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The small difference in average dry bulb temperature makes it easier to construct a building that can exploit the sun for heating in the winter and shade it in the summer. This is possible by optimizing the roof overhang and the size of the windows regarding the sun’s position on the sky. Furthermore, the position of the windows and the length of the building facing the sun is also a parameter that should be taking into consideration. Above it is explained that the vernacular buildings in Kathmandu are positioned with the long wall facing south, this optimizes the heating from the sun during winter and during summer the sun will be positioned higher in the sky and therefore not contribute in a high scale to the overheating. On the contrary, it is useful to store the heat from the sun in daytime so it can heat the building during night time. Another important consideration regarding heat loss is the placement of the different rooms. By using buffer zones, as for example bedrooms, you can reach a comfortable temperature in the main area, as for example the living room.
Another important parameter that is important to consider when designing a building in Kathmandu is the Monsoon rains. The envelope of the building has to be water proof and also has the ability to transport moist from the inside and out in the warm humid summer, in other words it has to breathe. The roof overhang will help to protect the walls envelope and with an inclined roof transport the water away from the façade. It is also important to consider how to transport the water away from the building’s foundation. In Kathmandu this happens naturally as it is in a hillside.
Considering all this it is easy to say that the vernacular buildings in Kathmandu is energy optimized and there is much to learn by studying their climate and their way of constructing.
But for what concerns summer, it should be necessary to reduce the heat entering the building, to do this, it could be useful to study the position of the building, orientating it in a way that doesn’t get direct radiation during the hottest part of the day, or maybe reducing the openings on that specific side that faces sun. Also studying a good shading system can be helpful to improve the comfort inside, or a specific type of glass that is able to block part of the radiation, leaving a good amount of light in, so that is not necessary to use the artificial one.
It is also possible to try to increase the heat losses, working on the ventilation, especially during the night. It is difficult nowadays to have just a natural ventilation system, especially if the are we consider has not strong winds phenomena, but it’s possible to install an hybrid system that helps the summer night cooling process.
From the latest news this summer, when we heard about a lack of water in the Capital city, it could be smart provide each new building with a water storage, to use it for the domestic custom.