Improving energy efficiency of school buildings during winter season using passive design strategies

Abstract

Passive building design can improve energy efficiency of buildings, while providing comfortable indoor environment for occupants with minimum mechanical energy use. The foundation of passive design depends on natural sources of energy, which uses building architecture and surrounding environment to minimise heating and cooling loads of buildings with minimum operating and maintenance costs. The correlation of local climate with shape and thermal performance of buildings is one of the main considerations of passive design approach to reduce energy use and increase thermal comfort of occupants. This paper focuses on a series of field studies and building simulation analysis to improve thermal performance of female secondary school buildings in the city of Tehran in Iran during winter season using passive design strategies. The field studies included measuring indoor air temperature, as well as a questionnaire-based survey in a cold winter season in a typical female secondary school building. The on-site monitoring assessed indoor air temperature of classrooms while the occupants completed questionnaires covering their thermal sensations and thermal preferences. Moreover, building thermal simulation analysis were carried out using DesignBuilder tool to evaluate and improve thermal performance of classrooms based on students' thermal requirements and passive design strategies. The simulation analysis started from the basic school building model, investigating various passive design strategies to predict the optimum design strategies for the case study. The simulation results determined how to provide classrooms that are more comfortable for students with minimum energy use. The results of the field studies indicated that indoor thermal environment were usually comfortable for female students based on 7-point ASHRAE scale. However, most of the occupants preferred their indoor thermal environment to be improved. Moreover, simulation results showed that building fabrics and thermal properties, as well as glazing and orientation had significant impacts on indoor air temperature and thermal comfort and using appropriate passive design strategies could improve energy efficiency of the building considerably. Therefore, in order to enhance indoor thermal environment and to increase learning performance of students, it is necessary to use appropriate low energy methods, which can reduce the needs for mechanical energy systems and hence save energy.