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Musings of an Energy Nerd

Energy Upgrades for Beginners

Advice for homeowners: to improve the energy performance of an older house, start with a thorough inspection

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When you climb up into the attic of an older home, you almost always discover a few surprises. The only way to determine the condition of your home's thermal envelope is to perform a thorough inspection.
Image Credit: Claire P - Flickr
When you climb up into the attic of an older home, you almost always discover a few surprises. The only way to determine the condition of your home's thermal envelope is to perform a thorough inspection.
Image Credit: Claire P - Flickr
Inspect your home from top to bottom, inside and out. The more you poke around, the more clues you'll get to how your home is performing.
Image Credit: Leonardo Aguiar

Owners of older homes often contact GBA and ask, “What can I do to make my home more energy-efficient?” My standard answer goes something like this: “The first step is to hire a certified rater to perform an energy audit of your home. The audit report will include a tailor-made list of retrofit measures to address your home’s specific problems.”

The advice is good, but it doesn’t do much to educate the questioner. Perhaps you are an intrepid homeowner who is willing to poke around your home’s nooks and crannies. Is there anything you can learn about your house without a blower door and an infrared camera?

Yes, of course there is. This article will explain the steps that homeowners can take to assess the condition of their house from an energy perspective.

Inspect the basement

If your house has a basement, that’s a good place to start your inspection. (If your house has a crawl space or an above-grade mechanical room, some of the advice in this section also applies to those areas.) The most important tool for this type of inspection is a powerful flashlight.

Check for air leaks. On a cold day, it’s fairly easy to locate basement air leaks; you may be able to feel infiltrating air with your bare hand. You may find that an incense stick is helpful in locating air leaks. Another way to locate air leaks is to turn off all of the lights in the basement and look for cracks of light. (This method only works during the daytime, of course.) Typical air leakage locations include the mudsill, around exterior doors, around windows, at utility penetrations, at pet doors, and at dryer vents.

Once you’ve identified where air is leaking into your house, you’ll have to start sealing the leaks. If your house is in bad shape, you may need a new door or window. But in most cases you can significantly reduce air leakage with caulk, canned spray foam, and weatherstripping. (For more information on this work, see Air-Sealing a Basement.)

Inspect the rim joist for insulation. Rim joists can be found at the perimeter of your basement, above the top of your foundation wall. (If your basement ceiling is finished with drywall or plaster, you won’t be able to inspect your rim joists without cutting a hole in your ceiling.)

Ideally, the rim joists will be insulated on the interior with rigid foam insulation or spray foam insulation. If the rim joists are uninsulated, it’s a good idea to air seal the area and install insulation.

If the rim joists are insulated with fiberglass batts, you may have a problem. Pull away some of the fiberglass and inspect the rim joists. If you see signs of mold or rot, it’s probable that the fiberglass insulation is the cause of the moisture problem. (This phenomenon is more common in very cold climates than in mild climates.) If you find mold or rot, you’ll probably want to remove all of the fiberglass insulation and allow the rim joists to dry out. Once these areas are dry, insulate the rim joists with rigid foam or spray foam insulation. (For more information on insulating rim joists, see Insulating Rim Joists and Basement Insulation.)

Inspect your basement walls for insulation. If the insulation is visible, it should be easy to inspect. In this location, what you want to see is rigid foam or spray foam insulation. If you see fiberglass batts, that’s worrisome. Peel back one of the batts to look for any mold that might be growing behind the batts. If you see rigid foam behind the batts, that’s good news, and the batts can probably stay.

If you don’t see any insulation on the interior of your basement walls, it’s possible that your basement walls have exterior insulation. Go outdoors and check the top of one of your walls. If your walls appear to be finished with stucco, pierce the stucco with an awl or a long punch. If you discover rigid foam behind the stucco, that’s good news.

For more information on insulating basement walls, see How to Insulate a Basement Wall.

Look for exposed dirt floors. If your basement or crawl space has a dirt floor, it should be covered with a durable vapor barrier (a layer of polyethylene that is at least 6 mils thick, or a sturdy membrane such as rubber roofing, Tu-Tuf, or a pond liner). If you see bare dirt, it’s important to install a vapor barrier soon.

Inspect your heating equipment. Most U.S. homes are heated by a furnace or an air-source heat pump connected to an air handler. These two types of systems use ducts to distribute hot air through your house.

A minority of U.S. homes are heated by a boiler that distributes heat through hot-water pipes.

If your furnace or boiler is more than 25 or 30 years old, you may want to consider replacing it with a newer, more efficient unit. (Hopefully, you know the age of your heating equipment, either because you remember when it was installed, or you were told how old it was when you bought the house.)

