Where do we go from here? Under Measure It – December 2011 you can see that we reduced consumption versus last year by 2,000kWh and had a small reduction in gas consumption. They key to reducing gas consumption at this house is to reduce heating demand. The set temperature has been set two degrees lower than last year but we can take other steps to further reductions in both gas and electricity
Air sealing is key to HVAC (Heating, Ventilation and Air Conditioning) savings. In 2010 two Blower Door tests were run on my house – one in June and the other in November – to measure the baseline and to see what affect a minimal amount of air sealing had on performance.
ACH is a pretty easy way to visualize how leaky your house is, it tells you how many times in one hour all the air in your house changes. How does it change? Air moves in and out of your house through all the little cracks, crevices and holes that you never even think about. In the winter heated and in the summer cool, conditioned air moves outside. This causes your systems to work harder to make you comfortable AND increases your utility expenses.
The benchmark results shown above provide a performance target for our house. The benchmark house is newly constructed and is well sealed. It has an ACH rate of 1.08 so all the air in the house changes once an hour. (Note that the Passive House goal is 0.5ACH and I recently heard a lecture where the contractor claimed attaining a 0.28ACH. Now that is tight!) I think 1.08ACH is a more realistic goal for this house.
What happened between June and November to result in a 21% decrease in ACH? Air sealing. Surprisingly some very simple efforts can make a big difference. So far we have:
- Installed gaskets to help stop air flow. One of the easiest projects you can do is to install insulating gaskets on every exterior wall outlet and wall switch. All you need is a screw driver. Look at the Hands-on-Green tab for easy to follow instructions.
- Checked, repaired and installed door weather stripping
- From outside, caulked around all penetrations through the house wall including hose bibs, electrical feeds, utility lines (including cable and telephone).
- From inside, caulked around basement windows and doors.
From 3.25 air changes to 2.56 air changes was easy. Our next steps include:
- More caulking from inside the basement at major penetrations and along the base of the sill plate and the base of the rim joist
- Installation of rigid foam insulation along the rim joist
- More caulking around the exterior of all doors and windows.
- Blower door test to see results.
{ 2 comments… read them below or add one }
Great article! I would love to hear more about the easy wins for us laypeople to do (like installing the gaskets) to make a difference in our heating and electricity use. Also, are there ways to test without having the industrial blower to determine where heat and AC are escaping?
More to come! One really easy way to see where there are leaks is to go around with a lit candle. Carefully moving it along the wall and watching the flame you will be able to see it flicker a little or a lot depending upon how much air is moving through the void(s) in your wall.
If you want to be a little more formal you can get a smoke pencil (see http://www.smokepencil.com). It will do the same job as the candle but may be safer and is more user friendly.
A really cool way is to rent a fog machine and watch the ‘smoke’ come through the holes in your walls…you might want to reserve this for a Halloween Party. Be sure to let your neighbors know that it is not a fire and if you live in an apartment or adjoining house hope that there are no holes over to their space.
The blower door is best because it provides the metrics but it doesn’t pinpoint the air pathways it pressurizes or depressurizes and makes the indicators (smoke pencil…) more effective.