ABSTRACT

The former is partly achieved by background trickle vents in window frames and by air gaps or undercutting to internal doors. Natural ventilation by these means is difficult to regulate in defined quantities, therefore low-energy-use mechanical ventilation systems, particularly those with a heat recovery facility, are becoming quite common in new-build homes. Ventilation and heating for an assembly hall or similar building may be achieved by admitting cool external air through low-level convectors. A mechanical assisted Ventilation System may be applied to dwellings and commercial premises where Passive Stack Ventilation is considered inadequate or impractical. Mechanical ventilation systems are frequently applied to commercial buildings, workshops, factories, etc., where the air change requirements are defined for health and welfare provision. Fan-assisted ventilation systems supplying external air to habitable rooms must have a facility to pre-heat the air. Galvanised sheet steel is the most common material used for ventilation and air-conditioning ducting.