Application of IR camera and pyranometer for estimation of longwave and shortwave mean radiant temperatures at multiple locations

Abstract

The thermal environment experienced by human is significantly affected by the radiant heat. Information regarding the effect of radiant temperature on the occupants in a building is necessary for a comprehensive evaluation of indoor thermal comfort and for a corresponding control of the building's passive and active systems. This paper presents a real-time estimation method of MRT distributions in indoor spaces that does not require a direct installation of measurement devices at occupant locations. To consider the effect of longwave radiation, a pan-tilt IR camera was applied to remotely measure interior surface temperatures. For shortwave radiation, a single pyranometer installed outside was applied to estimate diffuse and direct irradiance at the occupant locations. The real-time MRT monitoring process and the Pan-tilt IR scanning system⁺ are derived. An experiment was performed to validate the applicability of the derived MRT monitoring process. The MRT at three target locations were measured by a globe thermometer and also estimated by the derived method. The measured and estimated MRT values were compared, and the results showed high goodness of fits as the R2 values were higher than 0.80 for all target locations. The monitoring results confirm that the MRT value can differ up to 15 °C according to occupant locations because of solar radiation. This paper discusses the applicability in various fields and possible future works of the proposed MRT estimation process.