Air conditioning is responsible for a considerable proportion of households’ electricity bills. During summer afternoons when households usually run their air conditioners, the retail time-of-use electricity tariffs are highest, and there is a peak demand in the electricity network. Pre-cooling is a method to shift air conditioning demand from peak hours to hours with lower demand and cheaper electricity tariffs. In this research, the pre-cooling potential of nine different types of residential housing in Sydney constructed with different star ratings and construction weights is evaluated. Star rating is the method to represent the annual heating and cooling requirements of buildings in Australia. Results highlight that pre-cooling produces cost saving for most of the days in 6-star and 8-star buildings. For 2-star buildings, pre-cooling sometimes leads to higher electricity costs. Moreover, pre-cooling improves thermal comfort, especially in 2-star light and medium weight buildings.
In conventional building integrated photovoltaic thermal (BIPV/T) systems, heat is only recovered during cold seasons. However, no recovery takes place in hot seasons. Therefore, this study comes up with an answer to the question “how much improvement in the amount of annual recovered heat (ANRH), average exergy efficiency (AAEE), and CO2 saving (ACDS), as well as payback period (PBP), is achieved when heat recovery is done in hot seasons?”. These are representatives of energy, exergy, environmental and economic (4E) aspects, respectively. The results show a 135.6%, 1.8% and 123.0% enhancement in the ANRH, AAEE and ACDS, respectively, while PBP decreases from 6.10 to 3.94 years.
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