Findings from Innovate UK´s four-year Building Performance Evaluation (BPE) shows that we are able to “design tight”. We haven´t yet learned to “ventilate right”. Air pressurisation tests showed that sometimes the fabric is much tigher than expected while on other occasions it is substantially leakier. If a building is more leakier than planned, there is no longer a requirement for mechanical ventilation. When buildings are tighter, the mechanical ventilation is a necessity.
One point is that the actual occupancy rates and behaviour is often different from that assumed at the design stage. An effective solution would be to link future ventilation systems to a measurements of indoor air quality (IAQ) and to use this to allert occupants as to poor air quality.
Excerpt from the article “Home Truths” by Richard John, published at the Cibse Journal April 2016.