Tuesday, September 16, 2014

Passive solar building design

The world being more and more carbon constrained, needs means of energy that are environment friendly and produce minimum emissions. Along with acquisition of better means of energy and resources, reducing the emissions themselves by reducing environmental impact of emission sources is another essential factor to consider. As in case of buildings and construction, most buildings and infrastructures have a high impact on the environment and has been deteriorating to the environment since the industrial age. Modern buildings need to be built with environment friendly and resource efficient technologies. The strategy proposed for a building to keep its carbon emissions near zero is to make it a passive solar building. Such a design will reduce the cost of heating, ventilation and air conditioning to a new minimum and further reduce the building’s environmental impact (Doerr 2012). Passive solar concept aims to put the climate to its advantage. The building is constructed is such a way that the climate conditions favour the heating and cooling of the building which is well distributed throughout the structure by design (Doerr 2012). Many factors can affect the design of such concept, some being thermal insulation, thermal mass, shading, insulation type, glazing type and window placement. Correct use of these factors can help attain a balanced construction that can admit sunlight in winter, and reflect it in summers.

Keeping in mind that the winter sun is low on the horizon while the summer sun is high in the sky, the windows of the building are proposed to be constructed in angles that are facing the equator for maximum solar gain from the low winter sun. With a well insulated window pane angled south (towards the equator) the solar gain will further by complemented by preventing the loss of warm air through convection currents. Additionally, the building walls are proposed to be constructed with preplanned insulation to retain maximum warmth in winters and to avoid letting the summer heat in. The construction material can either be used in combination with insulation or the whole building can be constructed of insulative materials. Where the building interior is being kept warm in winters, summer sun’s glare can act like a furnace for a well insulated building. Although prevented by the window angles that are facing the sun in winters but are relatively at an angle of reflection to the sun in summers so as to act as reflective mirrors to prevent solar gain, the windows are to be complemented by correct shading from above that do not allow direct illumination from the sun when it is high up in the sky.

An affective design under this proposed strategy will assure the building’s environmental impact to be minimum and will lessen the need of energy wastage on heating and cooling. Operable windows and shading might just appear to be the only thing missing in this setup. To add comfort and avoid extra bright rooms in the building at times of year when sun directly faces the windows, the movable or rollable shades can help control the interior heating and lighting. The north side of the building does not get to benefit by the strategy directly as it doesn’t get direct sun light at right time of the year. This area can benefit from a implementing a good heat distribution design throughout the building. The central and the northern sides will still be identified as the areas needing mechanical ventilation and air conditioning though, due to limitations of passive solar strategy. The northern face of the building is proposed to be fitted with air conditioning equipment that follows the corridors or rooms to the central part. These areas will be equipped with suitable ductwork to distribute mechanical ventilation and air conditioning. As an additional strategic measure, it is also proposed that the seasonal wind flows be considered for the facing walls knowing which face of the building will be kept cooler by the natural wind flow and the roof might be lined with ‘through hole bricks’ that allow airflow through the roof to keep it cool, yet insulated (given that air is a good insulator as well) by the air gap. This kind of solar gain and insulation can also benefit from solar radiation by using a convection current through ductwork to allow warm air to reach the central parts of the building. The solar gain from one side or the roof of the building can be transferred to the central areas by passive heating techniques.The low energy strategy proposed also involves the ‘Green Building’ concept (Bauer et. al 2010; Mortgage Banking 2009).

It is proposed that the building be made suitable for the green building concept for a minimum CO2 impact on the environment. This includes installing well shading trees in front of windows that gain heat during summers. This can be optimized through making the best use of nature. Installing trees that shed leaves in winters will be the best optimization in this case. The trees will effectively act as season operated curtains that will gave way to sun light only in winters and provide efficient shading and cooling in summers. The approach to be considered is sustainability (Bauer et. al 2010) in terms of energy utilization. The building being energy efficient can further allow for more suitable ‘green’ or even zero energy integration. The green building concept is now not anymore a part of the future. Easily and cost effectively doable in the present, the concept can be used as a strategy to eliminate energy requirements for most situations significantly reducing the carbon footprint of the building in question (Anderson 1994).

Anderson, Katherine (1994). The Green Building - No Longer Just a Mirage? Journal of Property Management, Vol. 59, No. 4.
Bauer, Michael; Mèosle, Peter; Schwarz, Michael (2010). Green Building: Guidebook for Sustainable Architecture. Springer.
Doerr, Thomas (2012). Passive Solar Simplified. 1st ed. Alithea Press.
Editorial (2009). Reports Spotlight Growing Popularity of Commercial 'Green' Building. Mortgage Banking, Vol. 69, No. 4.

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