9.1   Introduction

This chapter covers key aspects of how the Standards apply to construction of residential additions, alterations to an existing residential building, or both. As explained further below, the Standards do not apply to repairs.

The chapter is organized as follows:

1.   Section 9.1, Introduction.  Highlights the applicable Standards definitions for additions, alterations and repairs; and provides several examples of each.

2.   Section 9.2, What’s New in the 2013 Standards.  Highlights of the requirements and compliance options which have changed or are entirely new in the 2013 Standards as compared with the 2008 Standards.

3.   Section 9.3, Compliance Approaches.  An overview of all prescriptive and performance compliance options available to meet the Standards for additions only, for alterations only and for projects which include both additions and alterations.

4.   Section 9.4, Mandatory Requirements.  Mandatory requirements for additions and alterations as they apply to the envelope, fenestration, mechanical system, water heating system, indoor lighting, and outdoor lighting.

5.   Section 9.5, Additions.  Detailed information on prescriptive and performance compliance methods and related information for additions, with or without alterations.

6.   Section 9.6, Alterations.  Detailed information on prescriptive and performance compliance methods and related information for alterations, with or without an addition.

7.   Section 9.7 Performance Method.  An explanation of the Existing + Addition + Alteration Approach with examples.

8.   Section 9.8 Online Registration.  Compliance Forms and Online Registration with a HERS Provider.


Whenever additions and alterations trigger mandatory measures - whether envelope, mechanical, water heating, indoor lighting or outdoor lighting - the Certificate of Compliance and the Mandatory Measures Summary must be submitted with the permit documentation and included in the building plans. 

When additions and alterations include changes to the envelope, mechanical and/or water heating systems, a Certificate of Compliance must be completed prescriptively or generated by compliance software with the performance approach.  The prescriptive Certificate of Compliance that should be used for additions and alterations in all climate zones is the CF1R-ADD or CF1R-ALT form.  For HVAC-only change-outs and other mechanical system alterations, a climate zone specific CF1R-ALT-HVAC form for prescriptive compliance may be used.  Almost all additions and alterations under the 2013 Standards that include changes in HVAC systems also include one or more measures that require HERS Diagnostic Testing and Field Verification.  When a HERS measure is specified, the Certificate of Compliance must be registered online with an approved HERS provider web site.  Refer to Section 2.2.2 and to Residential Appendix RA2 for more information about document registration.

For copies of the appropriate compliance forms, refer to Appendix A.

9.1.1    Additions

An addition is any change to an existing building that increases conditioned floor area and conditioned volume. See §100.1.

Examples of projects considered as additions include:

1.   Adding a conditioned sunroom or other rooms to an existing house;

2.   Converting a garage or other existing unheated space into conditioned living space;

3.   Enclosing and conditioning an existing patio area;

4.   Obtaining a permit to legalize an existing, habitable and conditioned space that was added to a residence without a permit;

5.   Adding a bay window that extends to the floor increasing both floor area and volume.

9.1.2    Alterations

An alteration is any change to a building's water-heating system, space-conditioning system, lighting system, or envelope that is not an addition.  See §Section 100.1.

Examples of projects considered alterations include:

1.   Adding insulation to any existing exterior roof or ceiling, exterior wall, or raised floor over a crawl space, garage or unheated basement;

2.   Replacing or installing a new top surface to an existing roofing assembly (re-roofing); replacing portions of or replacing the entire roof assembly;

3.   Replacing existing fenestration or adding fenestration area (e.g., windows, bay windows, greenhouse/garden windows, dynamic glazing, clerestories or glass glazed doors) to existing walls;

4.   Replacing an existing skylight or increasing the area of skylight to an existing roof;

5.   Constructing an entirely new roof over an existing conditioned space;

6.   Adding a loft within the existing conditioned volume of a residence;

7.   Replacing an existing heating system or adding a heating system (e.g., furnace, wall heater, heat pump or radiant floor);

8.   Replacing an existing cooling system or adding a cooling system (e,g., air conditioner or heat pump);

9.   Extending or replacing an existing duct system, or adding an entirely new duct system;

10.  Replacing the existing water heater or adding water heaters and/or hot water piping;

11.  Replacing existing lighting or adding new hardwired lighting fixtures;

12.  Adding window film, when complying under the Performance approach only.


9.1.3    Repairs

A repair is “the reconstruction or renewal for the purpose of maintenance of any component, system, or equipment of an existing building.  Repairs shall not increase the pre-existing energy consumption of the repaired component, system, or equipment. Replacement of any component, system, or equipment for which there are requirements in the Standards is considered an alteration and not a repair.”  See §100.1.

