Blower Door Test Results

Client: Brenda Slomka Location: 162 Pine Street, Kingston Time: April 11th, 2014. Students: Derek Jordan, Derek Signore, Michael Clarke What is a “Blower Door Test” and how does it work?

A “Blower Door Test” depressurizes a building resulting in outside air streaming in through cracks and air gaps. It is an extremely effective method for identifying major sources of air leakage in a building. This is important, because inflowing air from cracks must be heated to maintain the desired building temperature. A large heat load results in high heating cost. A blower door test is an essential part of an energy audit to identify and quantify these leaks, for which solutions can be designed.

April 11th Test Results

The two most valuable pieces of data obtained from the April 11th blower door test were the “ELA” and “ACH50” numbers.

ELA stands for “Equivalent Air Leakage”. Air leaks in a home can be thought of as many tiny holes in your walls where heat escapes and air penetrates. These holes have an area to them: the larger the area, the larger the air leakage and heat

loss. An Equivalent Air Leakage (ELA) is like the area of a single hole, equivalent to all the tiny holes that contribute to the air leakage of your home. The ELA of your home was found to be 205 in2. Therefore, if all the air leakage in your home was coming from a single source, it would be about a 14”x14” hole.

The next important piece of information obtained from the test is the ACH50 number. This value refers to an hourly rate that the entire building volume is replaced by air from leaks (@50Pa of pressure). For example, a building with ACH50 value of ‘1’ has its entire volume of air is replaced by leaked air once per hour. After our measurements were taken and calculations performed, your home was found to have an ACH50 of 6.75.

The following table should help to give a framework for understanding how “good” that number is, and how your home compares to other buildings:

ACH50 Value Description of the building

10-20 Older homes, very leaky.

7-10 Average new home with some air sealing but no verification; quite leaky.

7 OK infiltration level; modestly leaky.

3-5 Good and achievable target for most new homes; Air tight.

3 and lower Extremely tight home excellent air sealing.

.6 Passive House Standard

Since your home was 6.75 ACH50, we would consider it between moderately and quite leaky. The value suggests there are one or several significant sources of air leakage in the home. In the next section, we hope to describe them.

Areas of Leakage

Once the blower door was installed and running, we looked around the home for areas of air leakage. The list below summarizes some of our observations:

• Some slight leakage was noticed around several first floor windows and the front door, but it was not significant. • Upstairs, several slight leaks were noticed in the following places: “Attic hatch; corner of hall window; old light;

light in room at end of stairs.” • The cat door to the basement had a significant force of inrushing air. The plastic flap was nearly 45 degrees from

horizontal, indicating a very significant force of inrushing air from the basement. We thus focused our efforts in isolating the source of air leakage present within the basement.

The dryer exhaust line penetrated a wooden header beam and was insulated with loose fiberglass insulation. Some definite air leakage was felt entering the space from this area.

There was a small gap between the foundation wall and this floor joist, on the South end of the basement. Slight air leakage was noticeable all along this gap.

The most significant source of air leakage was found to be around where a heating duct penetrated the North facing basement wall. This duct is assumed to continue through to a crawlspace underneath the kitchen. Spray foam had been improperly applied in an attempt to seal these penetrations. Of all the leaks identified in the home, this were the most significant. It is likely that if this were sealed properly, there would be significantly less air leakage from the basement. The other sources were noticeable, but this was absolutely glaring.

It would seem that this wall penetration specifically contributes a great deal to the area leakage from the basement, and therefore the home. If only a single upgrade were undertaken, it is our recommendation to focus here.

The Crawlspace

The house has an addition, visible from the outside by its distinct blue paneling. It is assumed that there is a crawlspace underneath this addition in which the heating duct runs. Given the force of air streaming in from around this heating duct, it’s extremely likely that the crawlspace is improperly insulated. It was unfortunate that we did not investigate this possibility on the day of the test, as we could have conclusively identified the root cause. Since there wasn’t access the crawlspace from within the basement, we didn’t investigate further. It is likely that the entrance was from outside, and had we been more thorough, we would have found it.

Recommendation: Properly insulate the crawlspace

From what we understand of the constriction of the home, the heating duct in question follows this path: It begins from the furnace, runs along the basement ceiling, penetrates the North side wall, enters a crawlspace area, travels in this area underneath the kitchen, finally delivering its heat to duct vents in the kitchen area.

If indeed the crawlspace is as described previously, then we put forward the following recommendation: Properly seal the wall penetration with new spray foam. Insulate the foundation wall between the crawlspace and the basement with XPS foam, perhaps 1”-2”. Where the crawlspace walls meet the floor, pack fiberglass batted insulation. The result would be the total thermal separation of the crawlspace from the rest of the heated house. It this could be effectively achieved, it would go a long way to reducing air leakage and heat loss from the home.