Determination of Optimal Air Change Rate for Cooling the Bedrooms of Residential Buildings in Guangzhou

Abstract

Ventilation is a traditional strategy for cooling and energy saving in buildings in hot and humid climate. This study aims to develop correlations for calculating the optimal air change rate (ACH) for cooling that can be generally applied to residential buildings in Guangzhou. A bedroom prototype was built based on the typical design features of bedrooms, which were gotten through the investigation of 350 Guangzhou residential quarters. The impacts of three factors and ACH on cooling load were analyzed by simulations. ACH is the most important factor, followed by area ratio of window to wall, area and orientation. An increase from 5 to 10 ACH for 10-21 m2 bedrooms could decrease annual cooling loads by an average of 17%, and prediction models of annual cooling loads were obtained for bedrooms by multiple regression, which were tested to be statistically valid. The predictive correlations of optimal ACH were finally achieved, which could be directly applied to the ventilation design of bedrooms in Guangzhou. The optimal ACH for prototype bedroom ranged from 21.99 to 22.85 h−1 as change rate of ventilation contribution on cooling was 5%, and from 11.99 to 12.85 h−1 as change rate of ventilation contribution on cooling was 10%.