## 2.10 Additions/Alterations

Addition and alteration compliance is based on standards Section150.2. Alterations must model the entire dwelling unit. When there is no addition Section 150.2(b)2 requires at least two components of the residence must be altered. Additions may be modeled as an entirely new building (whole building), addition alone, or as “existing+addition+alteration”.

### 2.10.1 Whole Building

The entire proposed building, including all additions and/or alterations, is modeled the same as a newly constructed building. The building complies if the proposed design uses equal or less energy than the standard design. This is a difficult standard to meet as the existing building usually does not meet current standards and must be upgraded.

### 2.10.2 Addition Alone Approach

The proposed addition alone is modeled the same as a newly constructed building except that the internal gains are prorated based on the size of the dwelling. None of the exceptions included for prescriptive additions, which are implemented in the existing plus addition compliance approach (see Section 2.10.3) are given to the addition alone approach (see Standards Section 150.2(a)2.B.) The addition complies if the proposed design uses equal or less space heating, space cooling, and water heating TDV energy than the standard design.

The addition alone approach shall not be used when alterations to the existing building are proposed. Modifications to any surfaces between the existing building and the addition are part of the addition and are not considered alterations.

Proposed Design

The user shall indicate that an addition alone is being modeled and enter the conditioned floor area of the addition. Any surfaces that are between the existing building and the addition are either not modeled or are treated as adiabatic surfaces. All other features of the addition shall be modeled the same as a newly constructed building.

When an existing HVAC system is extended to serve the addition, the proposed design shall assume the same efficiency for the HVAC equipment as the standard design (see Sections 2.4.1 and 2.4.5).

When a dual-glazed greenhouse or garden window is installed in an addition or alteration, the proposed design U-factor can be assumed to be 0.32.

Standard Design

The addition alone is modeled the same as a newly constructed building, with the following exceptions:

A. When roofing requirements are included in Table 150.1-A, they are included in the standard design if the added conditioned floor area is greater than 300 ft2.

B. When ventilation cooling (whole-house fan) is required by Table 150.1-A, it is included in the standard design when the added conditioned floor area is greater than 1,000 ft2. The capacity shall be based on 1.5 cfm/ft2 of conditioned floor area for the entire dwelling unit conditioned floor area.

C. When compliance with indoor air quality requirements of Section 150.0(o) apply to an addition with greater than 1,000 ft2 added, the conditioned floor area of the entire dwelling unit shall be used to determine the required ventilation airflow. For additions with 1,000 ft2 or less of added conditioned floor area, no indoor air quality requirements shall apply.

### 2.10.3 Existing + Addition + Alteration Approach

Standards Sections 150.2(a)2 and (b)2 contain the provisions for additions and alterations to be modeled by including the existing building in the calculations. This is called the “Existing + Addition + Alteration” (or “E+A+A”) performance approach.

Proposed Design

The proposed design is modeled by identifying each energy feature as part of the existing building, the addition, or an alteration. The compliance software uses this information to create an E+A+A standard design using the rules in the standards that take into account whether altered components meet or exceed the threshold at which they receive a compliance credit and whether any measures are triggered by altering a given component.

For building surfaces and systems designated below, all compliance software must provide an input field with labels for the proposed design which define how the standard design requirements are established, based on the option selected by the software user:

• Existing: remains unchanged within the proposed design (both standard design and proposed design have the same features and characteristics).

• Altered: the surface or system is altered in the proposed design. No verification of existing conditions is assumed.

• Verified Altered: the surface or system is altered in the proposed design and the original condition is verified by a HERS rater (an optional selection).

• New: a new surface or system is added in the proposed design may be in the existing building or the addition.

Features removed are not included in the proposed design.

The user chooses whether an altered feature includes “Third Party Verification” of an existing condition (see Section 150.2, Table 150.2-B):

Altered with no third party verification of existing conditions (the default selection). This compliance path does not require an on-site inspection of existing conditions prior to the start of construction. The attributes of the existing condition is undefined, with the standard design for altered components based on Section 150.2, Table 150.2-B and the climate zone. Energy compliance credit or penalty is a function of the difference between the value for that specific feature allowed in Table 150.2-B and the modeled/installed efficiency of the feature.

Verified Altered existing conditions. This compliance path requires that a HERS rater perform an on-site inspection of pre-alteration conditions prior to construction. If an altered component or system meets or exceeds the prescriptive alteration requirements, the compliance software uses the user-defined existing condition as the standard design value. Energy compliance credit is then based on the difference between the verified existing condition for that altered feature and the modeled/installed efficiency of the proposed design.

