Fallacy of Summer Overheating in the Hot-Dry Climate: A Case Study of Learning Environments in Kano, Nigeria

Abstract

Enhanced thermal environment is known to improve occupants’ health, well-being and comfort and has the potential of saving energy especially when achieved through passive design solutions. As the provisions of international comfort standards may not be appropriate for all climates, it is imperative to confirm the comfort requirements of indoor occupants particularly in the tropical regions where comprehensive standards are lacking and where overheating majorly occurs. Three approaches were used to ascertain whether overheating as stated by these standards exist in Kano: measurements of predicted mean vote (PMV) and predicted percentage dissatisfied (PPD), the adaptive thermal comfort model as well as using overheating analysis as described by TM52. The research was conducted through both instrumental measurements and surveys undertaken in March/April of 2016. Instrumented measurement was conducted to obtain spot and logged values of thermal comfort variables, including: air and radiant temperatures, relative humidity and air velocity, while the survey was conducted through paper-based questionnaires. The PMV/PPD results showed that all the four spaces were overheated, while the adaptive thermal comfort under EN 15251 results revealed that three of the four spaces were overheated. Similarly, all the learning environments failed the three TM52 overheating criteria. On the other hand, the survey results showed that only one space was perceived to be comfortable and the other three were overheated. The results, therefore, negate the fallacy and uphold the standards’ predictions up to 80%.