Experimental study of radiator, underfloor, ceiling and air heater systems heat emission performance in TUT nZEB test facility

This paper reports the results of different heat emitter system measurements, which were carried out at the nZEB test facility near Tallinn University of Technology in early 2018. Radiators, underfloor heating, air heaters and radiant ceiling panels are studied as coupled with different control schemes ranging from ON-OFF to PI-type control. The objective is to assess and quantify the control accuracy and thermal comfort parameters among different configurations.

Scheduled heating dummies are used to simulate internal heat gains within the otherwise unoccupied test rooms. Along with outdoor temperature variation, the heating demand is therefore constantly changing and the control systems are continuously adjusting the heat output to maintain the desired indoor air temperatures. Control accuracy is then determined from the temperature deviations against this set value. Air stratification within the room is assessed with vertical temperature gradient calculations from measured air temperatures at different heights. The operative temperature at the point of expected occupancy is calculated from surrounding air and enclosing surface temperatures.

The quantified results provide a comprehensive comparison between the different system configurations, enabling further energy simulations in related software packages since these parameters directly influence the energy usage within a system.