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construction Basement: Ceiling sprayed with open-cell spray polyure­thane foam (adds thickness and R-value) Walls: 2×4 construction filled with cellulose; 4 in. of foil­faced polyisocyanurate foam outside of sheathing for a total of R-39 Roof: 6 in. of polyisocyanurate insulation installed above the existing roof sheathing, topped with a layer of ply­wood; 8 in. of open-cell […]

Paul Eldrenkamp is a Massachusetts remod­eler who has performed several deep-energy retrofits. When his clients balk at the high cost of a full retrofit, he sometimes advises them to work in phases. Although it is com­mon to perform energy improvements over time as finances permit, it’s also important to take advantage of upgrade opportunities even […]

Homeowners who undertake deep-energy retrofits are usually motivated by environ­mental or energy-security concerns rather than a desire to save money on their energy bills. These jobs are so expensive—in the range of $50,000 to $150,000 per house— that a homeowner would have to wait decades before the investment could be recouped. "In a retrofit situation, […]

An old house with a new shell. This deep-energy retrofit in Somerville, Mass., received 4 in. of spray polyurethane foam on its exterior. (For more information, see the case study on p. 45.) However, not all energy upgrades have to be so elaborate. home may be a better candidate than a home in a moderate […]

The best way to temper incoming air while reducing HVAC energy consumption is to use a heat-recovery ventilator (HRV) or an energy-recovery ventilator (ERV). These systems (see the drawing on the facing page) are balanced approaches that use the temperature and humidity of an exhaust-air stream (which otherwise would have been wasted) to temper the […]

A supply system has the advantage of allowing you to select where the air comes from and how it is distributed throughout your home. For example, fresh air can come from a duct run connected to the return plenum of an HVAC system (see the draw­ing on the facing page). This way, outdoor air is […]

When ventilation removes contaminants, it’s your friend, but in doing so, it usually brings in outdoor air that must be heated, cooled, or dehumidified, which costs money. Just because it costs money, though, doesn’t mean ventilation is your foe. The energy savings of a tight house more than offset the operating cost of a small […]

Because indoor air starts as outdoor air, then grows more polluted from contaminants in a house (see "Indoor Air Pollutants," p. 32),indoor air needs to be cleaned. Flushing a house with fresh air removes much of the indoor pollution. The most obvious way to control some contaminants is to isolate them. Paint thinner and other […]

■ BY MAX H. SHERMAN I hear it all the time: "Houses are too tight." "Houses didn’t used to make people sick." These assertions seem well founded: The most serious chronic illness of American children is asthma, and the Environmental Protection Agency lists poor indoor-air quality among its top five environmental threats. Are tight houses […]

This two-family Victorian house (circa 1860) was difficult to upgrade because we weren’t allowed to remove siding, replace the win­dows, or dig into the slate roof. The historic commission did, however, allow us to remove and replace the siding and windows on one wall where the siding was damaged and needed replacement, so we injected […]