Low energy house
The Passive House project is gaining popularity. Although low-energy house projects have been around for more than a decade, they have recently taken on a phenomenal character. These projects bring significant energy savings and other benefits to the owners.
What is considered a low-energy house project?
Many people often confuse the two basic terms – low-energy and passive house. What is the difference between them? The main difference lies in the maximum annual heat consumption for heating. In the case of a traditionally built house, this consumption is approximately 100 to 150 kWh/m2, while a low-energy house achieves significant savings with an annual heat consumption of no more than 50 kWh/m2. In the case of passive houses, even lower values are discussed, namely below 15 kWh/m2.
For the sake of living comfort, it is still essential that the design of a low-energy house includes a central heating system (be it underfloor heating, radiators or convector heaters). Passive houses go even further – their energy consumption is so low that traditional forms of heating are unnecessary. Heating via a central system is not necessary in this case. Sufficient heat is provided by household appliances, occupants, pets and solar energy. Almost any building material can now be used in the construction of a low-energy house. However, if you desire durability in addition to low-energy properties, the choice of brick is recommended.
The basic difference between a conventional and a low-energy house lies in the maximum consumption of thermal energy. Lower energy consumption is directly related to the amount of heat that escapes from the house. The most significant heat loss occurs through the roof (up to 30%). The roof is followed by the walls (25%), leaks (20%), windows (13%) and the basement (7%). At the other end of the spectrum are thermal bridges (approximately 5%), which represent the lowest heat loss.
For the sake of living comfort, it is still essential that the design of a low-energy house includes a central heating system (be it underfloor heating, radiators or convector heaters). Passive houses go even further – their energy consumption is so low that traditional forms of heating are unnecessary. Heating via a central system is not necessary in this case. Sufficient heat is provided by household appliances, occupants, pets and solar energy. Almost any building material can now be used in the construction of a low-energy house. However, if you desire durability in addition to low-energy properties, the choice of brick is recommended.
The basic difference between a conventional and a low-energy house lies in the maximum consumption of thermal energy. Lower energy consumption is directly related to the amount of heat that escapes from the house. The most significant heat loss occurs through the roof (up to 30%). The roof is followed by the walls (25%), leaks (20%), windows (13%) and the basement (7%). At the other end of the spectrum are thermal bridges (approximately 5%), which represent the lowest heat loss.
Benefits of passive house projects
The main advantage of passive house projects over conventional buildings is the reduced energy consumption, especially heat. These projects can deliver energy savings of up to 80% compared to conventional construction. This is also associated with less need for heating equipment, leading to lower depreciation and maintenance costs. Reduced energy consumption ensures greater independence from fluctuations in energy prices – changes in the price of any type of energy will have minimal impact on your budget. This approach also has a positive impact on the environment, as lower energy consumption also means reduced emissions. Heat leakage is minimised and heating achieves greater efficiency.
In addition, savings are made on storage space for heating fuel, thanks to the lower volume of fuel required. Thanks to the high quality thermal insulation of passive houses, excellent sound insulation against external noise is also ensured. However, the comfort of the inhabitants of these houses does not end with the energy aspects. The controlled ventilation system ensures more natural air circulation, resulting in a near-constant optimum temperature in the house, regardless of the season. And all this at a cost that is on par with, if not lower than, conventional homes. You may also be interested in: project for zoning decision or family houses projects.
What is important in a low-energy house project?
• Masonry composition. When designing low-energy houses, the composition of the walls and the related choice of building material is particularly important. The aim is to meet the stringent standards of the norm and to minimise heat energy leakage. A wide range of building materials can be used for construction, such as fired ceramic blocks, brick as a durable and affordable material, or other options.
• The importance of thermal insulation. In the context of low-energy buildings, excellent thermal insulation is key to maintain a comfortable indoor temperature in winter and to protect the indoor environment from the outdoor heat in summer. The current trend in thermal insulation is to use mineral wool, but also various organic alternatives such as sheep’s wool or hemp wool insulation.
