The ventilation requirements for decontamination are normally determined with a static calculation method. In some cases, the pollutant emission is intermittent, for example in the car park of an office building, where all the cars enter and leave the place nearly at the same time. Generally, in such a case, the volume of the garage is large, consequently the time constant of the system has a high value. So a static approach would no longer stay accurate and a dynamic evaluation is needed.

When an underground parking place is not ventilated frequently enough, it is natural that the concentration of contaminated air cannot be lowered to less than the safety limit. Further, when the supply or exhaust air is not of laminar flow, the contaminated air concentration will increase locally due to stagnation of contaminated air or due to vorticies generated in that place, even with a sufficient number of times of ventilation per unit time.

Richard Tully gives practical advice on ventilation requirements for underground car parks, emphasizing the need to remove fumes quickly from exit ramps where vehicles emit up to half as much carbon monoxide again as on the level.

Ventilation air distribution problems involving system design, installation, operation and maintenance are often suspected of causing air quality problems that plague many modern sealed office buildings, such air quality problems have resulted in occupants suffering symptoms of discomfort and ill health. Three case studies are described in which tests of ventilation performance appear to relate poor air quality to air distribution and ventilation. In all cases, ventilation system retrofits were designed to improve indoor environmental conditions.

New research shows that replacing low efficiency window air conditioners with high-efficiency units can produce measurable savings and can be cost-effective in homes with high air conditioning electricity consumption.