Electrify Everything ~ Part 2: The Energy Audit
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Grateful Acknowledgement:
Graphics and information for this article are taken from Rewiring America’s Electrification Coaching course, with verbal permission and use of the Creative Commons license. Their knowledge and presentation skills are incredible – all errors are my responsibility. Thank you, Rewiring America.
Latest download: from RewiringAmerica.org - the Go Electric Digital Guide
Find out whether your $$ for heating/cooling are going out the window, so to speak, or maybe somewhere else! Explore the financial, and perhaps also climate, implications of your home energy use. An energy audit will help you do that.
As outlined in Part 1 of this series, the energy audit provides the basis for planning, sequencing and making all future energy-related changes - large and small - in your home. You will appreciate how smoothly this knowledgeable stepwise process goes, avoiding potentially erroneous investments, and capturing the maximum of utility rebates and federal tax abatements.
It’s extremely important to do an energy audit before replacing your HVAC system, so that your system is sized correctly for your home. This is particularly important if you are considering installing a heat pump, which doesn’t operate at peak efficiency if it is under- or over-used. There is also no sense in buying a system that is larger and more powerful than needed, and costs more.
What Is An Energy Audit?
An energy audit investigates the details of your home’s design and its construction, to map out where you are using, and possibly losing, energy.
Energy is unavoidably lost through all of the solid interfaces of your home with the outside environment, including walls, windows, doors, attics, roofs, and basements. Unintended air leaks occur around fittings of all kinds. Dryer, stove, furnace and attic exhaust systems, gas and water intake pipes, and door and window fittings are among the many that contribute to unintended energy loss. Increased insulation does NOT help if the leaks are still occurring. Insulation DOES help if it increases inadequate R-values of any deficient solid surfaces to industry standard levels, once the leaks are fixed.
Leaks
While all homes must have ventilation, it is best to meet the accepted industry standard of 0.35 air changes per hour (ACH) Any value above 0.35 is considered to be a leak.
Although you can probably seal some of these leaks yourself, (e.g., weather stripping around doors and windows), it helps to have a professional identify all of the sources or remediate those that need relatively specialized treatment. Below is a diagram from Rewiring America that shows 19 sources of potential leaks in your home.
Leaks are usually sealed with polyurethane foam or similar material, e.g., the interfaces between plumbing fixtures and fans with the outdoors, or they are capped in the case of lighting fixtures.
Some contractors may perform a “blower door test”, in which a powerful fan and a measuring device is used to identify the size and location of leaks throughout the home. According to Rewiring America’s Electrification Coaching course , leakage could be responsible for 10% to 50% of a home’s total heating use.
Solid Surfaces
Solid surfaces like windows and walls serve as barriers and have measurable R-values that indicate how well they prevent heat from passing through them - to the outside in cold weather, and to the inside in the heat of summer. The higher the R-value, the more effectively the barrier impedes heat transfer. The total area of each type of surface is important. The contractor should measure the dimensions of all the rooms and windows in your home. For example, if you have small windows with low R values, but your walls are well-insulated, then energy loss is occurring through only a small percentage of your total interface with the outside. In this case, it is less important to replace the windows than if they were a larger percentage of the total interface area. This is a clear example of how your energy audit can guide effective decisions. Contractors will quantify these measurements with a mathematical “Manual J” computation and graph that shows the percentage that each of your home’s features, like windows and walls, contribute to overall heating and cooling losses. They should be able to show you the results of the Manual J computation.
Windows can be single-pane, single pane with storm, double-pane, or triple pane. Note: The U-Factor shown below is the inverse of the R-factor, meaning that the lower the U-Factor, the better the insulating quality of the window.
Window coverings of various kinds could be used to increase the R value, as well, but a discussion of these types is beyond the scope of the article. Here are some types you might want to consider, including this link which discusses them in more detail.
Walls can be made of wood or other building supplies, and can be insulated with various materials to produce different R-values. The need for walls to serve as insulators differs greatly. Inner walls, exposed only to other enclosed spaces like adjoining rooms and corridors, don’t need to be well insulated, while outer walls, directly exposed to weather fluctuations, need high R values. Some walls have a lot of solar gain, i.e., get heated from a southerly exposure and lack of shade, which can lead to uncomfortable indoor warmth in summer, and others are more shielded from outside variations. When walls are partially or entirely below-grade, their outside temperature variation is diminished, because the ground temperature varies much less over time. These walls have a lesser role to play in indoor temperature regulation. The outside expected temperature variation also affects what is acceptable in R-values over the course of a year, meaning that homes in a climate that get very cold or very hot need a higher-R value to prevent heat transfer.
