Ventilation at Homes
Though all the five Elements of Nature are
essential for the life of all living being on earth, air is without
dispute the prime among them. And within the house, we need
proper ventilation for a salubrious atmosphere and healthy living. For getting the welcome cool breeze inside
the house, it is imperative that the air should be able to flow around the
house freely. It is a proven fact that
on the windward side the air blows with some force or energy so that it not
only enters the house but also absorbs and carries the heat to the outside on
the leeward side of the building. To facilitate easy flow of air, we should
have lots of open space in the way of its entry and some space on the other
side for its easy exit as well. But the availability of more space in an urban
context can be just about 10 feet and in a metropolitan city like Bangalore,
even 5 feet will ensure quite a bit of natural ventilation.
A big house should mean that we have open
space around the house, especially on the windward side. It will be better and
beneficial to plan houses in such a way that the open space around the house
becomes part of the house, and extend the house outward visually so that we can
feel the house getting extended to the open space.
The sensible way to get this done is by
taking the outside inside by bringing the open space inside and make it part
and parcel of the house. If we build
from one end of the site to the other, covering more or less completely, then
we are sure to feel cramped and ultimately suffer from lack of light and
air. As far as light is concerned, the
natural light can be compensated to a certain extent, by artificial lighting,
but not the natural ventilation. A fan just churns the same stale air. The air
conditioners merely cool the air, recirculating a part of the used and exhaled
air to reduce the load on the system.
It is the nature of air to blow from an area
of higher pressure to that of lower pressure. On the windward side the air
pressure is higher, on the leeward side the pressure is proportionately lower.
Therefore to facilitate this we need to keep bigger windows on the windward
side and even small windows will do on the leeward side to exhaust the warm and
stale air.
Wind will have positive pressure on the
south and west during the summer monsoon months and similarly there will be
negative air pressure on the north and east during this season. We feel the
flow of air only when it passes by our body as a stream. But it flows rather
slowly most of the time, even if we do not exactly feel it. The reason for this
is the pressure differential between the two sides of a building, either
adjacent or opposite sides. Even this slow movement of wind brings many air
changes per hour and provide the much needed relief from heat.
Even when there is absolutely no air
movement, or the condition which people normally call a 'still air ' conditioner,
there certainly will be air exchanges happening. In this case there will be
gaseous movement due to air diffusion, which is nothing but gaseous exchange
from a higher level of concentration to lower level. Generally carbon monoxide, carbon dioxide, body
odour, cigarette smoke etc., which is being generated inside the house will be
exchanged to the fresh air from outside, carrying in the much needed oxygen to
the inside. This exchange goes on in a
passive way and even for this to happen we need sufficiently big windows to the
outside.
Trees are always helpful in directing and
cooling the breeze into the house. Trees with a large canopy not only cool the
house, but also guide the breeze inside the house through the windows,
likewise, shrubs and bushes could be strategically planted to guide useful
breeze to the inside of the house and filter hot rays of sun.
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