Drive-By Thermal Imaging Delivers Home Efficiencies

Want to find out home much heat your house is leaking? The trucks from Sagewell might already know.

If you knew how much heat was exiting your house, and where it was emerging from, you might do something to plug the gaps. That’s the proposition of a startup that’s heat-mapping big swathes of U.S. cities and suburbia.

While we’re sleeping, Sagewell sends out a Ford Escape that roves streets, taking thermal pictures. To its equipment, your house looks like an fuzzy purple and yellow blob—the yellow bits showing where heat is escaping, and wasting your money.

At a rate of up to 20,000 homes a night, Sagewell already has about 500,000 homes, from 10 states, mapped so far. And the plan is to go much further. Chief operating officer Brad Harkavy says by the end of the winter, the S.U.V will have doubled its area-coverage.

Harkavy says the pictorial evidence helps convince people that insulation is worth it. Finding out that many states have generous subsidies for efficiency improvements also helps. In Massachusetts, for example, utilities pay 75% of the cost. He recently insulated his three-story home in Cambridge (built in 1895) for a personal cost of $700; his energy supplier chipped in with another $4,000, or so. It will take him three years to pay back the $700, he says; the whole amount might have taken 10.

State law forces utilities to set aside efficiency funds, but the money comes from customer’s bills, Harkavy says. "Every householder pays into this fund. So, if you are not capitalizing on that, you’re stupid."

Householders go to Sagewell’s site, type in their address, and bring up their images. The company makes money by referring insulators or window suppliers, or by going through local community organizations. The most common work is to blow cellulose into gaps on the front of the house (Harkavy recommends doing it before painting).

Some people have been "weirded-out" by the surreptitious filming, Harkavy admits. But he says the equipment looks only at the outside—"it doesn’t go through the walls." Also, the images are available only to owners, and not the general public.

So far, Sagewell has concentrated on colder states (e.g., in the Midwest), or the coastal states, where environmental policies, and incentives are stronger. Homes in the South tend to be younger, and better insulated, Harkavy says. Eventually, you could imagine much of America heat-mapped—much like it’s been Google Street View-ed. If so, the maps could provide a strong catalyst for energy efficiency, with benefits to many.

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  • Thermoscan Thermal Imaging

    Interesting post. This article shows you can get creative with applications for thermal technology. We use thermal imaging on the inside for electrical equipment condition monitoring and to detect possible equipment failures before they happen. Looking forward to hearing what other creative uses are out there?

  • guest commenter

    Interesting and cool idea. Even more interesting because courts have noted that if the *police* use this type of equipment, they walk a very fine line between "plain view" and an illegal search since this type of IR equipment can be indicative of what is happening inside of a home (see Kyllo v. United States).

  • Langdon

    Have you ever looked through glass with an IR thermal imaging system?  I have.  Looking out through a vehicles glass or through building glass provides nothing.  IR light waves are such low energy that they are dispersed when contacting glass.   IR / Thermal images are from the internal heat of an object.  Glass absorbs IR light and will only show up as the temperature the glass is.  Night Vision equipment multiplies existing light and it is capable of limited through glass detection. Night vision and thermal are very different.  Night vision amplifies the existing reflected light.

    I have to find time to read the Kyllo V United States, but I am surprised that no one has commented on how impossible Thermal equipment is through glass. 

    On vehicles and buildings, the IR technology must be mounted externally. And if thermal were to see inside a house it would have to be on the inside of the glass.   Thermal is very different than reflected light, what we are used to seeing 99% of the time.  Thermal is the low energy light that is basically being emitted from the heat of an object.  A face looks so different in thermal that face recognition software is not functional at this time. Thermal is very useful. I can detect a person at 3500 feet away.  I can see them, but to recognize who they are is very difficult, as the image created is the hot parts of their face and body.