Energy flexibility of a nearly zero-energy building with weather predictive control on a convective building energy system and evaluated with different metrics

The implementation of energy flexibility using thermal storage of building structure is one of the key solutions for buildings in contributing to a stable exploitation and distribution of renewable energy. The objective of this study is to investigate the performance of energy flexibility of a nearly zero-energy building with weather predictive control of a convective building energy system. Analysis and comparisons have been conducted on different control strategies to evaluate the influence of the strategies on the energy flexibility. The investigated control strategies of a heating and cooling system include: normal control (reference case), adjustment of set points for heating and cooling and adjustment of set-points together with a rule-based weather predictive control strategy. The performance of buildings on conducting energy flexibility can be assessed from different perspectives. Comparison of the performance and potential is conducted with different evaluation metrics that represent benefits of different parties (power grid, building owners or tenants, building users), including the ability of power shifting, the efficiency of energy shifting, economic benefits and comfort level. The study shows that, compared to the reference case, a maximum decrease of around 0.005 kW/m(2) in peak power during high-price periods can be achieved by changing the set-points of heating and cooling according to the energy price. Around 80% of the energy consumption during high-price periods can be removed by the control strategies. However, energy cost has increased from 0.499 EUR/m(2).peryear to 0.703 EUR/m(2).peryear by implementing a simple control strategy. By adding weather predictive control on the simple strategy, the energy cost is 26% lower than the simple control strategy but slightly higher than the case that is without flexibility control.