Photograph of pink styrofoam insulating board © Daniel Friedman Home Energy Audit to Evaluate Building Heat Loss or Heat Gain & Choose Heating or Cooling Improvements

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Using a home energy audit to best advantage:

This article explains how to make best use of a home energy audit to reduce home heating or cooling costs. We provide related insulation and heat loss or heat gain analysis procedures including how to measure or calculate heat loss in a building, defines thermal terms like BTU and calorie, provides measures of heat transmission in materials, gives desired building insulation design data, and shows how to calculate the heat loss in a building with R values or U values.

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How to Get the Most Benefit from a Free Home Energy Audit

Here we discuss the following: How to measure or calculate heat loss (or gain) in a building. How to measure heat transmission in materials: definition of R-values, U-values, K-values, BTU, calorie, and rates of heat loss or gain. Building design temperatures & how to use a home energy audit or heat loss analysis. What insulation "R" values should be used in a building insulation?

Formula-R™ and Owens Corning™ which may be visible in our page top photograph of pink Styrofoam™ insulation boards are registered trademarks of Owens Corning® and were photographed at a Home Depot® building supply center.

Many people have heard of using "R" values to describe "how good" a building's insulation is. This article explains three measures of the flow of heat out of or into a building: R-values, K-values, and U-values. Each of these is defined below. But before moving on to these basic concepts of building heat loss (or gain) theory, it is essential that this still more basic point be considered:

It doesn't matter much how wonderful the building insulation is, how thick it is, or what the insulating material's "R" value is (see R defined below) if the building is leaky. If, for example, we're considering an older home with leaky windows or doors, or if we're considering a tall building with poorly controlled heat in winter, such that occupants of the upper floors are leaving windows open in winter then the heat flow out of these openings will be so terrific that the amount of insulation won't matter much.

How to make use of a home energy audit or free home energy use survey

A less precise and less computerized method for calculating building heat loss (or gain) is used by people who perform an "energy survey" or energy audit for a building. Home energy audit services may be free from your local utility company. The energy survey technician uses a pre-printed form whereon s/he records the areas of the building's walls, top floor ceilings, foundation walls, floors, and the number and type of windows and doors.

An "R" value is assigned to these and the sheet is used to manually calculate the building's rate of heat loss. We had one of these "free" surveys performed on a home built in 1900 when we were renovating it years ago. Regrettably the surveyor was either poorly trained or simply not very observant.

The free energy audit surveyor rated our building walls at a very high rate of heat loss by assuming that they were not insulated whatsoever (and then proceeded to try to sell us an insulation service).

What that particular home energy audit surveyor failed to notice was that the building walls had been insulated (with blown-in foam) - a condition that was quite easy to see since we had removed the building's exterior siding and wall sheathing. He just didn't look.

So while home energy audits are a great idea, make sure your auditor is awake before you believe the results of the home energy survey.

And remember that some "home energy auditors" are really trying to sell you replacement windows (very long payback time) or building insulation. (Remember the urban legend about the home energy auditor who was using a camera light meter as an "energy loss" indicator to convince home owners that they needed new windows?)

Question: who do I call to get advice on saving on my heating costs?


In 1985/86 local electric utility company's weatherization program did the following for my house:

1. blow insulation put between roof & ceiling, under home crawl space & some other don't know where all at places between exterior wood cedar shingles & exterior walls

2. former wood & rope frame windows replaced with new aluminium slide frame windows

In 2015 licensed, ETC roof business, now out of business, workers removed former roof tar paper & asphalt shingles, added some extra what i call beams, looked like maybe 2 by 4
replaced former roof tar paper & asphalt shingles with new roof tar paper & lifetime asphalt shingles all nailed to beams

There is no crawl space area between roof & ceiling

Each of my rooms has its own individual base board heaters with on heater controls. Some heaters, not all, were replaced once from 1900 - 2005. Not all of the electric heaters are working right, so I leave them turned off at circuit panel.

I need to know what type/kind of business, ETC i need to do what additional work re: current roof, insulation, ETC situation to help make my home less cold Sept through May every year

- Anonymous by private email

Reply: where to get energy program help from your state, warnings about for-pay or even "free" energy audits

If I understand your question is

"Who can tell me what energy-savings or heat-cost reduction steps I should take for my home?"

You live in Parkland Washington

This website:

provides information about your state's energy codes and gives links to its various energy programs.

Also you can use your web browser to search for

Parkland Washington energy audit

and you will see a list of companies offering that service.

You need to know:

Where are the most-important points of un-wanted energy-costs

Watch out: Beware that some energy auditors are better or more-comprehensive than others, and that many of them want to sell you a specific product, like insulation or weatherizing. Still their services are useful and often are offered at no charge.

Too many "home energy auditors" offer services like "blower door testing" that are not sufficiently diagnostic. Such tests, like any incomplete building inspection service, might tell you that your home is leaky and could save money by a weatherizing program, but the test alone will not tell you exactly what steps are needed.