Below is a figure that shows a typical wall, with its layers of materials. Note that the separate R-values are added together to get the total.
The next figure shows the R-values of commonly used insulating materials.
Other Factors
There are some other hard-to-quantify factors that contribute to energy usage and to the types of solutions that might be considered. For example, the number of people living in the house has a significant impact. More people use more hot water, they use more devices, they generate more heat themselves, and they may require more spaces to be heated to higher temperatures.
Where Can I Get An Energy Audit?
The good news is that there are multiple ways to get an energy audit.
Utility Companies
The easiest and probably safest and cheapest - possibly free - is to call your utility company and request an audit. Suggestions may include, for example, window replacement or coating, installing a smart thermostat, replacing all incandescent lightbulbs with LEDs, or meeting insulation needs.
However, these audits usually aren’t nearly as thorough as an insulation company’s audit. But they’re a great place to start.
DIY
There are several websites where you can enter data about your house and get recommendations, some with financial incentive information. Basically, these sites do the “Manual J” calculation described above by asking for your room dimensions, types of wall construction, and types of windows. If you’re technically inclined, one of the sites below might be a good starting place:
CoolCalc, a tool for doing Manual J computations
Energystar.gov Home Performance Program partners
Here are some DIY tasks that you can perform, while others should be left to the experts:
Insulation Contractors
Many insulation companies offer energy audits as a way to introduce themselves and make a bid for your business. They must do an energy audit and perform a Manual J calculation, as described above, as part of their bid preparation anyway.
An energy audit allows you to work with a company briefly without much investment. You can get a sense of their attention to detail and their willingness to work with you and answer questions. For this reason, choose your energy audit company carefully. Certification by BPI (Building Performance Institute) or RESNET )Residential Energy Services Network) is an indicator of training and maintenance of standards of performance. Recommendations from trusted people who have had a successful audit and follow-up work done are also valuable.
Your utility might have a list of recommended contractors, as PSE&G does. Make sure it’s not a self-registered, i.e. unvetted, list. Knowledgeable HVAC contractors, particularly those that install heat pumps, can often recommend good insulation contractors.
Climate and energy websites might have recommendations as well. In California, the SwitchIsOn.org website has a list of contractors. Angie’s List has recommended contractors. Other organizations are attempting to compile lists too; if you know of any, please put the URLs of their websites into the Comments following this article.
Check the Google Reviews and Angi’s List sites for reviews, and read both the positive and negative ones.
Some energy auditors/insulation contractors will ask you to give them the measurements from a past energy audit, so that they can quickly give you some estimates, and then will perform a site visit only if you’re seriously considering hiring them. In general, I don’t see an issue with this as long as there is a site visit before a written bid is submitted.
What Will Be In the Energy Audit Report?
Some auditors prepare formal reports. Other contractors simply prepare a bid, and include measurements and calculations that explain the reasons for the proposed improvements.
Most energy audits from insulation contractors focus narrowly on insulation and weather-stripping and other kinds of sealing of leaks. This is a good reason for using an auditor who is utility-recommended or a general contractor, as their audits will probably provide other important suggestions. A DIY tool may cover all the energy-saving bases too. An energy audit may include these topics:
Insulation
Weather-stripping and sealing
Window replacement
HVAC system replacement
Hot water system replacement
Replacing your incandescent bulbs with LEDs
Installing a smart thermostat (for non-heat pump systems) that turns down the temperature when you’re away or asleep
Replacing an inefficient refrigerator, which can comprise 18-20% of typical home energy usage
Replacing an inefficient clothes dryer
Below are some pages from a thorough report:
The table below taken from another report, that specifies the return on investment, or ROI, of undertaking three different remediation projects. This table provides the information you need to compare the investment cost with the likely savings, but that financial aspect may not be the whole picture for you - as it does not address your comfort levels. For example, eliminating drafts or cold spots in your home may be worth the money despite very little savings in dollars. In my husband’s and my home, the extreme heat in the summer in the upstairs led us to insulate the attic and garage, even though the ROI showed that we wouldn’t save any money
Financing
The report should contain the expected financial incentives – federal or state tax credits and/or rebates, 0% financing, etc. Remember to check federal, state, and utility rebates and financing. A great resource for federal rebates is Rewiring America’s IRA calculator. Check with your state and your utility for others. Contractors should be able to identify these for you, and often complete the applications for you.
