Door blower test


Old 08-09-08, 12:01 PM
HouseRedux's Avatar
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Door blower test

We just finished having the walls insulated in our 1840s village colonial house. The installers did a door blower test pre and post - and there wasn't much of a difference. What do these numbers mean: 2628 pre, 2148 post. The inspector is coming out next week, but I thought I'd try to be prepared for that conversation.
BTW- the attic is already insulated, probably not enough, but there is about 6" already up there - so I'm not sure where the infiltration is coming from.
Much thanks for any help.
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Old 08-09-08, 07:01 PM
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Join Date: Oct 2002
Location: Troy, VA
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Numbers mean your house is still "leaking". Read this:
Old 08-09-08, 08:42 PM
Join Date: Nov 2001
Location: USA
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I was interviewed not too long ago and that subject was part of my answer. apparently the reporter was unaware that the Energy Audit program was eliminated. The results of the blower door tests is a reduction of 483 cfm50 (Pascals). ASHREA, which is an Engineer Organization, provides tables for a variety of mechanical functions. The one that is the most important when air sealing is involved is known as "Minimum Ventilation Guidelines". The base for the blower door is 1,500 cfm50. Depending on the size of the house, number of occupants and even behavior of those occupants, this base number will increase. Pets are even included. Your Minimum Ventilation number should have been given to you. They probably did but if you're not sure, ask them for it.

Any house air sealed deliberately below the Minimum Ventilation Guidelines will require mechanical ventilation, such as an "Air to Air Exchanger".

The fan negatively pressurizes the house. When the amount of air going through the fan reaches 50 cubic feet per minute, the pressure reading is noted. In your case the post reading was 2148 cfm50.

If you want to know more, please feel free to ask.

The following are the 3 questions the reporter asked.

1) What are the most effective changes that can be made to a home in terms of energy conservation?

There is a saying known as “A chain is only as strong as its weakest link”. It has been my experience for well over 20 years that the weakest link in conserving energy in one’s home is the consumer. So the most effective change one can make to their home in terms of energy conservation is to become a more informed consumer.

2) What goes into an energy audit? Why are they important?

This is a website that replaces the energy audit program in New Jersey. The on-line energy audit has apparently been eliminated. I was involved in the pilot program in this State that was known as E-Team Partners. Today it is known as Comfort Partners. This program Home Performance with Energy Star is actually a derivative of Comfort Partners. Under Comfort Partners, measurements throughout the house are taken based on Protocol (prescribed conditions) prior to an action being taken. The same is true for Home Performance with Energy Star. Comfort Partners goes on to actually do the recommended actions, then measures in order to verify the impact of those actions, whereas Home Performance would probably give the homeowner a report detailing its findings, recommended actions, estimated savings and hopefully a list of contractors that will perform those specified actions. Hopefully the contractors on these lists are required to measure prior to performing the action and then measure to verify the results of their action.

This is very important because what it does for the homeowner. The Home Performance report should actually detail specific actions based on site measurements. For example, a pull down attic stairway does not close properly and is not insulated. A “Blower Door” test measures the house at 3,400 cfm50 (Pascal’s). The recommendation is to insulate and weather-strip the pull down stairs with a list of contractors estimating costs to install at $100.

Let’s assume in this case that the opening for the pull down stairs is 2 feet by 5 feet. Which equals 10 square feet. The thin plywood for the pull down stairs allows 1 British Thermal Unit (BTU) to conducts through one square foot of this material per hour. This means that 10 BTU’s are Loss/Gain through this material per hour. The contractor installs R-10 insulation to the plywood. The R-10 stands for 1/10 of a BTU conducts through one square foot of this material per hour. With the insulation installed, the opening for the pull down stairs only loses 1 BTU per hour.

The same is true for weather-stripping the pull down stairs. After it is done another Blower Door test shows 3,200 cfm50, which is a reduction of 200 cfm50. This represents the amount of airflow in the house at a specific pressure (cfm50). As with the insulation, the reduction in airflow can be used to calculate the reduction of Heat Loss/Gain.

Saying that one would save if they did something and showing them how they save are two different things. What do manufacturers (who claim one would save on their energy bill if they insulate their homes, install a new heating/cooling system or new windows) base their estimates upon? What makes programs like Home Performance with Energy Star important to homeowners is based on a simple principle, “Good decisions are made on good information”.