2.10.3.1 Roof/Ceilings

Standard Design

The standard design roof/ceiling construction assembly is based on the proposed design assembly type as shown in Table 21. For additions less than or equal to 700 square feet, radiant barrier requirements follow Option C (Section 150.1(c)9B). The standard design for unaltered ceilings and roofs is the existing condition.

#### Table 21: Addition Standard Design for Roofs/Ceilings

Proposed Design Roof/Ceiling Types | Standard Design Based on Proposed Roof/Ceiling Status
Add < 300 ft2 | Add > 300 ft2 and < 700 ft | Addition > 700 ft2 | Altered | Verified Altered
Roof Deck Insulation | NR | NR | CZ 4, 8-16 = R-13 below deck | NR | Existing
Ceilings Below Attic | R-22 / U-0.043 | R-22 / U-0.043 | CZ 1, 2, 4, 8-16 = R-38 ceiling CZ 3, 5-7 = R-30 ceiling | R-19 / U-0.054 | Existing
Non-Attic (Cathedral) Ceilings and Roofs | R-22 / U-0.043 | R-22 / U-0.043 | Same as above | R-19 / U-0.054 | Existing
Radiant Barrier | CZ 2-15 REQ CZ 1, 16 NR | CZ 2-15 REQ CZ 1, 16 NR | CZ 2, 3, 5-7 REQ CZ 1, 4, 8-16 NR | NR | Existing
Roofing Surface (Cool Roof) Steep Slope | NR | CZ 10-15 >0.20 Reflectance, >0.75 Emittance | CZ 10-15 >0.20 Reflectance, >0.75 Emittance | CZ 10-15 >0.20 Reflectance >0.75 Emittance | Existing
Roofing Surface (Cool Roof) Low Slope | NR | CZ 13, 15 > 0.63 Reflectance, >0.75 Emittance | CZ 13, 15 > 0.63 Reflectance, >0.75 Emittance | CZ 13, 15 > 0.63 Reflectance >0.75 Emittance | Existing

2.10.3.2 Exterior Walls

Proposed Design

Existing structures with R-11 insulation that are being converted to conditioned space using an E+A+A approach are allowed to show compliance using R-11 wall insulation, without having to upgrade to R-13 mandatory insulation requirements. The walls are modeled as an assembly with R-11 insulation.

Standard Design

The areas, orientation and tilt of existing, new and altered net exterior wall areas (with windows and doors subtracted) are the same in the existing and addition portions of standard design as the proposed design.

If the proposed wall area is framed, the gross exterior wall area (excluding knee walls) is equally divided between the four building orientations: front, left, back and right. The gross exterior wall area of any unframed walls is also equally divided between the four orientations in the standard design.

The standard design exterior wall construction assembly is based on the proposed design assembly type as shown in Table 22. Framed walls are modeled as 16-inch on center wood framing. The standard design for unaltered walls is the existing condition. The software does not implement the prescriptive provision that allows eliminating continuous insulation for walls being extended to an addition.

#### Table 22: Addition Standard Design for Exterior Walls

Proposed Design Exterior Wall Assembly Type | Standard Design Values Based on Proposed Wall Status
Addition | Altered | Verified Altered
Framed Walls | CZ 1-5, 8-16 = R19+R5 in 2x6 (U0.051) CZ 6-7 = R15+R4 in 2x4 (U-0.065) | R-13 in 2x4 R-19 in 2x6 | Existing
Framed Wall Adjacent to Unconditioned (Garage Wall) | R-15 in 2x4 R-19 in 2x6 | R-13 in 2x4 R-19 in 2x6 | Existing
Mass Interior Insulation | CZ 1-15 = R-13 CZ 16 = R-17 | Mandatory requirements have no insulation for mass walls | Existing
Mass Exterior Insulation | CZ 1-15 = R-8 CZ 16 = R-13 | Existing
Below Grade Mass Interior Insulation | CZ 1-15 = R-13 CZ 16 = R-15 | Existing

