Currently, 40% of the total energy consumption in the EU corresponds to buildings, construction and architecture, and that is why energy efficiency is beginning to be a serious issue in this sector. It is in this context where Passivhaus buildings or passive houses have become fashionable and are in great demand. Do you want to know what is a passivhaus building and what are its characteristics? From MCH Master we explain everything you need to know.
The concept of building to the Passivhaus standard is becoming increasingly well established in the construction industry. However, it is not something new, since in the late 1980s in Germany, professors Bo Adamson and Wolfgang Feist developed this concept.
Directive 2010/31 stipulates that by 2018 all newly constructed public buildings must be NZEB (nearly zero energy building) and by 2020 regulations must be established in the various EU countries to ensure that all newly constructed buildings are also nearly zero energy buildings (nzeb).
It is in this context that Passivhaus-compliant buildings are emerging. Homes built to this standard achieve savings in energy consumption of 90% compared to older homes and 75% compared to newly constructed homes.
In short, these are buildings in which thermal comfort is achieved by heating or cooling the required ventilation air flow. In this way, significant savings are also achieved in the installation of cooling or heating.
Passivhaus is the name of the certificate obtained by building according to certain parameters of efficiency and energy saving, comfort, hygiene, profitability and sustainability. It can be applied to any type of building, without necessarily having to be a new construction, as long as the five basic characteristics that define it are respected. These characteristics are supervised during the design and construction process by a Passivehaus consultant, who, once construction is complete, will carry out the necessary checks to determine whether the building meets the minimum requirements to obtain the Passivehaus seal, such as the famous blowdoor test. The basic characteristics are:
A key factor in Passivhaus is to achieve an envelope with a very low thermal transmittance. To achieve this it is necessary to place thermal insulation in abundance in walls, floors and ceilings of the building. The way it is placed, the material used, as well as the thicknesses and densities of the same influence.
Contrary to the belief of professionals in the construction sector, most of the energy in a building is lost by convection (movement of fluids, in this case air) and not by conduction (heat transfer through one or more materials). For this reason, in Passivhaus it is essential to guarantee airtightness to the outside air, i.e. to minimize the very common infiltrations.
To achieve this airtight envelope, it must be studied during the project and verified during the works that there is a continuous air barrier in facades, roof and floor to ensure airtightness. To meet this passive requirement, control during the construction process is very important.
Thermal bridges are points of the envelope where the thermal transmittance is higher, producing a considerable energy loss, as they are generally produced by a discontinuity in the insulation.
Passivhaus requires minimizing thermal bridges throughout the envelope, thus guaranteeing the continuity of the insulation. Thermal bridges also generate cold spots in the interior that can cause dampness, damage to materials and loss of interior comfort.
If we create an airtight envelope, for health reasons it will be necessary to ensure the renewal of indoor air. For this, in Passivhaus projects, it is necessary to incorporate a double circuit mechanical ventilation system which, in this case, will incorporate a heat recovery system that minimizes energy losses and represents a significant saving in energy consumption.
In certain climates, thanks to the heat recovery system, it is even possible to air-condition buildings using only ventilation and dispensing with specific air-conditioning systems. One of the advantages of mechanical ventilation, in a context of extreme pollution alert, is that it makes it possible to control the quality of the pollution much more precisely, treating it when necessary.
Passivhaus buildings require the use of high-performance, insulated and airtight windows and doors. In the case of windows, two or even three panes are used, the outer panes being low emissivity with an inert gas-filled chamber. This guarantees very low thermal transmittance, high acoustic insulation and energy reflection or maintenance in the different seasons.
Remember that if you are interested in architecture and want to know more about Passivhaus buildings, MCH Master is all you need.
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