Korean Case: Energy Zero, a ‘profitable and sustainable’ housing complex

The nation’s first “zero-energy” multi-unit housing complex, “NOWON EZ House,” was named after English initials of Energy and Zero. EZ is easy to pronounce and denotes “profitable and sustainable” housing. Energy-zero housing, NOWON EZ House, was completed in October last year and was created by Nowon-Gu with the support of the Seoul Metropolitan Government and the Myongji University Industry and Academia Cooperation Foundation under the auspices of Ministry of Land, Infrastructure and Transport. Since it is the first project of constructing a housing complex with a focus on independent energy production and greenhouse gas emissions reduction from the architectural designing phase, NOWON EZ House has drawn a lot of attention for its energy saving capability and sustainability. Benchmarking “passive house” technologies at the German level, the House applied 100% Korean zero-energy design technologies and domestic materials and was constructed with the technology of Korea reflecting Korean people’s lifestyle, local climate, and residential environment, which adds significance to the project. The House also contributed to the housing welfare of the vulnerable population as many public housing units were supplied.

“A house is a power station to live in. And its energy efficiency is determined by building envelops.” This axiom by Myoung-ju Lee, chief of research foundation for the project of NOWON EZ House in charge of planning, design, and R&D, speaks for the House itself. “A house is a power station to live in” means electricity needed for the house is generated on its own by the house, and “Its energy efficiency is determined by building envelopes” means that the insulation and air-tightness of building envelopes are as important as the installation of renewables. The House constructed is the first case of its kind for multi-unit housing in Korea, where highly energy-efficient installations are provided to a housing space that requires smaller energy consumption, and energy shortages are compensated by renewables so that residential activities can be possible without fossil fuels. 



NOWON EZ House is a national R&D project offered by the Ministry of Land, Infrastructure and Transport in 2013 and managed by the Korea Agency for Infrastructure Technology Advancement. The Myongji University Industry and Academia Cooperation Foundation, serving as project manager, founded a consortium (Zero Energy Housing Consortium) for zero energy housing research with KCC E&C and Seoul Housing & Communities Corporation as collaborative research partners and with ZED Architects, Nuri Telecom, Han kook Engineering, PRIMO as a collective research group. In July 2013, Myongji University’s Zero Energy Housing Consortium signed an MOU with Nowon-Gu and the Seoul Metropolitan Government and applied for a R&D project offered by the Ministry of Land, Infrastructure and Transport as a consortium. The Consortium was eventually selected as winner of the project in September 2013, and the zero energy housing research was launched in the form of industry-academia cooperation. The planning, design, construction, inspection, and monitoring were the responsibilities of the Zero Energy Housing Consortium led by Professor Myoung-ju Lee of College of Architecture at Myongji University. A plan was established to achieve complete annual zero energy for primary energy consumption needed for daily lives in each household such as heating (20°C) and cooling (26°C), quick hot water, lighting, and ventilation in 121 household units of NOWON EZ House. The housing complex consists of three apartment buildings (106 households); one row-house multi-unit housing building (9 households); two twin-house multi-unit buildings (4 households); and one detached-house multi-unit housing (2 households), or a total of 121 households (in total coverage area of 17,652㎡). Auxiliary facilities includes education & promotion hall, green park facilities, senior citizens’ community center, community hall, library, and seminar room. 

Goal Housing complex optimization model development and demonstration complex construction with existing technologies for expanded distribution of zero energy housing  
  • R&D project offered by the Ministry of Land, Infrastructure and Transport for the development of the nation’s first zero energy housing complex standard model that responds to climate change and eases residential costs
  • Demonstration of multi-unit housing where primary energy consumption and production are equal (net zero) in terms of five main residential energy consumptions (heating, cooling, hot water, ventilation, and lighting)
  • (Location) Hangeulbiseok-ro 97 (or Hagye-dong 251-9), Nowon-gu, Seoul
  • (Size) Land area: 11,344㎡; total coverage area: 17,652㎡ (two basement floors, seven stories high; 128 parking spots) 
  • (Project period) Oct. 29, 2015-Oct. 24, 2017
  • (Construction cost)* 32.2 billion won (10.9 billion won for R&D; national, city, and Nowon-Gu subsidy: 21.3 billion won)

* Including auxiliary facility constructions such as government ordered constructions, PR hall, community facilities, commercial facilities, balcony, and two basement floors, etc. 

