Source | new urbanism.

 

European countries for research and practice of energy saving building has always been very active and fruitful, a lot of new concepts and technologies from Europe, "Passive House" (Passive House) as a kind of energy-saving building, because of its unique research starting point and the gradually mature design, construction and evaluation system, in European countries is more and more get the favour of social from all walks of life, become academic research and design practice with a focus.

 

The basic situation of "passive house" building

 

The definition of "passive house" building

 

According to the European commission to support the European "passive house" to promote project definition of "passive house", "passive house" is the traditional way of heating and the initiative of the air conditioning situation to achieve a comfortable indoor environment in winter and summer construction.

 

Researchers from all countries agree that the biggest feature of passive house is that it minimizes the demand for heating and air conditioning through passive design.

 

Since the study and practice of "passive house" began in Germany, according to Germany's climatic conditions, most of the "passive houses" in Europe currently focus on the minimization of winter heating demand.

 

The concept of "passive house" was founded

 

"Passive house" in Germany in the 1980 s is the concept of low energy consumption building was set up, on the basis of 1988 Swedish Ada's deron Williams university professor Dr And German firth is first proposed this concept, they don't think "passive house" should be active heating and air conditioning system can maintain a comfortable and internal environment of architecture.

 

In 1991, the first "passive house" was built in darmstadt, Germany. In the past ten years since its completion, it has been operating in accordance with the requirements of design and has achieved good results.

 

In 1996, Dr. Fester created the "passive house" institute (PHI) in darmstadt, Germany. The institute is now one of the most authoritative institutions in the study of passive houses.

 

In Europe have tens of thousands of "passive house" is built, and the concept of "passive house" is no longer confined to residential buildings, in some public buildings, also gradually began to adopt the "passive house" standards for construction.

 

Passive house standard

 

The "passive house standard" is actually a design standard for building ultra-low energy consumption, which is not officially established, but rather a consensus among researchers.

 

In European countries, to really be certified as "passive house" must meet two criteria: 1) the annual heating energy consumption of no more than 15 KWH / ㎡; 2) building in total annual cost (heating, air conditioning, hot water, lighting, electrical appliances, etc.) not more than 120 KWH / ㎡.

 

 

According to these standards, existing buildings in winter heating can be reduced to Europe to less than 10% of the same kind of construction, construction of the total energy consumption can be reduced to less than 30% a year, carbon dioxide emissions can be reduced to less than 50%.

 

In Europe at present about ten thousand was certified as a "passive house" building, constructed in accordance with this standard, most of them are residential buildings, also include some office buildings, schools, kindergartens, supermarkets and other public buildings.

 

The main measures of "passive house" design

 

The current "passive house" project, design and build "passive house" architecture mainly committed to solve the problems of heating in winter, when the design concept of the core idea is to minimize building heat loss. The technical measures can be summarized into four aspects.

 

Strengthen the insulation performance of building maintenance system

 

The building maintenance system mainly consists of external wall, roof and exterior window, and strengthening the insulation performance of the enclosure system is the most important technical measure in the design and construction of "passive house". Just as one of the most important means of keeping warm in winter is to wear warm clothes, this is a very simple truth.

 

The "passive house" is the full play of this principle. On the basis of considering the performance and price of existing building materials, put on a warm coat for the building and block out the possible "cold bridge".

 

The exterior wall and roof of the building are the main body of the enclosure system. In the current "passive house" in Europe, XPS extruded polystyrene board and rock wool are used in the insulation materials of external walls and roof. In order to achieve the "passive house standard", the thickness used is very large.

 

Darmstadt, Germany, for example, built the first "passive house" building, the exterior wall with 275 mm of EPS polystyrene insulation board, the heat transfer coefficient is 0.14 w/(㎡ · K); Rock wool insulation roof adopted 445 mm, its heat transfer system is 0.1 w/(㎡ · K).

 

In other "passive house" projects have been completed, the heat transfer coefficient of exterior walls and roof are usually around 0.1 w/(㎡ · K).

