Climate change shifts the trade-off between lower cooling and higher heating demand from daylight saving time in office buildings

The original intention of daylight saving time (DST) was to save energy required for artificial lighting. This one-hour shift in working hours, however, also impacts the current and future heating and cooling demand of buildings, which is yet to be thoroughly investigated. Here, daylight saving time-induced heating and cooling demand of archetype offices across the United States are simulated for 15 cities for different representative concentration pathway (RCP) climate trajectories. DST reduces cooling more than it increases heating. Maximum savings of up to 5.9% for cooling and 4.4% increase in heating were simulated under current climatic conditions, noting that cooling dominates the buildings' demand during the DST period. Climate change increases future cooling demand, but does not significantly affect the combined (heating and cooling) potential of reducing energy demand when DST is introduced. However, the relative reduction (i.e. decrease in the percentage of total cooling demand) is smaller when considering climate change. The impact of DST on cooling and heating energy demand depends on the geographical location, which determines the amount and temporal pattern of cooling and heating demand. For the considered case studies, introducing DST with climate change generally resulted in overall combined savings with a maximum saving of 3% for Port Angeles, assuming an RCP 4.5 scenario. Policies that shift working hours need to be evaluated considering their impact on building energy demand and it is necessary to establish whether saving cooling or saving heating energy demand can achieve higher CO₂ emission reductions.