Improvement on Window Glassing for an Enhanced Indoor Thermal Environment of Tropical Office Buildings

Abstract

The intense solar radiation absorbed through the window glassing and transmitted into the indoor environment constitute thermal discomfort and increased cooling energy demand for buildings in the tropical climatic zone. This is because tropical climates are generally characterised by hot thermal distress almost all the year round. The need for improvement on window glassing of office buildings arise as a result of the global consensus on reducing energy demand of building sector. In office buildings, higher level of thermal and visual comfort is required for productive work performance within the indoor environment. This place office buildings in a position to enhance the realisation of a sustainable environment in the tropical climatic zone. This paper focus on effect of two types of window glassing on indoor air temperature and achieving improvement on single pane ordinary clear glassing window through the use of low-solar gain low-emissivity windows of two existing office buildings in the warm-humid zone of the tropical climate of Nigeria. An experimental investigation was scheduled during rainy and dry seasons of the year to collect outdoor and indoor microclimatic data of air temperatures in the west-facing natural ventilated office spaces within the existing office buildings through the use of Tiny Tag Ultra 2 Dual Channel Temperature/Relative Humidity (TGU-4500) Data loggers. Data collected were sorted and analysed through descriptive statistics. Improvement on single glassing window of existing office building was obtained through calculation of heat gain characteristics and comparison with that of low-solar gain low-emissivity glass window heat gain characteristics. Results showed that single pane ordinary clear glassing window exhibits higher indoor temperatures in the monitored office space. 89.54% improvement was recorded by using low-solar gain low-emissivity glass window over single pane clear glass window in the investigated office buildings. The study therefore recommends the use of low-solar gain glass low-emissivity window in office buildings within the warm-humid zone of tropical climate of Nigeria.