How Dwell-Vent works - Supply-air Windows

Supply-air windows have been the subject of research over many years in cold countries such as Canada and Finland, where they are used in combination with an extract fan to establish a pattern of ventilation by pulling air through the windows and across rooms.

In more temperate climates building codes now required buildings to be better sealed to conserve energy and yet to achieve healthy indoor air quality, particularly in wintertime when condensation is more prevalent. For this reason a research programme was instituted at the Martin Centre at Cambridge University into the use of supply air windows, but this time in combination with passive stack ventilation, to achieve a system that is both low in its use of energy and healthy.

What was discovered from this research is that for the 'supply-air' windows to function most efficiently, air flow from the outside which is through a vent at the bottom of the window, up between the panes of glass, and into the room at the top of the window, has to be controlled to a smooth and steady flow rate. Gusts of wind against the outside of the building can disturb this and so new 'smart' vents have been tested that regulate the flow speed and direction of the air stream. As the air passes through the gap between the window panes, it is warmed as it rises because heat that would otherwise be lost to the room through the glass is trapped within the air path and delivered back into the room. Also during the day, if the windows are facing towards the sun, the sun's heat also helps warm the ventilation air. The windows as a result are not only energy efficient but they give an excellent standard of ventilation, the relatively warm temperature of the air entering the room also guards against draughts.

The Dwell-Vent design program that can be accessed from this link can tell from some basic information about your locality, and the basic design of your houses or flats, whether they have the basic requisites for Dwell-Vent to work well.