2.10.3.3 Fenestration

#### Table 23: Addition Standard Design for Fenestration (in Walls and Roofs)

Proposed Design Fenestration Type | Standard Design Based on Proposed Fenestration Status
Add < 400 ft2 | Add > 400 and < 700 ft2 | Add > 700 ft2 | Altered | Verified Altered
Vertical Glazing: Area and Orientation | 75 ft2 or 30% | 120 ft2 or 25% | 175 ft2 or 20% | See full description below. | Existing
West Facing Maximum Allowed | CZ2, 4, 6 -16=60 ft2 | CZ2, 4, 6 -16=60 ft2 | CZ2, 4, 6 -16=70 ft2 or 5% | NR | NR
Vertical Glazing: U-Factor | 0.32 | 0.32 | 0.32 | 0.40 | See below
Vertical Glazing: SHGC | CZ2, 4, 6 -16=0.25 CZ1,3 & 5=0.50 | CZ2, 4, 6 -16=0.25 CZ1,3 & 5=0.50 | CZ2, 4, 6 -16=0.25 CZ1,3 & 5=0.50 | CZ2, 4 & 6-16=0.35 CZ1,3 & 5=0.50
Skylight: Area and Orientation | No skylight area in the standard design | No skylight area in the standard design | No skylight area in the standard design | NR | Existing
Skylight: U-Factor | 0.32 | 0.32 | 0.32 | 0.55 | Existing
Skylight: SHGC | CZ2, 4, 6 -16=0.25 CZ1,3 & 5=0.50 | CZ2, 4, 6 -16=0.30 CZ1,3 & 5=0.50 | CZ2, 4, 6 -16=0.30 CZ1,3 & 5=0.50 | CZ2, 4, 6 -16=0.30 CZ1,3 & 5=0.50 | Existing

Proposed Design

Fenestration areas are modeled in the addition as new. In the existing building they may be existing, altered or new. Altered (replacement) fenestration is defined in Section 150.2(b)1.B as “existing fenestration area in an existing wall or roof [which is] replaced with a new manufactured fenestration product...Up to the total fenestration area removed in the existing wall or roof....“ Added fenestration area in an existing wall or roof is modeled as new.

Standard Design

Standard design fenestration U-factor and SHGC are based on the proposed design fenestration as shown in Table 23. Vertical glazing includes all fenestration in exterior walls such as windows, clerestories and glazed doors. Skylights include all glazed openings in roofs and ceilings.

New fenestration in an alteration is modeled with the same U-factor and SHGC as required for an addition.

West-facing limitations are combined with maximum fenestration allowed and are not an additional allowance.

The standard design is set for fenestration areas and orientations as shown in Table 23:

• Proposed design < 20% total fenestration area:

In the existing building, the standard design uses the same area and orientation of each existing or altered fenestration area (in its respective existing or altered wall or roof.)

In the addition, new fenestration is divided equally between the four project compass points similar to new gross wall areas in the addition described above.

Proposed design > allowed % total fenestration area:

The standard design first calculates the allowed total fenestration area as the total existing and altered fenestration area in existing or altered walls and roofs + % of the addition conditioned floor area.

2.10.3.4 Overhangs, Sidefins and Other Exterior Shading

Standard Design

The standard design for a proposed building with overhangs, sidefins and/or other exterior shades is shown in Table 24. Exterior shading (currently limited to bug screens) is treated differently than fixed overhangs and sidefins as explained as explained in Section 2.5.6.9.

#### Table 24: Addition Standard Design for Overhangs, Sidefins and Other Exterior Shading

Proposed Design Shading Type | Standard Design Based on Proposed Shading Status
Addition | Altered | Verified Altered
Overhangs and Sidefins | No overhangs or sidefins | Proposed altered condition | Same as Altered
Exterior Shading | Standard (bug screens on fenestration, none on skylights) | Proposed altered condition | Existing exterior shading
Window Film | No window film | Proposed altered condition | Existing exterior shading

2.10.3.5 Window Film

Proposed Design

A window film must have at least a 10-year warranty and is treated as a window replacement. The values modeled are either the default values from Tables 110.6-A and 110.6-B or the NFRC Window Film Energy Performance Label.

2.10.3.6 Floors

Standard Design

Table 150.2-C requires that the standard design is based on the mandatory requirements from Section 150.0(d) The standard design for floors is shown in Table 25.

