Design optimization of Dutch single-family houses taking into account energy flexibility

Abstract

This thesis aims at analyzing the energy flexibility (EF) potential of building structural thermal energy storage (STES) by the implementation of active demand response (ADR) and providing a representative recommendation for building renovation and operation. The objective building type is existing Dutch single-family houses built between 1965 and 1974 which need to be renovated in the (near) future.
Firstly, ADR-event is used to activate the energy flexibility of STES by increasing the setpoint temperature of heat emission system. In order to quantitatively evaluate the energy flexibility potential, three indicators are defined: available storage capacity, storage efficiency, and effective storage capacity, which are time-dependent and closely related to dynamic boundary condition including occupant behavior and weather condition. With the ADR-event of 4 hours and the temperature increase of 2℃, the maximum available storage capacity is around 25 kW which is equivalent to a storage tank with the volume of 1070L with the assumption that the temperature is increased by 20℃ in a hot water storage tank.
Secondly, in building renovation phase, after replacing boilers to heat pumps and implementing PV system to create the interaction between the heating system and the electricity system for ADR-event, the impacts of different building design parameters on energy flexibility are assessed and energy flexibility potential of 15 building renovation options are quantified. The results demonstrate that with the improvement of building renovation level, for example, increasing insulation level or airtightness, the available storage capacity decreases significantly while the storage efficiency shows a better performance in the mild renovation level. Additionally, building with external insulation presents a high available storage capacity while a low storage efficiency. Furthermore, the renovation option with usual renovated external insulation level and 0.4ACH infiltration rate can be recommended to the users or house agencies considering the exploitation of building structural energy flexibility, offering the highest typical effective storage capacity and acceptable robustness to dynamic boundary condition.
Finally, from the operation perspective, appropriate use of STES can increase the penetration of renewable and reduce CO2 emission and operation cost. ADR-event is not beneficial under low PV production condition while 2 pm is regarded as the most profitable and environmentally-friendly ADR-event starting time for all building renovation options with high PV production. As for the future-oriented operation scenario which is with real-time electricity price and without net metering, energy flexibility plays a more crucial role in saving operation cost. Therefore, when starting ADR-event at 2 pm in the building with usual renovated external insulation level and 0.4ACH infiltration rate, the average reduction of CO2 emission and operation cost can both reach 9%.