant Barrier above Attic Spaces |
Package A: CZ2-15: Radiant Barrier above Attic Spaces, except when complying with Option B from §150.1(c) |
|
|
Option A (CZ 4, 8-16) |
Option B (CZ 4, 8-16) |
Option C (CZ 4, 8-16) |
|
Roof Deck Insulation1,2 |
Above deck continuous insulation: R6 (with air space), R8 (no air space) |
Below deck insulation: |
None required |
|
Ceiling Insulation |
R38 |
R38 |
CZ 4, 8-10: R30 CZ 11-16: R38 |
|
Duct Location |
Attic allowed |
Attic allowed |
Conditioned Space |
|
1. Roof deck insulation should be installed flush with the roof deck. Above deck insulation is applied as continuous insulation. Below deck insulation is installed in the cavities between trusses. 2. A designed air space may exist between the roof deck and the finishing roofing material, triggering lower required insulation values. | |||
|
Component |
Requirements of Additions |
Requirements of Additions |
Requirements of Additions > 700 ft2 |
|
Total Glazing Area: |
Up to 75 ft2 or 30% of Conditioned Floor Area, whichever is greater |
Up to 120 ft2 or 25% of Conditioned Floor Area, whichever is greater |
Up to 175 ft2 or 20% of Conditioned Floor Area, whichever is greater |
|
West-Facing Glazing Area: In Climate Zone 2, 4, 6-16 |
Up to 60 ft2 |
Up to 60 ft2 |
The greater of 70 ft2 or 5% of Conditioned Floor Area in Climate Zones 2, 4, 6-16 |
|
Glazing |
Package A: All CZs: U = 0.32 |
Package A: All CZs: U = 0.32 CZ 2, 4 & 6-16: SHGC = 0.25 |
Package A: All CZs: U = 0.32 |
|
1. See §150.0(q) and §150.1(c)3 for new and replaced window and skylight exceptions . | |||
|
Component |
Requirements of |
Requirements of |
Requirements of |
|
Exterior Framed Wall1 Insulation: |
Package A: CZ 1-5, 8-16: U=0.051 CZ 6 & 7:U=0.065 |
Package A: CZ 1-5, 8-16: U=0.051 CZ 6 & 7:U=0.065 |
Package A: CZ 1-5, 8-16: U=0.051 CZ 6 & 7:U=0.065 |
|
Raised Floor1 Insulation: |
Package A: All CZs: R-19 or U=0.037 |
Package A: All CZs: R-19 or |
Package A: All CZs: R-19 or U=0.037 |
|
Slab Floor1 Insulation: |
Package A: CZ1-15: No Requirement; CZ 16: R-7.0 or U=0.58 |
Package A: CZ1-15: No Requirement; CZ 16: R-7.0 or U=0.58 |
Package A: CZ1-15: No Requirement; CZ 16: R-7.0 or U=0.58 |
|
1. R-values refer to wood framing, and U-factors refer to metal framing. | |||
|
Component |
Requirements of Additions < 400 ft2 |
Requirements of Additions > 400 ft2 and < 700 ft2 |
Requirements of Additions > 700 ft2 |
|
Ventilation Cooling1 |
No Requirement. |
No Requirement. |
Additions < 1,000 ft2: No requirement Additions > 1,000 ft2: Package A Whole House Fan, §150.1(c)12 CZ 8-14 |
|
Adding New Space Conditioning System(s) |
All Package A requirements. |
All Package A requirements. |
All Package A requirements except requirements for Ducts in Conditioned Space2 |
|
Replacing Existing Space Conditioning System(s) |
All Package A requirements. |
All Package A requirements. |
All Package A requirements except requirements for Ducts in Conditioned Space2 |
|
Adding All New Complete Duct System(s) |
All Package A requirements. |
All Package A requirements. |
All Package A requirements except requirements for Ducts in Conditioned Space2 |
|
Extending Existing Duct System(s) by > 40 Feet |
All Package A duct insulation requirements; duct system sealing and HERS Verified |
All Package A duct insulation requirements; duct system sealing and HERS Verified |
All Package A duct insulation requirements; duct system sealing and HERS Verified. Except requirements for Ducts in Conditioned Space2. |
|
(Note: also mandatory mechanical ventilation per ASHRAE 62.2 with HERS verification for additions > 1,000 ft2) For more information about ducts in conditioned space, see Section 3.2.6 | |||
If an addition increases the number of water heaters serving a dwelling unit, the addition can comply prescriptively if any one of the following conditions contained in §150.2(a)1D.i, ii and iii are met:
1. If the additional water heater is a natural gas or propane water heater, there are two options to comply. In all cases, if recirculation distribution system is used, only demand recirculation systems with manual control pumps shall be used. The two options are described below:
Option 1: Install a natural gas or propane instantaneous water heater with an input rating of 200,000 BTU per hour or less.
