Scientific Principles and Comfort Levels in the Design of Buildings

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Students Name: Aaron Wright

Science and Materials

Intermediate Assignment 4

Scientific Principles and Comfort Levels in the Design of Buildings

Task 1

Explain in terms of scientific principles, why:

a) It is advantageous to shade the south facing windows of a modern office block with louvres, and specify, giving, a suitable material for their construction.

b) It is necessary to incorporate a vapour barrier in the construction of a flat roof of a multi storey office block.

a) Only surfaces facing South receive sun all year round, however, South facing windows lose heat in the winter and gain heat in the summer as the sun rises and sets at different times as well as taking different paths across the sky. The reason the sun is stronger in the summer than the winter is because the sun is higher and therefore the rays from the sun tend to be more direct hence more intense. Similarly in the winter the sun is lower and seems to move faster as it appears closer, this is illustrated in the diagram below:

(http://www.morehead.unc.edu/Shows/EMS/seasons.htm)

Glass is a poor insulator and when the sun falls, struggles to maintain the heat it has received from the suns rays particularly in the winter when days are much shorter. Louvres help improve insulation in buildings, and reduce heating and gas bills, doing their bit for the environment as you can close them when darkness falls.

Louvres can be made of various materials, for example, metal, timber and even tinted glass. Timber is sustainable and generally the cheapest solution, however the downside to using timber is that it may begin to rot if it is not looked after, therefore I would select metal although it is normally more expensive, it would require less maintenance, and in the long run may be cheaper. Glass the third alternative is the most expensive and least common however the advantage this offers is that you can see out of it when it is closed as the tint emits light however allow visibility.

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b) In a multi story office block with a flat roof a vapour barrier would be necessary to allow natural convection of warm air rising to escape through the roof and hence prevent interstitial condensation.

The vapour barrier is likely to be installed in the warm side of the roof (internal) so that condensation in the cold side (external) can escape. If a vapour barrier is not present continual build up of condensation would occur in the ceiling and ceiling space, this would dampen materials and if not controlled, lead to problems such as decay in timber ...

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