Introduction

Most of the activities in a city are taken place in the buildings which explain they are one of the key elements in an urban design. According to Dr. Cheong Koon, buildings in a city represent the muscular system in the human body, where all activities took place [1]. There are various categories of buildings such as residential buildings, commercial buildings, and government buildings. Buildings can too be an attraction for sightseers and visitors. With the intention of contributing to economic development as well as avoiding environmental effects, these building-related-factors must be considered in urban designs 1) resource conservation 2) cost efficiency and 3) design for human adaptation [2].

Discussion                     

Energy Conservation

Buildings in modern eco-friendly cities must be energy efficient, especially with the ever-depleting problematic fossil fuels. An ideal building by means of energy conservation must reduce energy consumption and produce energy through various green technologies. This term is called net zero which means it can produce energy as much as it consumes. A more preferred idea is sharing the extra energy generated in a building with other buildings. Moreover, this will reduce the reliance on unrenewable energy specifically from fossil fuels.

The approach to reducing the energy consumption is by harvesting natural energy surrounding the building to replace the current practices. For instance, commonly buildings obtain light from lamps and light bulbs, which will increase the usage of electricity. With precise designing, it is possible to use natural light from the sun through windows. If the sun is covered by the stormy clouds, light emitting diodes (LED) can be used to replace conventional incandescent bulbs as it is more durable, last longer, and way more efficient [3]. Although it is slightly more expensive, in a long run, it will be cheaper because it lasts longer due to the absence of filaments. Other than that, natural air ventilation is also a method to reduce energy consumption primarily from air conditioners that consume massive energy.

Nowadays, the world is gradually transitioning from expending fossil fuels to renewable resources. This forced scientists and researchers to discover numerous solutions as substitutes for the diminishing fossil fuels. There are several initiatives, technologies, and designs that can be implemented in buildings for a sustainable urban city.

Solar energy

The existing practice of harnessing solar energy is using photovoltaic panels or solar panels in photovoltaic power stations or solar farms which require open spaces. Nonetheless, urban areas have the lack of free space as they are crowded with buildings and infrastructures. Thus, by relating both ideas, photovoltaic solar panels can be installed on buildings where solar energy is available.

Picture 1: Photovoltaic power station that uses a lot of space [4]

Before installing the panels, gathering information is crucial as it determines the efficiency of the solar panels. The Global Horizontal Irradiance (GHI) is a guide to have photovoltaic installations in particular regions in the world. The higher the value, the more effective the photovoltaic installations are. GHI is the overall amount of shortwave radiation obtained from above by a surface horizontal to the earth [5].

Picture 2: The Global Horizontal Irradiation 2016 [6]

In a smaller scale, the technology of a 3D city simulator has already existed and is created by the city?s information. This can help to perform wind flow modeling to determine the air flow quality of the city, shadow analysis to select the suitable spots for outdoor sites, and determining solar irradiance within a city which helps to decide the best positions to install solar panels [1]. By benefiting this knowledge, solar panels can be installed in appropriate buildings.

Another recent yet very revolutionary innovation concerning solar energy is from the SolarWindow? Technology, Inc. which is the developer of transparent electricity-generating coatings for glass windows on tall towers and skyscrapers [7]. In other words, they succeeded inventing a glass that can harness energy from natural, shaded, and even indoor lights. Besides, it generates power significantly more efficient than other types of solar panels. This can be proved in the chart below. Plus, it is primarily made of hydrogen and carbon – two of the most abundant materials found in nature. However, it is not yet available for sale and is still under development for better results. This technology is without doubt very appropriate to imply in the buildings of an eco-city.

Picture 3: Transparent electricity-generating coatings for glass windows [7]

Chart 1: Comparison of SolarWindow? and other Solar-PV in removing CO2 chart [7]

Moving on, the benefits of solar energy are countless. Sustainability is one of the main rewards of solar energy. The future generation can continue to rely on the same buildings for many more generations and it will never run out. Next, the solar energy will significantly reduce the dependence of power stations. The solar panels will provide enough power even at night. So, electricity from power station can be more focused on other requirements such as transportation. Last, solar energy is clean and does not release harmful gasses during power generation. It also does not affect the environment.

However, there are some disadvantages such as high cost, and intermittent. These can be overcome. It is way cheaper in a long run and has a battery that will save energy during the night or cloudy days.

Wind energy

There are several concepts that relate to harness wind energy in buildings. This would be possible as the wind is also one of the renewable energies in the world. Basically, wind turbines will be installed in the design of the building and any wind will run the turbines thus generating clean electricity. This will also be improved by the wind flow modeling simulator technology that can determine the most efficient wind flow in the city. However, there are severe problems arise as the cost of wind turbines is enormous. Also, the buildings with wind turbines will affect the air flow of the city thus the air quality is reduced.

Biomass energy

Biomass energy is not an exception to renewable energy. It uses organic waste and converts it into primarily methane, CH4, a combustible gas through decomposition to generate electricity. It is not impossible to apply it to an efficient building. A recent yet also revolutionary innovation uses biomass which will be left decomposed by microbes and then benefits the biogas produced in stoves for cooking. This technology also produces high-quality liquid fertilizer. The technology is named Home Biogas and is used in households [8]. We can apply this to our situation. The residents in the apartment will dispose of organic waste such as food scrapes and animal manure. The waste will then go to the process and thus biogas and fertilizer are obtained. The only difficulty is that it requires at least three weeks after usage to produce biogas and might have occasional maintenance to check if leakage is present as it releases a horrible pong.

Picture 4: Home Biogas cycle [8]

Conclusion

Buildings are essential in any city and also consume a lot of energy. With precise and strategic design, it can be a power generator and not just a consumer. Therefore, when the buildings are efficient, the city will also be efficient.

Reference