Energy-saving and passive construction is becoming increasingly popular. It is connected with greater awareness of ecology and rational energy consumption. And although such houses are up to 10-20% more expensive compared to traditional construction, they can finally, thanks to the use of appropriate building materials and technologies, minimize our operating costs and contribute to responsible energy consumption.
Similarities between a passive and an energy-efficient house
The basis of both systems is a thoughtful design and elimination of unnecessary elements. In an economical building, a compact body, single-pitched or gable roof is used and many energy-intensive architectural solutions, such as balconies, dormers or bays, are abandoned. In addition, the design is developed to make the best use of the natural energy from the sun. The south side is therefore generously glazed, while the north side has no or small windows. The building’s orientation towards the world’s sides reduces heat loss and corresponds to the lifestyle of the occupants.
A common feature is also the solid insulation of the house and the use of mechanical ventilation with recuperation. Unlike gravity, it does not cause such large heat losses and guarantees fresh air in rooms without the need for ventilation.
Where do you see the difference?
- Energy consumption
A passive house is a building that is designed to extract passive energy from its surroundings and its energy consumption should be 15 kWh/(m2-year). An energy-efficient house, on the other hand, is a building with an annual heating requirement of about 70 kWh/(m2-years) to 160 kWh/(m2-years).
- The structure and walls
In energy-efficient construction you can afford a more complex architectural shape. However, it is important to keep the number of bends and faults to a minimum and to design as much glazing as possible from the south.
In the case of a passive house, the mass should be designed on a rectangular plan, with a single or gable roof. The southern façade must be almost completely glazed.
In the case of both types of projects, an important characteristic is also the presence of as few external partitions as possible in relation to the cubic capacity. In order to provide buildings with the best possible thermal insulation, external walls, floors and ceilings should adequately protect the interior from heat loss.
- Thermal insulation
In order for houses to meet their objectives, it is necessary to use the best thermal insulation. The values are more stringent in the case of passive buildings – here the value of heat transfer coefficient should not exceed 0.12 W/m2K. In the case of an energy-efficient building, this value cannot be higher than 0.2 W/m2K. These are not rigid standards. A detailed study on the application of insulation will be obtained from a professional analysis of the building carried out by the contractor.
Windows in houses with a low energy demand should extract this energy from the sun’s rays, but also cause the least possible heat loss. The proper location of windows – although very important – does not yet guarantee success. It is necessary to use window joinery with increased thermal parameters. In energy-saving houses the heat transfer coefficient of windows and external doors should not exceed 1.3 W/(m2K,), and in passive houses – 0.8 W/(m2K,).
The difference between an energy-saving and a passive house can also be seen in the requirements for using the heating system. In an energy-saving house, a traditional heating system, such as a condensing boiler or heat pump, is sufficient to use the energy from the ground, water or air.
There is practically no heating system in a passive house. This is due to the fact that the basic assumption of such a house is zero energy – the object does not need so-called active heating system. Instead, mechanical ventilation, heat from the sun’s rays and the heat emitted by the household members are used.
Energy-saving house or passive house – which one to choose?
Both energy-efficient and passive houses should be included in modern buildings that respond to current climatic conditions. They guarantee not only lower energy bills, but also a beneficial impact on the surrounding environment. Of course, the passive house wins in both categories. However, it should be remembered that it requires the use of more expensive solutions as well as more complicated works. An energy-efficient house is definitely easier to build, but it has slightly weaker parameters.
In order to determine whether our house can be assigned to one of the two discussed categories, the so-called leakage test should be performed, which indicates all parameters of the building. Thanks to this test we can be sure that all the work has been done properly.