Option 2: Install a natural gas or propane storage water heater with a rated storage volume greater than 55 gallons and an input rating of 105,000 BTU per hour or less. The user must also do one of the following:
1. Use a compact hot water distribution design for the addition, which requires a HERS Rater to verify that the system has been designed and installed in accordance with the Energy Standards. (See Reference Appendix RA4.4.16|topic=RA4.4.16 HERS-Verified Compact Hot Water Distribution System (CHWDS-H).)
2. Insulate all domestic hot water pipes for the addition, which requires that a HERS Rater verify that the pipe insulation is designed and installed in accordance to the Energy Standards.
2. If the building does not have natural gas or propane connected to the building, the additional water heater is an electric storage or instantaneous water heater with an EF equal to or greater than the federal minimum standards. If recirculation distribution system is used, only demand recirculation systems with manual control pumps shall be used.
3. A water-heating system determined by the Executive Director of the Energy Commission to use no more energy than the one specified in Item 1 above or, if no natural gas is connected to the building, a water-heating system determined by the Executive Director to use no more energy than the one specified in Item 2 above.
If none of these conditions can be met when adding a water heater to an existing dwelling unit, then the prescriptive addition compliance path cannot be used. In that case, the existing + addition + alterations compliance approach must be used to demonstrate overall compliance with whatever combination of existing and new water heaters serves the dwelling unit. This is summarized in §150.2(a)1Div|topic=(a) Additions. and discussed as part of the overall performance method in Section 9.7|topic=9.7 Performance Method\:.
For other alterations to the water heating system that occur as part of an addition, see Section 9.6|topic=9.6 Alterations.
Example 9 9
Question:
A small addition of 75 ft² is being planned for a house in Climate Zone 7. An existing porch off the master bedroom is being enclosed by using 2x4 wood-framed walls. The existing heating and air-conditioning system will serve the new conditioned space, including an extension of less than 40 linear feet of new ducts. The contractor wants to follow the prescriptive requirements. What requirements apply?
Answer:
Since the addition is smaller than 400 ft², the total fenestration area is limited to a maximum of 75 ft², and west-facing fenestration area is limited to 60 ft². The fenestration must meet the U-factor and SHGC requirements of Package A. For Climate Zone 7, these fenestration requirements are a maximum U-factor of 0.32 and a maximum SHGC of 0.25. For an addition of this size, insulation must meet only the mandatory requirements of R-22 ceiling insulation and R-19 floor insulation. The new 2x4 walls are extensions of existing walls, so they need only R-15 cavity insulation. Since the addition is also less than 300 ft2, there is no cool roof requirement.
Since the existing heating and cooling equipment is being used for the addition, that equipment does not have to meet the mandatory equipment efficiency requirements. Mandatory duct insulation requirements of §150.0(m) apply, including R-6.0 minimum in unconditioned space. All other mandatory requirements in §150.0|topic=SECTION 150.0 – MANDATORY FEATURES AND DEVICES must be met.
Example 9 10
Question:
If I remove a window from the existing house and reuse this window in an addition to that house, does the relocated window have to meet the prescriptive requirements of Package A?
Answer:
Yes, if using prescriptive compliance, in which case the relocated window must be treated as a new window and must meet the U-factor and SHGC requirements of Package A, §150.1(c)3|topic=(c) Prescriptive Standards/Component Package.. If you use this existing window in the addition, you must use the actual or default U-factor and SHGC of the window in showing compliance. Therefore, meeting the prescriptive requirements may not be possible, and performance compliance may be the only option. Window certification and labeling requirements of §110.6(a)|topic=(a) Certification of Fenestration Products and Exterior Doors other than Field-fabricated. do not apply to existing used windows.
