Impact of missing weatherstripping etc. on blower door results
I have a recently finished home in Raleigh, NC.
The Energy Star inspectors were by a few days ago and the blower door was 1.9 ACH. The house is 3,800 sq. ft. and has a decent amount of corners. Given the corners and me being too busy to check on a few things, I am happy with the results. The bulk of the attic is not foamed and I didn’t get to foam the lights etc. I did caulk from below except one that was 2 stories up (staircase).
The inspector found a ducted mini with too high of a leak rate to pass. It is fully in conditioned space so I think the contractors got lazy. So I will have to pay the raters to come back out if I want ES certification.
So the question is – can I make a meaningful difference in the ACH at this point. One spot is the attic pull down ladder does not have a cap. I think it’s weatherstripping is crap/basic stuff. Another spot is a speakeasy door on the front door. It needs better weather stripping as i can feel a small amount of air movement. I was stupid and thought he would test at that door so I was going to get to it later.
If I get the ACH lower, I will get a slight bump in a utility rebate. There is also bragging rights.
My challenge is weighing whether or not to pay them for coming back out. The utility rebate didn’t care about a duct leak in conditioned space. I will get that fixed regardless. If I could get the ACH down to 1.7, it would help pay for the rater coming back out. I have a CFO that follows every penny….
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
It's hard to say how much difference you can make. At 1.9ACH, you've got a lot more leaks than you have detailed here. Going from 1.9 to 1.7 should be pretty low hanging fruit. I don't think 1.7ACH is going to earn you bragging rights in many circles, so I would discount that motivation.
While in many circles 1.9 is pretty bad, this is NC. When infiltration on energy star houses of similar size costs just $100 a year, we are down to $40. Energy star requires 5.0; Utility rebate requires 4.0.
It would be nice to have some idea what certain things were "worth". Obviously 3 8-foot-tall doors with single point latches is not going to meet passive house standards. At the same time, upgrading to triple latches was not worth it especially since it is never done in my area.
My cfm number is 1200.
I guess I have done my own math at $40 a year for infiltration; Energy rebate gives us 9 years worth of savings. So if you save $10 a year, they give you $90. So there is zero chance it could justify the $150 for the retest. But I could get close.
It would be nice to have some average cfm leak rates for various things that could be upgraded. Hard info to find on Google. I guess it is probably too hard to estimate. I see that 1 square inch is about 10 cfm - that is the best I could find.
David,
Some of your questions are answered in this article: "Getting the Biggest Bang for Your Air-Sealing Buck."
Hi David -
It's too bad that your original blower door testing seems not to have included qualitative assessment of leakage in addition to quantitative. The final number is important but the distribution and the SIZE of particularly the bigger leaks are just as important.
I am not aware that programs that require a certain level of airtightness also require leak assessment but they all should.
Peter