Many people dream of a house that, while offering all the comforts necessary for modern life, is completely energy self-sufficient – but is this possible?
As has been constructed for several years in Luxembourg, the passive house makes it possible to considerably reduce energy consumption.
A passive house is a building designed to minimize energy needs while remaining comfortable all year round. It is called ‘passive’ as the need to use an ‘active’ heating system is limited through its orientation, structure, insulation and airtightness. Through this, we can for example seek to optimize interior temperature based on the natural radiation of the sun, but also consider other sources of heat, such as that emanating from the occupants or even household appliances, etc.
From floor to ceiling, via the walls, this airtight envelope prevents heat loss and, therefore, the need to compensate for this by activating a heating system.
A passive house must meet the following criteria:
The passive house corresponds to the highest energy performance level of a building (class A energy performance certificate). A class B energy performance certificate is awarded to low energy consumption housing. Class C corresponds to energy-efficient homes, with class I being the lowest classification.
According to figures communicated last year by the Ministry of Energy and Environment based on an assessment dating from 2021, 8.6% of single-family homes in the country are in energy performance class A and 12.1% in class B. The most represented category, however, is class G, which accounts for 13% of homes. The figures remain very high in categories H (11%) and I (11.7%).
The main drawback of passive houses is their higher initial cost. The price of a passive house is estimated to be 20 to 30% higher than a low-energy house. It should also be noted that constructing a passive house involves resorting to specialist expertise and accepting certain design constraints relating to location and orientation.
Central to the passive house concept, use of the heating system is limited. The home is guaranteed to maintain a comfortable temperature without additional energy input. A small heat pump, for example, can serve as a backup during certain key periods of the year and help meet hot water needs. The energy required for this system can be provided by a small photovoltaic system for self-consumption. The installation of thermal solar panels also makes it possible to limit energy consumption for environmental reasons.
As a result, the use of renewable energy as part of a passive house can make it easier to attain an energy positive home. In other words, the energy produced within the home becomes greater than that consumed. Given the evolution of usage and in particular the adoption of electric mobility, electricity needs linked to housing could be greater in the future. It is therefore interesting to study the possibility of using renewable energy and in particular photovoltaics to respond to these developments.
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