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TDPUD Sponsored Weatherization Update

Site characteristics or focus during construction or remodel:

Home was selected by TDPUD for a pilot energy project due to energy inefficient construction techniques resulting in substantial building envelope air leakage and great potential to make more energy-efficient. 

Construction Type: 

One story, been remodeled/add-on, raised floor, living room has vaulted ceiling. Remodel resulted in some building energy-efficiency problems.

Passive Solar System:

The home has an east-west axis and plenty of south-facing glass. The home is passively solar heated, but was not designed specifically to be passively solar heated as there is no thermal mass for solar heat storage.

Main Heating System:

There are two ground source heat pump units, 3.5 and 2-ton systems.

Auxiliary Heating System:

The home contains a gas fireplace, primarily for aesthetic purposes.

Conservation Features:

The home has gone through two rounds of conservation efforts. A lot of work has been done to seal the leaky building envelope and the two central air distribution systems. The house was also retrofitted with double-pane glass from single-pane. Other work performed included improving the central air distribution system’s airflow, sealing the crawlspace vents and floor penetrations and repairing insulation defects. Airflow improvements resulted in 20% additional air flow.The conservation work resulted in reducing duct air leakage on one distribution system by 41% and 50% on the other. Building envelope air leakage

Subjective Evaluation/ design considerations:

The home had a substantially higher heat loss and heating system sizing requirement than could have ever been imagined for a 1,625 sq. ft. home. Originally a 3.5-ton ground source heat pump was installed in the home to cover 100% of its heating requirements. Then a 2 ton GSHP system was added since 3.5 tons was not enough to comfortably heat the home. Due to all the advanced weatherization work that has been performed on the home it is now an energy-efficient home and can easily be heated with one or both ground source heat pump units. This is a prime example of how you can use a super-efficient heating system in a building, but still have high energy bills because the building itself it not energy-efficient. The morale of the story is do not expect to have low energy bills if you use high efficiency heating equipment placed in a low-efficiency building.

Owner: Fly

Size: 1625 square feet

Date of Construction: 1960s - 70s

Tags: Remodel/Addition
Ground Source Heat Pump

Mail can be sent to: SiGBA P.O. Box 4245 Truckee, CA 96160

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