Energy savings through implementation of a multi-state Time Control Program (TCP) in demand-controlled ventilation of commercial buildings

Regarding the energy intensity/consumption of all technical building services, HVAC systems are by far the most energy-intensive ones, when it comes to commercial buildings such as R&D Institutions/Universities, office buildings, hospitals and other buildings of similar use. As far as overall costs for HVAC systems are concerned, it can generally be stated that the initial investment costs for building services (e.g. for ventilation) are by far lower than the operating costs after a certain operating period. This paper presents a widely applicable, yet simple approach to reduce energy consumption of air handling units in a commercially operated building. The implementation of a Time Control Program (TCP) using multi-state operation by resetting the duct pressure values according to the well-known fan affinity laws yields respectable savings in energy consumption. Yet the expenditure of time for the implementation of these simple and effective measures has to be considered: a lot of time-consuming measurements and organizational briefings have to be performed regarding the size and complexity of a typical university building. In practice, savings of up to 55% in electrical as well as 39% in thermal energy can be achieved regarding one specific AHU with bad (24h-'comfort'-operation) initial set-up. It can be assumed, that far too many university/commercial R&D buildings of younger age (<15 years) in Austria are scarcely equipped with adequate metering or even automated energy monitoring systems, which would highly facilitate energy analyses and push the realization of crucial measures to reduce energy consumption.