Simulation-based Assessment of the Thermal Performance of High-rise Office Buildings in Ghana

The lack of empirical data and practical advice on thermal performance and efficient use of energy in our buildings are gradually becoming a burden to the country. Amidst the recent development in the usage of curtain walls for office buildings, high utilization of energy and poor thermal comfort issues have become paramount. Given the warm-humid climatic characteristics of Ghana, energy requirements for cooling of office buildings represent a growing burden for the environment and the economy. The current paper explores the implications of alternative design options for the thermal performance of four high-rise office buildings in Accra, Ghana. Multiple design alternatives were considered involving various glazing types, shading and shading schedules, thermal insulation options, lighting, various ventilation options and thermal mass. A numeric thermal simulation application was used to model the performance of these alternatives parametrically. Simulation results were expressed in terms of annual cooling loads (active building operation scenario) and mean overheating (passive building operation scenario). Careful combination of improvement measures (such as efficient glazing, thermal mass, façade insulation, night ventilation, efficient electrical lighting, form and orientation) has a significant potential to reduce buildings' cooling loads (31% – 49%) in the climatic context of Accra. Over-heating tendencies were also reduced from 8.6K to 3.9K depending on the air-change-rate per hour (ACH).