Additions: Relaxed Requirements Under the 2013 Energy Code

The 2013 Energy Code relaxes some requirements for Additions to Existing homes. (An addition is defined as: any change to a building that increases conditioned floor area and conditioned volume. Addition is also any change that increases the floor area and volume of an unconditioned building of an occupancy group or type regulated by Part 6. Addition is also any change that increases the illuminated area of an outdoor lighting application regulated by Part 6.)

The requirements below do not apply in kind to alterations to an existing home. (An alteration is defined as: any change to a building's water-heating system, space-conditioning system, lighting system, or envelope that is not an addition. Alteration is also any change that is regulated by Part 6 to an outdoor lighting system that is not an addition. Alteration is also any change that is regulated by Part 6 to signs located either indoors or outdoors.)

Additions ≤ 400 ft²

All prescriptive Package A requirements must be met except:

Total glazing area may be up to 75 ft² or 30% of conditioned floor area, whichever is greater;
West-facing glazing area may be up to 60 ft²;
Required exterior wall insulation:
1. In 2x4 wood frame walls, insulation shall be R-13 or an overall construction assembly U-factor < 0.102, for wood or metal frame walls;
2. In 2x6 or greater wood frame walls, insulation shall be R-19 or an overall construction assembly U-factor < 0.074, for wood or metal frame walls;
No requirement for a whole house fan (WHF) to provide ventilation cooling;
For additions ≤ 300 ft² cool roof compliance is not required.

Additions > 400 ft² and ≤ 700 ft²

All prescriptive Package A requirements must be met except:

Total glazing area may be up to 120 ft² or 25% of conditioned floor area, whichever is greater;
West-facing glazing area may be up to 60 ft²;
Required exterior wall insulation:
1. In 2x4 wood frame walls, insulation shall be R-13 or an overall construction assembly U-factor < 0.102, for wood or metal frame walls;
2. In 2x6 or greater wood frame walls, insulation shall be R-19 or an overall construction assembly U-factor < 0.074, for wood or metal frame walls;
No requirement for a whole house fan (WHF) to provide ventilation cooling.

Additions > 700 ft²

All prescriptive Package A requirements must be met except:

Total glazing area may be up to 175 ft² or 20% of conditioned floor area, whichever is greater;
West-facing glazing area may be up to 70 ft² or 5% of conditioned floor area, whichever is greater;
If the addition is < 1,000 ft², there is no requirement for a whole house fan (WHF) to provide ventilation cooling;
Additions > 1,000 ft² must include provide ventilation cooling with a WHF as indicated in §150.1(c)12;
If the Total Proposed fenestration area exceeds the Standard Maximum Glazing Area of 20% 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% of the conditioned floor area, then the performance compliance approach must be used;
If the addition has a floor area > 700 ft² and < 1,000 ft², all requirements of Package A apply except the West-Facing Glazing Area may allow up to 70 ft² for additions up to 1,400 ft² (since 70 ft² is 5% of 1,400 ft²). See §150.2(a)1A.

Prescriptive Addition Envelope Requirements
(see Notes below)

Notes (Information and image are from the 2013 Residential Compliance Manual):

Removed wall and window not included in the calculation.
Additions of 300 ft² or less are exempted for the cool roof requirement.
Insulation requirements from Package A; unless addition is 700 ft² or less, then R-13 for 2x4 walls and R-19 for 2x6 or greater walls is acceptable for wood frame.
Fenestration area is limited based on the size of the addition:
- For additions < 400 ft²: 75 ft² or 30% of CFA — whichever is greater — for total glazing area; and 60 ft² for west-facing glazing.
- For additions > 400 ft² and < 700 ft²: 120 ft² or 25% of CFA — whichever is greater — for total glazing area; and 60 ft² for west-facing glazing.
- For additions > 700 ft²: 175 ft² or 20% of CFA — whichever is greater — for total glazing area; and 70 ft² or 5% of CFA — whichever is greater — for west-facing glazing.

Every section above states that the addition must first meet the Prescriptive Measures of Compliance. Prescriptive measures are required energy features for the project and vary by climate zone. For further information on the Climate Zone specific Prescriptive Measures, contact us.

As always, I am available to discuss the process of meeting the California Energy Code for any building project. Contact me …