Demand-controlled hybrid ventilation –an alternative?

The performance of a demand-controlled hybrid ventilation system (DCHV) has been compared with that of a balanced mechanical ventilation system with heat recovery (MHR) in respect of their energy use and corresponding environmental impact in a typical Swedish school. Energy demands have been calculated with the IDA program, and environmental impact with the EFFem program. Technical and monitoring data from a pilot study in Falkenberg has been used in order to define and verify the simulation model. The results shows that the total energy demands are close to the same for the two ventilation principles, but with differences in the relative proportions of electricity and heat uses. The main factor that had an influence on the environmental impact was found to be the availability of district heating, based on energy from low environmental impact sources. It is therefore unsafe to base a decision on outdoor climate information alone. It is important also to make an environmental analysis, together with assessments of costs and analyses to ensure that adequate indoor environmental conditions will be delivered.