CONTROL OF THERMALLY ACTIVATED BUILDING SYSTEMS

A research project on the control and design of thermally activated building systems (TABS) has been started in May 2004. This paper presents one selected result after three years of work: A comprehensive TABS zone control strategy with a modular concept consisting of maximally four parts which allows creating four different control strategies. The (mandatory) first part of the comprehensive control strategy is an outside air temperature compensated supply water temperature control based on an unknown-but bounded approach to cope with uncertainties and variations in the heat gains during operation. The (optional) second part of the comprehensive control strategy is an algorithm for room temperature feedback control. With this part, room temperatures are controlled in an energyefficient way. The algorithm also corrects wrong parameter settings of the other control parts. The (optional) third part of the comprehensive control strategy is a pulse-width modulation (PWM) module for intermittent operation of the recirculation pump. The intermittent operation is used to save pump energy, but it is also applied to benefit from low-cost energy sources such as free-cooling during the night or electrical energy in low tariff phases. The (mandatory) fourth part of the comprehensive control strategy is a standard sequence controller to control the zone supply water temperature within the according setpoint range. In simulations, all four control strategies are applied to TABS and the simulation results are analyzed regarding comfort criteria and energy efficiency.