Field measurements on thermal stratification and cooling potential of natural ventilation for large space buildings

Abstract

Large space buildings often have high HVAC energy consumption, and the thermal pressure ventilation can be utilized to reduce the using of chiller. Temperatures were tested on two naturally ventilated large spaces, and it increased linearly towards the ceiling with its gradients α being in range of 0.1–0.4 °C/m. The traditional stack effect model is modified by introducing thermal stratification. For three hot and humid cities in China, the acceptable indoor air temperatures are discussed and determined based on its monthly outdoor air temperatures. Investigations are done to find out parameters’ influences on the indoor thermal environment. It is known that both the dimensionless neutral plane height Hn/H and the volumetric flow rate per unit floor area l are not sensitive to outdoor climate, but decrease with increasing of the lower-upper opening area ratio Rab; the occupied air temperature tn increases with the increase of Rab or q but with the decrease of α or H; under case of 0.2 °C/m and 150 W/m2, Nanjing has the maximum scopes of available upper opening areas in transition season to achieve natural ventilation cooling potential. Such results would be useful in design and management of upper openings for large spaces.