Passive control strategies for cooling a non-residential nearly zero energy office: Simulated comfort resilience now and in the future

Abstract

The average global cooling demand in non-residential buildings is expected to increase by over 275% between now and 2050. Controlled passive cooling is fundamental to successful operational performance of buildings and in mitigating energy that would otherwise be consumed by mechanical systems. The aim of this study was to determine the resilience of different passive cooling control strategies in delivering optimal comfort and energy scenarios in both current and future extreme conditions, for low energy indoor office spaces. Simulations were conducted using a calibrated TRNSYS 17 model of a nearly zero energy building. The performance of ten passive cooling control strategies was simulated for climatic conditions in two representative cities, Dublin and Budapest. Each strategy used different combinations of passive cooling systems such as day-time ventilation, night-time ventilation and dynamic solar shading. The effect of static and adaptive indoor temperature set-points and a limit on external relative humidity was also investigated. The thermal comfort performance of each strategy was assessed by using standardised thermal comfort, overheating and overcooling metrics. Findings from the study show that passive control strategies maintained comfortable internal conditions between 57% and 95% of the occupied hours, without the need for mechanical cooling. The most resilient strategies were those that combined multiple measures. Passive control strategies were found to be resilient in the medium-term in Dublin, however, the same systems were not able to maintain comfortable conditions in Budapest in 2050. The use of an external relative humidity limit resulted in increases overheating incidences and failure of some overheating criteria. Based on the reductions in mechanical cooling requirements, it was concluded that there is regulatory need to consider the use passive control strategies in the design of buildings.