This paper investigates the thermal performance of radiant and convective heating systems in a house and proposes a simplified method for evaluating the efficiency of these systems. The characteristics of the systems

·heat transfer on enclosed surfaces, temperature and velocity distribution
·were examined both by experiment in a full-scale experimental room and by numerical analysis. Convective heat transfer was calculated using a two-equation turbulent model along with radiant analysis. The following conclusions were obtained.
·With the convective heating system, convective heat transfer amounts to more than 70% of the total heat exchange. With radiant heating, the convective heat exchange is approximately half of the total heat exchange.
·When convective heat exchange is dominant, the heat loss through poorly insulated windows is larger than when radiant heat exchange is dominant.
· A simplified method to estimate the efficiency of radiant and convective heating systems is proposed. The simplified formula, which uses operative temperature as a criterion for thermal comfort, can give the ratio of heat load between convective and radiant systems that attains the same operative temperature.

Units: Dual