What is a passive energy-saving building? It mainly refers to a building energy efficiency approach that does not rely on building equipment, but fully achieves energy savings through the design of the building's own site, space, form, and components. Its core lies in the design concept of absorbing natural energy, reducing the building's own energy consumption, and recovering heat and cold from indoor exhaust air through heat and cold recovery devices, so that the temperature and air inside the building are not affected by region or climate, ultimately achieving low energy consumption and low emissions.

Leading the field of energy-saving buildings

According to materials, the so-called "passive low-energy houses" built in Frankfurt, Germany, adopt various energy-saving technologies to construct optimal building envelopes, maximize the building's thermal insulation and airtightness, and minimize the building's heating and cooling demands; at the same time, through various passive building measures such as natural ventilation, natural lighting, and solar radiation heat gain, they achieve indoor comfortable thermal and humidity environments and lighting environments as much as possible, and minimize or eliminate the use of active mechanical heating and cooling systems.

Over the past 20 years, passive houses, as energy-saving buildings with low energy consumption and extremely high comfort, have been rapidly promoted and widely applied around the world. After canceling all nuclear power plants nationwide, Germany announced that to solve energy and environmental problems, it would achieve passive energy-saving buildings nationwide by 2018. The EU stipulates that from 2020, only passive houses will be allowed to be built in the EU region. Passive energy-saving buildings have already stood at the forefront of the world's energy-saving building field. For China, which is under the dual pressure of an energy shortage crisis and a smog crisis, the introduction of passive energy-saving buildings is of practical significance.

Mature timing for promotion and application

As is well known, with the rapid development of urban construction, China's building energy consumption has risen significantly year by year, and total building energy consumption has increased. Enormous building energy consumption has become a huge burden. Comprehensive energy conservation in the construction industry is imperative. Building energy efficiency is bound to become a major direction and main focus of energy conservation and environmental protection in China. Experiments show that a passive energy-saving house with a floor area of 10,000 square meters can reduce carbon dioxide emissions by 103.43 tons per year and save 42.59 tons of standard coal per year compared with ordinary residences, with an overall energy-saving ratio of more than 90%. Passive energy-saving buildings are a path to energy conservation and environmental protection that is entirely feasible and worth anticipating.

At present, the domestic energy-saving design standard for public buildings is 50%, and the energy-saving design standard for residential buildings is 65%. The concept of "near-zero energy" buildings has gradually been accepted by people. The timing for the application and promotion of passive energy-saving building technology is mature.

The latest practical achievement of China's passive energy-saving building technology is the "Zaishui Yifang" project. In Qinhuangdao, where it is still chilly, this house built in the Haigang District is warm as spring. No traditional heating or cooling devices are installed in the house, yet the indoor temperature can remain between 19 and 26°C all year round. Test data show that the heat transfer index of the project's building envelope is about one-third of the domestic 65% energy-saving house design standard, and the building's airtightness n50 ≤ 0.6, that is, under an indoor-outdoor pressure difference of 50 Pa, the number of air changes per hour is less than 0.6, comparable to the world's advanced level. This shows that the building can fully rely on internal facilities and the normal heat emitted by the human body, such as heat from lighting, cooking, people, and office equipment, to meet heating needs. At the same time, a fresh air heat recovery system is also adopted, which can recover more than 75% of the heat from indoor exhaust air and, after filtering, introduce outdoor fresh air into the room. Even if windows are not opened frequently, it can ensure "spring-like air" indoors throughout the year.

Although passive houses have high construction costs, a one-time investment brings long-term enjoyment of zero energy consumption. There is reason to believe that passive energy-saving buildings will increasingly be accepted by the construction industry and the public in China.