Energetic, cost, and comfort performance of a nearly-zero energy building including rule-based control of four sources of energy flexibility

A focal point of ongoing research is matching the energy demand in the built environment to the energy supply from onsite generation, to maximize the self-consumption, and from the energy grids, to lower energy costs and reduce peak loads on the system. Energy flexibility addresses this task by modulating the energy demand in a building according to dynamic criteria such as electricity prices or onsite generation. This study addresses the potential of building performance simulation with real time rule-based control that provides energy flexibility based on onsite generation and hourly electricity prices, prioritizing energy matching, and reducing costs. The novelty relies on investigating four sources of energy flexibility simultaneously: shiftable machine loads, charging/discharging of batteries, hot-water storage tanks, and the building's mass. The energy matching and flexibility actions provided a decrease of up to 4% in annual energy costs, yet risk increasing the cost by 9% when the savings are offset by the increase in the energy demand. As well, the method for price categorization strongly influences the cost performance of the flexibility actions. The outcomes of this study provide insight to energy flexibility sources in nearly-zero energy buildings and how their outcomes are affected by price thresholds.