14 building stakeholders ask the State to act to fight against the overheating of buildings

As the problem of overheating of buildings is not sufficiently taken into account in public policies, these actors are alerting decision-makers to the urgency of implementing measures quickly, in order to anticipate increasingly hot summers to come. , threatening the health of the most fragile during heat waves.

“Madam Prime Minister,

The heat is just as formidable as the cold: summer has become synonymous with thermal suffering for many French people. In fact, 69% of them suffer from excessively high temperatures in their homes [1]. A situation that will not fail to worsen with global warming and to extend to periods that were once milder. Remember that in 2022, the first heat wave took place in the spring. However, no political measure is taken today to limit durably, effectively and without excessive overconsumption of energy the overheating of housing. We, construction players, have solutions to provide in line with climate and societal challenges. It is up to you, political actors, to seize it to meet the expectations of the French in terms of purchasing power, ecology and public health.

Achieving carbon neutrality by 2050 is an ambitious goal and we can only welcome it. Some would say, however, that it is inaccessible in view of recent reduction trajectories. However, this is a sine qua non condition to hope to contain global warming to +1,5°C, according to the IPCC. Unfortunately, France's climate action is insufficient. The experts of the High Council for the Climate have again reminded us recently: the French dynamic remains insufficient to meet the objectives of the Green Pact and imposes a burst of climate action [2].

Do not overlook the potential for energy renovation linked to the warming of buildings

France must accelerate its ecological transformation. If the fight against global warming is being played out on all fronts, the decarbonisation of the building sector is an essential lever. Responsible for 17% [3] of greenhouse gas emissions in France, building (residential and tertiary) is the largest consumer of energy [4]. Renovating the existing is positioned as an essential track, if indeed it is considered in its entirety. The subject of heating tends to eclipse summer issues. However, the rise in temperatures and the heat waves, which are becoming more regular and more extreme, contribute to the increase in thermal discomfort and social inequalities. Summer comfort, an expression commonly used in thermal regulations, no longer seems appropriate to the situation; it would be more accurate to speak of thermal suffering, given the health impact that heat waves can have on the French.

Nine out of ten French people believe that it is essential to find solutions to reduce the heating of their homes [1]. To lower the temperature, the French close the blinds and shutters (82%), ventilate the rooms at night (77%), close the windows (62%), use a fan (41%) and/or an air conditioner (21 %). And nearly one in five French people who do not already have one intend to invest in a cooling system, very often without having recourse to a professional who will be able to direct them towards appropriate and effective solutions.

The use of air conditioning must be reasoned and adapted

In France, the consumption associated with the cooling of buildings in 2020 amounted to 4,9 TWh in the residential sector and 10,6 TWh for the tertiary sector [5].

The use of air conditioning in homes increased by 78% between 2016 and 2020. This technology is today the source of nearly 5% of CO2 equivalent emissions in the building sector [5].

According to the IPCC, the increase in energy consumption linked to cooling in buildings is estimated at 31 to 73% in Northern Europe by 2050 and 165 to 323% by 2100 compared to 1996-2005 [6 ].

Unreasonable use of air conditioning contributes to fueling a vicious circle: the hotter it is, the more air conditioning is used, the more greenhouse gas emissions increase, the hotter it is necessary, etc. The least efficient systems – for example mobile equipment – ​​contribute directly to the warming of cities. For example, if the heat emitted by air conditioners doubles by 2030, the temperature could increase by 2°C in Paris [7].

It is urgent to combine energy sobriety and household comfort…

In a context of energy tension and shrinking purchasing power, let's remember that the cheapest and least polluting energy is the one we don't consume. Energy sobriety requires that all avenues be taken into account. If the use of active cooling systems is a legitimate need to which it is important to respond, this must be done using high-performance technologies, in a reasoned manner and in combination with passive measures, which do not consume energy, which limit the energy impact. Consumption related to cooling will thus be reduced to what is strictly necessary. It is also essential to call on a professional for the correct sizing and correct installation of the cooling equipment.

Energy sobriety is an attainable objective thanks to passive measures

Just as good insulation can limit heating consumption, there are many solutions to reduce the overheating of buildings in a sustainable way. With little or no energy consumption, this equipment and technical solutions make it possible to reconcile the habitability of buildings in periods of high heat and energy sobriety when cooling systems are present.

Install motorized or automated sun protection

Limiting the rise in indoor temperature to 2°C to 5°C in summer is possible simply by installing blinds or shutters. As for the automatic control of solar protection, it is far from being a comfort gadget: it allows optimal management of this equipment according to temperatures and solar radiation, including in the absence of occupants.

The use of solar protection could reduce energy consumption linked to the cooling of premises by up to 60% by 2050. It would prevent the emission of 100 million tonnes of CO2 and save 285 billion euros. euros in Europe [8].

A concrete example with the city of Poissy: it will equip 15 schools with solar protection. Out of the 6 school groups that have already been renovated, the results are very encouraging: during heat waves, the indoor temperature recorded is 10°C lower than outside and 5°C lower than the same classroom not equipped with blinds. An installation that will save around 300.000 kWh/year, the equivalent of an annual electricity bill of €50.000.