Relocated windows must also meet the maximum area-weighted average U-factor in §150.0(q)|topic=(q) Fenestration Products. with the EXCEPTION of up to 10 ft² or 0.5 percent of conditioned floor area, whichever is greater.
Example 9 11
Question:
I am doing an alteration in Climate Zone 12 in which I am moving an existing 25 ft2 window to another location within the same existing wall and am not increasing total glazing area. Does the relocated window need to meet any prescriptive requirements?
Answer:
Removing an area of glazing in an existing wall and reinserting up to the same area of glazing in a different opening is considered replacement fenestration as defined in §150.2(b)1B. Exception 1 to §150.2(b)1B| states that up to 75 ft2 of vertical replacement fenestration in Climate Zone 12 must meet a prescriptive U-factor = 0.40 and an SHGC = 0.35.
Example 9-12
Question:
For additions and alterations that include a greenhouse window (also known as garden window), what are the U-factor and SHGC requirements? What is the area used for calculations for greenhouse windows?
Answer:
Not many greenhouse windows meet the mandatory maximum fenestration U-factor of 0.58 or the prescriptive addition or alteration U-factors or SHGCs on their own. The default U-factor for a dual–pane, metal-framed greenhouse window from Table 110.6-A|topic=TABLE 110.6-A DEFAULT FENESTRATION PRODUCT U-FACTORS is 1.40, while the default SHGC from 110.6-B assumes fixed clear, glass is 0.73. By comparison, fenestration in prescriptive additions has to meet the Package A U-factor of 0.32 for all climate zones and an SHGC of 0.25 in all climate zones except 1, 3 and 5, which have no SHGC requirement. However, there are several options and exceptions available in the Energy Standards.
For alterations, Exception 1 to §150.2(b)| allows any dual-pane greenhouse windows to meet the prescriptive U-factor and SHGC requirements of Package A. This makes it possible for greenhouse windows to comply with the Energy Standards as part of a prescriptive alteration, as long as the U-factor and SHGC meet the requirements either by themselves or when area-weighted with all of the new and replacement fenestration in the project. The existing plus alteration performance method may also be considered if at least one other component of the building that will be upgraded in addition to the fenestration.
For new construction and additions, Exception 2 to §150.0(q)|topic=(q) Fenestration Products. exempts up to 30 ft2 of dual-pane greenhouse windows from the mandatory maximum U-factor of 0.58. This allows additions with up to 30 ft2 of dual-pane greenhouse windows to comply using the performance approach, even if the actual NRFC-rated or default U-values of the greenhouse windows are greater than 0.58. Compliance in that case would depend on higher than average energy efficiency for some other components of the project to offset the poor performance of the greenhouse windows.
Alternatively, greenhouse windows can also meet the prescriptive maximum area-weighted average U-factor and SHGC in combination with other new and replacement fenestration in the project.
Greenhouse windows may use one of three methods for determining the proposed SHGC:
1) NFRC rated SHGC
2) Default SHGC from Table 110.6-B
3) If site-built greenhouse windows, then SHGCT can be calculated from the manufacturer’s center of glass SHGC (SHGCc) and using the following equation: SHGCT = 0.08 + 0.86 x SHGCc.
Comparable methods are available for determining U-factors.
For compliance, the area used for greenhouse windows is the rough opening in the wall.
The table below summarizes the basic rules for modeling a low-rise residential building using the existing + addition + alterations performance approach. For more detailed information, see Section 9.7|topic=9.7 Performance Method\: and the Residential ACM Reference Manual.
|
Type of Component or System Modeled |
Standard Design Without Third Party Verification of Existing Conditions |
Standard Design With Third Party Verification of Existing Conditions |
|
"EXISTING" − |
Model each component or system as "Existing" |
Model each component or system as "Existing" |
|
"ALTERED" − |
Model each altered component or system as "Altered" but do not model the "Prealtered Existing" conditions |
Model each component or system as "Altered" and also model the "Prealtered Existing" conditions |
|
"NEW" − |
Model each component or system as "New" |
Model each component or system as "New" |
|
"REMOVED" − |
These components and systems are omitted entirely from the model |
These components and systems are omitted entirely from the model |