Building Envelope Thermal Mass and Its Effect on Spring and the Autumn Seasonal Transition Period

Abstract

Increases in fossil fuel usage and energy consumption have become important issues in most countries of the world. Recent statistics show that the building sector is the main contributor to the world total energy consumption, which makes it responsible for a significant amount of greenhouse gas emissions. Several studies have been carried out to design buildings focusing on reducing their energy consumption and improving occupants’ comfort. This study focused on the impact of parameters influencing the seasonal transition periods (STPs) and annual energy consumption through numerical simulations in residential buildings. For this purpose, the thermal performance of six different wall constructions with similar U values under different ventilation rates was investigated. In addition, the effect on building heating and cooling loads during spring and autumn STPs in buildings with diurnal occupation patterns in hot, arid climates was studied. A small building located in Tehran, Iran, was selected as a case study model and simulated as the reference building. The results showed that Wall 4 with an effective surface mass of 249 kg/m2 had the best performance in reducing energy consumption and had a significant effect on STPs. When Wall 2’s ventilation rate reached 10 ach (air changes per hour), its impact on STPs was significant within the 60 days of the autumn transition period. The effect of natural ventilation on STPs was minimal for Wall 4. It was also found that a 5 ach ventilation rate was the most appropriate for this period.