 

Outside the window of the thermal insulation performance of glass and the window frame to read is very high, in many European countries of the existing buildings, most of the double hollow glass and broken bridge aluminum alloy frame, its heat transfer coefficient is 2.4 w/(㎡ k.), still far less than "passive house" heat preservation performance requirements outside the window.

 

Has built "passive house", building outside the window usually adopt three layer hollow glass and window frames with insulation sandwich, its heat transfer coefficient can reach 0.8 w/(㎡ · K).

 

The "cold bridge" becomes an important factor that affects the insulation effect of the envelope. In the design of existing buildings, "cold bridge" has also become a concern, but it is far from being avoided in the "passive house" design. Avoid "cold Bridges" in "passive rooms".

 

Improve the airtight performance of the building

 

Based on the concept of "passive house", the building should be an independent system which should not be disturbed by outdoor environment. Building palisade structure, therefore, should have the function of the can isolate indoor and outdoor air permeability, it is especially important during the winter, so the "passive house" architecture and outdoor air exchange is achieved through can control the mechanical system.

 

The airtight property of the building is very important for "passive house". Besides reducing the loss of heat, it can also control the humidity of indoor environment and protect the building structure.

 

In "passive house" building design, a lot of window fan is fixed cannot open, partial can open window fan to also want to meet high air tightness requirement when close.

 

In "passive house standard" there is a don't be strict but recommend using indicators, is in the building air tightness test, the requirements under the condition of the indoor and outdoor 50 pa pressure difference, air osmotic quantity of no more than an hour building 60% of the total volume.

 

Existing buildings in Europe, the indicators are still far cannot meet the requirements, usually between 200% and 400%, and in darmstadt, Germany built the first "passive house", which is only 30%, effectively reduce the heat loss in winter.

 

Mechanical ventilation and heat recovery

 

When the air-tight performance of the building is greatly improved, the appropriate ventilation and ventilation mode is especially important for "passive house".

 

To keep indoor air clean and health, must meet certain new wind force, in Europe, the new air volume indicators from indoor air ventilation 0.4 ~ 0.9 times per hour, the Beijing residential building energy efficiency design standards specified in the winter ventilation index was 0.5 times, and the requirements of the European countries are roughly the same.

 

In the existing buildings, open the Windows and doors and Windows aperture infiltration is the common way to realize construction ventilation in winter, but it will no doubt bring a lot of heat loss, and met the blow a cold wind over produce indoor comfort.

 

In "passive house", the ventilation index is completely needs to complete by means of mechanical ventilation, in every house, indoor air pollution from the kitchen and the bathroom vents into duct, air supply of fresh air from the living room and bedroom mouth into the room.

 

The construction of the exhaust heat recovery, and used to preheat the outdoor fresh air into the indoor is the realization of "passive house standard" one of the key technologies, currently in use in Europe the heat recovery efficiency of heat exchangers is very high, heat recovery can reach 75% ~ 90%, so the traditional building ventilation heat loss in winter in the "passive house" architecture is largely avoided.

 

The volume of the new air exhaust heat exchanger is small, usually installed in the ceiling of the building or in the attic. Due to "passive house" needed for the construction crew heating heat demand has very few, so can even through the fresh air system to regulate the temperature of the room, after heating of fresh air into the room is enough to keep the design of indoor temperature, in this way, buildings can be completely don't have to install traditional heating system.

 

Of course, in the eyes of the designer, another advantage of the mechanical new wind is that the air quality can be guaranteed. In fresh air handling process, except to recovery heat, can also filter the dust of the outdoor air, control the humidity of the air, the air quality can greatly improve the air quality than that of natural ventilation.

 

Therefore, even in the non-heating season, without considering the heat loss, many architects still adhere to the design of a new mechanical ventilation system.

 

The heating mode of low heat load

 

Through the above three aspects of the measures, "passive house" the extent of the demand of heating in winter has been reduced, the minimal quantity of heat that can achieve the indoor design temperature, researchers put forward in the "passive house standard", "passive house" building heating heat load should be less than 10 w / ㎡.

 

At this time, as the design concept of passive construction has achieved, on the basis of this, for building heating of the heat source can completely get rid of the dependence on traditional heating equipment, designers can give full play to the imagination, use a variety of "free" energy to provide heat for buildings.

