Spoiler Alert! The City of Aspen has customized their energy code. This blog is about the residential code, I’ll tackle the commercial modifications later.
What are the significant changes?
- The first change to the code drops the prescriptive allowable fenestration U-factor to .28.
- If submitting under the total UA trade-off compliance option, you will be required to go 2% beyond the passing line, in order to compensate for the fenestration glazing U-factor change.
- The option for exhaust-only occupant ventilation and air-cycler systems have been taken away, as balanced heat recovery systems are made mandatory. The HRV or ERV must have an efficiency of at least 65% and its fan powered by an EMC motor. All fans are required to meet a higher standard of efficacy; CFM/watt.
- Air sealing is still required, but infiltration (blower door) testing is not required.
- Mechanical sizing (ACCA Manual J calculations) is not required.
Here’s the interesting part, the City has sought to simplify the code by deleting the IECC ERI compliance alternative and replacing it with their own version. It’s called the Simplified Equivalent Compliance Alternative. Dwellings must meet the following criteria to comply with this alternative.
- Equivalent space cooling energy. The ratio of the air conditioning capacity to conditioned space is less than or equal to 12,000 Btu/hour per 1,000 square feet.
- Equivalent space heating energy. The ratio of the space heating system capacity to floor area of conditioned space is less than or equal to 32,000 Btu/hour per 1,000 square feet.
- Equivalent hot water. The distance from the hot water supply outlet to hot water pipe to the hot water entry to a room where hot water is used shall be no more than 10 feet. This shall apply to the kitchens, bathrooms with showers or tub, and rooms with a clothes washer.
- Equivalent lighting. Lamps over 15 watts shall be CFL, LED, or have an efficacy not less than 90 lumens per watt. Or, at least 90% of the lamps or fixtures shall have an efficacy not less than 75 lumens per watt.
This code change deletes equipment sizing, infiltration testing and energy modeling; the very tenets of the energy rating paradigm. I like the simplicity, but I fear it is too simple. I guess time will tell how Aspen fairs under this code.
Confluence Architecture & Sustainability can provide third-party insulation and air barrier inspections, and certification of compliance with the other provisions of this code.
Pitkin County’s “Matrix” could not be more different from Aspen’s energy code amendments. Click here to read about those.