We get our electric through a co-op and just had an energy audit completed. It consisted of a blower door test and then an infrared audit. The quick results were an ACH@50 with our result being 4.6 and a couple quick fixes before the report arrives within 2 weeks. The quick fixes were gap found under basement cantilever beam that extends underneath our fireplace that leads directly outside...it's about an inch wide and 18-24 inches long....spans a couple rafters two can lights in great room exterior door seal shot allowing exponentially more leakage than should My question right now is the ACH@50 calculation. How is this determined regarding the basement square footage? Is the basement included? We have main floor of 2100 sqft, upstairs of 700 sq ft and basement of 2000 sq ft. The upstairs is a loft so another 1000 sq ft is open to the downstairs and I believe is 16 foot high.... Home built in 2005 with poured basement.