What does Infrared actually tell you about your home?

Infrared Imaging, commonly referred to as IR, is a very useful tool for anyone practicing building science. It provides visual images that offer clues to what is happening, temperature wise, in the wall (or floor, ceiling, roof...).

Wait, that last sentence is rather, well, limiting. Doesn't IR see through walls?

No, IR isn't magic. It's simply making a best guess about the temperatures on the surface of the walls based on a lot of assumptions. The operator of the equipment has supplied some of those assumptions as has the manufacturer of the imager. The manufacturer made his assumptions based on solid physics and years of testing. The operator is making his assumptions based on what he remembers from his training and how he is interpreting the conditions of the objects he's imaging. This can be a weak link, and it's where most bad IR interpretation starts to go wrong.

That's the other thing. IR doesn't tell you anything, it gives you information that you need to interpret. The operator needs to understand the workings of the system that's being imaged or the images make no sense. I work with buildings and I'm comfortable interpreting IR images of buildings. Ask me to evaluate an image of a horse and you might as well flip a coin, I'd be way in over my head on that.

Still, IR is a powerful tool to have. Because of the relative speed of acquiring information and because it can present that information graphically it makes diagnosing problems quicker and better. Homeowners get a better understanding as well. Seeing the effect of missing insulation really brings the point home quicker than the proverbial thousand words of explanation.

Let's take a look at a few images. The first one is simple. We're looking at a ceiling on the top floor of a building. The attic above is cooler than the room and the sun hasn't warmed it up yet. This attic had no access so I had to base my interpretation solely on this image. Fortunately when the contractor made an access to insulate the area properly I was proven correct.

The fiberglass insulation is in batt form. One end of a batt is being held up by the can light in the picture and the cold air in the attic is getting under it to the drywall ceiling. This is a classic situation and all too common. But this had been in place for 12 years and until I came in with a thermal imager no one knew about it. If you read my post on gaps in insulation you know how bad this can be.

One of the most useful things you can do with IR is find air leaks. With a reasonable temperature difference between inside and out I can use the blower door to create airflow. Once the door has run a few minutes you can get images like the one below. The cold air flowing from the attic creates the cold (blue) streaks on the warmer surfaces. Not only are these powerful for illustrating the effect, an air sealing contractor can use this as a guide to what needs to be done.

Important note: Ask anyone offering air sealing if they use a blower door and IR to find leaks and confirm results. Working without these tools is like tying your hands behind your back.

Once in a while you run into airflow strong enough that you can see it without a blower door. Every building science professional I have shown this image to assumes I had the blower door running on a cold day. The temperature difference was 20 - 25 degrees between in and out. My blower door was still in the van, so what happened?

I was in the lowest level of a former barn converted to child care. The building was a tall 4 stories and a really good example of the stack effect in a building that is leaky at both the top and the bottom. Think what the airflow would be like on a really cold day!

Sometimes unexpected patterns show up. Below is a small section of wall in a half basement. At the very top right is the edge of the board that caps the wall that is against the concrete wall. (BTW, this should not be done the way it was, that deserves a separate post.) The lower left is just a chair that intruded into the image. The orange-ish section on the right is mostly undisturbed fiberglass insulation under drywall. The center area, with those dark splotches are tunnels and nesting cavities created by mice. We confirmed this by removing the drywall (wearing protective masks and clothing) and cleaning out the mess and damaged insulation. Excluding vermin is really important in buildings both for health reasons and because they can cause damage to insulation and structure.

All of the above information was inferred from the temperature of the surfaces I looked at. With the IR and knowledge and experience with buildings I got the right answers. Ask your prospective energy auditor how much experience they have with buildings. If they were selling cars last month will they be able to adequately interpret the information they gather? Having the tools doesn't give you the skills and knowledge to use them.

Sometimes you can have a little fun with IR. I worked on several child care centers over the past few years. It was the most fun I've had on any project I've done. IR is not ideal for portraits but I got a lot of requests from the kids (Take my picture! Me too! You took her picture. Take mine). This little girl had just been playing outside and she was warming her cold hands on her forehead.

I'm told that IR is commonly being used in some countries as a medical diagnostic tool. The only interpretation I was able to make was that she had been having fun.

