Implementation of night cooling in VHC building 5 : A study on the effects of night cooling on energy demand, power demand and indoor climate

The ongoing climate change is increasing the demand for more energy-efficient buildings with lower emissions. Currently, buildings are responsible for around 40 % of total energy use in Sweden, with a significant portion of that energy consumed by heating and cooling systems. Reducing the cooling demand during the summer is therefore an important step toward improving energy efficiency. One potential method for lowering cooling demand is night cooling. This technique uses the cooler outdoor air available at night by allowing the building's ventilation system to remain active overnight. In collaboration with Akademiska Hus, this study aims to simulate and evaluate the impact of night cooling on cooling demand, total energy consumption, and peak loads for Building 5 of the VHC complex. The thesis involves a literature review, data collection, site visits, and detailed simulations of the building. The initial simulations were conducted without night cooling. A second set of simulations was then performed after integrating a night cooling system into the model. By comparing the results from both scenarios, the study assessed the effect of night cooling on energy performance and system efficiency. The results showed that night cooling reduces the building's cooling demand by 17 %. However, energy use, fan power, and fan power demand in the building increased because of the fans being turned on during the night. The cooling power demand was reduced by 19 %, which could lead to lower costs by reducing the variable power charge. The implementation of night cooling also improved the indoor climate in the morning by lowering the average temperature. The conclusion is that night cooling has a positive impact on the building's cooling demand. However, it increases energy use, fan power, and fan power output. Despite this, night cooling can be recommended due to its positive effect on the indoor climate in the morning as well as the reduced cooling load.