Occupancy-equivalent, operative temperature control for an energy-saving operation of direct electric, low-capacity heating systems. (December 2022)

• Record Type: Journal Article
• Authors: Schmitt, Lukas; Schaub, Michael; Brandt, Stefan; Kriegel, Martin
• Is Part Of: Building and environment. Volume 226(2022)
• Publication Date: 2022-12
• Subjects: Operative temperature control -- Occupancy-equivalent heating -- Direct electric heating -- Radiative heating -- Heat transfer; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2022.109638
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: 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. Highlights: Infrared sensor is suitable for control of low-capacity, radiative heating systems. Low-capacity heating systems allow energy-efficient, intermittent heating. Thermal comfort is utility-equivalent to a non-setback operation. Higher reheating factor enlarges energy savings.