Investigations of Different Control Strategies for Heat Pump Systems in a Residential nZEB in the Nordic Climate

Abstract

The paper investigates different control strategies for a ground source heat pump of a Norwegian residential zero emission building, with detailed dynamic simulations (here using IDA ICE). These rule-based controls aim at activating the energy flexibility of the building to improve grid interaction, lower energy costs, perform load shifting and reduce energy needs. Three load shifting controls load the building before pre-defined peak hours based on the electricity grid, whereas three other control strategies are based on hourly electricity spot prices. One additional control promotes the PV self-consumption in order to improve the grid interaction. Investigations showed that none of the proposed controls was able to maximize all objectives at the same time. The controls for peak load shifting were able to activate the water storage tank, but did not manage to activate the thermal mass of the building. Price-based heating control strategies for temperature set-points for space heating and domestic hot water heating led to an increased energy consumption of up to 25% as well as increased operational costs for the heat pump, but also decreased the total annual heat pump run time above 30% part load ratio by 13%. The controls were able to shift the electricity consumption to low-price hours, but failed to achieve savings for annual operational costs. A control for improving the PV self-consumption increased the building´s self-generation by 9% (up to 61%) and the building´s self-consumption by 5% (to up to 28%).