9.1 Introduction

This chapter covers key aspects of how the 2019 Building Energy Efficiency Standards (Energy Standards) apply to construction of residential additions, alterations to an existing residential building, or both. As explained below, the Energy Standards do not apply to repairs.

The chapter is organized as follows:

Section 9.1 – Introduction. Highlights the applicable standards definitions for additions, alterations, and repairs and provides several examples of each.

Section 9.2 – What’s New in the 2019 Energy Standards. Highlights of the requirements and compliance options in the 2019 Energy Standards.

Section 9.3 – Compliance Approaches. An overview of prescriptive and performance compliance options..

Section 9.4 – Prescriptive Approach. Detailed information on prescriptive compliance methods for additions.

Section 9.5 – Performance Method. An explanation of computer compliance approaches for additions, including existing + addition + alterations.

When additions and alterations include changes to the envelope, mechanical systems, and/or water heating systems, a certificate of compliance must be completed prescriptively or be generated by compliance software with the performance approach. The prescriptive certificate of compliance is the CF1R-ADD-01 or CF1R-ALT-02 form. (See Appendix A for a full list of forms.)

Changes to the HVAC systems will likely include one or more measures that require Home Energy Rating System (HERS) diagnostic testing and field verification. If a HERS measure is required, the certificate of compliance must be completed and registered online with an approved HERS provider using the provider’s web-site. Refer to Chapter 2 for information about document registration and to Residential Appendix RA2 for more information about HERS measures.

For copies of the appropriate compliance documentation, refer to Appendix A of this manual.

9.1.1    Additions

An addition is any change to an existing building that increases conditioned floor area and conditioned volume (including conditioning a previously unconditioned space). See §100.1.

Examples of an addition 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 residential dwelling without a permit.

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

9.1.2    Alterations

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

Examples of 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 roof (reroofing) and replacing portions of or the entire roof assembly.

3.  Replacing existing fenestration or adding fenestration area (for example, windows, bay windows, greenhouse/garden windows, dynamic glazing, clerestories, or glass 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 home.

7.  Replacing an existing heating system or adding a heating system (for example, a furnace, wall heater, heat pump, or radiant floor). (NOTE: Adding heating to a previously unconditioned space is an addition, not an alteration.)

8.  Replacing an existing cooling system or adding a cooling system (for example, an 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.

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 Energy Standards is considered an alteration and not a repair.” (See §100.1).

Note: Repairs to residential buildings are not within the scope of the Energy 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, the component, system, or equipment is replaced with a new or different one, the scope of work is considered an alteration and not a repair and requirements of the Energy Standards must be met.

Examples of work considered repairs include:

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

2.  Removing fenestration and other envelope components for maintenance or repair and then reinstalling the same fenestration or other envelope components in the same location.

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

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

Note: When any existing envelope component is moved to a new location, even when that location partially overlaps the previous location of the item, the work is considered an alteration.

Note 2: Replacement of some HVAC components for repair are defined by the Energy Standards as alterations, therefore triggering requirements that must be met. Section 150.2(b)1E of the Energy Standards 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 linear feet of new or replacement space conditioning ducts are installed, then the entire duct system must be sealed and leakage tested to be equal or less than 15 percent. (See §150.2(b)1D.)

Note 3: Some cooling system component replacements are defined by the Energy Standards as alterations, which require meeting certain requirements. Section 150.2(b)1F of the Energy Standards defines installing or replacing a compressor, condensing or evaporator coil, refrigerant meting device, or refrigerant piping as an alteration, which triggers several requirements, including thermostat and, depending on the climate zone, airflow, and refrigerant charge requirements. (See §150.2(b)1F.)

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 nonhabitable or unimproved space. Under what conditions will the Energy Standards apply to this addition?


Unconditioned Sunspace


The mechanical and envelope requirements of the Energy 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 weatherstripped 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 Energy Standards apply.


Example 9-2



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


Yes, this remodel is considered an alteration. However, due to the limited scope of work and since no new conditioned space is being created, the remodel must comply only with the applicable mandatory measures described in §110.1 for appliances and §150.0(k) for residential lighting.


Example 9-3



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


Since floor area is added but not conditioned volume, this is an alteration and not an addition. It needs to comply with the Energy Standards using either the prescriptive or performance method, as well as meet all the applicable mandatory measures. To comply prescriptively, the new and replacement windows must meet the maximum U-factor and Solar Heat Gain Coefficient (SHGC) requirements of §150.2(b)1A and B. (If needed, area-weighted averaging may be used to meet these requirements.) Newly installed and replacement windows must also comply with the mandatory measures for caulking/sealing around windows per §110.7. In alterations, it is recommended to install insulation in the exposed walls if no insulation is found when walls are opened; for 2x4 wood framing install the mandatory minimum R-13 and for 2x6 wood framing install R-20.

Alternatively, the performance approach may be used to demonstrate compliance for 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 exposed or open, this allows the opportunity to insulate the walls and contribute the energy efficiency of the building. Such upgrades are unlikely to contribute to the compliance of the building without third party verification of existing conditions.