Recommendation points
- Passivity and energy efficiency concepts
- What is the main idea of a passive house
- Materials for thermal insulation
- Roof and warm attic
- Windows, doors and other leaks
- Power supply for a passive house
In order to save natural and energy resources, mankind has developed comprehensive measures to insulate buildings and bring the level of thermal insulation to a value close to absolute. This material will reveal the essence of the passive house as a modern and economical type of housing..
Passivity and energy efficiency concepts
Our review will bypass the generally accepted list of benefits and technical indicators. For example, a building is considered to be energy efficient if its heat loss does not exceed 10 kWh per square meter during the year, but what should this tell the reader about? If we recalculate, then for a year from a small (up to 150 m2) the house takes about 1.5–2 MW of energy, which is comparable to the energy consumption of an ordinary cottage in one winter month. The same amount is consumed by 2–3 incandescent lamps of 100 W, turned on constantly for one year, which is equivalent to 200 m3 natural gas.
Such a low energy consumption allows, in principle, to abandon the heating system in the house, using heat generated by humans, animals and household appliances for heating. If the house does not require targeted energy consumption for the operation of heating installations (or requires, but an insignificant minimum), such a house is called passive. In the same way, a house with very high heat losses can be called passive, the need for which is met by its own power plant operating on renewable energy sources..
So an energy efficient house does not necessarily claim to be passive, and the opposite is true. A house that not only covers its own energy needs, but also transfers some type of energy into the public network is called active.
What is the main idea of a passive house
It is customary to combine all three of the above concepts: a passive house has the most extended set of measures to ensure energy autonomy. In the end, no one is interested in testing their home for years, seeking the heat loss standard to receive an honorary title. It is important that the inside is dry, warm and comfortable..
There is an opinion that today any new building should be built using passive house technology, since there are technical solutions even for multi-storey buildings. This makes sense: the cost of maintaining a house during the period between repairs is usually even higher than the cost of building.
A passive house with larger initial investments practically does not require costs for the entire service life, which, moreover, exceeds the service life of ordinary buildings due to the absolute protection of load-bearing and enclosing structures in combination with the most modern and technological solutions for construction and repair.
The main technical feature of a passive house can be called a continuous loop of thermal insulation, from the foundation to the roof. Such a “thermos” retains heat well, but not all materials are suitable for its construction.
Materials for thermal insulation
Expanded polystyrene in such volumes is not applicable, it is flammable and toxic. In a number of projects, this is solved with a fire retardant layer at the bearing pillar and under the facade finish, which leads to an unjustified rise in price. The use of glass and mineral wool also does not solve the problem. In it, as well as in expanded polystyrene, pests (insects and rodents) actively settle down, and the service life of cotton wool is 2-3 less than that of the passive house itself.
The material suitable for passive house purposes is foam glass. Brief summary of characteristics: the lowest thermal conductivity of known materials of widespread consumption, complete environmental friendliness due to the inertness of glass, simple processing and good adhesion. Of the minuses – the high price and complexity of production, but the material is definitely worth the money.
A less expensive but suitable material for passive house insulation is polyurethane foam. Technically, such houses cannot be called passive, their heat loss is 30-50 kWh per square meter per year, but these figures are quite acceptable. Polyurethane can be installed as sheet material or applied by gunning plastering.
Roof and warm attic
Another key difference between passive houses is the presence of an unheated attic or a warm attic and high-quality roof insulation without cold bridges. With this approach, two temperature boundaries are distinguished: on the ceiling of the upper floor and in the roof itself. Due to the separation of thermal protection, the formation of condensate in the roof insulation is guaranteed to be eliminated and heat losses are significantly reduced.
The overlap of the upper floor is usually made frame on wooden beams, the voids are filled with a layer of medium density mineral wool 20–25 cm thick. It is better to insulate the overlap with sheet materials with a cross-cell frame and precise adjustment of the insulation plates. All seams and joints are filled with special glue or polyurethane foam. Particular attention is paid to the device of a protective belt at the place of support of the rafter system on the walls.
A warm attic is arranged according to the principle of ventilation system recuperation. The exhaust ventilation ducts lead directly into the sealed attic space, from where they are removed through a single forced outflow hole. Often this channel is equipped with a recuperation unit that transfers part of the heat from the extract air to the supply air..
Windows, doors and other leaks
With windows for passive houses, everything is simple: they must be of high quality and must be certified for use in the energy saving industry. Signs of a suitable product are double-glazed windows with two or more gas-filled chambers, low-emissivity glasses of different thicknesses and double-glazed glass unit adjoining to the profile, sealed with a rubber tape. For doors, honeycomb filling and the presence of a double rebate along the entire perimeter are important. It is equally important to follow the rules of installation and protection of the junction points.
The passive house has its own characteristics of the foundation. To protect the concrete structure, it is hydrophobized by injection and additionally protected with an outer layer of coating waterproofing. The insulation is lowered to the entire depth of the foundation, thus the basement becomes the second buffer zone after the warm attic.
Power supply for a passive house
Gas is usually not supplied to a passive house; for household purposes and heating, a single-phase electrical network is completely sufficient. With electric heaters, everything is simple: how many kilowatts are invested in a house, so much remains in it, the efficiency is almost 99%, unlike gas boilers.
But the electrical network as the only source of energy supply has a lot of drawbacks, mostly in connection unreliability. Often houses are supplied with a rather complex electrical network, including an emergency generator with auto start, or use a battery park or solar panels for backup.
Heating of domestic water is usually performed by solar collectors, mainly vacuum ones. In general, autonomous energy sources are quite diverse; among the varieties, you can choose the optimal solution for objects with different conditions.
What are some of the key energy-efficient technologies used in passive houses and how do they help reduce energy consumption?
What are some of the most effective energy efficient technologies that can be implemented in a passive house?
Some of the most effective energy efficient technologies that can be implemented in a passive house include:
1. High-performance insulation: Properly insulating the walls, roof, and floor of a passive house helps minimize heat loss or gain, reducing the need for heating or cooling.
2. Energy-efficient windows: Installing triple-pane windows with low-emissivity coatings and thermally broken frames helps improve insulation while allowing natural light into the house.
3. Airtight construction: Ensuring the passive house has a continuous air barrier and sealing all potential air leakage points reduces energy loss, maintaining a comfortable temperature year-round.
4. Mechanical ventilation with heat recovery: A mechanical ventilation system with heat recovery helps maintain a constant supply of fresh air while recovering heat from the outgoing stale air, reducing the need for additional heating or cooling.
5. Efficient heating and cooling systems: Passive houses often utilize heat pumps, which extract heat from the outdoor air or ground, as well as radiant floor heating to provide efficient and even heating during the colder months.
6. Energy-efficient appliances and lighting: Choosing energy-efficient appliances and LED lighting can significantly reduce energy consumption within a passive house.
7. Solar panels: Installing solar panels on the roof helps generate renewable electricity, reducing reliance on the grid and further minimizing the carbon footprint of the passive house.
By implementing these technologies, a passive house can drastically reduce energy consumption, resulting in both environmental benefits and long-term cost savings for homeowners.