QUALITY INSTALLATION OF INSULATION
A California Energy Commission’s (CEC) study found air infiltration problems of the thermal envelope were also linked to lower than expected performance of insulation in the walls, ceilings and floors of the house. This study uncovered an industry wide problem of deficient insulation installation, not in compliance with the manufacturers specifications. Small gaps and voids, common place in the installation, were found to promote air movement through the insulation reducing it’s performance. As an example, a 1/2” gap from the face of the insulation to the inside face of the wall, reduces the R-19 value of the insulation to an actual R-3.5. Knowing this, the California Energy Commission down grades all insulation by approximately 20% when buildings are modeled for compliance with California Energy codes. So, If you think you have R-30 insulation in your roof/ceiling, it is really R-24 or worse.
Improperly installed insulation coupled with leaky building envelopes, requires the insulation in Energy Efficient Designs to be specially inspected by a certified HERS Rater. When this is done the performance of the insulation would more closely match the manufacturers specifications.