Cooling system energy flexibility of a nearly zero-energy office building using building thermal mass: Potential evaluation and parametric analysis

Abstract

Building energy flexibility has been considered as a key resource in achieving reliable energy systems. The nearly zero-energy buildings are low-energy and usually equipped with self-production energy systems, which are developing rapidly and play an important role in the energy network. This work aims to investigate the cooling system energy flexibility using building thermal mass in nearly zero-energy office buildings. A simulation-based methodology is proposed to obtain and evaluate the energy flexibility, including a rule-based control strategy and quantification method. The methodology is applied to assess the energy flexibility of a nearly zero-energy office building in Beijing. The influence of different structural parameters, internal heat gains, and cooling terminals on the cooling system energy flexibility performance is considered. Compared with the traditional night set-back control, the peak power and the peak energy can be curtailed by 55.6% and 54.0% in the investigated building under the rule-based control, respectively. The parametric analysis shows that the flexibility realized from thermal mass is highly dependent on the total structural thermal capacity, internal heat gains, and types of cooling terminals. However, the external wall insulation level is a non-significant parameter influencing the cooling system energy flexibility in nearly zero-energy office buildings.