3.6   Additions and Alterations    

The Standards offer prescriptive approaches and a performance approach to additions and alterations (but they do not apply to repairs). Relevant definitions from §100.1(b). are provided below:

A.   Addition is a change to an existing building that increases conditioned floor area and volume. See §141.0(a)and §100.1(b) for detailed definition.

When an unconditioned building or unconditioned part of a building adds heating or cooling so that it becomes conditioned, this area is treated as an addition.

Alteration is a change to an existing building that is not an addition. An alteration could include a new HVAC system, lighting system, or change to the building envelope, such as a new window. See §141.0(b)|topic=(b)  Alterations. and §100.1(b)|topic=(b) Definitions.. Roof replacements (reroofing) and reconstructions and renewal of the roof are considered alterations and are subject to all applicable Standards requirements. For alterations, the compliance procedure includes:

1.   The prescriptive envelope component approach

2.   The addition alone approach

3.   The existing-plus-alteration performance approach

4.   The existing-plus-addition-plus alteration performance approach

B.   Repair is the reconstruction or renewal of any part of an existing building for the purpose of its maintenance. For example, a repair could include the replacement of a pane of glass in an existing multi-lite window without replacing the entire window. Repairs must not increase the preexisting energy consumption of the repaired component, system, or equipment; otherwise, it is considered to be an alteration. See §141.0(b) and §100.1(b).

For more information on the performance approach with additions and alterations, refer to Section 9.3 of this Manual.

3.6.1    Mandatory Requirements

A.   Additions

All additions must meet the applicable mandatory measures from the following Standards sections:

•      §110.6 - Mandatory Requirements for Fenestration Products and Exterior Doors;

•      §110.7 - Mandatory Requirements for Joints and Other Openings;

•      §110.8 - Mandatory Requirements for Insulation and Roofing Products (Cool Roofs);

•      §120.7- Mandatory Requirements for Insulation.

B.   Alterations

All alterations must meet the above mandatory requirements stated for additions, with the exception of the insulation requirement of §120.7 for opaque envelope components (roofs, ceilings, walls and floors).  Alterations for nonresidential, high-rise residential and hotel/motel buildings must meet the following:

1.   Insulation levels for roofs and ceilings shall follow the prescriptive requirements of Section 141.0(b)2Biii of the Standards.  These requirements are explained in more detail in Section 3.3.2 of this document.

2.   Light mass and heavy mass walls do not have mandatory requirements for minimum R-value and maximum U-factor.

3.   Insulation for walls that separate conditioned space from either unconditioned space or the exterior shall comply with the mandatory requirements of §141.0(b)1B of the Standards.  This section provides two options for wall insulation compliance; either a minimum insulation R-value or a maximum assembly U-factor.  The mandatory requirements are determined by the wall type:

A.   Metal buildings:  a minimum of R-13 insulation between framing members, or a weighted average U-factor no greater than 0.113 is required

B.   Metal framed walls:  a minimum of R-13 insulation between framing members, or a weighted average U-factor no greater than 0.217 is required.

C.   Wood framed walls and other wall types:  a minimum of R-11 insulation between framing members, or a weighted average U-factor no greater than 0.110 is required. 

D.   Spandrel panels and glass curtain walls:  a minimum of R-4 insulation, or a weighted average U-factor no greater than 0.280 is required.

Insulation for floors that separate conditioned space from either unconditioned space or the exterior shall comply with the mandatory requirements of §141.0(b)1C of the Standards.  This section provides two options for compliance with the mandatory requirements; either a minimum insulation R-value or a maximum assembly U-factor.  For floors, the mandatory requirements are determined by both building type and floor type:

A.   Raised framed floors:  a minimum of R-11 insulation between framing members, or the weighted average U-factor no greater than 0.071 is required. 

B.   Raised mass floors in high-rise residential and hotel/motel guest rooms:   a minimum of R-6 insulation, or the weighted average U-factor no greater than 0.111 is required.

C.   Raised mass floors in all other occupancies:  no minimum U-factor is required.

3.6.2    Prescriptive Requirements    

Additions

Prescriptive compliance for the building envelope of additions is addressed in §141.0(a)1 and §140.3 of the Standards. §140.3(a) provides prescriptive compliance alternatives for the building envelope including tradeoffs between roofing insulation and the solar reflectance of roofing products (cool roofs) in Table 140.3-A. Tradeoffs between other envelope components are no longer allowed in the prescriptive method. The Simplified Performance Tradeoff Approach described in section 3.6 may also be used. The performance method may be used for tradeoff for both new construction and alterations.

All additions must also comply with §140.3(c), Minimum Skylight Area for large enclosed spaces in buildings with three or fewer stories.

For more details on the prescriptive requirements for additions, see Sections; Overview (Building Envelope); 3.2.4, Window Prescriptive Requirements; 3.2.5, Skylight Prescriptive Requirements; 3.3.2, Prescriptive Requirements (Opaque Envelope Insulation);

Alternatively, the addition may meet compliance by using the performance compliance approach of §140.1, which compares the TDV energy (space conditioning, lighting and water heating) of the proposed building addition to a TDV energy budget that complies with prescriptive requirements.

RA1.1.1.1.1 Alterations

In general, any alteration to an existing building that involves changes to a portion of the building envelope triggers the Standards. The prescriptive requirements for alterations to building envelopes are in §141.0(b)2A and B of the Standards.

The altered components of the envelope shall meet the applicable mandatory requirements of §110.6 and §110.8 of the Standards.

RA1.1.1.1.2 Fenestration

For all nonresidential, high-rise residential, and hotel/motel occupancies, when fenestration is altered or where there are alterations that do not increase the fenestration area, all altered fenestration shall meet the requirements of Table 141.0-A of the Standards (table duplicated below) based on climate zone.

When new fenestration area is added to an alterations it shall meet the requirements of; §140.3(a) and Tables 140.3-B, C or D of the Standards.  In cases where the fenestration is temporarily removed and then reinstalled compliance with §140.3(a) is not required.

In cases where small amounts of fenestration area are changed, a number of options exist. If less than 150 ft² of fenestration area is replaced throughout the entire building, then the Standards require that only the U-factor requirements in Tables 140.3-B, C or D are met. The SHGC, Relative Solar Heat Gain Coefficients or Visible Transmittance requirements need not be met. The same requirements and exceptions apply if 50 ft² or less of fenestration (or skylight) area is added. A typical example of this may be changing a door from a solid door to a glass door.

Table-3-19 (Standards Table 141.0-A) Altered Window Maximum U-Factor and Minimum RSHGC and VT