 

Use of solar energy is the most common way to meet the "passive house standard" architecture, can be gained through the design of passive solar heat, can also through the design of the building facade, is plenty of sunshine in winter, direct exposure to the interior construction of solar energy can provide a significant number of heating of the heat.

 

In addition, the thermal energy generated by electric lights, household appliances and kitchen facilities in the building heats the room, and even the heat generated by the body itself can maintain the temperature of the room.

 

Of course, these are unstable sources of heat, so there are usually small heating facilities in the building as a backup. By heating fresh air or install small cryogenic heat radiator is a common way, the quantity of heat of heating facilities can be achieved by small ground source heat pump, biomass burning stove, solar collector and other renewable energy facilities.

 

The development direction of "passive house"

 

Build a diversified "passive house

 

Since the origin of "passive house" is in the central European countries such as Germany and Austria, the relevant standards and technical measures are more specific to the climatic characteristics and regional characteristics of this region.

 

To promote the design concept of "passive house", it must adapt to different regions and environments and develop diversified "passive houses".

 

In other European countries, this diversification trend is deepening. Europe a vast, climate differences, the Nordic countries the winter cold, summer is hot and Mediterranean countries, the climate characteristics and Germany have very big different, must adopt different strategies in the design.

 

Residential building is the building way also have different characteristics, such as walls, exterior wall coating is very common in Germany, the Netherlands, Belgium and other countries more hollow brick wall, Sweden, Finland and other countries usually adopt wooden buildings.

 

In view of these different construction methods, different ways are needed to make the insulation performance of the wall outside the wall to meet the requirements of "passive house".

 

With the continuous promotion of the concept of "passive house", a number of "passive house" construction examples have been built in European countries.

 

At present, the concept of "passive house" also spread to countries outside Europe. Minnesota in the United States in 2006 Mr Secret ji built North America's first certified "Passive House" architecture Waldsee Biohaus, "Passive House" in 2007, the United States Institute (Passive House Institute US) in Illinois urbana-champaign was established.

 

In Asian countries, there are researchers in South Korea to apply the concept of "passive house" in the feasibility study of urban high-rise residential, these projects on east Asian neighboring countries will also play a demonstration role.

 

"Passive house" the pace of development in Europe soon, have a German researchers are optimistic that Germany over the next 10 years will be fully USES the "passive house standard", after 10 years of all new homes will be "passive house".

 

In that case, if the idea of "passive house" can be widely spread, the technical measures, can be widely used in the future a certain period, the city's buildings are meet the standard "passive house", all the buildings can easily solve the problem of heating in winter, within the building that is as important to municipal infrastructure, urban heating system can quit the historical stage.

 

In this way, "passive house" will change people's lifestyle and urban form while achieving energy conservation and environmental protection goals.

 

Improve the cost performance of "passive house" buildings

 

As with other energy-efficient buildings, high additional costs are often the bottleneck that affects development. To popularize the "passive house", it is necessary to improve its cost-performance, making it an attractive and affordable building for ordinary city dwellers.

 

"Passive house" reflects the passive design concept, its main technical means is to improve the peripheral system of heat insulation performance, so relative to other energy saving buildings, it is mostly low technology adopted by the measures, there are certain advantages in cost.

 

"Passive house" will not like other energy-saving buildings as always follow the latest technology, make construction regulation and control is complex, and energy-efficient buildings become synonymous with high technology, high cost. Therefore, in the long run, "passive house" is very marketable.

 

According to the German institute of "passive house", data released in Germany for a new built into the "passive house" of the 100 ㎡ residential, increase additional investment of 7669 euros, another set of newly built 130 ㎡ "passive house" housing, increase the investment for an extra 13140 euros, and they save energy consumption cost every year between 511 ~ 1023 euros.

 

In Germany, under the fiscal subsidies and preferential tax policies for energy-efficient buildings, it is very easy for buyers to accept such a price.

 

Of course, the performance of energy-saving buildings is always influenced by various factors. Since the price of non-renewable energy such as oil, natural gas and coal will rise for a long time, the increase of popularity will gradually reduce the cost of technology, which is a big trend.

