Homes and gardens

Insulating buildings

Nature inside A courtyard with arched corridors, clay tile flooring and tiled roof ensures ample natural light and ventilation.

Nature inside A courtyard with arched corridors, clay tile flooring and tiled roof ensures ample natural light and ventilation.  

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Look back to traditions to see how buildings were created to be naturally cool, says Anupama Mohanram

In a place like Chennai with its warm and humid weather, our indoor environment should be one to look forward to, a place where we can leave the heat behind during those hot summer months. How can this be achieved without the reliance on mechanical air-conditioning which we have come to depend on?

Mechanical cooling not only consumes a lot of energy and damages our earth but can also be detrimental to our health.

One obvious answer, of course, is to look back to our traditions to see how buildings were created to be naturally cool before the advent of air-conditioning.

The design itself would facilitate breezeways through the buildings by means of orientation and ventilation. A few features incorporated for this purpose included central courtyards and thermal vents placed high. Other than design aspects, the material used in construction prevented the entry of heat from the outside. This ‘insulated’ the building. These materials resist or slow down the transfer of heat from exterior to interior spaces.

The insulative value of a material is defined by its ‘U’ value, which is the overall rate of transfer of heat through a unit area of the building material.

The lower the ‘U’ value, the better the insulation. In any building, the materials that make up the exterior walls as well as the roof are the ones that would need to be the most insulative. Traditionally, materials such as mud mixed with straw and thatch would provide this insulation.

The wall and roofing materials of today such as fired clay bricks, cement blocks and concrete have very low insulating properties, resulting in uncomfortable indoor environments that can only be made comfortable via mechanical cooling.

The use of double brick walls or bricks arranged in a “rat trap” bonding can help improve the insulation capacity of walls by introducing air cavities.

However, these techniques require more material or skilled labour, thereby increasing cost and construction time.

The good news is, with the technological advances today, alternative materials are available that are more insulating than the conventional ones.

One option for exterior walls is hollow clay blocks wherein the multiple air cavities inside provide twice the amount of insulation as solid clay bricks.

Similarly, aerated concrete blocks which are produced by means of aeration, thereby providing air pockets within the material, are another option.

Insulation on the roof can be provided by sloping the roof to prevent direct heat ingress into the space below. For flat roofs, a layer of insulation can be provided either above or below the conventional slab.

A few options include rigid polystyrene boards or mineral wool and fiberglass.

Concrete slabs that use a ‘filler’ material such as pot tiles or coconut shells are more insulating than plain concrete.

Creating roof gardens is another option that would provide the necessary insulation from the heat due to the presence of soil and vegetation. Considering these numerous options it is possible for us to ensure that our buildings stay cool through most of the year without mechanical cooling by means of conscious choice of our building materials.

The author is founder

of Green Evolution,

a sustainable architecture company

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Printable version | Jan 29, 2020 1:23:53 PM | https://www.thehindu.com/life-and-style/homes-and-gardens/insulating-buildings/article25851102.ece

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