Influence of time constants on low energy buildings' heating control

This paper estimates the range of time constant values for buildings with different insulation, thermal mass, and heat emitters for efficient temperature control by PI controllers, and comparing heat emission efficiency of the systems. Detailed models of the room, the heat emitter and the control system were used for dynamic simulations. For one case, the results were compared with measurements in a test building. Large variance in time constant values was found depending on the heat emitter, building parameters and the method used for the calculation. Time constant values were in the range of 1.9 to 94 hours. PI control with calculated parameters resulted in up to 8% heating energy difference between the low temperature water radiator and underfloor heating. The measurements showed lower time constant values than the simulations.