  • (Demonstration goal) Energy-zero multi-unit housing in terms of five main energy consumptions  
  • (Composition) 121 households of Public Happiness Housing*, one mock-up housing, and one PR hall 

* 106 households of multi-unit housing (39-59㎡), 9 households of row-house (49㎡); 4 households of twin-house (59㎡); and 2 households of detached-house (59㎡). 

Result Building Energy Efficiency Grade: 1+++; Top Grade of Green Architecture; and certified international passive house


Concept of Zero Energy

Five kinds of energy demands essential for residence are heating (20°C), cooling (26°C), quick hot water, ventilation, and lighting. When the energy independently produced within the housing complex suffers shortage, energy from outside supply loop is borrowed, which is returned when the complex has excess energy. This way, when borrowed consumption and return of primary energy cancels each other out with the sum being zero, it is referred to as “net zero primary energy.” To achieve this, NOWON EZ House combined passive design technology and active design technology including high-efficiency facilities.


The convergence of passive design and active design

Key to human-oriented design is to maintain the most comfortable temperature with minimal energy consumption without tolerating cold or hot environment to save energy. The House ensured that no internal heat or cold air seep out of the building by applying passive design technologies including external insulation, triplex-glass window, thermal break, enhanced air-tightness, external blind, and heat recovery ventilator. With these passive technologies energy efficiency of the building was maximized, with energy shortages being compensated by renewable energy produced within the housing complex enabled by active technologies including facility technology.


According to the Passive House Institute in Germany, a passive house is technically both economical and environmentally friendly as residents can feel thermally pleasant in both summer and winter with only post-cooling and post-heating through a heat-recovery ventilation system without extra installation of traditional heating/cooling facilities. To go beyond passive house, a lot of work was done from the phase of design to dramatically reduce energy consumptions of heating, cooling, quick hot water, ventilation, lighting in an effort to make NOWON EZ House a zero-energy housing complex. To stably supply energy for five primary energy demands at extreme recent temperatures of 40°C in summer and -20°C in winter in Korea, insulation and air-tightness of the building envelopes were enhanced first, with installation of central heat recovery system afterwards. In addition, a high-efficiency facility system was installed with a design of convergence with renewable energy source. Photovoltaic cells were designed to supply electricity for the operation of geothermal heat pump–responsible for heating (20°C), hot water, and cooling (26°C), and ventilation through heat exchanges–and for lighting. The total capacity of photovoltaic cells installed at NOWON EZ House is 409 kW (3.4 kW x 121 households). During power shortage, power is supplied through an energy grid connected with the outside, which is returned with surplus power. NOWON EZ House aims to be a “net-zero primary energy” housing with the debits and credits of energy consumption and production canceling each other out.



Saving energy costs

NOWON EZ House’s electric bill per household was 43,705 won in July 2018 and 47,718 won in August 2018 (including VAT). This includes other electric consumptions such as cooking, home electronics, and electric consumption in common areas of the complex, as well as five primary energy demands of the building needed for cooling/heating/hot-water, etc. needed to maintain indoor temperatures at 26-28°C for 24 hours a day during the whole month of 31 days. The same amount of energy consumption in ordinary residential households would incur three to five times bigger electric bills. Whether the House will achieve net-zero primary energy in terms of the consumption/production of the five primary energies will be learned after monitoring energy consumptions in the winter season. For this purpose, Myongji University’s Zero Energy Architecture Center is monitoring the House jointly with Korea District Heating Corp. and Nowon-Gu, which will continue until 2021. In terms of ECO2 in building energy evaluation program, the House is expected to save energy costs 60% more than ordinary houses. Actual measurement will be announced after the monitoring of annual energy consumption is completed in February 2019.


