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Residential Energy Efficiency Blog
Sunday, January 10 2021
Did you know that when you participate in a Home Performance with ENERGY STAR project on your home that the results are actually measurable?
Is there any other home improvement project that when it is all said and done you can actually test and get immediate, unbiased results? I can't think of any!
Let's take replacement windows as an example. Often times windows are replaced around a home to improve comfort and reduce drafts. But, results are typically subjective and more times than not there is a walk away feeling for both the homeowner and contractor that the windows did not really perform, but there is not much anyone can do now.
Home performance work on the other hand is instantly measurable and to take matters further, a home performance project actually focuses in on physical attributes of your home to really move the comfort needle in your favor.
ANALOGY: If a jet is not able to take off from the runway, do you want the airline company mechanic to just fix a perceived issue and give it a whirl, or would you rather the technician employ diagnostic tools, real time onboard computer information and proper calculations to get the plane back in the air?
Of course we all want the more informed approach to ensure our safe return to flight.
So how does this work in home performance you ask? How can we be sure to target the right connections to the outside in a home so that we can get the results we want?
The blower door test! A blower door test does two things...
First, it measures the leakage rate of your home. It quantifies the amount of air that leaves through a large industrial sized fan that essentially "sucks" the air out of your home.
Physics demands that for every cubic foot of air that leaves an enclosure, a cubic foot of air will replace it through an crack, crevice, hole, connection, etc.
So as the fan pulls air out and creates a negative pressure fresh outside air is pulled in through all of the outside connection points in your home and as new air enters and flows through the house and back through the fan, a flow rate is achieved and recorded. This is the starting number to then measure against after the work is completed.
The second benefit of a blower door test is that is allows the contractor and the homeowner to physically inspect the house while the test is running to discover the leakage points in a physical sense - rather than in a hypothetical sense.
This is very important for the average homeowner that has a thousand other things they would rather be doing and rather be learning about.
When a homeowner can actually participate and see that air leakage can be attributed to many other things before windows it has a profound effect. For every leaky window discovered at a blower door test there are five hundred examples of recessed lights that were much worse offenders.
One great example of a home that made huge gains in comfort, reduced drafts and overall energy usage was a home in which not a single window was replaced. The results from the air leakage test were huge and the customer noticed a difference the first day.
Here are the blower door results as seen on the pressure and flow gauge (manometer).
The results show a 29% reduction in the leakage of this home. This means that actual holes in the home's shell were proper sealed and the results have been measured through diagnostic testing.
So, what did we do to treat this house and make huge gains on reducing air leakage you ask?