Overheating risk assessment of different dwellings during the hottest season of a warm tropical climate

Abstract

Cities with hot tropical climate suffer generally from warm conditions during all year long, which could result on buildings ‘overheating’ or high energy consumption by cooling. This paper is the first of its kind in Central America, region that lacks studies regarding thermal performance of buildings. This study develops an overheating risk assessment to twelve dwellings of Tegucigalpa, Honduras, with a warm tropical climate, based on 41-day field study measurements of indoor air temperatures during its hottest season of the year. The aim of the study was to find if overheating risk differed depending on the building typology, single-family (SD) or apartment-type (AT), and based on the latter, to what extent roof exposure to solar gains and material properties, such as u-values and thermal mass, are parameters that influence the risk of overheating. The adopted methodology followed CIBSE TM52 Overheating Risk Methodology, and EN15251 and ASHRAE 55 adaptive thermal comfort approaches. Overheating risk was found to vary depending on the residential building typology. Dwellings with high roof exposure and high u-values in roof were found to be ‘overheating’ more. Following CIBSE TM52 methodology, some AT and SD dwellings experienced hours of exceedance above 3% of occupied hours, reaching up to 12.5% (61 h) and 20.3% (133 h) of occupied hours, respectively. Passive strategies such as improving roof properties (e.g. low u-values), shading and night ventilation may be necessary to reduce the risk of overheating in Tegucigalpa and similar tropical contexts where air conditioning is less affordable.