Opportunities in the design of control-on-demand HVAC systems

Control-on-demand operation of HVAC-systems can reduce energy for heating, cooling, and the drive energy of fans and pumps resulting in better control at a lower operational cost. Analysis of typical Nordic CAV and VAV systems indicates a potential for substantial sav-ings using new components and alternative system design. Component developments include more efficient motors, variable speed drives, pumps and fans as well as laminar flow heat exchangers and smart air-supply devices. Alternative system designs can reduce pressure drops by replacing valves and dampers with direct speed control of the pumps and fans and reduce mean flow rates by means of control-on-demand. Furthermore, separating the condi-tioning and distribution pressure drops, e.g. going from in-line to parallel conditioning, adds another dimension of design to further reduce the energy to fans and pumps.