REVIEW OF RELATED LITERATURE Carbon Dioxide is a natural gas that is essential for plants for producing food and oxygen through the process of photosynthesis and the levels of these gases kept balance through the years

REVIEW OF RELATED LITERATURE
Carbon Dioxide is a natural gas that is essential for plants for producing food and oxygen through the process of photosynthesis and the levels of these gases kept balance through the years. However, since the Industrial revolution, using fossil fuels, oils and natural gas become the primary source of energy for these growths and it increased the levels of Greenhouse gases exponentially by 260% that caused Global warming. (Horton, 2018)
2.1 Greenhouse gas Emissions of the Philippines
According to the report of European Commission, Philippines emits 126.9 Mt of CO2 per year recorded in 2016, this is 3-times higher compared to 41.57 Mt of CO2 which recorded in 1990 ( Janssens-Maenhout, et al., 2017). Based on a 2010 report, energy and building sectors are responsible for 43% for total contribution of GHG emissions ( Janssens-Maenhout, et al., 2017). In a recent report of Department of Energy, 2016 has a significant increase in consumption of electricity by 10%, such increase was caused by commercial sectors which is about 27.9 %, residential sectors 27.7%, Industrial 25.4%, Others 1.4%, Own-use 9.7% and system loss 7.9%. (Philippines Electricity Demand-Supply Snapshot, 2016).
According to a recent study, energy consumption would increase up to 189 Tera-watt/hour in 2030, mostly will come from commercial sector with a 3.6 times increase and would use 26% of electricity. To supply this increasing demand, the Philippines draws energy from coal 48%, natural gas 22%, oil 6% and renewables 24% (Esguerra, et al. 2010).
2.2 Improving efficiency of buildings through architectural design
In a published book of (Trubiano, 2013), she stated that by taking advantage of the natural resources and following design principles, Climate responsiveness can be achieved to maximize the performance of the building. Maintaining thermal, lighting, cooling and ventilation within the comfort range significantly reduces amounts of additional energy. Proper selection of site is crucial in the design process, access to sun, air and water determines possible power generation, lighting, ventilation and thermal heating. In addition, by manipulating the building’s orientation lessen excess heat gain and maximizes exposure to fresh breezes.
As stated by (Trubiano, 2013), a well-constructed energy-free design reduces the likelihood of needing excessive energy while maintaining comfort of the users. Building performance can be calibrated through transmission of daylight, natural ventilation, vegetation and thermal lag to achieve maximum efficiency. Thermal Lag is the time delay of heat being absorbed by the mass and reradiated. In this way, the temperature within the building is cooled down with minimal use of mechanical ventilation or cooling.
2.3 Concepts of low impact building
Zero Energy Buildings (ZEB) preferably is a building that through optimal energy efficiency it satisfies and generate the energy demand through renewable sources (Torcellini, et al. 2006) added that primary source of energy may come from sun, wind earth and water. In a recent study states that zero energy buildings produce energy equal to the energy it spent and have less to zero carbon emission over a period of time (Kilkis, 2007). Zero energy buildings achieve sustainability not only through renewable sources of energy, but also through the building materials and energy-efficient design. (Torcellini, et al. 2006)
While zero energy building uses non-polluting renewable resources, it usually uses conventional energy sources such as natural gas and electricity. When the building generated excess energy on site, the excess electricity is exported back to the utility grid to achieve energy balance, energy offsets is reserved for later use. Zero energy buildings without a utility grid would be difficult due (Torcellini, et al. 2006) limited amount of energy storage and might not sustain demand during peak season.
Zero energy building is defined in many ways, but depending on the boundaries, focus and project goals of the design. Net zero site energy is the amount of energy used is equal to the amount it uses every year on-site. Net zero source energy is the amount of energy used is equal to the amount it uses every year from the source. Source energy refers to the prime energy used that is being generated and delivered to the site (Torcellini, et al. 2006).
Net zero energy cost is the amount of money for the energy that the owner pays for the utility is at least equal to the amount of the utility pays for the energy exported of the building to the grid over a year. Net zero energy emission produces as much non-emission renewable energy, as it uses from emission producing sources of energy (Torcellini, et al. 2006).
2.3 Low carbon-embodied construction materials
While buildings consume energy during operation, it also consumes energy and produce carbon emissions during material selection in design phase. Materials that are used in building envelopes, interior and finishes has embodied energy and contributes to overall impacts to the environment. Embodied energy is the total consumed energy to manufacture, transport and hazardous emissions during the process. It is advisable to investigate materials for embodied energy during design phase, working with vernacular and recycled materials is highly recommended. (Shanin, 2013)
Natural materials do not only contain low-levels of carbon, but also said that these materials are toxic free compared to synthetic materials. Moreover, natural materials have low environmental impact during manufacture and disposal. It is said that natural materials perform better in insulation, breathability, permeability to moisture and thermal performance. Some examples of these natural renewable materials includes hemp, flax, straw, sheep’s wool, bamboo, cork, wood, and timber composites. (Woolley, 2013)
2.5 Gathering low-carbon renewable energy
Integrating and Harnessing renewable energy in the building is one of the best practices in sustainable building design. These forms of energy source do not diminish nor emit toxic waste like fossil fuels and nuclear power. There are some sources though renewable but emits carbon, such as Biofuels which is a type of energy manufactured from plants, composts and other organic materials.
Solar energy is where Sun is the most notable source of renewable energy. Light and Heat from the sun can be harnessed to generate energy. Wind energy depends on topography and location wind currents can be converted into energy through mechanical process using wind turbines. Geothermal energy is form of energy is harnessed from earth using vapor or water to transfer heat, but also varies from geographical location. Hydropower energy is a form of energy harnessed from moving water like lakes, rivers and water streams.
Energy from renewable technology does not provide constant flow of energy, it fluctuates depending variables such as weather, location and climate. That is why storage system is recommended to balance out energy demand and prevent power outage during high peak demand. (Shanin, 2013)
2.6 Human Factor in Building Performance
It is estimated that half of the energy used in structures varies on physical feature, equipment and behavior of the users. While buildings achieve sustainability, high performance and reducing energy consumption, the patterns of inhabitant makes a significant effect for the overall consumption of resources. Building occupants can be oriented to develop a lifestyle which is energy-conscious and familiarity with conservation (Trubiano, 2013).
Lifestyle such as group-oriented activities that includes exposure to daylight and natural environment helps occupants of the building to improve their communication and well-being. Integrating passive design does not only help save energy consumption but also helps the mind and body of the users to do their everyday tasks. (Heerwagen & Zagreus, 2005)
2.7 Related projects and their low-carbon practices