Note:  Repairs to residential buildings are not within the scope of the Standards.

For example, when a component, system, or equipment of an existing building breaks or is malfunctioning and  maintenance  fixes are needed for it to work properly again, it is considered a repair and not subject to the Standards. However, if instead of fixing the break or malfunction, it is decided to replace the component, system or equipment with a new or different one, the scope of work is considered an alteration and not a repair and requirements of the Standards pertaining the that measure must be met.

Examples of work considered repairs include:

1.   Replacing a broken pane of glass but not replacing the entire window;

2.   When fenestration and other envelope components are uninstalled for maintenance or repair purposes and the same fenestration or other envelope components are re-installed in the same location, this is considered a repair; 

3.   When any existing envelope component is moved to a new location (even when that location partially overlaps the item's previous location), the work is considered an alteration;

4.   Replacing a failed fan motor or gas valve in a furnace but not replacing the entire furnace;

5.   Replacing a heating element in a water heater but not replacing the entire water heater.

Note, replacement of some HVAC components for repairs purposes are defined by the Standards as alterations, therefore triggering requirements that must be met.  Section 150.2(b)1E defines the following HVAC component replacements as an alteration that triggers the requirement for duct sealing: ”replacement of the air handler, outdoor condensing unit of a split system air conditioner or heat pump, or cooling or heating coil.”  Similarly if more than 40 lineal feet of new or replacement space conditioning ducts are installed the entire duct system must be sealed, tested and verified for low duct leakage. §150.2(b) 1D.

Example 9-1


A sunspace addition is designed with no mechanical heating or cooling and a glass sliding door separating it from all existing conditioned space. This design is approved by the enforcement agency as non habitable or unimproved space. Under what conditions will the Standards apply to this addition?

Unconditioned Sunspace


The mechanical and envelope requirements of the Standards do not apply if the space is not considered habitable or improved and therefore can be unconditioned as defined in  §100.1; however, per §100.0(c)2, the sunspace must still comply with the applicable lighting requirements of §150.0(k). The sunspace is unconditioned if:

▪ The new space is not provided with heating or cooling (or supply ducts)

▪ All openings between the new space and the existing house can be closed off with weather-stripped doors and windows

▪ The addition is not indirectly conditioned space (defined in §100.1 under CONDITIONED SPACE, INDIRECTLY)

A building official may require a sunspace to be conditioned if it appears to be habitable space, in which case the Standards apply.


Example 9-2


An existing duplex is remodeled, which includes only the installation of new faucets, and bathroom lighting. Do the Standards apply?


This is an alteration since no new conditioned space is being created, the remodel must comply with applicable mandatory measures described in §110.1 for appliances and §150.0(k) for lighting.

Example 9-3


An existing house is remodeled by adding additional floor area but not increasing the volume of the house. This was accomplished by adding a loft through an area in the house with a vaulted ceiling. As part of this remodel new fenestration are replacing existing ones, and two new windows are being added. Several exterior walls are being opened up to install new wiring. What requirements will apply?


Since floor area is being added but not conditioned volume, this is an alteration and not an addition. New and replacement  fenestration must meet the maximum U-factor and SHGC prescriptive requirements of §150.2(b)1.  Newly installed fenestration must also comply with the mandatory measures for caulking/sealing around windows of §110.7.  In alterations, the Energy Commission recommends installing insulation to walls being exposed if no insulation was found when the walls were opened; for a 2x4 wood framing use R-13 and for 2x6 wood framing use

Alternatively, the performance approach may be used to demonstrate compliance for overall building (the entire house) even if individual windows fail to meet the prescriptive requirements, as long as the building meets all applicable mandatory requirements.  At this time, since the exterior walls are expose or open, this allows the opportunity to insulate the walls and contribute the ability to meet energy compliance; otherwise it would be difficult to comply with overall building compliance.