 

And at present, the market acceptance of energy-saving residence is largely affected by the investment and benefit balance, for the average urban residents if additional housing costs in the foreseeable period by greatly reducing heating costs and recovery, it is very attractive.

 

Establish a design method based on the concept of "passive house"

 

In sustainable building environmental targets such as energy saving, material saving and environmental protection strategy, generally can be divided into two parts: the part of "minimum requirements" strategy, is another part of the supply optimization strategy.

 

The control of demand can be accomplished by passive method, which is an example of full use of this method. On the one hand, passive house is an energy-saving building type. This type of building needs to meet the requirements of "passive house standard". On the other hand, the concept of "passive house" can also develop into a sustainable building design method -- passive method.

 

Passive mode is a method to meet the requirements of building physical environment by using the building itself rather than the equipment, and to realize the energy conservation, environmental protection and other environmental sustainable goals of the building.

 

Can the construction of energy and resources of daily demand control to a minimum is the core of the passive method, these needs involve building heating, air conditioning, lighting, water, etc., for the buildings are located in different climatic conditions and social environment, these requirements will vary, architects need to play enough wisdom, use various strategies to well keep these requirements to a minimum.

 

"Minimum requirements" is an important content of sustainable architecture, on the basis of this, and then take the renewable energy, energy efficiency, resource recycling "supply optimization" specific strategies, such as the biggest environmental benefits can be achieved.

 

For residential buildings, passive method can cover the residential area planning, residential design, management mechanism, from several different aspects, such as living pattern in these aspects have their own can implement control measures, the organic combination of these measures together, can put the house to minimize the daily demand for energy and resources, thus forming a residential building environment sustainable goal of "passive system".

 

Analysis of the application prospect of passive house in China

 

"Passive house" has developed more mature design, construction and evaluation system through continuous research and practice in European countries. From the result of a large number of completed projects, the "passive house" building has a very good development prospect.

 

The research and practice of "passive house" architecture has also begun in North America and Asia. China has always attached great importance to energy conservation building. In recent years, many positive achievements have been made in research and practice, which can be combined with national conditions to absorb the experience of European "passive house" architecture.

 

Firstly, we should consider the climatic characteristics of different regions of our country. "Passive house" of the original design principle and technical method based on central European countries such as Germany, Austria, on the basis of the climate and the northern and southern European countries have already developed on the basis of their own "passive house", the eastern European countries such as Hungary, the Czech republic are also related research and practice.

 

Our country land area and approximation of Europe, there are seven different climate region, the regional climate characteristics and the demand for heating and ventilation is different also, build "passive house" in different regions of our country can reference the experience of European climate characteristics corresponding countries according to the circumstance.

 

At the same time, the cultural differences between our country and European countries also affect the design of "passive house".

 

Our diet, for example, the requirement to the residential kitchen and European countries are quite different, in the residential kitchen lampblack and smell often need through natural ventilation or smoke lampblack machine to walk, and the "passive house" architecture and interior ventilation has specific requirements.

 

Therefore, how to meet the requirements of energy saving and living habits in residential design is a comprehensive consideration.

 

In addition, most of housing marketization in our country, the "passive house" earnings and can increase additional investment balance, which is accepted by the market, it is also can affect the "passive house" to promote the key factor.

 

The use of local building materials and related products as far as possible is an effective way to reduce the cost of construction, which requires more attempts in research and practice.

 

Of course，Experience from European countries , "passive house" cost significantly lower than other high-tech energy-efficient buildings, and with the popularity of the increase in demand and related products, the production cost advantage will be more and more big.

 

The basic concept and technical strategy of "passive house" can be realized in China. Policies and regulations of energy saving construction in our country, building planning and design, construction and building materials research and development production already have a certain foundation, the European "passive house" building materials and equipment required by the most in our country have the same or similar products.

 

Architects need to use "passive house", on the basis of basic conception, combining with the actual situation of our country, the creative design "passive house" that conforms to China's national conditions, adding new bright spot for the development of sustainable architecture.