### Image Credits:

1. Alex Wilson

1.
Jun 14, 2012 7:12 AM ET

Go team!
by James Morgan

Congratulations Brattleboro on a great coop and a great building. Good job!

2.
Jun 17, 2012 10:14 AM ET

by David Meiland

>>By manipulating the two blower doors in a way I couldn’t quite figure out, Andy and Terry were able to determine that of the total 6,200 cfm50 air leakage, only 940 cfm50 (15%) was attributed to the two floors of apartments

If there's a chance to clarify what was done, I'd be interested

3.
Jun 17, 2012 12:55 PM ET

Measuring the tightness of part of a space
by Alex Wilson

David,
Here's what Andy had to say. Makes sense:

"When you have two adjoining volumes separated by walls (which have holes as they always do), if you depressurize or pressurize both volumes to the same level (say 50 Pascals, for example) relative to outdoors, there is no air flow between them. No pressure difference across the demising wall and floor, so no flow. Basic physics: no pressure, no flow. You do this with two blower doors.

"We had both spaces depressurized to 50 Pa relative to outside. The only air leakage then to each space is from the outside, so each blower door measures the outdoor air leakage rate of the space to which it is attached. The apartments and the store are separated by walls and by a floor, so it was quite easy to set this up. You have to be able to communicate between blower doors that they are at the same pressure, either with people and phones or radios or a single control point, which is what we did at the Co-op. We verified no leakage between store and apartments with a separate pressure measurement, measuring between store and apartments, and we made sure that the pressure difference between them was zero."