花牌评级网： Near Zero Energy Consumption Enters Smart Farm Houses
Is there a building in the world that does not need air-conditioning during a hot summer or heating in cold winter, to keep its interior at a comfortable temperature? But can a building adjust to these changes on its own? Pushing open the door to the entrance of Banbidian Village, Weishanzhuang Town, Daxing District, Beijing, the "Ling (Chinese for Zero) House" with its nearly 400-square-meter beautiful courtyard, is such an intuitive building.
According to China's National Technical Standard for Nearly Zero Energy Building, the Ling House was renovated based on a traditional farmhouse in 2019. It is the first Nearly Zero Energy Building (NZEB) that obtained an assessment logo in China, and won the Silver Award in the 2020 World Architecture News (WAN) Award for Sustainable Architecture.
Energy saving is the purpose of building NZEB
In recent years, against the background of the current global energy crisis and low-carbon emission reduction targets, countries worldwide have begun to find ways to carry out energy conservation and emission reduction initiatives, and the concept of NZEB arose spontaneously.
According to Zhang Shicong, a researcher at the Chinese Academy of Building Research, buildings account for about 30 percent of the world's total electricity consumption. With the aim of effectively reducing building energy consumption, developed countries have begun to research ways to improve building energy efficiency, and the development of NZEB has been significantly promoted.
Zhang said the term NZEB came from the EU, which issued the Energy Performance of Building Directive (EPBD) in 2002, and updated it in 2010, proposing that Europe should enhance building standards and make NZEBs compulsory.
As a result of the economic imbalance of EU member states and the large span of climate zones, the EPBD defines NZEB as a building with "very high energy efficiency". Based on the actual situation of various countries and on the premise of fully considering the cost-benefit ratio of energy-saving technology, no unified and clear quantitative energy-saving target exists yet.
However, China defined NZEB with mandatory index requirements. In common circumstances, compared with previous standards implemented in 2016, the energy efficiency of NZEB is improved by 60-75 percent.
At present, NZEBs in China refer to the buildings that minimize heating, air conditioning, and lighting needs by passive building design and maximize energy equipment and system efficiency by innovative technical measures, providing a comfortable indoor environment by making the most of renewable energy sources and minimum energy consumption, and whose indoors environmental parameters and energy efficiency indicators comply with standard provisions.
Save energy actively: make full use of solar energy
Looking around Ling House from the outside, there is a red brick and tile-roof local style building under the shade of green trees. The interior is designed with bright and clean lines, featuring large windows and a well-arranged layout.
"The roof cover is composed of 14 colored photovoltaic film panels, with a total area of 22.7 square meters, which not only have good light transmittance but also can generate electricity," said Ren Jun, professor of School of Architecture at Tianjin University.
Climb up the steps to the terrace on the roof of the house, and people can see plenty of gray-and-black tiles covering the entire roof. "These are Hanergy solar tiles," said Ren. "It covers an area of 96.4 square meters, and together with the roof of the sun gallery, it can generate enough electricity to supply most of the electrical equipments in the house."
"The angle of the main roof and the roof of the sunroom is at 40 degrees, so that even if the snow falls heavily on it, it will soon melt away. It can maximize the use of the solar energy and store more electricity," said Ren. In addition, a solar hot water system is set up on the terrace to provide hot water for the kitchen and bathroom.
Passive Energy Conservation: "Dress the house in a padded jacket"
The outer walls of the house are filled with insulation material, and are 80cm thick (generally house walls are only 30cm thick), while the roof and floors are all covered with a 30-centimeter-thick insulation layer, as if the whole building has been placed in a warm bed.
With this design, Ling House's airtightness coefficient of passive energy-saving transformation measures 0.6, far lower than that of traditional buildings which measure 10. In other words, even if the wind blows to force 6 or 7, the people in the house standing near the windows will not feel any cold wind coming in.
"We aim to achieve Nearly Zero Energy Consumption, which requires us to study different structural systems for the technological paths and construction nodes of Nearly Zero Energy Consumption. Therefore, brick-wood structures (retain units), light-wood structures, and modular structures (new units) are adopted," said Ren.
But will the construction be stuffy and how is the interior temperature and airflow adjusted? "This depends on the operation of the air source heat pump, which saves power, while ensuring the environment is cool in summer and warm in winter," said Ren.