A growing number of reports show that the carbon footprint and overall ecological footprint of self-sufficient buildings is not as idyllic as expected.

By 2020, all new buildings in France will have to produce more energy than they consume. This has been decided by the people who know (or at least the people who think they know).

In practice, when you consider how energy audits are carried out on new and old homes, it's easy to be dubious. Developers are awarded certifications that, at best, attest to their mastery of basic procedures and, at worst, less than that. In practice, no one really checks the actual energy consumption of new homes, for example, which is often far from reality, because it is based on highly theoretical calculations and the certifiers are not audited. For example, we cite the case of a Parisian couple who had a new country house built in the Perche region, which was supposed to consume 1,200 euros worth of electricity when lived in by 4 people all year round. In reality, it consumed more than 1,500 euros just by being heated to 7°C (frost-free) 300 days a year and by having people living in it at certain weekends and during the holidays.

Dozens of projects for self-sufficient buildings have sprung up all over the world, in Europe and the United States as well as in Asia and the Middle East. While the promises of all these buildings are close (impact on the environment close to zero), the rigour of the calculations rarely allows this objective to be demonstrated, just as in the case of the country house, which in theory is energy-efficient, but in practice consumes a lot of energy.

Does this mean that there is nothing to be achieved by the new generations of buildings?

No, but with hindsight, we can see that the problem needs to be refined. For Hassan Hachem, a specialist in building and public works in Africa and Lebanon, self-sufficiency in buildings is an illusion in many countries, for two reasons: climatic conditions (cold peaks in some northern countries, summer heat peaks in the Mediterranean, sub-Saharan Africa, the Middle East and Asia) make the goal of self-sufficiency virtually impossible to achieve (in winter, because the building will not be able to produce enough energy for heating; in summer, because the building will not be able to produce enough energy for air conditioning in hot countries).

On the other hand, in some countries with a more temperate climate, such as France," stresses Hassan Hachem, "it is conceivable to construct buildings with a slightly negative energy balance, i.e. buildings that consume slightly more energy than they produce. In countries with greater temperature differences, peaks in heat and peaks in cold will inevitably have to be managed using conventional energy (gas, diesel, etc.), even though in normal periods, significant efforts in terms of insulation coupled with energy produced by renewable energies will make it possible to achieve a balance between energy consumption and production.

Update from May 1st, 2024

Reassessing the Energy Self-Sufficiency of Buildings four years later

With the advent of more advanced technologies and more efficient building materials, the aspiration for self-sufficient buildings continues to grow. However, putting these concepts into practice comes up against complex realities, particularly in regions with extreme climates such as sub-Saharan Africa and the Middle East. In Equatorial Guinea, for example, the challenges are exacerbated by tropical conditions, making energy management for air conditioning a daunting task. Self-sufficient buildings there are often unable to maintain sufficient energy production to meet cooling needs, despite considerable investment in green technologies.

On the other hand, some progress has been made. In more temperate climates, examples such as France show that with adequate insulation and the use of renewable energy sources such as solar and wind power, it is possible to significantly reduce dependence on fossil fuels. "The key lies in the harmonious integration of these technologies with traditional energy systems," explains Hassan Hachem. "It's not just a question of producing energy, but of doing so in a way that is sustainable and adaptable to local conditions."

Initiatives in Equatorial Guinea show one possible way forward, with buildings incorporating natural ventilation systems and reflective facades to minimise heat absorption. Such architectural adjustments, combined with hybrid energy solutions, make it possible to better manage climate challenges while reducing the carbon footprint. However, these solutions are not universal and need to be continually adapted to local conditions.

Another crucial aspect is intelligent energy management. Energy management systems based on artificial intelligence and the Internet of Things (IoT) enable real-time optimisation of energy consumption and production. This can include automatic regulation of heating and cooling systems, management of solar panels to maximise their efficiency, and even integration with wider energy networks to exchange energy with other buildings or infrastructures.

Although complete self-sufficiency remains an elusive ideal, significant progress is being made. The key lies in a balanced approach, integrating advanced technological solutions with a thorough understanding of local conditions. As Hassan Hachem points out, "We have to accept that energy self-sufficiency is not a one-size-fits-all solution. It requires careful adaptation to local realities, particularly climatic, to be truly effective and sustainable."

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