Improve the thermal inertia of buildings

The thermal inertia corresponds to the capacity of the materials of the walls, roofs and insulation to absorb heat or cold, then to restore the thermal flux in the phase shift phase. The more a building has a high inertia, the more comfortable it will be during heat waves. The indoor temperature in the building can thus be reduced by up to 3°C [9].

In addition, suitable insulation of the outer envelope of the building also contributes not only to efficiency in winter, but also to protection in summer.

Automate window opening

Like shutters and blinds, the opening of the openings can be automated in order to cool your home when the outside temperatures are coolest, in the evening or at night. The cooling potential that can be activated by the intelligent control of window opening in the summer period has thus been measured between 4°C and 5°C [10], [11].

In general, particular attention must be paid to the ventilation of the building in order to ensure the quality of indoor air.

Greening buildings

The revegetation of the building, roofs and green facades, contributes doubly to the adaptation against global warming. On the one hand, it brings freshness to the neighborhood scale thanks to the evapotranspiration of the plants, which makes it possible to reduce the ambient temperature by up to 3°C. Thus, on a non-vegetated roof terrace, the surface temperature, under the effect of solar radiation, can reach 60°C or 70°C. It will be 35°C or even 32°C if it is vegetated. For facades, the phenomenon is equivalent, with measured temperature reductions of 3 to 10°C. At night, the planting of buildings limits the effects of heat islands [12].

On the other hand, the greening of the roofs and facades allows more thermal comfort within the building itself, in particular for the underlying interior premises.

Implement reflective waterproofing coatings on flat roofs

Light-coloured waterproofing coatings have a high power of reflectivity and emissivity. They reflect incident solar radiation without significantly increasing the surface temperature. As the temperature rarely exceeds 40°C, these coverings contribute to combating urban heat islands and can improve thermal comfort in living spaces under the roof [13].

Promote (finally) energy-efficient passive solutions in renovation incentive policies

Why are these solutions largely absent from French public energy renovation policies? Why not extend the support systems currently limited to auditing and reducing heating consumption?

To achieve carbon neutrality within 30 years, France does not have the luxury of depriving itself of effective levers that are within its reach. Other countries, such as Italy and Germany, have understood this and already incorporate support devices for the installation of shutters and blinds, for example. Strong measures must be taken as soon as possible to adapt our country to climate challenges.

However, an ideal window of opportunity presents itself before us so that we can give ourselves the means of our ambitions with the adoption before the 1st half of 2023 of the 1st five-year programming law on energy and climate (LPEC), then with , the following year, the 3rd Multiannual Energy Program, the 3rd National Low-Carbon Strategy and the 3rd National Climate Change Adaptation Plan. The next two years will be decisive: you will draw the precise outlines of the French Energy and Climate Strategy (SFEC) and engage our country and future generations for the coming decades.

These laws must be the vector of hope and solutions for French people who suffer from overheating in their homes. We therefore ask you to integrate passive means of improving summer thermal performance as quickly as possible into the renovation aid schemes.

This is a historic opportunity to rise to the greatest challenge in the history of mankind. Let's not miss it! »

Signatories:

• Yannick Michon, President of the Actibaie Group
• Mohamed Abdelmoumene, President of the AICVF technical committee (Association of Engineers and Technicians in Climate, Ventilation and Cold)
• Jean-Pascal Roche, President of ICO (Comfort Engineering Objective 2050)
• Jean-Luc Buchou, General Delegate of the Cercle Promodul INEF4
• Damien Racle, President of CINOV (Federation of Trade Unions for Intellectual Consulting, Engineering and Digital Services),
• Pascal Bresso, President of the French Federation of Passive Construction
• Anne-Sophie Perrissin-Fabert, General Delegate of IGNES
• Pascal Coppens, President of the SFJF (French Joints and Façades Union)
• Bruno Léger, President of the SNFA
• Christophe Bieber, Elected member of the UMB-FFB (Union of Woodworking Trades)
• Pascal Housset, President of the UMGCCP (Union of trades in climate engineering, roofing and plumbing)
• Yannick Hervé, President of the UMPI-FFB (Union of Plaster and Insulation Trades)
• Yannik Beix, President of ADVIVET (Association of Green Roofs and Façades)
• Gérald FAURE, President of the CSFE (French Trade Union Chamber of Waterproofing)

[1] Source: Ifop study for Groupement Actibaie – July 2022

[2] Source: High Council for the Climate. Press Release – 2022 Annual Report released on June 29, 2022

[3] Source: Citepa

[4] Source: SDES, France's energy balance sheet

[5] Source: Ademe study "Comfort air conditioning in residential and tertiary buildings" - June 2021

[6] Source: IPCC report - 2022

[7] Source: National Meteorological Research Center

[8] Source: study conducted by Guidehouse for the European trade union ES-SO - 2022

[9] Source: Cercle Promodul / INEF4

[10] Source: Armines ParisTech study, January 2013

[11] Source: DTS/RT/2016/COMEPOS VELUX Technical Report

[12] Source: "Developing with nature in the city" - Ademe - 2018, "VEgDUD study - Role of plants in sustainable urban development - Impacts of plants in the city" - Plante&Cité - 2014, Bouchie - "Study report on CSTB for RT 2012" – 2011

[13] Source: CWA 17890 "Guide to the implementation of cool surfaces for buildings' envelope to mitigate the Urban Heat Island effects"