Ventilation for good indoor air quality and energy efficiency

As a result of new energy efficiency directives and legislations in Europe and elsewhere, the ventilation component of energy usage in buildings has increased relative to the total energy consumption. At the same time, the air quality in some buildings has in recent years deteriorated as building designers and managers have been aiming to design more air-tight buildings and reduce the energy consumption. This article gives a brief overview of the types of mechanical ventilation and air distribution systems that are used for buildings. It briefly describes the performance of traditional and some new types of ventilation systems in terms of indoor air quality (IAQ) provision. A method for evaluating the performance of air distribution systems that uses the ventilation and energy effectiveness is then introduced. This is based on the Air Distribution Index which has two different expressions, depending on the nature of the room environment in which the air distribution system is used. One method is for use in uniform environment and the other for both uniform and non-uniform conditions. The two methods are then applied to different types of room air distribution to compare their performances in terms of IAQ provision for occupants and energy efficiency