Performance assessment of ventilative and radiant cooling systems in office buildings during extreme weather conditions under a changing climate

The buildings' HVAC system design and indoor conditions are affected by climate change. This study aimed to investigate the effects of climate change on office buildings' cooling system design and indoor temperature conditions in the Nordic cold climate. Thus, two types of mechanical cooling systems, the all-air (ventilative) and the air-water (radiant), are designed in a new office building by using new cooling design days (1% risk) of the current and future climate of southern Finland. Moreover, dynamic simulations of energy and indoor conditions are performed using different average and extreme climate scenarios. The results showed that the dimensioning cooling power demand with the current climate design day (1% risk level) in the all-air system is higher than in the air-water system by about 18% and it increases significantly when using future climate design days depending on the climate scenarios. The annual maximum cooling power demand in the current and future average climate is below the current climate dimensioning power for both systems. While during extreme weather conditions of the current and future climate, it is higher than the current climate dimensioning power for both systems. Despite the increase in cooling power demands, the dimensioned cooling system using the current climate design day can provide a thermal comfort level of category I of EN16798-1 in all the spaces during the current and future average climate, and category pi during the current and future extreme weather conditions. Thus, ventilative and radiant cooling systems equally perform under a changing climate.