How can we decarbonize the building sector?

Understanding the building sector's carbon footprint

The building sector plays a key role in France's energy landscape. It accounts for 43% of total annual energy consumption, and contributes 23% of the country's greenhouse gas (GHG) emissions, making it one of France's main contributors to GHG emissions.

It is therefore essential to take up a triple challenge to make this sector more responsible:

📉 reduce the energy consumption of buildings,

⚡ control energy-related costs,

🚧 reduce the carbon footprint of construction.

🏢 What factors contribute to a building's carbon footprint?

There are many factors that contribute to a building's carbon footprint, but what are they?

🏗️ Building materials: the construction materials used in a building, as well as the production and transport of materials such as concrete, steel and glass, have a significant impact on its carbon footprint.

⚡ Energy consumption: energy consumption throughout the life of a building is a major factor in its carbon footprint.

👷‍♂️ Transport and logistics: transporting building materials, workers and occupants also contributes to a building's carbon footprint.

💧 Water use: water consumption in buildings, particularly for heating and cooling, can also generate greenhouse gas emissions.

♻️ Waste management: managing construction and demolition waste is another factor that generates GHGs.

What methods can be used to assess the carbon footprint of the construction industry?

Measuring carbon footprints is essential for assessing the environmental impact of the construction industry. It enables us to identify the areas that emit the most carbon, and to direct our efforts towards more sustainable, environmentally-friendly solutions.

🌿 The GHG inventory® carbon footprint

The GHG inventory® is a tool for calculating greenhouse gas (GHG) emissions linked to a given activity.

It consists of 5 key stages:

👨‍💻 Data collection: in this first phase, companies collect information on all their construction-related activities. This includes energy consumption (electricity, fuel, etc.), use of building materials, transport of materials and waste, and all other sources of greenhouse gas emissions.

🟢 Calculating emissions: once the data has been collected, various databases (BEIS (formerly UK DEFRA), ADEME's EMPREINTE database, etc.) provide standardized emission factors for each type of activity. Alternatively, and preferably, you can use the emission factors specific to each product or service, calculated according toISO 14 067, their PCF (Product Carbon Footprint). Global Climate Initiatives offers this online service free of charge. These factors are used to convert data into equivalent CO2 emissions. In this way, the emissions of each item are calculated individually.

📊 Analysis of results: once emissions have been calculated, companies can identify the items that contribute most to the carbon footprint of their activities. This enables them to target the most effective reduction actions.

✅ Proposing solutions: the next step is to propose solutions for reducing greenhouse gas emissions. These solutions may include using less emissive materials, optimizing energy consumption, using more environmentally-friendly transport, etc.

🔎 Action follow-up: oncethe solutions have been implemented, it is important to monitor changes in greenhouse gas emissions. This step enables us to assess the effectiveness of the actions undertaken and adjust reduction measures and strategies if necessary.

🌿 Life Cycle Assessment (LCA)

Life Cycle Assessment (LCA) is an essential method for assessing carbon footprints in the construction industry. This approach enables a complete and detailed analysis of the environmental impacts of a building throughout its life cycle, from the extraction of raw materials to its demolition.

LCA in the construction industry generally involves four key phases:

1️⃣ Life cycle assessment: in this first phase, all stages of the building's life cycle are identified and divided into different phases, such as materials extraction, manufacturing, transport, construction, use and end of life.

2️⃣ Data inventory: in this stage, all the data required for analysis is collected. This includes quantities of materials used, energy consumption, greenhouse gas emissions, as well as other environmental impacts such as air and water pollution, and the depletion of natural resources.

3️⃣ Impact assessment: once all the data has been collected, it is assessed in terms of its respective contribution to environmental impacts, including the carbon footprint. This makes it possible to determine which stages of the building's life cycle have the greatest impact on the environment.

4️⃣ Interpretation of results: the final phase involves interpreting the LCA results and identifying opportunities for improvement. Construction companies can then make informed decisions to reduce the carbon footprint of their projects.

