Analysis of the Energy Flexibility of Residential Buildings in the Heating and Cooling Season

The present paper evaluates the potential of using the thermal inertia of building structures to shift their heat load pattern, i.e. to participate to Active Demand Response (ADR) programs. The methodology adopted relies on two energy flexibility indicators proposed by previous researchers: the available storage capacity for demand response (C-adr) and the efficiency of the ADR event (eta(adr)). The study analyses the effect of the building , envelope, the user behaviour and the installed capacity of the heating system on the flexibility indicators for three reference apartments -from the 70s, 90s and recently built- in both heating and cooling season. The results show that the available storage capacity increases with the design thermal load of the considered building, i.e. it increases from new to old buildings. However, part of the thermal energy shifted is lost through the envelope after the ADR events, resulting in lower efficiencies for old buildings. In general, upwards and downwards modulation events are preferable just before and just after the peak load periods, respectively. The paper shows that severe weather conditions and intermittent setpoint schedules lead to exceptions to this general rule. Moreover, the indicators were used to evaluate the energy flexibility of the considered buildings in the summer season. Here, the choice of the best ADR events is more difficult due to the high variability of diurnal heat gains, especially in buildings with low thermal insulation.