• New thermo-technical standard. Insulation thicknesses for low-energy houses are strictly controlled by standards. As of 1 January 2013, the STN 730540 standard on thermal protection of buildings has been in force, replacing the older 2002 standard and introducing stricter conditions. For buildings built after 2015, even stricter requirements apply – values that were previously recommended for ultra-low-energy buildings have become mandatory. The most significant changes are for ceilings above the outside environment, where the values have more than doubled – from 4.8 m2 . K/W to 9.8 m2 . K/W. There is a similar upward trend for flat and pitched roofs with a slope ≤ 45° – from 4.9 m2 . K/W to a record 9.9 m2 . K/W. For other types of construction, the increase is significant but not as dramatic. The trend of increasing standards is expected to continue in 2023.
• Thermal resistance and thermal conductivity coefficient. Thermal insulation of the house is essential to minimize heat leakage. An important factor is the thermal conductivity coefficient, which characterises the ability of a material to conduct heat. The thermal resistance of the structure is calculated according to the formula R = h/λ, where:
– R is the thermal resistance of the structure (m2 . K/W),
– h is the layer thickness (m),
– λ is the thermal conductivity coefficient of the material (W/(m . K)).
• Impact of windows. Windows have a significant impact on the thermal efficiency of a house, especially their size. Windows that are too large can cause significant heat loss, but on the other hand, windows that are too small can restrict the flow of heat and light. Nowadays, triple-glazed windows are common to improve thermal protection.
• The importance of thermal insulation. In the context of low-energy buildings, excellent thermal insulation is key to maintain a comfortable indoor temperature in winter and to protect the indoor environment from the outdoor heat in summer. The current trend in thermal insulation is to use mineral wool, but also various organic alternatives such as sheep’s wool or hemp wool insulation.
• New thermo-technical standard. Insulation thicknesses for low-energy houses are strictly controlled by standards. As of 1 January 2013, the STN 730540 standard on thermal protection of buildings has been in force, replacing the older 2002 standard and introducing stricter conditions. For buildings built after 2015, even stricter requirements apply – values that were previously recommended for ultra-low-energy buildings have become mandatory. The most significant changes are for ceilings above the outside environment, where the values have more than doubled – from 4.8 m2 . K/W to 9.8 m2 . K/W. There is a similar upward trend for flat and pitched roofs with a slope ≤ 45° – from 4.9 m2 . K/W to a record 9.9 m2 . K/W. For other types of construction, the increase is significant but not as dramatic. The trend of increasing standards is expected to continue in 2023.
• Thermal resistance and thermal conductivity coefficient. Thermal insulation of the house is essential to minimize heat leakage. An important factor is the thermal conductivity coefficient, which characterises the ability of a material to conduct heat. The thermal resistance of the structure is calculated according to the formula R = h/λ, where:
– R is the thermal resistance of the structure (m2 . K/W),
– h is the layer thickness (m),
– λ is the thermal conductivity coefficient of the material (W/(m . K)).
• Impact of windows. Windows have a significant impact on the thermal efficiency of a house, especially their size. Windows that are too large can cause significant heat loss, but on the other hand, windows that are too small can restrict the flow of heat and light. Nowadays, triple-glazed windows are common to improve thermal protection.
Frequently asked Questions
01. What is the difference between a low-energy house and a passive house?
Low-energy and passive house are two different concepts related to energy efficiency. The main difference between them lies in the maximum annual heat consumption for heating. For traditional family houses, this consumption is approximately 100 to 150 kWh/m2, while a low-energy house achieves a consumption of no more than 50 kWh/m2 per year. The passive house goes even further with values lower than 15 kWh/m2 per year.
02. What is the importance of a central heating system in low-energy and passive houses?
The central heating system is an important element in low-energy houses in terms of the comfort of the residents. It ensures the optimal temperature in the house, which is essential for comfortable living. Unlike passive houses, which do not require traditional heating systems, low-energy houses still need heating, even though their energy consumption is much lower.
03. What are the main advantages of low-energy and passive houses?
The main advantage of low-energy and passive houses is reduced energy consumption, especially heat. These projects can bring energy savings of up to 80% compared to traditional constructions. This leads to less need for heating equipment, which means lower amortization and maintenance costs. Less energy consumption also ensures greater independence from fluctuations in energy prices and a positive impact on the environment through the reduction of emissions. In addition, passive houses offer excellent sound insulation and comfort in the form of an optimal temperature throughout the year.