Heat Flux Transducers Measure in-situ Building Thermal Performance

Abstract

This paper presents an overview of heat flux transducers (HFTs) used for in-situ measurements of building performance. HFTs that are mounted in labora tory testing apparatuses are beyond the scope of the paper. The overview is based on HFT literature from the past five years. The overview covers how HFTs are constructed to measure heat flow and touches on the near relatives of HFTs, portable calorimeters and thermal probes. The question of calibration is key to the appropriate use of HFTs. The paper discusses the range of building thermal performance applications for HFTs from roofs to foundations to mechanical systems. A variety of ASTM (American Society for Testing and Materials) standards exist that relate to characterizing the building thermal context the HFT is used in. They pertain to: • Using thermography • HFT measurements • Calculatmg thermal resistance from in-situ data • Calibrating the HFT The paper discusses key elements to consider in the use of HFTs for in-situ measure ments and addresses current developments in the construction and use of HFTs.