Occupancy-equivalent, operative temperature control for an energy-saving operation of direct electric, low-capacity heating systems

Conventional heat supply systems for indoor environments merely show annual efficiencies of net energy usage for room heating of 70% to 80% due to an inertia-related oversupply in unoccupied periods. In this study, a new method for increasing this efficiency is introduced. Low-capacity, direct electric heating systems are used to realize an occupancy-equivalent heating concept which only heats the room during occupancy. Using a fast-responding infrared sensor, these heating systems can be controlled by operative temperature, preventing significant oversupplies whilst rapidly heating up a space. A model-based algorithm enables a setback of the room temperature in unoccupied periods while guaranteeing a predefined temperature in the beginning of occupied periods. Thus, the control algorithm enables a utility-equivalent heating operation compared to a non-setback operation. During a first parameter study, net energy savings of up to 21 % could be realized due to the new control method compared to a conventional schedule-based operation. The reheating factor of the heat supply system is identified as the main indicator affecting the energy saving potential in occasionally occupied rooms.

Automated summary

Conventional heat supply systems for indoor environments have a low annual efficiency due to an oversupply in unoccupied periods. This study introduces a new method using low-capacity electric heating systems to achieve an occupancy-equivalent heating concept. The use of fast-responding infrared sensors allows for efficient control of these heating systems, preventing oversupplies and enabling rapid heating.