Identification of overheating in the top floors of energy-efficient multilevel dwellings

摘要

This study investigates summer indoor temperatures in energy-efficient multilevel houses built since 2010 in Adelaide to identify and define overheating during summer months. The method includes three steps: 1) calculating the number of days with top-floor maximum daily air temperature above 32 degrees C during four summers (December-February of 2011-2015); 2) calculating the frequency, integral and average of outdoor air temperature above 35 degrees C and the same parameters for top-floor temperature exceeded ground floor temperature for the naturally ventilated (NV) mode during eight summers (December-February of 2011-2018); and 3) correlation between ground floor temperature and outdoor sunshine hours as well as running mean outdoor temperature for NV mode during the same eight summers.Results showed the top-floor maximum daily air temperature was above 32 degrees C for 21% of the summer days for a mix of air-conditioned (AC) and NV modes. Overheating occurred in the top floors. Overheating occurs in low-performance energy-efficient houses about twice more often than high-performance energy-efficient houses. While the ground floors of high-performance houses matched the adaptive thermal comfort standard, the top floors exceeded the adaptive thermal comfort by overheating for 243 h, with 250 integral and intensity of 3.5 degrees C. Overheating in top floors lasts significantly longer than the outdoor high summer temperature. The paper also proposes novel parameters for evaluating the occurrence of overheating based on analysis of the data. Crown Copyright (C) 2019 Published by Elsevier B.V. All rights reserved.