If you are planning major energy retrofit work that will include a new heating system, you may want to read Choosing HVAC Equipment for an Energy-Efficient Home.

Inspect your ductwork. If your home is heated with a boiler, there probably isn’t any ductwork in your basement. If you have a furnace or air handler, however, you’ve got ducts. Inspect the ducts to see if any ducts are disconnected, or if ducts are so poorly connected that there is a visible gap between duct sections. Disconnected ducts will need to be re-connected and sealed with mastic or high-quality tape.

If your house has ducts in a vented, unconditioned crawl space, all of the duct seams need to be sealed with mastic, and the ducts must be insulated. You should also plan on converting your vented crawl space into an unvented crawl space. (For more information on this topic, see Building an Unvented Crawl Space.)

For more information on duct sealing, see Sealing Ducts: What’s Better, Tape or Mastic?

Inspect your water heater. At a minimum, you should note the water heater’s age, if known. You should also look for leaks, puddles, and drips. If it is a gas water heater, inspect the flue pipe to see if it looks secure, with flue pipe sections well connected. If your water heater is more than 15 or 20 years old, plan to replace it soon.

If you are contemplating the purchase of a new water heater, you may want to read All About Water Heaters.

Attic inspection

Now get out your step ladder, tape measure, and flashlight, and head for the attic. If you’re unfamiliar with attics, you should know that you can easily step through the ceiling if you don’t place your feet carefully on the joists spanning the attic floor. If you don’t like balancing on joists, bring a couple of 2 ft. by 3 ft. pieces of plywood to step on while inspecting your attic.

Inspect the attic hatch. A good attic hatch is secured in place with latches that pull the hatch tight against the weatherstripping. On the attic side, the hatch should include several layers of rigid foam with a total thickness of 6 or 8 inches. If any of these elements are missing, you have work to do. (For more information on attic hatches, see How to Insulate and Air Seal an Attic Hatch.)

If your house has pull-down attic stairs, you probably have a major air leak in your ceiling. For more information on this topic, see How to Insulate and Air-Seal Pull-Down Attic Stairs.

Inspect the insulation on the attic floor. Most varieties of fluffy insulation (including fiberglass and cellulose) have an R-value of about R-3.5 per inch. For the purposes of an attic inspection, you can use that number to get a rough idea of the amount of insulation in your attic.

If you live in Climate Zone 1, 2 or 3 (including most of California, Oklahoma, and South Carolina, or anywhere further south), you want at least 9 inches of fluffy insulation (about R-30).

If you live in Climate Zone 4 or 5 (including Oregon, Nebraska, Ohio, or Massachusetts), you want at least 11 inches of fluffy insulation (about R-38).

If you live in Climate Zone 6, 7, or 8 (including Montana, Minnesota, or Maine), you want at least 14 inches of fluffy insulation (about R-49).

For more information on insulating attics, see Insulating Roofs, Walls, and Floors.

Look for air leaks. Because most attic air leaks are hidden, they can be hard for homeowners to find. But if you’ve been reading GBA articles, you may know where to look: above kitchen soffits, at chimney chases, at plumbing vent pipes, above partition top plates, at the perimeter of ceiling-mounted duct boots, and near bathroom fans and recessed can lights.

If you’re willing to play detective, lift up a few fiberglass batts in these areas and snoop around. If you see that the underside of a batt is black, that’s a good indication that air has been leaking through the batt for years.

For more information on sealing attic air leaks, see How to Air-Seal an Attic.

Inspect your ducts. Attic ducts, like basement ducts, need to be checked to be sure that no ducts are crushed or disconnected. All attic ducts must have sealed seams and should be insulated or relocated so that the ducts are inside your home’s thermal envelope. In general, it’s bad news if your house has ducts that are located in a vented, unconditioned attic. (For more information on attic ducts, see Keeping Ducts Indoors.)

All of your bath exhaust fan ducts should lead to the outdoors. The best place to terminate an exhaust duct is at the gable end of your house. If your house has a hipped roof, you’ll have to extend the duct through the roof.

Look for moisture problems. Inspect the underside of the roof sheathing for signs of roof leaks, mold, or other moisture problems. If the sheathing has lots of mold, that’s a sign that your ceiling has air leaks that allow warm interior air to enter the attic. In most cases, homes with moldy roof sheathing also have a damp basement or crawl space.

Check your above-grade walls

Assess the insulation. If you want to poke around in your walls to see if there is any wall insulation, the first step is to turn off your main circuit breaker. Choose an electrical outlet on an exterior wall; plug a light into the outlet to verify that the electricity is off.

