- The history of the creation of a passive house
- Passive house components
- Ecohouse location
- Construction materials
- Thermal insulation
- In conclusion
In this article: the first eco-house – the Eskimo igloo; European developments of the passive house; requirements for the location of the house; thermal insulation of all structural elements of an eco-house is required; how to provide air supply in a passive house; economical heating.
About a century ago, the final solution to the problem of providing houses with thermal energy was seen in the transition to convective heating, since there was an abundance of hydrocarbons in Russia. The central heating supply, supplying hot water to residential and office buildings, worked with high heat losses during transportation, “spoiled” citizens with periodic accidents, but everything was compensated by low prices. Nowadays, the heating network does not work better, but its prices have increased significantly, which is explained by the constant increase in world prices for hydrocarbons. The only way to save on heat bills is to reduce its consumption by reducing the heat loss of the building’s structural elements. And for this purpose, buildings of a special type are being developed and erected – eco-houses, or, as they are also called, passive houses..
The history of the creation of a passive house
Over the millennia, mankind has seriously advanced in the construction of various structures, but has not solved the problem of heat loss, preferring to compensate for it with the development of heating equipment. Indeed, even three decades ago, there was no need to save energy resources, since they cost consumers quite inexpensively. Not much time has passed since then, but the prices for utilities have increased significantly and the only way to reduce them is to acquire energy-efficient housing..
The first eco-house of its kind was created by the people who traditionally lived in the northern part of our planet – the Eskimos. In the polar regions of Europe, energy resources were almost completely absent, even ordinary wood was a rarity. In addition, the only “building material” available to the Eskimos always and in abundance was only snow. Yes, the passive house of the northern people was created precisely from snow – it is called igloo, it is laid out of snow bricks and has the shape of a dome.
There are two sources of heating in the Eskimo igloo – lamps filled with whale or seal fat, as well as heat radiation from the bodies of households. The snow house perfectly keeps heat, after a short time a comfortable temperature for a person is created in it up to +18 ° C, and the excess moisture is absorbed by the snow bricks. What is especially surprising, the Eskimo builders of the past managed to solve the problem of air supply to the igloo so that the heat from it did not evaporate during ventilation – the entrance to the house from the snow was arranged at the lowest point of the floor so that the heavy CO gas2 evaporated through this channel, being replaced by light oxygen coming from outside.
Construction experiments to create buildings with the lowest energy consumption were carried out in the last century in the USA and Finland. Buildings erected according to special designs, one in the American Manchester (New Hampshire), the second in Finnish Otaniemi, were erected according to the climatic conditions in the area, there were no glazed openings on their northern facade, the shape of the roof was calculated at the angle of incidence of sunlight at different times years, the roofing was painted in light colors. Each house was equipped with a complex ventilation system that absorbed solar radiation, the role of heat exchangers was performed by specially designed double-glazed windows and shutters, heating was based on geothermal heat pumps. The energy consumption in these houses was significantly reduced, but it was not possible to significantly reduce the structural heat loss of buildings..
The idea of creating a full-fledged passive house belongs to Professors Bo Adamson (University of Lund, Sweden) and Wolfgang Feist (Institute for Housing, Germany), who decided to implement it after their meeting in May 1988. The development of the eco-house concept was funded by the government of the state of Hesse (Germany) – the results were so impressive that in September 1996 in the Hessian city of Darmstadt, where experimental eco-houses were erected in 1990, the Passive House Institute was opened.
Over the past two decades, several thousand passive houses have been built, both in Europe and in North America, in the coming years their number will only increase – energy savings for Europe are more than critical.
Passive house components
A building that meets all the characteristics of an eco-house is practically an independent power system that consumes 10 times less energy from external sources than any other building structure. It does not have the systems of heating, hot water supply, ventilation and air conditioning that we are used to, the heat loss of an eco-house does not exceed 15 kWh per square meter per year, which is 15–20 times lower than that of ordinary European buildings and 30 times lower than heat loss of houses in Russia.
