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.
Nowadays, it is a common occurrence to see the houses
being constructed so close to each other that we cannot expect fresh air from
our neighbour's site. One can depend only on the open space that is
there around the house to allow fresh air to come inside. For this to happen,
we need to keep more open space on the side from where we want the summer cool
breeze to enter the house. This can be accomplished by keeping more open space
on the south and west. The south side
open space is more useful because the sun will be at high angle on this side
and it is easy to control the sun by providing minimum projections. Even though we get a good breeze from the
west too, because of the low angle of the sun from this direction in the
afternoon, it is comparatively difficult to control sunlight penetrating the
house.
However, we can keep large projections like portico and
pergola covered gardens in the open space on the west and filter the sun light
to a maximum possible extent, while allowing easy access to summer freeze.
We have very little control over the open spaces around
only site. For this specific reason, it
is all the more important to leave sufficient open space around the building
within our site since every inch of space cost multiples of hundreds of rupees
in urban areas, we have to leave it where it really adds to the quality of
living in the house and most importantly, open space has to be left taking into
consideration the summer wind directions.
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