Thermal and ventilation modelling of large highly-glazed spaces

Highly-glazed spaces are attractive in many ways (solar heating, aesthetics, etc.), however, their thermal behaviour remains difficult to predict. In such spaces, the assumptions or methods generally used in building thermal simulation tools — e.g. homogeneous air temperature in the room, simplified calculations of radiative heat transfer between walls, absence of airflow modelling within the room — do not seem appropriate. We have developed a new model (AIRGLAZE) to improve the prediction of the thermal behaviour of large highly-glazed spaces. It consists of an envelope module to calculate conductive and radiative heat transfer in the building envelope. It is coupled with a zonal airflow model to predict air motion within the room. Particular attention is paid to sun patch modelling and the internal distribution of shortwave and longwave radiation within the building; direct retransmission, reflection to the outside, and transmission to other zones of the building are taken into account. The results of AIRGLAZE are compared with measurement data from two experimental test cells: the IEA Annex 26 experimental atrium, and a test cell at ENTPE. Compared to the one-air-node approach, the zonal method significantly reduces the mean discrepancy with measurement data during stratified conditions (from 3.9°C down to 0.4°C for the Annex 26 atrium). In general, experimental and numerical results tally well in both cases.