• Fix the envelope bottom‐up, insulate outside‐in, air seal inside‐out

    One of the most important undertakings in a deep energy retrofit (DER) is to reconfigure and improve the building envelope. The “building envelope” is the conditioned space within the building structure. Ideally, this space should have controlled air movement, heating and cooling, ventilation and moisture management.

    Given the internal pressures within a building, a stack effect is created that moves air from lower in the building (infiltration) to exhaust (exfiltrate) in the upper parts of the building. Most people have practical experience with basement air – it tends to be cool, moist and musty. The latter condition can be caused by a combination of issues, such as mold, combustion appliances, water vapor and noxious gases like radon. If unchecked, this air naturally moves through the house. The above photo shows a crawl space with poor, improper insulation and clear evidence of water infiltration through the foundation walls. This is a condition that will undoubtedly lead to mold and other moisture problems as well as poor thermal performance.

    With DER we begin by thoroughly sealing basements and crawlspaces and bringing them within the conditioned space by insulting the floor, sidewalls and joist/plate connection points. Next, we seal and super-insulate the attic/roof and building sidewalls. Our guideline for insulation R-values is R-10 on the basement floor, R-20 on basement walls, R-40 on upper floor sidewalls and R-60 on the roof. The most effective and least disruptive way to super-insulate the sidewalls and roof is to apply foam insulation on the exterior of the building and to reside and reroof over the added protection.

    Finally, we use a blower door and duct blaster tests to guide and confirm the effectiveness of our air sealing and duct sealing on the inside of the house.