Modification of thermal pressure ventilation model and its predicting on cooling potential of natural ventilation (NVCP) for large space buildings

Abstract

More and more large space buildings have occurred in China due to its multiple functional zones and architectural aesthetics, but heavy HVAC energy consumptions have been often accompanied. Effective use of natural ventilation may largely reduce the use of chillers during cooling periods. Field measurements were carried out on the large space in Nanjing, a city of south China. It was found out that linear thermal stratifications were evident with the gradients α being in range of 0.1~0.4 °C/m, Traditional thermal pressure ventilation model is modified by introducing solar radiation and vertical temperature gradient. The dimensional neutral plane height Hn/H and the mass flow rates per unit opening area G are calculated out under circumstance of Matlab. Its accuracy is verified by that from energy model software EnergyPlus. Results show that the outdoor temperature has much influence on the α; the dimensionless neutral plane height Hn/H increases with the increasing of α; The change of flow rate is not obvious for the different regions; This study provides theory basis for optimizing design of upper opening for maximum use of natural ventilation in large space buildings.