In order to ensure that the house has minimal heat losses, i.e. to achieve a low-energy or passive standard, it is necessary to adequately insulate the walls, roof and basement and install windows and doors with the lowest possible heat transfer coefficient.
With the energy used today to heat an average house, we can heat 3-4 low-energy houses or 8-10 passive houses. The difference becomes even more shocking when comparing old houses. Investment that is normally used for space heating can be used for better insulation, better windows and ventilation.
It's estimated that the cost of building a passive house is approx. 20% higher than the classic one, but the savings achieved many times exceed the investment after 8 years. In addition, this type of construction is often highly encouraged through favorable subsidies.
Today, the world is faced with three major problems related to energy:
- environmental pollution and climate change due to the release of CO2 into the atmosphere and excessive and irrational consumption of energy;
- constant growth in the prices of energy and energy products, and constant growth in the consumption of both heat energy for heating and energy for cooling, especially with the mass introduction of air conditioning in buildings;
- lack of energy and uncertainty in energy supply.
Low-energy and passive houses, in addition to helping to preserve the environment, provide very high living comfort, a pleasant temperature throughout the year without a classic heating and cooling system, and very low energy consumption costs.
Low-energy construction, and in the very near future also passive construction, is the basis of sustainable construction throughout the entire lifespan, starting with the use of construction materials whose production does not pollute the environment, to energy efficiency and rational energy consumption, and up to rational and proper waste management.
Low-energy house vs. passive house
The total energy used in a passive house is usually 2.5 times less than the energy for a low-energy house, and ten or more times less than the average energy consumption in buildings.
The low-energy house has a max. annual consumption of thermal energy 30-40 kWh/m2. The group of low-energy houses also includes the passive house, which is a step forward, whose annual need for heat is so reduced that there is no longer a need for an active heating system.
With a passive house, the total annual need for thermal energy is reduced to below 15 kWh/m2.
The main idea of passive construction is to use solar energy to heat the house in the winter period and to prevent the intrusion of solar radiation in the summer period in order to reduce the need for cooling, all with well-insulated openings and walls.
Principles of passive house construction
We should always think about ways the sun can save energy and money for heating.
Here are some basic rules when designing passive houses:
- The facade should be of lighter colors with a reflective surface. In summer, the leaves on the trees or shades block the sun's radiation. The side of the house that has the most glass surfaces should be oriented towards the south in order to maximize the use of solar radiation, while on the north side the windows should be smaller to prevent heat loss. Kitchens, corridors, bedrooms, bathrooms and storage rooms should be placed on the north side of the house.
- Houses should be designed in a way that most of the living areas are located on one side of the house, with the windows in those rooms being the largest.
- In winter, in addition to heating, solar energy is also used for natural lighting.
- The winter garden on the south side of the house helps to harness solar energy.
- Using blinds or shades on the windows. In winter, blinds and curtains should be used at night to prevent heat loss from the house. Some blinds can reduce heat loss by 10%.
- The heat accumulated in the walls during the day radiates into the space during the night.
- Vegetation planted on the north side of the house provides shelter from cold north winds.
- In the summer, a house should be ventilated during the night when the outside temperature is lower. External air currents help to cool the house and supply fresh air.
- For multi-story buildings, the buoyancy effect can be used due to the fact that warm air rises and cold air falls.
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