Effects of greenhouse gas emissions reduction

NOWON EZ House, certified as Passive House Germany, is expected to play a big role in reducing greenhouse gas emissions. Since the reductions of CO2 achieved by photovoltaic cells outrun the CO2 emissions from the House as a whole for the year (-34.905 tCO2/yr), the House can also be called “net-zero CO2 emission housing.” In comparison to ordinary houses constructed under the 2016 Housing Act which emits (166.247 tCO2/yr), the House is projected to reduce CO2 emissions by as much as 120% a year.


Analysis of economics

A total construction cost of NOWON EZ House is 32.2 billion won, spending 5,990,000 won per pyong (3.3㎡) for a gross floor area of 17,652㎡. The cost includes the construction of all auxiliary facilities such as community facilities, commercial building, and underground parking floors. For the application of active design (photovoltaic and geothermal facilities, etc.) and passive design (insulation, air-tightness, etc.) needed to achieve zero energy housing, an additional cost of around 48 million won is incurred per household (16 million won for passive design and 32 million won for active design on average). In other words, zero energy housing requires 30% greater construction costs compared to ordinary buildings. The challenge is to reduce installation costs of renewable energy facilities responsible for heat supply. In addition, further research is needed on values created by fossil fuel use reduction and carbon dioxide emissions reduction for a comprehensive analysis of zero energy housing economics. NOWON EZ House will allow for the collection of big data on zero energy housing for the first time in Korea though the monitoring of energy consumption and production of the House. This will contribute to the standardization of data collection and measurement of zero energy housing, which will advance the distribution of zero energy housing with economic benefits.


Achievements and benefits

Various results were accomplished with the construction of zero energy housing complex as 100% domestic technologies and 98.3% domestic raw materials were used to demonstrate an optimal model of housing complex based on existing technologies aimed at expanding the distribution of zero energy housing. Major achievements are as follows.


No. Achievements
1 Built the nation’s first 2Bay-3Bay zero energy housing complex with buildings facing south
2 Net-zero primary-energy multi-unit housing built
3 Electricity production of 418,000 kWh/yr with photovoltaic installation
4 Integrated large-capacity photovoltaic panel installation on the façade of the building
5 Application of fire-resistant external insulation system
6 Highly air-tight multi-unit housing complex achieved (61% energy consumption reduction with passive technology, 13% reduction with high-efficiency facilities, and net-zero primary energy)
7 Triplex glass window (tilt and turn) applied
8 Thermal breaker installed at protruded balcony
9 External electric blind installed for all households
10 Central heat recovery ventilation equipment installed for dual use of heating/cooling and ventilation
11 Facility advancement combining heating/cooling and quick hot water with geothermal system
12 Enabling separate measurement of five different energy consumptions in the building
13 Monitoring screen installed for occupants and operators
14 Enabling large-scale energy production monitoring
15 Application of micro grid (power production and consumption)
16 Development of zero energy multi-unit housing business model, design guideline, and operation manual
17 Certified as top-grade Green Building
18 Building Energy Efficiency Grade 1+++ obtained
19 Barrier-free Certification
20 Certified as Passive House Germany in multi-unit housing category


Moreover, NOWON EZ House is contributing to the residential welfare of the vulnerable group as it was planned for distribution as public lease housing. The 121 units of the housing were occupied by 101 newly-wed households, 12 households of the aged, two households of industrial workers, three households of EZ Community (expert households), two households for research and monitoring, and one guest house. The Nowon Energy Zero Housing, multi-unit housing in the form of cooperative run by the residents, brought about additional benefits, including residential welfare improvement and state-of-the-art residential environment experience, as well as climate action. It also runs a PR hall with exhibitions and a short-term experience house, giving the general public an access to the zero energy housing for experience, while contributing to the community of the village through community center. Community activities in combination with design and technological advances with multiple technologies applied and optimized model development are realizing the four-fold philosophies of NOWON EZ House: “Happy People; Shared Village; Pleasant Environment; and Warm Building.”