PASSIVE HOUSES, PASSIVHAUS ENERGY STANDARD

In Europe, buildings consume 40% of all energy. More than industry and transport.

Passive houses need 90% less energy than a conventional house, which can be generated by your own body heat, the sun, household appliances and good solar control. They were first studied in Germany in the 1980s under the Passivhaus standard.

According to one of its creators, Dr. Wolfgang Feist, the Passivhaus standard : “is a method of designing a building in such a way that it has such a low energy requirement that it does not need its own heating and cooling system. In this way, the remaining energy required can be provided by the mechanical hygienic air renewal system”.

This is not only an energy certification, but an international building concept that is concerned with limiting the energy demand of the building during its lifetime. It is more than 20 years old and has been applied in more than 28,000 buildings.

Each Passivhaus project requires different solutions and must be adapted to its environment, but there are essential factors to take into account in the design of a Passive House.

If we orientate openings to the south to capture the maximum solar energy, we will minimise or even eliminate the need to use heat sources to obtain an optimum temperature inside the home.  

If we also use protection such as porches or awnings in very exposed areas, we can protect ourselves from the sun at times of maximum incidence so that, helped by the cross ventilation of the spaces, we can dispense with air conditioning and avoid overheating.

Strategies such as these govern the criteria when designing to the standard.

FIVE BASIC PRINCIPLES OF PASSIVHAUS

1_Excellent thermal insulation is fundamental, as it is the construction element that keeps the heat inside.   

The use of solar protection, avoiding the incidence of solar radiation by means of elements that generate shade such as awnings or overhangs.

The optimal use of solar energy is achieved through the correct orientation of the openings and by protecting the house from adverse atmospheric factors such as wind or low temperatures.

2_Thermal bridges are points where discontinuity is generated in the thermal insulation of the envelope causing energy loss. For this reason, it is necessary to minimise them as much as possible in the standard.

3_Windows are the weakest point in the building envelope and therefore it is necessary to take special care of their technical characteristics and their installation. Passive houses install very efficient carpentry with triple glazing filled with low emissivity argon gas, combined with high thermal performance frames.

4_Heat losses through the envelope are what cause buildings to need energy to achieve thermal comfort. The way to minimise these losses is to build airtight houses, i.e. without air infiltration losses. Passive houses are airtight. This does not mean that windows cannot be opened, only that it is not necessary to do so, as the house, with the help of mechanical ventilation, is able to breathe on its own.

5_Passivhaus dwellings require the installation of mechanical ventilation by means of heat recovery. Controlled ventilation recovers part of the energy that goes outside through its ducts, which limits the energy demand of the house as well as filtering harmful particles from outside, improving the quality of the air we breathe.

PASSIVHAUS CERTIFICATION

The certification of a passive house requires verification by an external technician of compliance with the standard from the design phase to the end of construction. It is a way of auditing the process and verifying compliance with the parameters that make a house meet the energy standard.

Tests such as the blower door test, which measures the airtightness by checking the pressure inside the building, as well as temperature and humidity measurements, are carried out. A passive house must have less than 0.6 renovations per hour, at 50 pascals of pressure, to meet the standard.

If everything is correct, the Passivhaus certification is issued and the house becomes part of an international network of Passive Houses certified by the Passive House Institute (PHI).