How to reduce heat transfer for Windows

Windows may be considered as a replacement of the concrete/brick walls.While choosing the type of windows you need to select both the glass and the sysyem in such a way that the U Value reduces to a significant extent.Soft coated or Low E glass has the best heat transmission properties.Double glass is also an option to reduce heat transmission but is more expensive than a normal 6 mm toughened glass.

Be careful about choosing the system properly as it should match the U value of the glass to get a better U value.Care should also be taken to as to allow maximum light inside which again depends on the choice of glass.

Finally the joinery must be done with good workmanship like gasketting,siliconing so as ro prevent water, air penetration.

Yuo can also go fer a thermally broken system which cuts off the possibility of hear transmission through you system (which is mainly of Aluminium).

Sometimes venetian blinds are also used to ward off direct sunlight during summer months and allow sunlight during winter.

It is importatnt that we stop heat coming in to house in the summer and going out in winter. It ha sbeen rightly said that window is the placew from where maximum heat tranfer will take place.

Windows shall have some fixed glazing where double glass shall be provided.

All other joints of frames and shutters shall be leakproof or tight enogh to stop flow of heat. Rubber gaskets shall be used. Specially designed blinds aor shades shall be used. Shades made of bambo mattine can be improved by providing foams in between two layers of bamboo matting. Foams having low coffcient of thermal conductivity can be used with very good results. Suitable Overhangs shall  be provided over the windows to cut direct entry of sunlight. Position of windows in walls in south west and south east side is adbantageous keeping in view the movement of sun. And no windows or minimal windows on north east and North west side.

The orientation of the building is the most important aspect to reduce heat transfer for windows. Apart from that energy modelling of the building will help a lot. The total fenestration should be around 50% of the gross wall area. Lastly you can use films, external shading devices, internal shading devices, blinds, curtains, etc. but care should be taken that in the process, quality of daylight inside the room should not be negotiated otherwise you will end up using electricity during day times as well, resulting in inflated power bills. 

Thanks Naimish, Sanjay and Mehernath for your views....

Agree with Naimish answer.

sbdikshit

There are various ways to control it.

1. By Providing wather shed in such manner  to avoid direct sun light over the windows.

2. By means of Plantation for G+1 buildings , shadow of the trees should cover the window.

3. By using Insulated double glazed windows.

4. As stated above by using Sunglass or film or curtains in side.

5. By using thicker glasses.

The cheapest way is to use sun control films and see that all the joints of the widow seal are perfect, you can use tinted and coated toughned glass for window panel so that the maximum heat is deflected.  

In my idea there are few ways to avoid heat loss. One major point at the time of designing the structure is that it should be designed in such a way that it avoids or at least have minimal direct sunlight. It can haeavily reduce the heat transfer. The other way is to use reflector/ tinted glass for window panels. The appropriate thickness of the glass is also important, though use of exesive thick glass is not viable. The other important thing is that the window panels should be fitted in such a way that it has minimum gaps which may lead to transfer of outside from inside and vise versa. This too is a major cause of loss.