When you get an energy audit don't forget to have your picture taken as part of the process!

Paying for advise can be cheaper than paying for the wrong product or service.

I cringe every time I hear it. "We replaced our (boiler/windows/insulation) and the house is still uncomfortable and the heating still costs too much."

Usually I'm on the phone. Someone has called, they've already spent a lot of money, have very little satisfaction and now find themselves calling someone who is probably going to charge them money to tell them they made a mistake. To be honest I probably feel just as bad as they do. I'm going to charge them money, tell them they need to spend money on something else to save energy and feel more comfortable and I have to do it without saying that they made a mistake. My job isn't to rub it in.

So make us both feel better, pay me first. Really.

Why call me (or perhaps some other building consultant) instead of just calling a contractor? So that when you spend money on your home you'll be comfortable that it was well spent, because you had a plan. I don't sell anything, I only work for you. My job is to make the process easier for you. I help you make the plan.

How do we start? Usually with an energy audit. The process gets me to see the important parts of the building. Plumbing, heating, electrical and structure in addition to the insulation, ventilation and windows. We might be done at this point. Depending on your goals you might feel that you have enough information to proceed on your own. A lot of people do and that's fine. Please drop me a note after you're done to tell me what you've accomplished. Send some pictures too.

Suppose you've got big plans for your house. An addition or major rehab, residing, new electrical work or maybe finishing the basement for that man cave. Do you want to use this as an opportunity to add insulation? Does the basement have water problems? Is there some mustiness in the laundry room that you'd like to get rid of too? How do you know where to start?

We can make a plan. Once the energy audit is complete we can talk about how you can integrate the information from that with your overall goals. If you need further guidance I can write specs for each step of the process. I can suggest the best order to do things so that work doesn't have to be undone and redone. That can get expensive. Do you need help evaluating bids from contractors? Perhaps you need someone to inspect the work as it progresses to see to it that your work is done according to the specs we laid out earlier.

The important thing is that each plan is designed for you. The combination of services will be what you need, no more or less. I like to think of myself as a mapmaker for my customers. I want to get you safely, efficiently and cheerfully through your projects.

It all starts with a call. If you call me first you can call the rest of the contracting team with more confidence. You'll have a plan.

Dot Edie Ewe

I harp on this subject constantly so I thought it rated a blog post. The most important thing we deliver to our customers and clients is education.
We should be delivering the specific tasks we are asked for, whether analysis of building flaws, recommendations for new equipment or building shell improvements. That is what we were hired to do. But unless we leave them with a broader understanding of the hows and whys have we accomplished anything?
There are and always will be clients who want only specific answers to specific questions. I guess they are good for business because they will pay you over and over to answer the same questions on different projects. I have a hard time enjoying that kind of work, there is very little challenge.
Answering the same question for different clients can be interesting because it is an opportunity to teach the answer, not just supply it. The client may not need you to answer that same question anymore but when other questions need answering your name should come up.
That is an opportunity for you to learn something else to educate on. And to then create a more interesting client who will ask more interesting questions which will require you to learn something... It's almost like perpetual motion. Hmm, I wonder if I can attach a drive shaft to that.
Ultimately a client who you have educated is a client who will respect you. It is also a client who will advertise for you, which is not a bad thing either.

More on Infrared

In my latest newsletter (check my website for newsletter archives) I talked a bit about interpreting infrared images. It got me thinking about the state of the technology and where it fits into building science.
When I took my course for my level 1 thermographer certification  I was impressed by the technical knowledge and skill of the instructors on all things IR. But in the section where they talked about building investigations there were a few things they said that made me realize that they were a bit weak in some building science details.
The current state of IR usage in buildings is still on the cusp as to who is using it. For years it was like the early days of computers. The tasks were performed by computer people, not people who were the experts in the task. As desk top computers proliferated and became increasingly easy to use the focus shifted back to having task experts use computers to do the job. It became easier to teach the use of the computer than to teach the task to a computer expert.
My only concern is that there are people who are learning building science only through use of infrared technology. I hope that they will come to understand that all they are seeing with the IR are clues, not facts. They still need to have a good solid understanding of what can be happening to figure out what is happening.
As always, other voices are welcome.