Megan wrote about a startup, Essess in Startup Takes Google Street View Approach to Home Energy Audits back in April. She described it:
It's basically a merging of two already successful ideas: Google Street View and online real estate libraries like Zillow or Trulia. The company plans to send cars to take thermal energy scans of every building in the country, find energy leaks and give the buildings each an energy score, and then build an online library of that information.
I had some questions about it at the time that I didn't raise, but now that the Company has come around again on Grist and Cleantechnica, I will raise them now, with some additional questions that arose out of comments to a Greentech post last March.
- The amount of heat that moves through a wall is dependent on the temperature difference between inside and out. How do you know the heat loss without knowing the temperature inside the house?
- In a drive-by, the camera is looking at the front of the house. How can you judge without knowing what is happening on the other five faces (three other sides, floor and roof)?
- What if people are having a party vs going to bed early? Conditions inside could be completely different.
- Of the three kinds of heat loss, conductive, convective and radiant, it's radiant that makes the pretty colored windows and walls (and is the most expensive to fix) , but it is convective, through air leaks, that causes the most heat loss. How do you measure leaky ducts vs leaky walls?
- Different materials look completely different on a thermographic image. A stucco on block house will look totally different than a stucco on styrofoam. How do you distinguish?
- How many days per year in most of the country do get enough of a temperature difference for the camera even to get a decent picture?
- People make choices, say those who live in old houses. What if they have a super-efficient heat pump or no air conditioning to compensate for the fact that they want to preserve what they have? How can you possibly figure out the cost of heating the house (as shown in the screenshot below) without knowing what kind of heating and cooling system is in the house?
Finally, is it legal? In Kyllo v. United States in 2001, the Supreme Court looked at a case where the Feds used thermal imaging cameras to confirm a grow-op that had high intensity heat generating lamps. Justice Scalia wrote the opinion:
We have said that the Fourth Amendment draws 'a firm line at the entrance to the house' … That line, we think, must be not only firm but also bright—which requires clear specification of those methods of surveillance that require a warrant. While it is certainly possible to conclude from the videotape of the thermal imaging that occurred in this case that no 'significant' compromise of the home-owner's privacy has occurred, we must take the long view, from the original meaning of the Fourth Amendment forward …Where, as here, the Government uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a 'search' and is presumptively unreasonable without a warrant.
If it is not the government trolling the website for grow-ops, it might be the replacement window vendors looking for suckers. I am an architect and know enough about heat loss to get into trouble, but would love to hear what others think; my immediate reaction is that a) the results would be almost useless and b) it is a serious invasion of privacy.