Book excerpt: Infrared thermography has been developed as a tool to measure the temperature of various types of surfaces. Notable applications include thermal detection of buildings to detect heat losses. It was the intent of the NBS IR program to build on these technologies to assist energy conservation engineers to assess heat losses in industrial plants. Our intent in this project was to survey furnaces and heating systems in addition to electrical and mechanical systems to find areas suggesting energy conserving actions. This survey method described in this paper was carried out in fifteen industrial plants to develop a methodology and examine the feasibility of the approach. In addition to the qualitative survey quantitative data was gathered by calibrating the temperature of the 11 hot spots uncovered in the survey. This information was very useful in developing priorities and estimating the magnitude of the heat loss due to a given defect.