Building orientation can be defined as the way a building is positioned in relation to the prevailing wind direction and path of the sun’s direction.
Sunrise and Sunset
The earth is made up of four cardinal directions: North, South, East, and West. Usually, the sun rises in the east and sets in the west regardless of country or continent. The distance from the equator and the path of the sun determines not only the time of sunrise and sunset. The farther a country is from the equator, the more oblique the sun’s path is to the horizon and this causes a different duration that a sunset take. Abuja in Nigeria, for instance, lies on the 9th degree of northern latitude and thus very close to the equator. While a sunset in the northern USA or central Europe can take almost an hour, in Nigeria it only lasts an average of 23 minutes. Nigeria is so close to the equator that there is no noticeable difference even between June and December.
Wind Movement
Wind normally follows through southeast towards the northwest direction. Winds are one of the main factors that affect the climate of a place, it is therefore important to have a good knowledge of the movement of air mass or wind. A critical element in the process of generation of rainfall of any type is wind which is also useful as a source of energy generation. Sea and land breezes are experienced in the coastal area of Nigeria, which is close to the southeast. During the day, the land area is heated more than the sea, thereby causing air over land to expand and rise, causing low-pressure areas on land. This causes cooler air from the sea to move inland toward the low-pressure area on land resulting in light wind known as the sea breeze. At night the reverse process is experienced where the land cools more rapidly than the sea resulting in the land breeze.
The air mass in Nigeria oscillates between North and South in harmony with the movement of the thermal equator and it is influenced by land mass and water bodies. Nigeria has two types of wind movement in a year, also known as the North Western trade wind, the harbinger of harmattan season, and the South Eastern trade wind, which brings the rainy season. The South Western wind (June/July) is a result of the dominance of the tropical maritime air mass from the South Atlantic which causes the rainy season. During the period (December/January), the wind system shifts down from the tropic of Capricorn with the Sahara becoming the high-pressure zone. This brings about the dry and cold wind – the tropical continental air mass with a northeasterly wind with a low-pressure belt in the south. At this time, the inter-tropical front will be in the southern coastal fringes of Nigeria. Thus, in Nigeria, as well as obtained elsewhere, it is necessary to determine the amount of air mass in motion to enable:
1. Proper design of civil engineering structures.
2. Planning for siting of wind turbines/generators.
3. Evaluation of productivity and cost-effectiveness of a particular wind energy system based on available wind resources.
4. Determination of operational requirements such as resource information, load management, procedure, and prediction of maintenance or system life.
Importance of Building Orientation
The importance of orientation cannot be overemphasized because it helps to improve comfort in the house and reduces heating and cooling needs. Oftentimes, the provision of artificial heating and cooling needs in homes requires the use of fossil fuels which are not sustainable. Thus, there is a need to utilize natural resources. Orientations are usually unique to climatic zones and this should be considered when locating houses. In Nigeria, for instance, houses usually face or back roads in almost parallel directions. This is done to avoid runoff from roads entering homes in dangerous conditions and to enable easy movement of vehicles. These should also be considered in the orientation of buildings.
Since orientation in a broad sense is usually about how the house especially the living spaces is oriented with regard to true or solar north, it is necessary that the best orientation is aimed to ensure that the living areas of the home face the path of the sun. Figure 1 shows typical suggestions for aspects suitable for a residential building.
For further reading
Geography of Udi Cuesta Contribution to Hydro- Meteorological Pattern of the South Eastern Nigeria by Ngene Ben Uchechukwu, Jonah C. Agunwamba, Imokhai T. Tenebe and Gideon O. Bamigboye. April 18th 2018. DOI: 10.5772/intechopen.72867.
