The adaptability of night cooling technology under different climates

The demanding for cooling in buildings significantly increases worldwide with living standard. In the last few decades, the energy consumption for cooling shared a large part of the total energy consumption in buildings and the trend is still on the rise. The night-time ventilation as a passive cooling method has a potential to reduce the energy consumption for buildings cooling. Employing night cooling ventilation technology can not only save energy, but also improve indoor air quality. However, the effectiveness of the night cooling ventilation is climate dependent. Location has a significant influence on the efficiency of this method. In this study, the adaptability of night ventilation cooling technology under different climate conditions was analysed from a macroscopic view. The analysis was based on the theory of “climate cooling potential” and “climate cooling demand” which is calculated from degree-hours of the difference between the ambient air and inside building temperatures without specifying building parameters. This study examined the values of the climate cooling potential and the climate cooling demand in 34 cities located in different climate zones. It was found that the potential of night cooling ventilation in the east coast cities of the Pacific and the Atlantic Ocean were always higher than the same latitude cities in west coast. The study also quantified the effectiveness of night ventilation cooling by simulating a nominal building in different cities with the energy consumption analysis software “design builder”. The results showed that among different places, for every 10kh increase of the climate cooling potential, the corresponding indoor temperature could be reduced by approximate 0.12ºC. In the application of the night cooling ventilation combining with air-conditioning system in commercial buildings, the night cooling ventilation showed positive effect when the ratio of local climate cooling potential and demand is larger than 1, i.e., the reduction on HVAC energy consumption for cooling excesses the additional fan power consumed on night cooling.