Joe Biden’s first job as the 46th President of the United States in January of this year was to sign an executive order to return to the Paris Agreement on Climate Change. The Paris Agreement on Climate Change, which almost lost its light when the US withdrew as it was unfavorable to its own country, once again received a spotlight and received great strength from the international community.
The Paris Climate Change Convention, adopted by 195 countries at the 2015 UN Climate Change Convention Conference of the Parties, is a treaty that contains the goals of reducing greenhouse gas emissions from countries around the world to prevent future climate catastrophes. Greenhouse gas, represented by carbon dioxide, has rapidly increased as a result of mankind’s massive use of fossil fuels to obtain energy, and it is pointed out as the cause of global environmental problems, such as global warming, where the earth’s average temperature rises and changes in weather occur.
Korea, which participates in the Paris Climate Change Convention, is the seventh-largest greenhouse gas emitter in the world, and aims to reduce as much as 37% based on the projected GHG emissions by 2030. In order to achieve the reduction target, a national roadmap was drawn up that set detailed targets for each sector. Buildings are the sector that has the highest reduction rate in the future, which should reduce greenhouse gas emissions the most. In buildings, 32.7% of emissions should be reduced, which accounts for 20.5% of the total greenhouse gas reduction.
Zero energy mandatory for apartments from 2025
Living organisms need energy for their life-sustaining activities, and this applies equally to buildings. Buildings are supplied with energy to light up the darkness, adjust the indoor temperature against cold and heat, and operate internal facilities such as elevators and ventilation systems. However, the amount of energy used by buildings is quite large, accounting for about a fifth of the total energy consumption and about a quarter of the total greenhouse gas emissions.
In order to reduce the generation of greenhouse gases in buildings, that is, to reduce energy consumption, Korea introduced the’Zero Energy Building Certification System’ in 2017. Zero Energy Building (ZEB) is literally zero energy consumption and does not consume energy. The relevant statute, 『Green Building Construction Support Act』 stipulates that it means a green building that minimizes energy consumption by minimizing the energy load required for buildings and utilizing new and renewable energy.
The zero-energy building certification system is expected to be changed to mandatory rather than optional, so it is predicting a major change in the future. Following the mandatory zero energy requirement for new public buildings in 2020, the mandatory requirement will be extended to the private sector from 2025. Private buildings of 1,000 square meters or more and apartment houses of 30 households or more are required to obtain a zero energy building certification in order to obtain a building permit.
Zero-energy building certification is mandatory for new public buildings, and will be expanded to private buildings. Ⓒ Ministry of Land, Infrastructure and Transport/Ministry of Trade, Industry and Energy/Korea Energy Agency 『Zero Energy Building Certification Guide』
In order to be certified as a zero energy building, it is necessary to first obtain a rating of 1++ or higher in the building energy efficiency rating evaluation. For residential buildings above 1++, the annual energy consumption should be less than 90kWh/m², which is about a third of the size of a regular building.
In addition to using less energy, the building must be able to produce a certain portion of the energy it uses. Among the energy used by buildings, the proportion of energy produced is called the’energy self-sufficiency rate’, and in order to be certified as a zero-energy building, at least 20% (level 5 standard) must be exceeded. In addition, for efficient energy management, a building energy management system (BEMS) or a remote inspection electronic meter is essential.
Although it is the lowest grade even if it produces only 20% of the energy used by a building, it is recognized as a zero-energy building because increasing energy self-sufficiency requires considerable cost and still has many technical problems to be solved.
Zero-energy buildings are attracting attention around the world to reduce greenhouse gases generated by buildings, but each country has a different target level. Standardization is not easy because climatic conditions, houses, architectural styles, economic conditions, technology levels, and costs are all different. In common, the goal of advanced countries is that they are not targeting completely zero energy, but virtually zero energy buildings (nZEB).
Passive house that reduces consumption and prevents spillage
All apartments built in Korea from just four years later cannot escape the zero-energy building certification. The most important thing to realize zero energy in the apartment is to reduce the energy consumption itself.
Minimizing the energy load in a building is called a passive strategy, and a house made in this way is called a passive house. The passive strategy aims to maximize the ability to control the natural indoor environment of the building and install only the required capacity to a minimum.
In order to reduce the load such as cooling/heating, ventilation, and lighting, which uses a lot of energy in the apartment, after analyzing the occupancy conditions such as climate and ground conditions, determine the direction and arrangement of the main building of the apartment in consideration of the azimuth and altitude of the sun and the wind path You need to do something. In terms of life, how and in which direction each building is arranged in an apartment is closely related to determining the basic metabolism, so it is the first and perhaps the most important task for realizing a zero energy building.