LCA is particularly useful because it takes into account environmental impacts in their entirety, thus avoiding the transfer of problems from one stage of the building's life cycle to another. For example, the use of more sustainable materials can reduce CO2 emissions during the construction phase, but it is essential to take account of their extraction and manufacture.

➡️ By using Life Cycle Assessment, construction companies can commit to a more sustainable approach by choosing more environmentally-friendly materials and construction practices.

Environmental regulations for the building industry

⚖️ RE2020

Introduced by the 2015 Energy Transition Law for Green Growth (LTECV), the RE2020 aims to continue improving the energy performance and comfort of buildings while reducing their carbon footprint. It focuses on three main areas:

✅ Improved energy performance and reduced consumption for new buildings. The RE2020 goes beyond the requirements of RT2012 by placing particular emphasis on the efficiency of insulation, regardless of the heating method used, and by tightening requirements concerning the bioclimatic need indicator, Bbio.

✅ Reducing the climatic impact of new buildings by taking into account all the building's emissions over its lifecycle, from construction to end-of-life (building materials, equipment), including the operating phase (heating, domestic hot water, air conditioning, lighting, etc.) thanks to a lifecycle analysis.

✅ Creating living and working spaces adapted to future climatic conditions, while maintaining the objective of summer comfort. Buildings will have to be more resistant to heatwaves, which will become more frequent and intense as a result of climate change.

The implementation of the RE2020 is based on a gradual transformation of construction techniques, industrial sectors and energy solutions, in order to keep construction costs under control and ensure that the sector's professionals continue to develop their skills.

The overall aim is to promote more sustainable, environmentally-friendly construction while offering greater comfort for occupants.

⚖️ The Bâtiment Basse Consommation (BBC) label

The Bâtiment Basse Consommation (BBC) label is an environmental certification attesting that the building meets strict energy consumption criteria, going beyond the requirements of RT2012. BBC-labeled buildings are characterized by their low energy consumption for heating, air conditioning, domestic hot water and lighting.

There are two types of conditions for obtaining the BBC label, depending on the age of the property:

• For new homes: They must meet an energy consumption target of no more than 50 kilowatt-hours of oil equivalent per square meter per year (50 kWhep/m².an).
• For existing homes: Energy consumption must be less than 50% of conventional consumption. The energy consumption target for these homes is set at 80 kilowatt-hours of oil equivalent per square meter per year (80 kWhep/m².an).

The BBC label is a guarantee of environmental quality and energy efficiency for buildings. It encourages builders and owners to adopt eco-responsible construction and renovation practices, thereby helping to reduce greenhouse gas emissions and combat climate change.

BBC-labeled buildings also offer occupants benefits in terms of comfort and lower energy bills, promoting a more sustainable way of life.

What can be done to limit the environmental impact of the construction industry?

Decarbonizing the construction sector is no easy task, but there are many levers to activate to make this industry more eco-responsible. Here are just a few of them:

⚒️ Energy-efficient building materials and techniques

Using sustainable, environmentally-friendly materials in construction can significantly reduce a building's carbon footprint. Materials such as wood, bamboo and recycled bricks are eco-friendly alternatives. In addition, energy-saving construction practices, such as thermal insulation and the use of natural ventilation systems, can contribute to more environmentally-friendly buildings.

⚡ Integrating renewable energies into buildings

The integration of renewable energy sources is essential to decarbonize the building sector. Solar panels can be used to generate electricity, while geothermal and wind systems can provide heating and cooling. These solutions help reduce dependence on fossil fuels and lower the environmental impact of buildings.

☀️ Energy-efficient heating, ventilation and air conditioning systems

Heating, ventilation and air-conditioning (HVAC) systems account for a significant proportion of energy consumption in buildings. Technological advances such as smart thermostats and heat recovery systems enable more efficient use of energy. Improving HVAC energy efficiency is key to decarbonizing the building sector.

🚧 Renovating existing buildings

Renovating existing buildings is an essential step in decarbonizing the sector. By improving the energy efficiency of existing structures, we can reduce their environmental impact. Systems such as insulation, energy-efficient windows and solar panels can be integrated into existing buildings.

On the same theme, find out more about the industrial carbon footprint.