Important Things to Know About Factors Affecting Building Orientation
Orientation is the positioning of a building in relation to seasonal variations in the sun’s path as well as prevailing wind patterns. Good orientation can increase the energy efficiency of your home, making it more comfortable to live in and cheaper to run. With rising energy costs, it’s becoming increasingly important for builders to orient buildings to capitalize on the Sun’s free energy. For developers and builders, orienting a new home to take advantage of the warmth of the Sun will increase the home's appeal and marketability. For homeowners, it will increase their indoor comfort and reduce their energy bills.
Thus, building orientation, along with daylighting and thermal mass, are crucial considerations of passive solar construction that can be incorporated into virtually any new home design.
Objectives of Building Orientation
The orientation of a building is done to:
- give the correct direction to the building according to the surroundings;
- provide natural light and air to the inhabitants;
- save the inhabitants from dust and smoke;
- save the inhabitants from noise;
- provide privacy to the inhabitants;
- save the building from damages due to rain;
- save the inhabitants from the bad effects of the worst weather; and
- add beauty to the building.
Principle of Good Orientation
The power of passive solar heating and cooling is not to be underestimated. Good orientation, combined with other energy efficiency features, can reduce or even eliminate the need for auxiliary heating and cooling.
Ideally, choose a site or home with good orientation for your climatic and regional conditions and build or renovate to maximise the site’s potential for passive heating and passive cooling, North orientation is generally desirable in climates requiring winter heating. Solar north deviates significantly from magnetic north throughout Australia and needs to be taken into account when orienting a home or determining a buildings thermal efficiency.
Orientation does not have to be precise: there is a degree of flexibility. You can achieve good passive solar performance at minimal cost if your site has the right characteristics. Where possible, choose a site that can accommodate north-facing daytime living areas that flow to outdoor spaces with similar orientation.
Factors Affecting Building Orientation
Solar Radiation and Temperature
The intensity of solar radiation depends on the direction of sunrays. The temperature of a structure and living space increases due to sun radiation and affects environment of the house. Solar radiation acts in two ways.
- Sunrays directly come to the house through openings.
- Radiation comes indirectly through walls and roof of building by absorbing heat.
For comfortable living particularly during summer season, radiation, temperature and treatment of room are considered. From solar radiation point of view, the best orientation is that which receives maximum solar radiation during winter and receives minimum solar radiation during summer season.
The South façade has advantage of receiving more solar radiation during winter than that of receiving during summer. Even for openings on south facade, small overhang such as curtains can cut off direct solar penetration during summer and allows it during winter. Obviously, this is most beneficial aspect, not available on any other façade.
Rain and Clouds
Rains and clouds have lower importance while planning building orientation. The openings and glazing should be planned according to the rain direction, as the rain direction is same as the wind’s direction during storms. If your architect does design glazing for your building, then you should cover it with a sunshade. Thinner walls of the building should not be oriented towards heavy rain direction.
It depends on weather condition of the area and has little role in orientation of building. The movement of air and use of prevailing wind are very important during periods of high humidity. Humidity can be classified into four categories i.e.
- Very dry
- Very humid
When humidity is low, dry or very dry, it is easy to take advantage of evaporative cooling in summer. When it is humid or very humid it is desirable to regulate the rate of air movement either artificially with aid of electric fan or with help of prevailing winds.
The wind direction and velocity should be studied at your site for the whole of the year. The building should be oriented in such a manner that the wind flow should be more in the building during the humid season than in other seasons.
The prevailing winds at your location can create natural ventilation, especially in highly humid conditions. The windows and doors should be at the proper locations to provide maximum advantage due to wind.
Humidity Design Consideration
The comfort in relation to humidity becomes complex. In humid environment, there is very warm feeling when there is no breeze and air temperature is 300C. On the other hand, if humidity is low, one may feel cool even if the temperature rises up to 320C with little breeze. It will be cooler at the same temperature if there is reduction in relative humidity. And if there is breeze in high humidity area, the building should be designed in such a way as it has more natural air and ventilation.
The factors affecting building orientation must be identified and considered when designing building orientation. This will help achieve the objectives of the orientation in line with its principles.