Infrared heat guns: Cut your home energy costs with this handy tool
An infrared point-and-shoot thermometer can give you a thorough understanding of where your house is losing heat in winter, or gaining it in summer. The more you know about where heat is entering or leaving your home, the more effective you'll be at controlling energy waste.
With an infrared point-and-shoot thermometer, you just wander around the inside and outside of your home on a hot summer day or a cold winter evening, and take readings at windows, outside doors, walls, or wherever else heat may leak through. The device helps you get a complete picture of problems with insulation, sealing, or windows in need of replacement.
Professional home energy inspectors often use infrared imaging to show you where you're gaining or losing heat, but infrared cameras cost a lot and an audit can cost you more than $200. An infrared point-and-shoot thermometer doesn't provide the same pretty printout, but they only cost about $50, so they put this level of detail within reach of the average person.
Most infrared heat detectors come with a beam ratio of 1:12, which means that if you point the gun at a wall 12 feet away, then take a reading, you'll get a reading for a one square foot area of the wall. These guns also come with a laser beam to show exactly what spot the reading was done from.
I suggest beginning your thermal leak audit from outside. Standing 12 feet back, take a series of measurements with your infrared heat detector to figure out what the baseline temperature is. You are looking for the coldest reading in winter, or the hottest in hot weather when the air conditioner is running.
Don't take readings on a sunlit surface, because it can mess up your results. Rather, wait for overcast weather, or for the sun to move.
Write out each reading on a drawing of the wall or in note form. Pay particular attention to window readings, as these are big areas of thermal leakage both in hot and cold weather. You might benefit from an inside helper to close shades and curtains after your first measurement so you can then measure the impact of these window coverings on stopping thermal leaks.
Where readings are considerably worse than your reference (hotter in cold weather, cooler in hot weather), take more readings close by, to locate the extent of the thermal leak. You might have missing or settled insulation, cracks or even holes in the wall, or a gap in a window or door.
Next do an indoor heat audit of the exterior walls, floor, and ceiling of each room. Choose an interior wall as your reference temperature; exterior wall readings should be cooler than the reference in winter, or warmer in summer. Again, you are looking for thermal leaks on window glass, around windows and doors, through ceiling light fixtures, in cracks in drywall or plaster, or anywhere that is touching an exterior wall. Take close-up readings of any wall outlets or light switches that are close to the outside, even if they are on an interior wall.
Check the temperatures of top floor ceilings, as insulation, especially blown in insulation, can get disturbed or matted down in leaky attics. For summer readings, do your ceiling readings twice: once early in the morning before the sun has warmed the attic space, and once in the afternoon when the attic is hot, so you can determine how much of that heat leaks into your living areas.
You will probably find that windows without their window coverings will be your biggest heat leaks, as even the most energy efficient windows have a much lower thermal barrier capability than walls or ceilings. You can either upgrade old windows with more efficient ones, add thermal curtains or shades, or apply energy efficient window film to the window pane itself.
You will also probably find drafts in walls, particularly at light fixtures or where wires or pipes enter the home. You should seal these as much as possible, as drafts can be major contributors to home energy costs. Seal around the edges of window frames; use wall outlet foam pads to block air from flowing through the outlets. Your bricks may need tuck pointing, or you may have a more serious problem: settled cellulose insulation between wall studs, in which case the only solution is to take down the walls from within and put in new insulation and drywall. If you have no insulation whatsoever you at least have the option to inject foam insulation, which costs less than a complete gut and reno.
You should consider doing your own mini-audit with your infrared gun first, and call the contractors later. If you have identified your big thermal leaks, you'll be able to ask each contractor what approach they recommend to your problem. Calling a contractor over and just telling them the house is freezing in winter, or too hot in hot weather, means inviting major repairs that may not do any good.
You can use an infrared heat gun for countless other measurements around the house, such as checking hot water pipe temperature before and after adding pipe wrap; reading the temperature coming out of forced air registers and going into the air return register, if you have central air conditioning, to gauge air conditioner efficiency; measuring frying temperatures on your stove; or finding the best location in your basement for a wine cellar.
Whatever model infrared gun you choose, you are sure to get many hours of use out of it, finding the hotspots and cold spots in your walls, floors and ceilings, your garage, your fridge, freezer, your car engine - anywhere you want to know the surface temperature. You can even use it to measure the temperature of your compost heap - without getting your hands dirty!
