ENERGY EFFICIENT BUILDINGS USING RENEWABLE ENERGY CONSTRUCTION

The latest scientific report’s primary goal was to address the application of green energy technology in buildings to improve energy sustainability. Solar energy was used as the green technology in this scenario. Solar energy was chosen as the renewable energy of choice because it is a plentiful and limitless renewable resource that is not limited by landmarks or the terrain of the house, unlike wind energy. It is estimated that the total amount of sunlight consumed by the planet is 174 PW, which is close to 10,000 times the amount of energy produced by all other sources of energy combined (Rhodes, 2010). However, most of the sunlight is not harnessed; it is dissipated in the environment.

According to the US Department of Energy, some considerations should inform the choice of renewable energy technology; the considerations include state-level codes and regulations, economics, resource availability and minimal maintenance considerations. Solar energy fits these considerations (US Department of Energy, 2017). It should also be noted that there is a need to determine the energy loads of a building before installing solar energy systems.

The need for energy efficiency in building structures has been informed by the burgeoning demand for energy in modern structures. Given that some of the sources of energy in use today are nonrenewable, there is a need develop alternative sources that will lower the maintenance cost of the buildings, global warming and the carbon footprints. According to the Energy Information Administration, commercial and residential buildings consume 40 percent of the cumulative energy generated in the US (Energy Information Administration, 2017). Given that the leading sources of energy used in buildings today are natural gas, electricity, and some of the electricity is generated from coal and nuclear power plants that use nonrenewable raw materials. Solar energy use would help address this challenge by reducing the energy demand by buildings.

Solar Energy Technology

Solar radiation is converted to renewable energy using photovoltaic modules. The modules hold the semi-conductors. The most common material that is used in the design of semiconductors is silicon crystals; however, other materials such as carbon nanotubes (Lee, Gipp and Heller, 2004) and graphene are under development. The p-type and n-type junctions are laminated using silicon crystals. Subsequently, when the solar cells are exposed to sunlight, a photovoltaic effect is generated. The photovoltaic effect results in the generation of electricity. Nonetheless, the power that is generated is in the form of DC. The DC power is transformed into AC using a DC to AC converter or an inverter. This is because most of the electronic devices that are used in building utilise AC power. The standard p-n junction that is available in solar modules is depicted in Figure 1. The type of the junction plays an integral role in solar energy systems primarily because contact between the p and n junction induces a different pattern compared to when each of the sections is in isolation. One of the common patterns is forward bias in which the electric current flows unidirectionally. Unidirectional current flow results in the development of a diode. The energy bands at equilibrium illustrate both electron holes (the empty electron slots on the valence band) and electron pairs (electrons in the conduction band). The electron holes act as positive charge carriers while the electron pairs are the negative charge carriers. At the junction, the electron pairs, and holes combine; this results in a depletion region (Nave, 2017). The depletion region was depicted in Figure 2.

Figure 1 P-N junction and equilibrium energy bands (Nave, 2017)

Figure 2 Depletion region (Nave, 2017)

Apart from photovoltaics, other systems that may employed in the incorporation of solar energy in buildings are solar thermal power, solar furnaces, water heating systems on rooftops, hydrothermal conversion and photosynthesis (Rhodes, 2010).

The use of photovoltaic systems in buildings has been mediated by building integrated photovoltaics. Such systems feature photovoltaic arrays installed on the roof systems or on the walls or any other sections of the building where there is direct exposure to sunlight. Presently, a new technology features ceramic tiles with engrained photovoltaic cells to facilitate the capture of solar radiation. One of the key advantages of solar energy is that it can be easily be incorporated into buildings that had been constructed without provisions for solar power. Nonetheless, in-design incorporation of solar energy provisions is much more preferable.

In the development of building structures that are off the grid, batteries are used to store the electricity generated from the solar radiation until when there is a demand for energy. However, if the building is located close to the power lines, the electricity generated from the solar radiation can be easily fed into the national grid.

Solar panels can be installed in different types of roofs such as pitched and flat roofs. Besides, solar panels can be installed on facades or glazed on the walls of skyscrapers. The glazing of the CIS Tower in the UK (Nave, 2017) with solar panels is an illustration that solar energy use provides flexibility, which is not the case in wind energy harvesting. Wind turbines have to be installed on the ground and in a region with stable winds.

Thin film cells are primarily installed on flat roofs, and polymer membranes support the structures. Solar shingles, which assume the shape of cascading roof tiles, are used in pitched roofs. Façade structures are solar modules that are installed on the exterior of buildings. In addition to harvesting solar energy, the solar façade installed on the exterior of the building also enhances the aesthetic appeal and weatherproofing against the elements (Nave, 2017). Partially transparent solar modules are employed in the glazing of skyscrapers. The glazing helps in reducing the cost of construction by substituting some of the building components that are made of glass such as skylights and windows (Rhodes, 2010).

The state of the art developments in solar energy includes the development of quantum dot p-n junction that has an advanced photovoltaic effect and better solar energy absorption capabilities (Semonin et al., 2011).

Conclusion

The present technical report aimed to discuss the utilisation of solar energy in energy efficient building structures. It was noted that solar energy is a better source of solar energy for buildings based on cost and maintenance considerations. The depletion of fossil fuels resources and the growth in energy use by buildings are some of the factors that justify the use of solar energy. Besides, the report outlines the mechanisms through which solar radiation is converted to direct current using solar modules, p-n junctions, and inverters. It was deduced that the radiation that is provided by the sun could satisfy all the energy requirements of the modern worlds.

References

Energy Information Administration (2017) How much energy is consumed in U.S. residential

and commercial buildings? [Online]. Available at: [Accessed 16 October 2017].

Lee, J. U., Gipp, P. P. and Heller, C. M. (2004) ‘Carbon nanotube p-n junction diodes’,

Applied Physics Letters, 85(1): 145–147.

Nave, R. (2017) P-N Junction, Georgia State University [Online]. Available at:

[Accessed 17 October 2017].

Rhodes, C. J. (2010) ‘Solar energy: Principles and possibilities’, Science Progress, 93(1): 37–

112.

Semonin, O. E. et al. (2011) ‘Peak External Photocurrent Quantum Efficiency Exceeding

100% via MEG in a Quantum Dot Solar Cell’, Science, 334: 1530–1534.

US Department of Energy (2017) Planning for Home Renewable Energy Systems [Online].

Available at: [Accessed 17 October 2017].