Should future HVAC systems be demand controlled?

Demand controlled HVAC-systems have many advantages. The principle is to optimize comfort and to minimize energy consumption simultaneously. In modern office buildings, indoor temperature is very often a useful control parameter. Thequestion is, whether it should govern the system for each room individually or for a zone. In the latter case: how shall the zones be defined? Above all, performance criteria have to be weighed against the investment cost. This paper discusses different strategies, which have been or are going to be realized for office buildings. The results are from computer simulations and show the fields of application. The investigation concentrates on ceiling cooling by a water system(which is part of combined water/air HVAC-system).