Assessing the effectiveness of several passive design strategies using the CIBSE overheating criteria: case study of an Earth Brick Shell House in Johannesburg, South Africa

Abstract

This study seeks to evaluate the efficacy of several passive design strategies to reduce the risk of overheating in a Compressed Stabilized Earth Brick (CSEB) house situated in Johannesburg. The roof features CSEB masonry vaults and the walls were built from dry-stack (mortarless) masonry. The vaults were initially coated with maroon paint, which resulted in uncomfortably high temperatures during summer months. Several passive design strategies were considered to improve the thermal performance, and the effectiveness of each were assessed against the CIBSE TM52: 2013 overheating criteria. Surface shading and painting external surfaces white were especially effective at reducing the potential of overheating in the first-floor vaults. Ventilating the space in the late afternoon and evening reduced the period during which indoor operative temperatures exceeded Tmax. An insulated ceiling proved effective at reducing the indoor temperature in early- and late-summer but had little impact on the severity of overheating during mid-summer.