Measurement errors with surface-mounted heat flux sensors

Abstract Surface-mounted heat flux sensors (HFSs) have been increasingly used for measuring thermal performance in buildings. These measurements are inherently subject to some error, but the size and sources of these errors has been uncertain. This paper offers comprehensive, quantitative predictions of the magnitudes of the errors and of their relative influences. It concludes that there are three (predictable) regimes in which such HFSs may operate, each having very different sensitivities to particular physical environmental factors. There are some unexpected consequences in how these devices should be selected and used, particularly that large sensors have both accuracy and stability advantages, and that sensitivity to surface heat transfer coefficient depends on the operating regime, being most acute with small, low-resistance sensors.