An energy audit

The following description of a home energy audit is based on the New Jersey practice and so is probably more relevant to a heating climate, but should be much the same elsewhere.

The trick with the US North-East, say from Philadelphia up to Boston, is that it’s a heating climate alright, but still gets hot and humid during the summer. We’ve already had 90 degree days in April of 2009. [That’s about 32º Celsius…Oh how I wish the US would switch to metric, but I digress…]

Here are the steps an auditor will take:

1. Talk to you over the phone about your issues, concerns and plans. Are you worried about high gas or oil bills? Is the place full of drafts? Are you worried about moisture and mold? Did a contractor do some work and it doesn’t look right. The auditor will want to get some history of the house; age, style, any recent renovations, type of windows, type of heating and cooling system. He or she will ask for a one year history of your electricity, gas and oil bills. With that information they can calculate your usage and compare it to the average in your area.

You should take the opportunity to ask the auditor about his or her background, and what their primary business is. If they are a heating/air conditioning supplier and installer you can allow for that when they, probably, recommend a new heating system. It’s hard for a company to make any money on the audit alone – in fact most make a loss, hoping for follow on business to earn their living. And you need to recognize that these guys bring about $10,000 worth of gear to your house, plus their van and trained people.

2. On the day of the audit – and be prepared for the auditor to crawl through every part of your house for the best part of a day – there will be introductions, measurement of exterior carbon monoxide (CO) – (it’s surprising how high that can get if you live near a highway on calm day), wind, temperature and so on.

3. This is followed by a quick walk through of the inside for the auditor to get the lay of the land. The audit can NOT go ahead if:

* CO levels are higher than 35 parts per million (ppm)

* There is any vermiculite insulation or any loose, friable asbestos

* If there are any lit fires

* If there is anything loose or suspect (like a dangling window) that could get damaged by depressurizing the house (see step 7 below)

The auditor will ask you where various access points are, where the thermostats are. He will then ask you to get the place set up in “winter” condition; all windows and doors closed, lights on, blinds and drapes open, pets taken care of. He’ll also ask you take out any food in the oven.

4. At this point the auditor, much as he likes you, would rather be left alone. The reason is simple; if you follow him all the way and ask questions the audit will take all day, and for sure he will miss something by not concentrating properly. Thanks for understanding!

A thorough exterior inspection comes next. It’s uncanny what an experienced guy can see; the pattern of rust on a chimney pipe can tell a story. Peeling paint indicates moisture. Badly sloped garden beds indicate possible problems. The auditor will measure and sketch out a floor plan (if you already have one that will make things quicker) and calculate the volume of the house. Using that volume and your location he’ll calculate how much airflow the house should ideally have. This is the BAS (Building Airflow Standard). [More on this subject in another entry – it’s not as easy as it sounds]

He’ll also test for any gas leaks – if you have gas…

5. The audit then moves inside for a detailed assessment. The interesting spots are usually the attic and basement, or crawl space [more on crawl spaces later]..

The auditor will test for gas leaks inside and test the oven (if it is gas) for CO. For that it needs to heat, and that’s why he asked you take the roast out in step 3.

6. Now we look in detail at the heating appliances, inside the “CAZ” (combustion appliance zone). They are set to OFF or Pilot and checked for CO and gas leaks.

7. The next step tests the appliances under worst case conditions, so all the fans in the house get turned on, including the dryer, and doors are shut to see if the appliances get enough airflow to establish adequate venting when all the other fans are competing for air. A manometer, CO tester and smoke stick are used in the test. Not strictly part of an audit, but usually done anyway is an efficiency test using a combustion analyzer.

8. Finally the auditor gets to bring in the heavy gear. A blower door in this case. This takes a bit of setting up, some base line measurements wit the manometer and then the house gets depressurized (to about -50 pascals (pa). The auditor either has a smart manometer or has to do some calculations and arrives at how many cubic feet per minute (cfm) are leaking into the house. [Later he’ll compare that to the BAS calculated in step 4].

While the house is depressurized he’ll check leakage between areas and rooms, particularly the attic), he’ll check leaks in ducts and look for less obvious leakage places with the smoke stick.

9. Time to pack up all the gear, and go prepare a report. The report will probably come a day or so later and make recommendations, probably in this order: Any health and safety issues, air sealing, insulation, heating (hot water and house), general improvements. You need to decide what you want to do.

State subsidies

In NJ, and in differing ways in other states, the audit is subsidized by the state (i.e. by you, the tax payer). A full audit like the one above, for $125 is an outstanding bargain. Air sealing will be a recommendation in many cases. With stick built houses over say 10 years old it’s almost certainly the best way to improve the efficiency of the house. NJ pays $1000 of that, another bargain. The rules are changing so that to qualify for the subsidy the air sealer needs to do another blower door test after doing the sealing to prove the job has resulted in improvement and the building is still at the BAS (i.e. it hasn’t become too tight). To save another trip to your place the contractor will probably try and do the audit, the sealing and the second test all in one day. Personally I think that’s rushing it, but don’t know how they can make money any other way.

Infrared thermography

You will have noticed no mention of IR in the description of the audit. It’s not a requirement of the audit. An auditor who does use an IR camera will need to charge more – those babies cost $3000 and up. And he or she will need to have some training and experience to really get the best out of those machines. In good hands they can be well worth while – showing insulation gaps, badly sealed light fixtures and water leakage behind walls. It’s a nice extra – but seriously, IR is best in industrial setting where spotting a hot connection on a high voltage line, or an over-heating bearing on a motor can save thousands of dollars and reduce outages (not to speak of medical and military uses).

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