Haikarainen J, Kohonen R
Bibliographic info:
11th AIVC Conference "Ventilation system performance" Belgirate, Italy, 18-21 September 1990

The controllability of room air temperature in different heating systems connected to demand controlled ventilation systems was studied. Studied ventilation systems were exhaust, supply and exhaust and a system with exhaust and an individual supply to each apartment. Studies were made using PIPNET-simulation program package. It is designed to allow detailed simulation of entire building systems: the building shell, heating and ventilating plant and the dynamic thermal interactions among the subsystems. First single zone calculations were performed. The control of the supply air temperature in warm air heating was studied in case where heating coil was designed for airflow of 1,0 m³/s. The airflows varied from 114 to 111. The supply air temperature was controlled using PI-controller. According to the calculations it is possible to control the room air temperature within +/- 1K even if the heating coil is overdimensioned. The dynamic behavior of a water radiator and a floor heating panel system was studied in an exhaust ventilation system. The control of the room air temperature was also studied with P-, PI- and P D -controllers. Simulations showed that a thermostatic valve is not fast enough if the airflows in the room change rapidly in the exhaust ventilation system, while the supply and extract ventilation system PI- and PID -controllers kept the room air temperature quite well in the set value. Secondly multizone calculations with an apartment of 89,5 m² were done. The heating system consisted of floor heating panels in 4 rooms and water radiators controlled by thermostatic valves in other rooms. The water rate in the floor heating panels was constant and the supply water temperature was compensated according to the outdoor temperature. The duration curves of room air temperature with different ventilation systems were calculated using daily heat load and ventilation profiles. Based on the calculations recommendations for the range of air flow rates to provide acceptable room air temperature will be given.