Two images of a 3-season room. Left image: This is a false-color infrared (IR) image. It shows the heat given off by the objects in the image.  The image was taken at night, and the scene was totally dark. In this picture (and the other IR images in this post), white is the warmest (that is, the area where the most heatis being lost), pink next, then yellow, green, and blue (the least heat leakage and energy loss). The scale at the bottom shows what temperatures the colors represent. The large number at the upper left in the image is the temperature at the center of the photo, where the target symbol is. In this case, you can see that the 3-season room was warmer than its surroundings, particularly near the ceiling. Right image: This is a normal, daytime image of the same scene.

As most of you know, I am keenly interested in Kendal’s use of energy. If we are to stop global warming, we have to stop putting carbon dioxide into the atmosphere. Everyone, everywhere, will have to help with that—and that includes us here at Kendal.

Last year, Larry Kirwin did a careful analysis of the Kendal-Crosslands carbon footprint (the amount of CO2 we generate) based on our use of electricity, natural gas, gasoline, diesel fuel, propane, and heating oil. He used data on Kendal-Crosslands fuel consumption provided by Seth Beaver. It showed that about 80% of our carbon footprint comes from our use of electricity.

And where does all that electricity go? The biggest use is heating and cooling—especially heating. Seth has provided hourly electrical data for every day of the year, and the highest recorded usage occurs during the morning on the coldest days of the year, when everyone is getting up and turning up the heat. We will not be able to put a serious dent in our carbon footprint until we can figure out how to heat our cottages (and our central buildings) better.

This post is the first of three that will address this topic. The first two will address heat leakage.  The third one will address a related issue of indoor comfort, temperature stratification.

Visualizing the heat losses. I am indebted to Charles Robertson, who lent me an infrared camera that provided the images for this article. This device is akin to the non-contact thermometers that we have become familiar with when checking into the Center during the pandemic. But instead of just taking a temperature measurement, the infrared camera takes a picture, with different temperatures represented by different colors.

I walked around Kendal on a cold evening, taking pictures to show where buildings were losing their heat. Using the camera, I could see that different cottages were losing heat in different ways, some obvious and some not. Some of the principal ones are described below.

Before I discuss what I learned, let me emphasize that these are a layperson’s observations. I have no background in construction, engineering, or architecture. Furthermore, the experts tell me that infrared temperature measurements can be off by a few degrees, since they depend (to some extent) on the smoothness and color of the surface being measured. So take the temperatures reported here with a grain of salt.

Finally, remember that infrared photos like these are useful as a clue pointing to a possible heat leak. They can also be helpful following repairs, to determine if a leak has been successfully fixed. But they are not diagnostic tools that can tell you what is wrong or how to fix it.

Consider yourself warned!

Windows and doors. It should come as no surprise that windows and doors (especially windows) were a major area for heat loss. Here’s a typical IR photo showing heat loss through windows.

3-season rooms. Even the best of our 3-season rooms leak heat. The cottage loses heat through the sliding glass doors between the living space and the 3-season room, and the 3-season room loses heat through its door, its windows, and its uninsulated roof. The photo at the beginning of this post shows a 3-season room giving off heat.

Chimneys. We expect chimneys to be warm when there’s a fire in the fireplace. But I noticed that many chimneys that apparently weren’t being used were warmer than their surroundings. (The ones that were being used were far warmer, of course.) Is a lot of heat just going up the chimney? I would estimate that something like 20% of our cottages have fireplaces with chimneys. Here’s an example.

Heat leaks at the sill. Here’s one I didn’t expect. Our cottages are built on concrete slabs. Many of our cottages leak heat where the exterior wall meets the slab—the area called the sill. Not only does heat leak there, in cases where the sidewalk is right next to the exterior wall (which is the case for about half of our cottages), heat seems to flow directly from the slab to the sidewalk. Here’s an example, where the sidewalk is 42 degrees, while the adjacent wall is 10 degrees colder. I observed this problem alongside many cottages (although the temperature difference was usually not quite so extreme).

I learned a lot just by borrowing Charles’ infrared camera and wandering around outside. The camera can teach you even more about your heat loss if you use it indoors. In my next blog post, I will describe some of the things we learned about our own cottage.