Careful selection of the shape of the building, orientation of its position on the ground and the planning of adjacent buffer zones (areas with green spaces). Depending on climatic conditions, relief and wind rose in a given area, the most rational orientation of the building is calculated from the standpoint of energy conservation. For example, in temperate climates, south-facing windows should have a large area, and on the north side of the house they should be completely absent (ideally). For a subtropical climate, the opposite is true – the northern facade with large (panoramic) windows, on the southern side of the eco-house, there are either no windows or have a minimal area.
There are no strict conditions for the materials used for the construction of a passive house – the only requirement concerns their environmental safety.
In order to completely insulate the passive house from the external atmosphere, thermal insulation materials are mounted on the outside and inside of each enclosing structure – walls, ceiling and floor, attic, basement and foundation. In the northern part of Europe, the thickness of the layer of external and internal insulation of all building envelopes (except for the roof) is 335 mm, the thickness of the roof insulation is 500 mm. It is especially important to completely eliminate cold bridges – their presence is unacceptable.
Window openings are glazed with one- and two-chamber double-glazed windows, the chambers between the glasses in which are filled with krypton or argon, the window frames must ideally match the openings for subsequent sealing of the adjoining perimeter. In insulating glass units, tempered glass is used, covered with energy-saving films that reflect the sun’s rays. To increase the thermal resistance, the windows are equipped with blinds, curtains or shutters.
If in houses of a conventional design, the flow of fresh air into the premises is realized through slots or special valves in the window frames, and the output through passive or active ventilation systems of bathrooms and kitchens, then in a passive house everything is much more complicated. The window structures in the eco-house are completely sealed, there are no ventilation shafts – displacement-forced ventilation is carried out using the natural heat of the soil and a recuperator.
The inlet of the air duct through which fresh air enters the house is located near the facade of the building. Having entered the air supply system, the air moves through an air duct laid in the ground under the building, its temperature rises due to the heat of the earth. At the entrance to the house, through a channel, fresh air enters the filters and a recuperator equipped with a heat exchanger that absorbs heat from the exhaust air taken out from the building – thus, warm air enters the eco-house in winter, and cooled air in summer. The “exhaust” air is removed through a forced air intake system inside the house with its output outside the building after taking heat in the recuperator. A completely non-volatile air intake system in a passive house cannot be used, because in this case, large internal air intakes are required, and this will increase the heat loss of the building.
Sources of thermal energy for a passive house are solar radiation accumulated by a solar collector and a heat pump. Due to the high thermal insulation characteristics, the sources of indirect thermal energy in the eco-house are households whose bodies generate radiant heat, as well as any electrical appliances, such as lighting lamps, computers, televisions, etc..
It should be noted that a heat pump for a passive house is needed only in harsh climatic conditions, for example, in Siberia – in Europe, internal heat supply is based only on air recovery and indirect heat sources.
Since LED lamps have the lowest energy consumption, the eco-house lighting system is created on their basis..
The atmosphere of passive houses is isolated from the outside, a complete change in the air volume inside the eco-house occurs no more than once every three hours, so homeowners are obliged to pay special attention to furnishings – the elements that make up low-quality furniture can emit formaldehyde.
The air temperature inside the house is always uniform, that is, there is no stratification into a cold layer at the floor and a hotter one at the ceiling. Since the air when entering the house passes the recuperator and heats up, moisture will not be deposited on the walls of the eco-house, especially since the walls themselves are thermally insulated and their surfaces have the same temperature as the air in the premises.
In the cold season, the doors and windows of the passive house must be tightly closed, in the event of their short-term opening, there will be no serious harm to the air temperature in the house.
The cost of building a passive house will cost about 10-12% more than building a regular building of equal area. One of the advantages of eco-houses is that they can be built anywhere, regardless of the proximity to the construction site of central communication networks. Finally, such a house does not need a classic heating system – pipes, heating radiators and boilers are not needed.