Civil Engineering Reference
In-Depth Information
Ventilation: Thermal Efficiency
and Health Aspects
J. Laverge
Abstract This chapter will focus on the performance of ventilation, both in
reducing adverse effects of indoor air on building occupants and in reducing the
energy required for this. The first section of the chapter elaborates on the adverse
effects stemming from airborne pollution: why do we need fresh air? The next
section than explores the specific merits and limitations of ventilation as a strategy
to renew air, while the last section focuses on the different ventilation concepts and
their performance. The main focus in that section is on technologies that allow to
reduce ventilation heat loss without increasing the exposure of occupants to air-
borne pollutants, more specifically air-to-air heat exchangers, exhaust air heat
pumps (EAHP) and demand-controlled ventilation.
1 Airborne Pollutants
The very first question in constructing a framework to assess the performance of
ventilation self-evidently asks for the goal of ventilation. What do we hope to
achieve by ventilating? And why? Since ventilation is nothing else than replacing
the air in a room with new air from outside the room, its effect can be no other than
making the indoor air more like the outdoor air. The fact that this is desirable
implies that indoor air and outdoor air are different and that there are either
positive effects associated with exposure to outdoor air or adverse effects associ-
ated with exposure to indoor air. In other words, indoor air is polluted.
There are a large number of pollutants typically found in indoor air, and new
pollutants are introduced at an astounding rate (Weschler
2009
). The properties of
these pollutants depend on their physical nature, in which the two main categories
