[Strawbale] Strawbale Digest, Vol 10, Issue 11

[JAY WALSH]

> Once the blower door test is done, the leak points are identified (and an  
> equivalent leakage area number provided) and the leaks are either sealed  
> or not sealed. And that (ie the sealing of the leaks) is what it's (blower 

> door testing) all about. Isn't it ?

For the Energy Star program we use the blower door to find leaks and seal what
is accessible. We also use the BD result to determine the air exchange rate to
ensure there is a healthy exchange of oxygen replacement. Our goal is approx
.35 ACH (Air Change per Hour). If the ACH is below this number we then look to
mechanically bring the ACH up to this level. This is done either by using the
bath fan run on a timer (24 hr programmable) or with an HRV (or ERV). To
properly program the run-time for either of these devices we first measure the
actual flow rate for the fan or HRV. This must be measured as these devices
never achieve their rated CFM due to flow restrictions caused by ductwork. We
can then run these devices to an optimum rate to achieve the ACH of .35 for
the occupants and minimize the air exchange for energy conservation.

For air sealing and weatherization of existing homes we use the blower door to
ensure we do not make the house too tight which may cause a back drafting
issue with atmospheric appliances (water heaters, boilers, furnaces). This can
bee a deadly mistake. 

Thirdly we use the blower door in conjunction with infrared scanning. The
blower door is a very useful tool here as we can spot and watch the paths of
air leaks in walls, roofs, floor assemblies as well as leakage around doors
and windows. This approach goes way beyond what you can determine with just
the blower door and a smoke smoke stick. 

The blower door is a tool I use on a weekly basis and and feel that it should
be used on every home being built today.

Sincerely
Energy Analyst 
Energy Star and LEED-H rater