demand controlled ventilation (DCV)

Demand controlled ventilation systems are representing a large majority of installations in France. They are commonly used for more than 35 years. The strong development of these systems can be explained by the French regulatory framework for air renewal. These demand controlled systems have been developed in order to optimise the energy consumption and at the same time to ensure indoor air quality and building durability. In residential buildings, demand control is based mainly on humidity whereas in commercial buildings it is based on occupancy and/or CO2 levels.

Energy performance of mechanical ventilation systems in modern low energy and passive buildings is a crucial factor influencing overall energy performance of building. Energy balance is commonly used tool in evaluation of mechanical ventilation systems. In the case of low energy and passive buildings that tool might be insufficient and should be replaced by exergy analysis taking into account the first and the second Law of Thermodynamics. The paper presents principles of exergy evaluation of mechanical ventilation systems and case study calculations for an office building.