Peak load reductions: Electric load shifting with mechanical pre-cooling of residential buildings with low thermal mass

Abstract

This study uses an advanced airflow, energy and humidity modelling tool to evaluate the potential for residential mechanical pre-cooling of building thermal mass to shift electricity loads away from the peak electricity demand period. The focus of this study is residential buildings with low thermal mass, such as timber-frame houses typical to the US. Simulations were performed for homes in 12 US DOE climate zones. The results show that the effectiveness of mechanical pre-cooling is highly dependent on climate zone and the selected pre-cooling strategy. The expected energy trade-off between cooling peak energy savings and increased off-peak energy use is also shown. The best pre-cooling results (more than 75% energy use shifted away from peak while minimising the total energy penalty) for most climates were obtained using a medium (5 h) pre-cooling time window with a shallow (23.3 °C) pre-cooling set point temperature. All of the pre-cooling strategies investigated caused the annual cooling energy demand of the simulated buildings to increase. Additionally, all of the pre-cooling strategies shifted at least 50% of the on-peak cooling loads away from a peak period window of 4pm–8pm in all climate zones.