Throughout the re-construction phase great attention was paid to air infiltration. Every penetration (windows, doors, pipes, ducts, etc) was sealed with expanding foam. A foam gun is very helpful and less wasteful than “foam in a can.”
Blower door testing before, during, and after is very helpful to quantify, locate, and fix leaks.
Blower Door Results
Before: 3950 CFM50 (cubic feet/minute @ 50 pascals) = 1.3 ACH (air changes/hour)
After: 750 CFM50 = 0.2 ACH
FRESH AIR: Because the house is now much tighter, we have added mechanical ventilation to ensure fresh indoor air and save energy. The air-to-air heat exchanger pulls stale moist indoor air out of the house, bringing fresh outdoor air into the house and, MOST IMPORTANTLY, recycles 60-70% of the heat already paid for by warming up the cold outdoor air so you don’t have to heat it again. It is controlled by variable timer in master bathroom to run from 10-100% of the time depending on tightness of the house calculated by blower door testing. For our project it runs 35% of the time (about 20 minutes per hour) and uses 7 cents of electricity while saving $2 of heat per day and insuring fresh indoor air quality!!!
Sealed Combustion: We have also added a 4 inch fresh air duct to both the oil furnace and wood stove. This insures that each has its own air supply rather than pulling air out of the living space causing increased cold air leaks and competing with you for fresh air.
Safety: A combination smoke alarm and carbon monoxide detector are now required for all new and retrofit construction (1 per floor) and HIGHLY recommended for all homes!