Remove the cover plate. One side of the electrical box should be attached to a stud; on the other side of the box, insert one or two wooden chopsticks and see what you can find. If the crack is large enough, shine your flashlight in there. Widen the crack if necessary, but don’t make the crack any wider than the plastic cover plate.

You may be able to snag a sample of the insulation with your wooden chopsticks. You may also be able to tell whether the wall includes a polyethylene vapor barrier, or whether the batts have kraft facing. (To snag a sample of insulation, it’s also possible to use a Zip-It tool — an inexpensive plastic tool that is usually used for clearing clogged drains — instead of wooden chopsticks.)

Once you are done snooping around, replace the cover plate. Perform a similar inspection on all four sides of the house; in an older house, it’s possible to discover different types of insulation in different locations.

If your stud bays are empty, you should plan on hiring an insulation contractor to install dense-packed cellulose in your walls. (For more information on blowing cellulose into the stud bays of an older uninsulated house, see How to Install Cellulose Insulation.)

Look for mold or water damage. Mold or water damage are important clues. If you find any, use deductive reasoning to come up with an explanation for why the area is damp. Possibilities include water entry through the wall due to bad flashing, or condensation on cold surfaces. (For more information on wet walls, see All About Wall Rot.)

Inspect your windows

How many layers of glazing? Does your house have single-pane windows, double-pane windows, or single-pane windows with storms?

If you’ve never thought about the issue, here’s how to tell the difference between a single-pane window and a double-pane window. Open a window so you can put one finger on the interior side of the glass and another finger on the exterior side of the glass. If your fingers almost touch, it’s single glazing. If there is a gap of 1/2 inch or 5/8 inch between your fingers, you have double glazing.

If you look at the perimeter of double-glazed windows, you will be able to see the metal spacer that separates the two panes.

If you have double-glazed windows or single-glazed windows with storms, you are all set. If you have single-glazed windows without any storms, you should probably plan to invest in storm windows.

Are there any signs of rot? Go outdoors and inspect your window sills for rot. If you see lots of rot, you may need to replace some of your windows. Remember, though: replacing older windows with new double-glazed or triple-glazed windows is so expensive that you will never save enough energy to justify the cost of window replacement.

For more information on this topic, see What Should I Do With My Old Windows?

Do you have too much unshaded west-facing glass? In a hot climate, west-facing glass often causes problems. In mid-afternoon, when the sun moves around from the south side of your house to the west side, outdoor temperatures are usually highest. During this time of day, the sun is lower in the sky than at noon, so the sun’s rays reach deeper into your house.

If you live in a hot climate, and your house has big, unshaded west-facing windows, you should consider installing window films that reduce solar heat gain. For more information on window films, see Window Film: An Overlooked Retrofit Option?

Assess your appliances

How old is your refrigerator? If your refrigerator is more than 20 years old, you should consider replacing it with a newer, more energy-efficient model. (For more information on this topic, see Choosing an Energy-Efficient Refrigerator.)

Do you have any duplicate appliances? If you have a second refrigerator or a freezer in your basement or garage, now is a good time to determine whether you really need it. You can save a lot of energy by getting rid of an extra refrigerator or freezer.

Check your light bulbs

Get rid of your incandescent bulbs. Last but not least, check all of your light fixtures to make sure that your home is incandescent-free. Replacing incandescent bulbs with compact fluorescent lamps is one of the most cost-effective energy-saving measures you can perform. (For more information on CFLs, see Lighting and Phantom Loads.)

If you want, buy a few LED lamps and see if you like the light they produce and can stomach their relatively high cost. They’re worth checking out: prices are dropping and light quality is improving. (For more information on LEDs, see The Continuing Revolution in LED Lighting.)

OK, I finished the inspection. Now what?

Now that you have finished inspecting your house, you have a much better idea of the home’s condition than when you started, and you may have identified a few serious flaws that need to be remedied.

However, you haven’t yet performed an energy audit. While this article explains how you can look for holes in your thermal envelope, many such holes are hidden and hard to discover. To do a good job of reducing air leakage in an older home, you need to use a blower door. (For more information on blower-door-directed air sealing, see Blower Door Basics.)

If you can afford to hire an energy auditor, you won’t regret it. Not only will you then get a blower-door test and an infrared inspection — both of which are invaluable — you’ll get something even more important: an inspection by a trained expert who knows what to look for. And the energy auditor will help you answer the question, “What should I do next?”

Martin Holladay’s previous blog: “Passivhaus Buildings Don’t Heat Themselves.”

Click here to follow Martin Holladay on Twitter.


  1. Curt Kinder | | #1

    Great summary - two minor additions
    I would add an assessment of laundry - front load washers save lots of water, water heating energy (if warm or hot cycles are used) and drying energy via more effective final spin.

