Green Building and Renewable Energy

Globally, the building and construction sectors combined are major contributors to energy consumption and greenhouse gas emissions. According to the United Nations Environment Programme, buildings account for nearly 40% of global energy-related CO2 emissions when including building construction. Of this, operational emissions – from energy used to heat, cool, and light buildings – account for 28%, while the remaining 12% comes from embodied carbon associated with materials and construction processes throughout the building lifecycle. In response, the building industry worldwide is increasingly adopting renewable energy sources to mitigate environmental impact and improve energy efficiency. In 2022, energy consumption from renewable energies in the building sector was 7.8 EJ and aims to be 18.2 EJ by 2030 according to the International Energy Agency (IEA). Innovative solutions in solar, wind, and geothermal energy are at the forefront of sustainable building designs, offering a promising pathway to reduce the sector's carbon footprint and operational costs.

Solar Energy

In 2021, the global capacity for solar photovoltaic (PV) energy production reached approximately 714 GW, compared to just 40 GW in 2010, as per the International Energy Agency (IEA). This significant increase indicates a global trend towards cleaner and renewable energy sources. 

Principles and technologies :

Solar energy is captured in two main ways: photovoltaics (PV), which convert sunlight into electricity, and solar thermal, which uses the sun's heat. PV technology leads due to its flexibility and wide application, from residential roofs to large solar parks. Although less widespread, solar thermal plays a crucial role in heating water and spaces, as well as in some industrial processes.

Advantages and Applications : 

The primary advantage of solar energy is its abundance and almost limitless availability. Unlike fossil fuels, it does not emit CO2 during electricity production, making it essential for reducing overall greenhouse gas emissions. Moreover, solar energy can be produced locally, reducing dependency on energy imports and promoting energy security. In 2020, residential PV systems accounted for about 40% of all solar capacity installed in the European Union, according to Eurostat.

Challenges and Solutions : 

Despite its many benefits, solar energy faces challenges, notably in terms of variability and the need for significant surface areas. Solar energy production is directly dependent on weather conditions and sunlight, leading to fluctuations in electricity production. To overcome this challenge, the development of more efficient and affordable energy storage systems is crucial. Furthermore, ongoing innovation in photovoltaic materials promises to increase the efficiency of solar panels and reduce their environmental impact, notably through recycling. Today's PV panels have an efficiency range between 13% and 24%. Integrating solar energy into buildings, through roof-integrated panels or solar facades, offers a promising solution to increase energy production density while minimizing land use. For example, solar roof tiles are a type of building-integrated photovoltaïc system. These tiles function as both roofing material and solar panel with an efficiency range between 10 and 20% according to GreenMatch.

Wind Energy

Wind energy is a vital component of the global energy mix. In 2020, the global installed wind energy capacity exceeded 743 GW, marking a significant increase from the previous decade, which was estimated at about 200 GW in 2010 (Global Wind Energy Council, 2021). Although the building sector benefits less from this source, which is primarily used on a large scale, it remains an important area of innovation. 

Principles and technologies :

Wind energy is produced by converting the kinetic energy of wind into electricity through turbines. There are two types of production: onshore and offshore.Offshore represents turbines used on the sea and are not used in the building sector. However, turbines can be installed on rooftops or integrated into the structure of buildings themselves. These systems, often smaller compared to their counterparts in wind farms, are designed to exploit urban airflows. These turbines are generally less than 10 kW in power, mainly installed on roofs.

Advantages and Applications : 

Integrating wind energy into buildings offers several advantages. Like solar, it allows for reduced dependence on the traditional electrical grid and lowers greenhouse gas emissions associated with building energy consumption. Furthermore, in some configurations, it can contribute to architectural aesthetics and the building's sustainable profile. In the application of wind solutions for buildings, two types of turbines can be distinguished: HAWT (horizontal axis) and VAWT (vertical axis). Horizontal axis turbines offer better performance (25% according to a university comparative study) but are noisier, suited to limited wind ranges, and difficult to orient to the wind. In contrast, vertical axis turbines, quieter and easily integrated into buildings, show lower performance and require a start-up device.

Challenges and Solutions : 

The use of wind energy in buildings is less compared to solar or geothermal, yet it remains an innovation axis in the building sector. Its integration comes with challenges such as managing wind turbulence, the visual and sound impact of turbines, and the initial cost of installation and maintenance. Moreover, like solar, wind is a variable energy source dependent on weather conditions. Developing more efficient and affordable energy storage systems is crucial to overcoming these challenges.

Geothermal Energy

Geothermal energy, literally meaning "Earth's heat Energy," is a renewable energy source from the heat stored beneath the Earth's surface. This inexhaustible energy can be used to produce electricity, heat buildings, and more. The United States is currently the world leader in geothermal energy production with 3.6GW of geothermal energy capacity according to the Green Building Alliance.

The use of geothermal energy in the building sector can reduce by up to 50% of the building’s energy consumption, making the geothermal energy a necessity for green buildings.

Principles and technologies :

Geothermal energy exploits the Earth's internal heat, stemming from sources including the radioactive decay of minerals and residual thermal flow from the planet's formation. Geothermal systems use wells drilled into the ground to access hot water reservoirs or steam, which can then be used to power electricity-generating turbines or for direct heating applications. However, geothermal systems can also produce cooling by using reversible geothermal heat pumps (GHPs), allowing the subsoil to be used as a source of cooling for building. This technology, known as geocooling, offers a particularly cost-effective and ecological solution for building cooling in summer. Earth-to-air heat exchanger represents another approach, using the relatively stable underground temperature to cool or preheat outdoor air introduced into the building depending on the season.

Advantages and Applications : 

One of the main advantages of geothermal energy is its low carbon footprint compared to fossil fuels, thus contributing to the fight against climate change. Moreover, unlike other renewable energy sources like solar and wind, geothermal provides a constant energy output, independent of weather conditions. Geothermal energy also finds application in the simultaneous production of heat and cold, particularly suited to the building sector. One of the biggest benefits of geothermal energy is energy efficiency with a potential reduction by up to 50% of buildings energy consumption, meaning lowering operating cost for building owners and occupants.

Challenges and Solutions : 

Despite its many advantages, geothermal faces challenges. The initial costs are high, especially for geothermal drilling on probes, ranging from €2,700 to €11,000 for the study, and from €75 to €115 per linear meter for the test drilling. Heat pumps can cost between €195 to €645 per kW. These costs reflect the significance of the initial investment in geothermal projects but also the potential for long-term savings, with an average return on investment of 7 to 8 years on building heating, according to Geo Green.

Conclusion

The use of renewable energies is not only essential for reducing greenhouse gas emissions but also beneficial for the energy efficiency of buildings. Solar, wind, and geothermal solutions offer promising opportunities for the future of the building sector. Despite challenges, including initial costs and production variability, innovations and supportive policies play a key role in accelerating their adoption.

To learn more about how you can integrate renewable energies into your construction or renovation projects, contact us today!