Trends of building envelope design and materials selection: Electricity utilisation implications in Ghana’s building sector

The work presented here investigated the trend of a typical standard office building envelope design and materials selection implication on minimising solar radiation and moisture control in order to improve building energy performance. It is a known fact that building performance is hugely influenced by architectural design, weather and climate, occupant’s behaviour, building service equipment, technology and regulation/code used. From a survey questionnaire administered, an average of 18% of building professionals assess building performance in Ghana. In light of this, building envelope design and material selection are not sufficiently informed on their suitability to control the transfer of moisture and heat from the building external envelope leading to unacceptable building performance. This research was aimed at redesigning the building envelope and new material selection in order to enhance energy utilisation in an air-conditioned office building in Ghana. Mixed research methods were used in the data acquisition due to insufficient simulation data on typical building designs and material selection. EDSL Tas building modelling and simulation tool were used to model and simulate the impact of building design trends as well as material selection on the electricity utilisation. Significant findings were: (1) a single wall layer with plastered mortar for both internal and external wall have remained unchanged; (2) use of low thermal conductivity fabric was insignificant in building designs in Ghana; (3) the cooling load of a standard office building is about nine times that of the standard cooling load of “good practice” air conditioned buildings per meter square of the floor area; (4) proposed wall system designs considered: Low Transmittance Single Wall System (current block thickness), Low Transmittance Single Wall System (proposed block thickness) and Redesign Double Wall System, minimised the base case cooling load meaningfully, contrary at an increasing additional cost respectively; (5) the use of proposed redesigned low thermal conductivity fabric for window pane, wall and roof resulted in 28% reduction of cooling load and subsequent electricity utilisation. In conclusion, building envelope design and material selection have considerable impact on electricity utilisation. Hence the rising electricity utilisation in commercial building sector can be minimised through proposed redesigned low thermal conductivity fabric. As a recommendation, building performance assessments should be encouraged in Ghana.