The Test Results

My last post talked briefly about the cost per square foot and I will revisit that subject in future posts. I would like to discuss the performance #'s that were verified by Amy Musser (www.vandemusser.com). Amy, who I consider the leading building scientist in this region, and her technician Jeff came out to the job site to perform the Energy Star and NC Healthy Built Homes Certifications. Because all of the duct work is located within the thermal boundary of the building envelope the most important test was the blower door test. This test depressurizes the house to measure the leakage of air in the conditioned space to the outside. A large fan is attached to a blower door bracket as you can see in the picture. One of the prerequisits for the NC Healthy Built Homes program is to achieve 3.5 air changes per hour (ACH 50-pascals) or less of leakage. This means that the volume of air within the conditioned space of the house exchanges with the outside air 3.5 time or less per hour with all the windows and door closed. Although I don't specifically know the best blower test results I encountered when I was doing the certifications, typically anything less than 1.5 ach was really good. After Jeff set up the blower door, he started the fan and was not able to get a reading. It took all 3 of us to finally get a reading. Jeff was running the fan, Amy was checking the diagnostic equipment and I was holding the bracket in the door opening with all my strength so it wouldn't pop out-which it did twice. After a few attempts, we were finally able to get a reading and I'm glad we did because I wasn't sure I could hold the bracket in place any longer. As a former H.E.R.S rater, I knew that this was a very good sign that the house was really tight. It wasn't until later that evening that I got the results from Amy. The previous best results that any of us knew about for any home was 220 cfm of leakage. This test came from another home built in the Asheville area (also using Eco-Panels) and is about 1440 square ft. This other home is 430 sq ft smaller than my prototype and has about 4500 less cubic feet of volume. My prototype only had 181 cfm of leakage and a final ach reading of .48 ach50. It felt great to have such an impressive score and be the new record holder. Another way (in my opinion a better way) to measure leakage of the envelope is ELR (envelope leakage ratio). My ELR is .039. I talked to the director of the Earth Craft House Certification program at the Southface Institute in Atlanta about my scores. Although he was very impressed with the test results, he admittedly couldn't believe it. ELR standards for the Earth Craft House program is around .4. Obviously my prototype at .039 is 10x better than that standard. I will continue to research and find out how this score compares to other top blower door test results throughout the country. Although having a super tight house is a great achievement, please remember that proper ventilations is as important. I am currently running my ERV on high (as it is advised to do this for the 1st month), but this week I will reset the ERV to the low setting after cleaning the filter. I attribute the superior blower door test results to two factors. 1) Using Eco-Panels and 2) Paying close attention to proper air sealing anywhere and everywhere I could think of. It was a few days later that I received some more good news. My prototype home achieved Gold Level for the NC Healthy Built Homes Certification. Over the next year, providing everything works out properly, between the landscaping points and PV solar panel points, this protoype with achieve the highest level of Platinum.