    Also consider a brief search for phantom loads - use an advanced tactile thermal response sensor (palm of hand) to find things that run warm while "off" Those items, typically older media gear and chargers, should be put on a power strip or on a curb on collection day.

  2. User avater GBA Editor
    Allison A. Bailes III, PhD | | #2

    What?! Nothing about air conditioners?
    I know you're in Vermont, Martin, but a lot of people in the US have air conditioners in addition to heating systems. Here are a few tips:

    Similarly to looking at heating equipment, checking the age of the AC system can give you an idea of how soon you might need a new one. Some units will give the date of manufacture on the condensing unit (the noisemaker outside). If it's more than 10 years old, it's time to start saving for a replacement. If it's 15 years old, you're about to need a new one. I replaced our 24 year old AC a few years ago, but it was long past due. Here are 5 questions to ask when replacing your air conditioner.
    Go outside and look at the condition of the condensing unit. If the fins are all bent up or filled with dirt, it needs to be cleaned. If it's got a lot of plants or other obstructions around it, clear some space for it. An AC condensing unit needs to breathe!
    Check the filter. Dirty filters are a common problem that makes your system waste energy and not cool as well.
    Get the AC serviced. If it's been more than a year, you need to get a pro to open up the system and do the regular maintenance, including checking the state of the evaporator coil and cleaning it if necessary. You don't want a sludge that kills, like this one had.
    Here are some tips for getting better performance from your air conditioner that I wrote last year during the heat wave, when we set a record for high temperature in Atlanta.

    In addition to the regular ductwork, don't forget to check the dryer vent. If it's clogged, it can burn your house down. Even if it doesn't do that, it can waste a lot of energy by making your dryer run longer to get the clothes dry. Here are some products that can help with dryer vents.

  3. User avater GBA Editor
    Martin Holladay | | #3

    Response to Curt Kinder and Allison Bailes
    Curt and Allison,
    Great tips from both of you. Thanks for the additions.

  4. David Beck | | #4

    Role of Fiberglass batts
    What is the mechanism of fiberglass batt insulation causing mold on rim joists?

  5. User avater GBA Editor
    Martin Holladay | | #5

    Response to David Beck
    Rim joists are cold during the winter, so you don't want to use an air-permeable insulation like fiberglass to insulate the interior of a rim joist. The insulation does nothing to stop the warm, humid interior air from contacting the cold rim joist.

    When the warm, moist interior air contacts the cold rim joist, the moisture can condense (in the form of frost) or the joist can absorb moisture. Once the joist is damp, it will grow mold or begin to rot.

    Acceptable insulation materials for insulating rim joists include rigid foam insulation and closed-cell spray polyurethane foam. If you use rectangles of rigid foam, remember to seal the perimeter of each piece of rigid foam with caulk or canned spray foam.

    For more information, see The Best Way to Insulate a Rim Joist and Basement Insulation.

  6. David Beck | | #6

    Rim joists
    Is spray painting the joists an effective method of reducing mold and rot?

  7. User avater GBA Editor
    Martin Holladay | | #7

    Response to David Beck
    David Beck,
    To avoid mold and rot, don't insulate with fiberglass. If you have fiberglass insulation on the interior side of your rim joists, paint won't prevent problems.

    Remove the fiberglass and leave the rim joists uninsulated. Don't insulate the rim joists until they are dry. If you don't have time to insulate the rim joists correctly, it's better to leave them uninsulated than to insulate them with fiberglass. Once the rim joists are dry, insulate with rigid foam or closed-cell spray foam.

  8. David Beck | | #8

    Rim joist and fiberglass batts
    To preserve the heat in the house can I leave the batts cutting away 4-6" at the exterior ends?

  9. User avater GBA Editor
    Martin Holladay | | #9

    Still another response to David Beck
    You are remarkably resistant to my advice. I've tried twice to point you in the right direction. At this point, all I can say is, "It's your house. You can do whatever you want."

  10. Woody McMahon | | #10

    3” termite inspection gap
    If you are using CC spray foam for crawlspace rim and band joists as well as crawlspace wall insulation, how/where do you create the 3" inspection gap?

  11. User avater GBA Editor
    Martin Holladay | | #11

    Response to Woody McMahon
    Regulations governing termite inspection gaps vary widely from one area to another, depending on local practices and the severity of the local termite problem. Your best source of information is your local building department.

    If local regulations require a 3-inch-wide inspection strip, the usual practice is to omit the insulation at the top of the wall, so that you can see the top 3 inches of the concrete wall -- just bare concrete. Of course, following this practice incurs an energy penalty; but if the alternative is an infestation of termites, then the penalty is worth it.

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