It is estimated that buildings contribute as much as one third of total global greenhouse gas emissions and consumes up to 40% of all energy (Adeleke, 2010). This is primarily through the use of fossil fuel during their operational phase. Given the massive growth in new construction in developing countries such as Nigeria and the inefficiencies of existing building stock worldwide, if nothing is done, greenhouse gas emissions from buildings will be more than double in the coming years (Adeleke, 2010).
Figure 1-1 shows the electricity growth pattern in the different sectors in Nigeria. As at 2009, the residential sector consumes the most energy, followed by commercial and street lighting, and trailing behind is the industrial sector. This is an indication of the decline in the industrial sector due to poor energy supply. It is also an indication that conservation and efficient measures in residential and commercial sectors may yield significant energy savings.
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Figure 1-1 Electricity consumption pattern in Nigeria published by the Central bank of Nigeria (Oyedepo, 2012)
Total energy consumption in Nigeria was 18,051 gWh in 2009 according to the International Energy Agency (IEA, 2009). Combustible renewables and waste
accounted for 80.2% of total energy supply due to high use of biomass to meet off-grid heating and cooking needs, mainly in rural areas, see
Figure 1-2. Natural gas and oil similarly supplied 9.9% and 9.4% of energy respectively. Hydro power supplied the least energy in the mix at 0.5%.
Uyigue et al.(2009) claim that of the approximately 12% energy delivered by the utility (ESMAP, 2005), half of the energy is wasted due to inefficient user behaviour. There is obviously a need for not just cost-effective buildings, but also healthier and more productive living environment. The relationship of buildings with their environment;
determines a building's sustainability. Architecture that raises standards and promises improved quality of life can help to achieve these sustainability goals (Edem, 2010).
Energy conservation and efficiency practices and technologies should be actively promoted to ensure rationalized consumption of energy in the country (Sambo, 2008).
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Figure 1-2 Energy supplied by type in Nigeria (International Energy Agency, 2007)
Electricity conservation policies can be initiated without deteriorating side effects on the economy as shown by Akinlo (2009) and Emeka (2010). Energy conservation can result in increased financial capital, environmental quality, national security, personal
security, and human comfort.
So far, barriers of energy conservation and efficiency development in Nigeria according to Uyigue, Agho et al. (2009) include:
1. Inefficient lighting with 65% of our respondents using incandescent light bulbs of 40-200 watts
2. Poor occupant control leaving lights on overnight in unoccupied areas and security lights left on during the day
3. Proliferation of private water boreholes in an effort to achieve regular water supply. In addition to power outages or as a result of, there are also water shortages experienced in Nigeria
4. Poor land use policing evidenced by industrial activities in residential areas 5. Inefficient use of electrical appliances
6. Purchase of Second hand appliances 7. Lack of policy and legislation 8. Lack of awareness
9. Lack of trained personnel and energy efficiency professionals 10. Importation of used machines
11. Lack of research materials on energy efficiency
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13. Low electricity pricing
14. Proliferation of inefficient equipment 15. Desire to minimize initial cost 16. Low income
17. The most significant is the fact that 99% of the respondents do not get electricity supply for up to 24 hours straight. There is a general feeling of injustice over the fact that the state is asking the public to save energy when they are not supplied the energy to save
To overcome these barriers, there is a need to live within global constraints and to ensure more fairness in access to limited resources. This concept drives this work to adopt the concepts of sustainable development.
In order to achieve sustainable development in the power sector, a holistic approach to balancing economic prosperity, social wellbeing and environmental quality is required.
Sustainable development is also required for developing the built industry and saving electricity (Sambo, 2009).
Technological advances and policy have been advocated as the main solution to rise in energy consumption (Mockett, 2011); however this argument lacks a sustainable and holistic approach to energy conservation and efficiency. Up to 20% overall energy conservation is possible by including passive design concepts in buildings.
A further 40% can be saved by using a combination of passive and advanced energy systems (Santamouris et al., 1996).
The triangle for low energy building design is shown in Figure 1-3. Mockett (2011) goes further to say a more sustainable built environment requires a holistic approach that marries efficiency and conservation of traditional buildings and technological advances. Energy savings in Nigeria will lead to personal income saving; reducing the building of more power stations allowing the funds to be spent on other sectors of the economy; improve access to energy; and decrease load shedding.
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Figure 1-3 Triangle for low energy building design (Haase and Amato, 2006) ranking the efficiency of energy conservation, efficiency and renewable energy
1.8.1 Bio-climatic design
A bio-climatic system uses design features such as shading, orientation, insulation and thermal mass of the building to reduce or eliminate the heating and cooling
requirements of the zone (Khalifa and Abbas, 2009). Bioclimatic principles affect the energy flows within a building, such as heat transfer through building fabric or from internal gains. Adopting bioclimatic design principles saves energy as buildings are designed based on natural ventilation, local climate and materials, and using renewable and clean technologies.
The Nigerian -climate may be broadly classified as tropical according to Komolafe (1988). Correct site orientation of buildings for thermal efficiency paying attention to solar radiation and the resultant heat load, wind direction and force and topography of the site are beneficial. Open facades should face north or south as much as possible to avoid direct radiation from the east and west. In hot areas, screening of openings and protection from the sun is always necessary. This is because the intensity, duration and the angle of incidence of solar radiation to a particular surface are the main determinants of the design precautions necessary for comfort. These techniques are used within the climatic and building use context to achieve thermal comfort.