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Mechanicals

Before the remodel, the house had an electric water heater and in-wall electric resistance heaters. We kept the existing water heater but replaced the old electric wall heaters with new ones.

  • To improve indoor air quality in the now-tight house, the author installed a Panasonic energy-recovery ventilator in the ceiling of the living area. This small, inexpensive unit installs like a bath fan, except that there are two ducts to the exterior instead of one.
    To improve indoor air quality in the now-tight house, the author installed a Panasonic energy-recovery ventilator in the ceiling of the living area. This small, inexpensive unit installs like a bath fan, except that there are two ducts to the exterior instead of one.

A house this tight should be equipped with mechanical ventilation. The budget on this project didn’t allow for a fully ducted whole-house HRV, so we put a continuous-duty Panasonic FV-04VE1 in the main living area. This low-cost energy- recovery ventilator sells for about $350 and has a maximum capacity of 40 cfm. Except for the presence of a 4-inch outdoor air intake, it installs in the ceiling in much the same way as a bathroom fan.

Improved Performance

Near the end of the job, we performed a second blower-door test. It showed a more-than-tenfold reduction in air leakage — from the original 11.9 ACH to just 0.9. We’re confident that the leakage figure would have been even lower if we hadn’t been saddled with the existing doors and windows.

The owners have a few utility bills from the previous tenant, and have been tracking electrical use after the renovation. Electrical use this past winter was half what it was during the same time period the year before — down from about 1,250 to 625 kilowatt-hours per month. We suspect that the bulk of current consumption goes to lighting and heating water, and hope to verify this through future monitoring. By my estimate, the air-sealing and extra insulation added about $15,000 to the overall $140,000 cost of the project.

Terry Nordbye is a building contractor in Point Reyes Station, Calif.