Your energy audit needs to identify:

  1. Cold air leaks into the building
  2. Heat losses out of the building
  3. Areas of missing insulation
  4. Causes of excessive stack-effect air movement upwards drawing cold air into the building during the heating season

Window gap seal project (C) D FriedmanA casual energy audit by an experienced weatherization or insulation company might spot common points of heat loss and may walk around your home commenting on common problem spots like recessed ceiling lights, gaps in trim caulk, or roof ventilation.

But without a more careful, better-informed analysis, perhaps using thermography or other measurements during the heating season, often such generic advice is plain wrong.

Examples of Some Energy Auditors & Their Advice

Case 1: wrong assumptions about building insulation

In the 1980's a New York State energy auditor examined a home built in 1900, that had blown-in foam insulation in the 1970's, and that I [DF] had renovated, weather stripped, caulked, and sealed in the 1980's.

He noted the age of the home and said "well your walls are uninsulated, you need to have us insulate them". A rather careless conclusion that was not helpful.

It's not entirely sensible to assume that by 2015 a home built in 1900 has never had insulation added to its walls and attic, and a careful inspection can usually spot signs that insulation has indeed been added.

This home sported round drill marks where insulation had been blown into walls, and in both attic and basement oozing foam insulation was readily visible had anyone bothered to look.

An experienced auditor might have known that during the 1970's Arab Oil Embargo energy crisis many people blew UFFI into their older home's uninsulated walls.

Mixed-wrong UFFI could cause temporary but un-wanted high levels of formaldehyde off-gassing, and later owners might have discovered that their UFFI shrunk,leaving gaps around the insulation in walls.


To be fair, no inspector can discover every important construction detail, defect, or condition at a property. But where there is clear visual evidence, it'd be helpful if she'd take a look at it.

Case 2: missing the energy savings target by shooting (your caulk gun) in the dark

Infiltec blower door test courtesy Steve Bliss - Solar AgeRecently an experienced energy auditor examined another home with me. That house, built in 1970, has undergone extensive energy savings improvements that focused on finding and fixing air leaks.

Details of that project are at WINDOW / DOOR AIR LEAK SEALING HOW TO.

Our energy auditor

  1. Did not ask if we had already taken any steps to save on energy costs - that might have enabled him to see mistakes in what we had done, or to focus on what remaining steps would be most-beneficial
  2. Did not use any instruments to examine for points of heat loss or air leaks
  3. Did make a casual (and free) walk-around the outside and some of the inside of the home, suggesting that we would benefit from better caulking and sealing of exterior trim and interior pot lights or ceiling lights. He also suggested providing outdoor air supply to a heating boiler (located in a garage into which outdoor air leaks around the garage door).

We were left with a couple of nice suggestions but no idea whether or not those suggestions were accurately drawn rather than drawn just from general experience. There was not mention of where we had actually found the major air leaks previously, discussed at the window and door air leak sealing project cited above.

To be fair, nobody can, in a casual walk-through, know the detailed history of a building, nor can they have a complete picture with objective data showing the priorities of attention to stop un-wanted energy costs.

But an energy auditor could ask about building history or spot evidence of renovations and discuss what has been done in deciding what remains to be done.

The auditor offered a for-fee blower door test that would tell how much air leakage the building was still suffering.

While blower door tests are useful diagnostic tools, they're not prescriptive. We'd have still needed to guess at where the air leaks were and thus would be shooting our caulk guns in the dark.


Using infra-red or thermography to screen buildings for un-wanted heat loss, leaks, or heat gain points

Home energy loss surveys using thermography or simple infra-red thermometers are a great way to pinpoint individual points of heat loss (or unwanted heat gain) in a building.

In the hands of a properly-trained expert (not a window salesman) this equipment can help find unexpected building air leaks or heat loss points even when you think that the building has already been insulated.

Having a "high-R" insulated wall or ceiling is not going to be enough to make a building energy efficient if there are many unidentified air leaks or insulation voids in the building's walls, ceilings, or floors.

See THERMAL IMAGING, THERMOGRAPHY for an series of articles explaining what thermography is, how it works, how it is best-used to save energy in buildings, and where to buy thermography scanning cameras and equipment.

What is the Typical Design Temperature for buildings and Building Insulation?

The "indoor design temperature" for a building refers to the assumed target indoor temperature that the building owner or occupants want. Typically 70 deg. F. is used unless the owner specifies something different.

The "outdoor design temperature" for a building is (for heating purposes) assumed to be the average lowest recorded temperature for each month between October and March (the heating season in most climates).

If we are specifying a "design temperature" for cooling climates we'd use the average outdoor highest recorded temperature during the heating season, perhaps April through September.

Building Energy Codes & Standards for Energy Ratings

These codes include detailed specifications for testing and reporting on HVAC system air leakage


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