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Energy efficiency:An efficient home that keeps residents cool in the summer and warm in the winter begins with smart design. http://www.greenspacencr.org

By  Asadul Hakim, Architect

Character of buildings of the world is determined and governed by climate, society, economy, availability of labor force, transportation, climate, skilled manpower of the country in question. Buildings in North or South Pole do not represent the same character as in equator or on Capricorn or cancer. In addition to the above several other conditions like rain fall, temperature, vegetation, and topography, availability of local buildings materials and industrial development also plays a great role.

In our discussion here we are going to touch energy conservation and its use in buildings inBotswana.Botswanahas endless heat energy all over the country. In this case it is our prime task to utilize this energy and simultaneously save the buildings from extreme heat providing appropriate design and correct orientation on siting the building. In winter, sunlight is required for warming up and to avoid heat in summer.  In addition to this serious temperature difference from day to night, there are possibility of cracking in roof (Reinforced concrete roof) and walls if not well treated. Radiated heat inside the building definitely produce serious discomfort and users take shelter of artificial ventilation in terms of air conditioning which definitely commands money and energy and this problem can be treated with proper designing of structure. Closing windows with brick walls in buildings does help users from heat and users become psychologically frustrated. Therefore, a compromise is to be made with window openings on walls. To attain goals – solar movement behavior is to be studied and properly introduced. For comfort several items are responsible for the creation of comfortable environment within the house. A factor which is playing major roles is narrated below:

Shading devices:

Shading devices can be plotted in the same manner as sun paths show during what time sun is excluded. Shading masks are projections of the surface covered on the sky vault. These projections also represents those parts the sky vault from which no sun light  will come, if the sun passes through such an area, the observation point will be shaded.

Masks of horizontal shading devices (overhangs) will show a segmental character, those of vertical fins produce a radial pattern, and masks of egg crate type, are basically a combination of these forms. Shading masks can be drawn for any shading device, even for very complex ones, by simple geometrical methods. Since they are geometrical projections, they are independent of latitude and orientation, and may be used in any location.

By overlaying a shading mask in the proper orientation on the sun path diagram, one can read off immediately the times when the sun rays will be intercepted. For design purposes, the process can be reversed. One can determine the needed shading mask and then find the proper device for it.

General rules can be deduced for the types of shading to be used for different orientations. Southerly orientations call for shading devices with segmental mask characteristics, and horizontal devices work in these directions efficiently. For easterly and westerly orientations vertical devices serve well, having radial shading masks.

InBotswanaand the country with extreme heat it is always advisable to completely close with brick work on the west which is most vulnerable of extreme glare and to avoid penetration of heat through walls inside the house. Some users feel that a solid wall will never look beautiful and produce darkness due to absence of windows and is ready to use heavy curtain inside to avoid glare and heat. Practically what happens is that with curtain inside the building you have already invited heat within the building and it remains inside and produces discomfort as well as demands for artificial weather conditioning. It is better to provide curtain outside the window opening which is not possible. In some country, baffle walls are used to intercept penetration of heat through walls. Let us come back to eastern side- sun remains only for few hours in the morning when the atmosphere is not yet heated and passes on to the western sky. Therefore, a window may be provided for morning sun and can give you a breathing scope. I have no reservation on south and north side for window provision. But we should not forget that due to extreme heat existence inBotswananorth side is the best for all seasons. Any building can demand for a wall wide window from floor to ceiling without any heat hazard. In addition to this let us not forget that excessive light does cause discomfort in viewing and therefore regulated opening in proper orientation will satisfy for eye comfort and excellent viewing.

Whatever we talked about is inside the building. Heat preservation and conservation does not only command for interior- exterior of the building also plays a great role in weather conditioning and comfort. A micro climate can be created outside the building to counter adverse condition. This micro climate can be achieved through providing landscaping with various elements. As sun also heats ground around the building, it is required to protect building from heat for comfort. From a hard surface around the building, sun heat reflects from ground next to the buildings and sends heat inside through the openings like doors and windows. Therefore it required to plant grass and flower beds which is the best items to absorb heat and protects buildings from heat. It also produces soothing effect in eyes. In science we term this weather as micro climate. Tree plantation can also help saving buildings from heat by casting shadows and is only limited to a single storied height. Further, let us go inside the building. Choice of color on walls and ceiling plays a great role in producing comfort in the building. There are some colors which reflect heat and light and some colors absorbs. In winter warm colors like yellow, white, orange and shades of these colors will produce psychological heat inside the buildings. On the other hand green, blue, purple, black and their shades absorbs heat which is comfortable in summer. Looking at the duration of winter and summer it best to use cool colors all the year round. I find it necessary to mention here that psychology of colors plays a vital role in determining behavior and character of occupants and specially children. Therefore it is necessary to think twice to choose color for your house. Cross ventilation for breeze does not help inBotswanaweather which brings heat or cold inside the building. Whatever we discussed above is naturally protecting the building without the help of any artificial process.

Read next installation on: INTERMEDIATE TECHNOLOGY

© 2012, Boidus. All rights reserved.



  1. Can’t agree with you any more.

    Big glass asseblies/ curtain walling whatever it be called can harness the usefulness of natural light cutting on high volatage non energy saving artificial lighting.

    More and better design approach can be implemented including natural ventilation biomass heating etc….

    Posted by NTHWANA | 23. Jan, 2012, 3:33 pm

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