[noise] So skylights are light transmitting fenestrations,
which are horizontal and which are on the roof of the building space. So, the advantage
with skylight is that they can bring light from the top as compared to the windows which
bring light from the side. Windows would generally have some orientation. So, it might not be
able to bring light throughout the day. But skylight being open to the sky or viewing
the sky, they are very good in capturing the light throughout the day and also in illuminating
the space in [vocalized-noise] larger [vocalized-noise] spaces throughout the day.
However this skylight also has problems, that it can get too much of sunlight when
the sun is there at very high altitude during the summer. So, a skylight glass should also
be carefully selected, you would like to have high visual transmittance and low solar heat
gain coefficients for the skylight. Now let us see how we can further enhance the the
functionality of the skylight. So, one of the techniques is called lens guides
these guides. Direct the light coming from the skylight and they can focus some of the
light and bring it to a piece of art or some installation at the bottom and can illuminate
it, and the remaining light can be diffused from these lenses all around so, that [vocalized-noise]
it can give more light to the volume of the space inside, and to the facade which is opening
inside the building. So, this unguided light illuminates the surrounding space with a light
that has a feel of a sunlight, whole interiors get very nicely illuminated.
This application of laser cut panels which is applicable to skylights, in this we have
these pyramid shaped skylight and these surfaces are made up of laser cut panels how do they
help? The low altitude angle in winters or in the morning that sunlight is bent and brought
inside and the high altitude one which is there in noon or during the summers is bent
twice and is sent back to the sky [noise]. So, this system automatically controls which
angle is admitted and which angle is reflected back.
There are lots of interesting commercial technologies that are coming, which have movable elements
which can close that is stop the radiation from coming inside or control how much radiation
is coming inside just like louvers. They are not only control they can also redirect the
light in two different directions depending on the time of the day, where the sun is and
depending on where if you want the light to be redirected. There are also interesting
systems like sun tracker skylights, which can track the sun and reflect the light and
bring it into this space. [noise] Here are some of the installations of sun tracker skylight.
Now, in both these methods whether its a lens guide or some kind of a tracker or some kind
of louvers, the basic principle is just like a vertical fenestration. That there is an
opening and we are trying to control the amount of light that is coming through these openings.
[vocalized-noise] But what if if we do not have a possibility of an opening or we want
to have a a smaller opening and bring light into the deeper spaces into the building [noise].
So, there is a simple mechanism called light pipes. In the light pipes basically there
are three components one is a collector where the sunlight is collected, then there is a
pipe in which the interior surface is highly reflective. So, the sunlight which enters
into this pipe keeps on getting reflected again and again and it emerges from the other
end [noise] where there is a diffuser which diffuses the light into this space.
So, like this we can bring light from one part of the building into deeper parts of
the building, and we need not have a hole into the wall a full window or a full skylight
we can bring it inside from different ways. So, let us see one of the possible ways is
this, here the light is being captured and then it is put into this light pipe and the
light pipe is bending. So, light is actually coming from the walls and it goes inside the
false ceiling and then again it it is the diffuser is in the false ceiling. So, inside
it looks like as if its just an artificial light in the false ceiling, but actually it
is a light being captured from the roof taken through the side walls into the plenum
and then brought it, at the interiors just as if it is from a ceiling.
So, there are various ways light pipes can be installed. Now, the the basic problem with
light pipes is that these pipes are rigid. So, once we have installed you cannot move
them and because they are not flexible [noise] and they cannot be moved during the operation,
you cannot have a system which tracks the sun. It would be great if we can track the
sun so, that we can capture more daylight and bring it inside this space, and it will
be even better if not only we capture the sun, but if you can concentrate the light.
So, that we need a smaller sections of these light guiding devices light pipes or whatever
and bring it inside this space. So, to achieve that we can use fiber optics. Now fiber optics
is basically a transparent dielectric material, usually glass or plastic and usually a circular
cross section. It has a cylindrical core which is surrounded by a cladding and the refractive
index of the core is more than the cladding. So, what happens when the light strikes the
core and cladding interface, it gets totally internally reflected [noise] and this total
internal reflection is quite efficient. So, this light keeps on getting reflected and
emerges from the other end of the fiber. So, what we can do we can have a collector like
this, which has lenses, these lenses concentrate the solar spectrum or the sunlight into the
fiber and then the fiber takes this and brings it inside and then there can be a diffuser
which diffuses the light. In this picture you can see some collectors
which are installed on the roof and these collectors can track the sun so, that you
maximize the amount of light that is captured. Now, when it comes inside there are various
ways they can be put into [noise] the building, here you see that it is illuminating the wall
and here you see that the light is coming from the ceiling. This looks pretty conventional
kind of lighting and it it looks as if the light is coming from an artificial source.
So, you have seen lots of ways by which we can improve the performance of our building
facade and bring in more daylight and control it, you might be thinking that its too much
of work. But just see this daylight is so, important
that people in this small village in Norway, they were really deprived of the daylight
most of the parts of the year because they are located at a place which is surrounded
by hills. So, they would get very little daylight illuminating the wall and here you see that
the light is coming from the ceiling. This looks pretty conventional kind of lighting
and it it looks as if the light is coming from an artificial source.
Thank you. [noise]