3) Do you see more homeowners looking for ways to improve their energy efficiency? If so, why do you think this is?

Yes, I do see homeowners making improvements involving energy efficiency. There are other reasons why someone would make improvements to their home. These reasons are usually combined with energy efficiency to make the improvements. One of the most popular home improvements are replacement windows. Clearly these other reasons have value to the homeowners, like aesthetics and maintenance. Unfortunately rarely are the manufacturer’s claims of savings ever realized. This includes items like heating and cooling systems.

This site is from the U.S. Department of Energy, Energy Information Administration and it lists English websites on energy conservation. It may be useful to you in your research.
Old 08-11-08, 07:23 PM
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Thanks Resercon,
That's how we got to doing insulation - a home energy audit in Massachusetts. Here they are still free, if a little difficult to track down. Since the outside walls in this old house were never insulated, the auditor thought that was the first best thing to do. The ceiling over the second floor was already insulated (including the pull down stairs to the attic), but the walls were "very empty" as the insulation guys said. What should I be pushing for with the inspector? They didn't do the whole first floor front of the house because the siding is vertical (not the usual horizontal) and they would have to take it all down to drill their holes. Shouldn't they do that anyway? (Especially since it's the coldest room in the house.)
One of the things I picked up on is the company that does the audit then hires out other companies to do the insulation - I'm guessing there are some complications with that.
Any thoughts? We are expected to pay in excess of $2,000 for something that doesn't seem like it worked all that well, there is still a ton of leakage.
Old 08-12-08, 08:10 AM
Join Date: Nov 2001
Location: USA
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The State actually administers these types of programs, like the Energy Audit. The State prohibits evaluation companies to provide services connected with the evaluations. For example, if the evaluation company was a heating contractor, they would always recommend replacement furnaces/boilers. What the State is trying to do is to avoid a "conflict of interest". The insulation contractor applies to be on an "Approved Contractor" lists. To be on this list the contractors must meet certain standards and requirements. Furthermore both the evaluation and contractor companies are periodically evaluated to verify that they are meeting these requirements and standards.

The funds for programs like these come from a charge on your utility bill. In my State they gave it a name, "Societal Benefit Charge" (SBC). In some instances these funds are collected by the utility and disbursed accordingly to State approved programs. These programs have budgets worth several million dollars. For companies who are involved in these programs, they make a ton of money. In fact most of these companies will work exclusively for the programs.

Regardless who is involved in these programs, the State has the final word. For example in my State, the utilities were disbursing the funds accordingly. Some of the utilities wanted to promote some programs and it appeared that other programs that were mandated were not given the utilities full attention. So the State decided to create an agency that would collect these funds from the utilities and it would disburse the funds accordingly.

You need to understand this because it pertains to your situation. The SBC is actually a tax on your utility bill. As such the governing body in my State which is known as the NJ Board of Public Utilities (BPU) looks out for the interest of the public. Your State has a similar agency. Complaints are not taken lightly. Depending on the gravity of the complaint companies can lose their contract under the program and the contractor can be removed from the Approved List. So companies and contractors involved in these programs have a vested interest not to have you complain. And you will be astonished the steps they will take to avoid you complaining to the State. Even a number of minor complaints will have a negative effect on their continued participation in the programs.

When you talk to the inspector, mention about the governing body. Don't threaten him/her with it, just mention it. He/she will immediately ask if you have spoken with the agency. Say no. If you say yes, they will immediately stop what they are doing and leave your home. After you tell them no, explain your situation to him/her and what you were led to believe. NOT WHAT YOU WERE EXPECTING!!! Ask how the situation can be resolved and options available under the program. Appear to be receptive to their recommendations and the program as a whole.

Good luck.
Old 08-13-08, 02:26 PM
Join Date: Dec 2005
Location: Wisconsin
Posts: 71
insulation alone will not improve the air leakage significantly. insulation and air infiltration are two separate issues that must be addressed separately. Both are important. Just adding insulation is not going to help air leakage that much.

the insulation work will help with retaining heat, that it the purpose of insulation. If it is dense pack cellulose in the walls, it may help some with air leakage, but not a ton. For reducing air leakage I would be looking primarily at the following areas:

Attic - hatch, around light fixtures, around plumbing stacks & chimney, walls

Basement - around sill box, any penetrations through floor above

All windows and doors

You are not insulating these areas, but sealing with caulk, weatherstripping, expanding foam etc.

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