Attic Insulation in Energy Efficient Home

Belmonte High Performance LEED HomeNewport Ventures worked with Belmonte Builders to build a home for the NYSERDA High Performance Home Challenge. The home is LEED certified and was also part of the Saratoga Builders Association’s 2008 Showcase of Homes, where it swept the competition by receiving first place in every category including Best Exterior, Best Floor Plan, Best Workmanship, and the coveted Realtor’s Choice Award. This blog entry discusses Belmonte home’s ceiling insulation strategy, 1 inch (R-6) of BASF SPRAYTITE spray polyurethane foam covered with blown fiberglass insulation (R-54) for a total R-Value of R-60 in the attic.

SPRAYTITE provides a “critical seal” over any air penetrations resulting from utilities, chases, and recessed lights.  Blown fiberglass insulation provides an additional R-54 at an economical price. Without counting the reduced air leakage from the spray foam, the insulation value of the spray foam and blown fiberglass is expected to provide an energy savings of 6% beyond a baseline NYECCC compliant home.

To ensure that the full depth of insulation was achieved across the entire ceiling plane, a raised heel truss was specified.  A raised heel or “elevated” truss permitted full depth insulation to be installed at the eaves, while still maintaining clearance for ventilation.  These pictures show the raised heel truss above the master bedroom before and after insulation. 

Raised Heel Truss in Belmonte Home

Spray Foam in Belmonte Master Bedroom

 

 

 

 

 

Small air leaks caused by envelope penetrations at multiple locations can have a large cumulative effect on the energy performance of high performance buildings.  One of the more common locations for air leakage to occur is around recessed lights. Recessed lights can provide conditioned air with a direct path to an unconditioned attic, either through the inside of the light fixture or around the outside of the fixture itself. Because typical recessed light fixtures get hot during operation there are restrictions on how close insulation can be to them. Newport recommended installing enclosed recessed lights specially tested and rated for direct contact with insulation. CFL recessed lights were specified to increase the lighting efficacy of the fixtures as well as maintain lower temperatures in the fixture. As the pictures show, spray foam was applied around the entire recessed light fixture in the attic, greatly reducing the chances of conditioned air seeping out of the home and into the attic.Recessed Light Before InsulationRecessed Light with Insulation

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