#### Table 25: Addition Standard Design for Raised Floor, Slab-on-Grade and Raised Slab

Proposed Design Floor Type | Standard Design Based on Proposed Floor Status (Tag)
Addition | Altered (mandatory) | Verified Altered
Raised Floor Over Crawl Space or Over Exterior | R-19 in 2x6 16” o.c. wood framing | R-19 in 2x6 16” o.c. wood framing | If proposed U < 0.037, standard design = existing raised; if proposed U > 0.037, standard design = Altered
Slab-on-Grade: Unheated | CZ1-15: R-0 CZ16: R-7 16” vertical | Proposed design | Existing unheated slab-on-grade
Slab-on-Grade: Heated | CZ1-15: R-5 16” vertical CZ 16: R-10 16” vertical | Proposed design | Existing heated slab-on-grade
Raised Concrete Slab | CZ1,2,11,13,14,16: R-8 CZ3-10: R-0 CZ12,15: R-4 | Proposed design | Existing raised concrete slab

2.10.3.7 Thermal Mass

Standard Design

The standard design for thermal mass in existing plus addition plus alteration calculations is the same as for all newly constructed buildings as explained in Section 2.5.4.1.

2.10.3.8 Air Leakage and Infiltration

Standard Design air leakage and infiltration

The standard design for space conditioning systems is shown in Table 26.

#### Table 26: Addition Standard Design for Air Leakage and Infiltration

Proposed Air Leakage and Infiltration | Standard Design Air Leakage Based on Building Type
Addition | Altered | Verified Altered
Single Family Buildings | 5 ACH50 | 5 ACH50 | Diagnostic testing of existing ACH50 value by HERS rater or 7.0 ACH50, whichever is less
Multi-Family Buildings | 7 ACH50 | 7 ACH50 | 7 ACH50

2.10.3.9 Space Conditioning System

Standard Design

The standard design for space conditioning systems is shown in Table 27.

When cooling ventilation is required by Sections 150.1 and 150.2, the capacity is 1.5 cfm/ft2 of conditioned floor area for the entire dwelling unit.

When compliance with indoor air quality requirements of Section 150.0(o) apply to an addition with greater than 1,000 ft2 added, the conditioned floor area of the entire dwelling unit is used to determine the required ventilation airflow. For additions with 1,000 ft2 or less of added conditioned floor area, no indoor air quality requirements shall apply.

#### Table 27: Addition Standard Design for Space Conditioning Systems

Proposed Design Space Conditioning System Type | Standard Design Based on Proposed Space Conditioning Status
Added | Altered | Verified Altered
Heating System: | See Section 2.4 and 2015 Federal Appliance Stds based on fuel source and equipment type. | Same as Addition. | Existing heating fuel type, and equipment type/efficiency.
Cooling System: | See Section 2.4 and 2015 Federal Appliance Stds based on fuel source and equipment type. | Same as Addition. | Existing cooling equipment type/efficiency.
Refrigerant Charge | Climate zones 2, 8-15:Yes Climate zones 1, 3-7: No | Same as Addition. | Existing
Whole House Fan (WHF) applies only if addition > 1,000 ft2 | Climate zones 8-14; 1.5 cfm/ft2 |  | Existing condition. To count as Existing the WHF must be > 1.5 cfm/ft2 and be CEC-rated
Indoor Air Quality applies only if addition > 1,000 ft2 | Meet mandatory ventilation for entire dwelling | N/A | N/A

2.10.3.10 Duct System

Standard Design

#### Table 28: Addition Standard Design for Duct Systems

Proposed Design Duct System Type | Standard Design Based on Proposed Duct System Status
Altered | Verified Altered
All | CZ 1-10, 12-13: Duct insulation R-6 and duct sealing < 15% CZ 11, 14-16: Duct insulation R-8 and duct sealing < 15% | Existing duct R-value and duct leakage of 15%.

Note 1: Refer to Section 150.2(b)1Diia for definition of
an “Entirely New or Complete Replacement Duct System”.

2.10.3.11 Water Heating System

Standard Design

#### Table 29: Addition Standard Design for Water Heater Systems

Proposed Design Water Heating System Type | Standard Design Based on Proposed Water Heating Status
Addition (adding water heater | Altered | Verified Altered
Single Family | Package A water heating system | Mandatory and Prescriptive requirements (excluding any solar). | Existing water heater type(s), efficiency, distribution system.
Multi-family: Individual Water Heater for Each Dwelling Unit | Package A water heating system for each dwelling unit (see Section 2.9) | Mandatory and Prescriptive requirements (excluding any solar). | Existing water heater type(s), efficiency, distribution system
Multi-family: Central Water Heating System | Central water heating system per Section 2.9 | Mandatory and Prescriptive requirements (excluding any solar). | Existing water heater type(s), efficiency, distribution system