Zero-energy buildings are made with passive, active, and renewable technologies. Ⓒ Ministry of Land, Infrastructure and Transport/Ministry of Trade, Industry and Energy/Korea Energy Agency 『Zero Energy Building Certification Guide』
The next thing to think about after completing the main layout of the apartment is to conserve the heat produced by investing energy inside the building and hold it so that it does not easily escape outside. It’s like applying Munpoong paper to the entrance door on a cold winter day, and putting a pop-poong on the window to prevent external cold air and to protect the internal warmth from escaping.
At the end of the 19th century, Norwegian explorer Friedschof Nansen, when exploring the North Pole, maximized natural light from his rover, covered it with a high-insulation jacket, sealed it to prevent air leakage, and used triple glass to prevent heat from escaping. Thanks to this, Nansen’s probe was able to maintain a temperature of 22 degrees Celsius without heating when exploring the Arctic.
Over a hundred years have passed, but today’s passive technology that minimizes energy loss is no different from Nansen’s probe. First, reinforce the insulation of windows, walls, and roofs where heat can easily escape. Thick insulation is used for the outer wall, and windows with poor insulation performance are made into double windows, or argon gas is injected between the windows to significantly improve the insulation performance. In order not to build up heat through gaps such as windows, doors, and walls, construction with improved airtightness and tight finish are important.
Need for economical technology development to mandate
In order to achieve the goal of a zero-energy building, an active strategy that can reduce the energy use of the building or generate energy by itself is also required. The active strategy aims to increase the energy efficiency of facilities and devices used mainly in homes, and to actively manage buildings so that they do not waste energy.
High-efficiency boilers, which are gaining popularity in individual heating apartments, are technologies that increase the energy efficiency of boilers by using condensing heat exchange and waste heat recovery, which reuses the heat of steam contained in exhaust gas. Although the power of LED lighting is one-fifth of that of general lighting, it has a whopping 15 times longer lifespan, which is very effective in saving energy. For this reason, these days, there are cases where LED lighting is used throughout the apartment complex.
Periodic ventilation is required to create a comfortable indoor environment in an apartment, but there is a problem that heat loss is large because the air must be changed when ventilating. When ventilation is equipped with a total heat exchange ventilation device that exchanges heat energy of the outside air entering the room and the indoor air outside, it is possible to save energy by reducing heat loss.
The Building Energy Management System (BEMS), which is required to obtain a zero-energy building certification, measures the amount of energy used in the building in real time, and through various sensors, the indoor and outdoor environment of the building and the efficiency and energy consumption of each facility It is a system that optimally manages to create a pleasant indoor environment after analyzing the data. Since it helps the efficient operation of ventilation and heating and cooling, energy consumption can be actively reduced.
Hillstate Lake Songdo, the first apartment in Korea to be certified as a zero-energy building. You can see the solar panel attached to the wall of the apartment. Ⓒ Hyundai E&C
Renewable energy is a technology that directly produces the energy required for buildings, and it uses a lot of sunlight, solar heat, geothermal heat, wind power, and fuel cells. Among them, solar power is by far the leader, and solar panels are installed on the roof and exterior walls of apartments to generate electrical energy from sunlight. Electricity produced through solar panels is used for common facilities such as elevators and parking lot lighting.
Fuel cells, which have recently attracted great attention due to the obligatory zero-energy buildings, are technologies that produce electric energy by reacting hydrogen with oxygen in the air. Unlike solar power generation, since it is not affected by the weather or time, it is possible to supply stable energy, but it still has the disadvantage of lack of economic feasibility.
Zero-energy buildings are reality, not the future. If the apartment is made into a zero-energy building, you can live in a comfortable indoor environment without paying almost any energy cost even in the midst of a heat wave or cold wave. By realizing a zero-energy building, it is possible to achieve the effect of one stone and two trillion, contributing to environmental protection by reducing the generation of greenhouse gases, while reducing the burden of various energy costs.
However, in order to create a complete zero-energy building with the current technology level, the cost of construction rises by more than 40%, so economic feasibility cannot be secured. Experts assume that the annual energy cost per apartment household is approximately 1.5 million won, and then determine that approximately 25 million won, the amount used for 15 years, is appropriate as the initial installation cost of zero energy. In order not to increase the sale price of new apartments in the future, it is very important to develop an economical and efficient zero energy technology.
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