Preparing To Act On Recommendations
How do you decide what actions you are going to take on the basis of the energy audit?
First, identify whether each proposed task is one that is important because of
financial savings
comfort
safety
decarbonizing your home!
or some combination of the above. The audit report should include how the recommendations were reached. For example, were the Manual J calculations and/or the blower door test performed? What is the expected financial saving from each task? Do they solve the comfort problems in your home?
Actions should be spelled out in detail, as to what materials will be used and what the remediation projects will entail. Below is an example from a bid my husband and I received.
Any attic insulation work must include air sealing as well as weatherstripping of doors and access hatches.
The contractor should tell you about all financial incentives and apply for you. In some cases, you might owe nothing at the beginning of the job if the contractor agrees to wait for, and accept, the rebate, or if the utility offers 0% loans.
The energy audits were all done by excellent insulation contractors. I received 3 bids, with different approaches and recommendations.
Contractor 1:
Very thorough written report, but the agent could not adequately answer my questions.
Multiple options were presented, ranging from ~$10K to ~$43K, with about 30-40% tax credits and rebates.
My sunroom presented the worst problems with insulation, but this contractor ignored it, even after I asked to speak to the company expert about it. Since it didn’t fit into their standard pitch, they didn’t deal with it.
Contractor 2:
No written report but a very experienced agent came on site, who could immediately answer all questions.
He immediately noticed that the sunroom was the worst problem, and told me to put all my efforts into getting a door and window installed between it and the main house, even though he wouldn’t be bidding for that job.
He also noted that our attic did not have a ridge vent, due to building code changes, and linked it to my home’s serious overheating issues. Again, he would not be bidding on that job.
~$10K bid, about half of it as a rebate, ROIs calculated. He insisted on using blown cellulose insulation in our attic, even though we use it for storage, and wouldn’t discuss using fiberglass batts instead.
Contractor 3:
Very experienced agent who spent 90 minutes in the house, answered all questions as we went room to room, took extensive pictures and measurements.
Emphasized that his company would do what we wanted, but would make recommendations about what was most important and why. We had 3 follow-up phone calls and multiple emails. In the end, he convinced us to use blown cellulose with damming, although he would have done the job with fiberglass for the same price.
While we were reluctant to insulate every wall of our house, he recommended several southerly facing walls with a lot of solar gain, to decrease the overheating problem. Due to financial considerations, we chose not to insulate some of the walls with large window areas now. In the future, it might be a more effective [use of money to do window replacements there instead of insulating the walls. Or possibly we would do both in another year.
Very detailed written bid. ~$11K minus $5K in rebates and then 0% financing of remainder by my utility company.
We chose this contractor because of his knowledge and responsiveness, his ability to tell us exactly why he was recommending certain actions, and why others were not as important, and his hundreds of positive reviews. We had fixed the sunroom and ridge vent issues before he came on-site, so I don’t know whether he would have commented on them.
And humorously, this was the kick I needed to finally clean out the attics! Whether a benefit or a drawback, it required more work than most home upgrade projects.
The Takeaway
The energy audit will give you an accurate picture of how your house is performing and provide you with the information you need to develop a roadmap of energy saving improvements to your home. The audit is foundational, pointing the way from small changes, such as LED bulbs and weatherstripping, to overhauling your home’s insulation and replacing your HVAC system. All are important. You will be able to invest your money efficiently and effectively in the logically sequential changes that bring you the most in money savings, and personal comfort. I have found satisfaction in combatting climate change, as well.
If you think that you will be replacing your HVAC system in the future, and especially if you will be considering a heat pump, it is critical to have slimmed down your heating and cooling requirements, in order to properly size a new system. More on that in a future article about heat pumps.
And finally, don’t ignore any energy audit suggestions, from LEDs to appliance replacement, even though most audits tend to concentrate on insulation and air leaks.
Last updated: 19 Feb 2024
Here's an article on inexpensive ways to make significant cuts in home energy use - can be used in tandem with your energy audit and reinforces some points made by Betsy, above. https://www.washingtonpost.com/climate-environment/2024/03/12/make-home-energy-efficient-savings/?utm_source=newsletter&utm_medium=email&utm_campaign=wp_climatecoach&wpisrc=nl_climatecoach
Very well written and very informative. My HVAC and Central Air is old and will need to be replaced in the next few years. This information about Energy Audits will be very useful when I have to replace my current system.