It never ceases to amaze me how many Chartered Surveyors and self styled Listed Building Surveyors start using buzz words like thermal imaging, and buying a shiny new imaging camera to make pretty pictures of buildings. It is just not that easy. One chap I know publishes pretty pictures of heat loss in windows, and keeps copying our technical information - talking about finding things with his camera. At one level, imaging can indeed find hot water pipes - and yes, it can show you, on a cold day, that your windows are cold. You don't need to be a rocket scientist to know that..
We use imaging to look at much more subtle variances in heat patterns within buildings. The most important use of these things is to pinpoint areas that are likely to be susceptible to interstitial condensation. You don't need a very big difference in the temperatures of a wall for this to happen - a drop of half a degree is enough for condensation to start forming, and for moisture to be trapped into a wall. Our cameras are usually connected to the thermo hygrometers, so we can analyse the atmospheric conditions, and use these to predict where moisture may form - to plan and map condensation weak points, and predict damage before it happens. By mapping buildings in this way, we can assess overall heat loss characteristics, relate them to moisture levels and atmospheric conditions, and help owners to better insulate, heat and manage their home. Many of the scientific details used in this work are derived from our own extensive scientific research, coupled to the BRE work mentioned elsewhere in this site. I use thermal imaging a lot with timber framing to map weak points in the frame and assess where we need to prevent water ingress and seal the joints.