Building Envelope Renovation: A Critical Aspect of Sustainable Buildings
The building envelope can be simply defined as the protection between the interior and exterior, composed of roofs, walls including doors and windows and the floor. The design of the building envelope will determine its heating and cooling needs and will influence air quality, acoustics, and safety within. An inefficient envelope will encounter thermal bridges, reinforcing thermal losses often at the junction between different components such as walls and windows. Consequently, it emerges as a vital element in designing energy-efficient and environmentally friendly buildings.
Towards Greater Energy Efficiency
On the one hand, since the 2000s, floor area has increased by 60% while energy consumption per m² has only decreased by 20%: the progress made in energy performance does not compensate for the growth of the global real estate market. Despite more stringent sustainable construction regulations and increased renovation rates reducing global heating needs by 10%, this progress can't keep pace with the rapid growth of new construction in emerging and developing countries. Moreover, cooling needs have increased by more than a third in these same countries for the same reason.
On the other hand, 80% of buildings in 2050 are already built and the average renovation rate of the real estate stock is currently 1% per year globally, which is below the recommendations of the Net Zero Emission by 2050 Scenario set at 2.5% per year. The report The Global Status of Buildings and Construction in 2020 states that electricity consumption related to the use of buildings accounts for nearly 55% of total electricity consumption. Therefore, if renovation and adaptation measures for buildings are not taken, the real estate will remain largely energy inefficient.
The building envelope is a critical component in reducing its energy needs. By designing buildings with a high-performance envelope, allowing efficient thermal insulation, and coupled with the production of renewable and/or decarbonized energy, the real estate will be more resilient and sustainable.
A Tool for Decarbonizing the Real Estate Market
The two significant items in a building's carbon footprint are emissions linked to construction and demolition on the one hand and those related to operation, through energy consumption, on the other hand. Generally, the overall structure and envelope of the building represent the most significant portion of the carbon footprint, reaching up to 60% for office buildings. This is mainly due to the use of a large quantity of materials with a high carbon footprint like glass, concrete, or steel. Renovation, on the other hand, has ten times less carbon impact as it preserves the exterior envelope and prevents emissions related to deconstruction and demolition. On average, renovation and rehabilitation save 300 kg of CO² per m² of floor area.
Moreover, the UN predicts that by 2050, 70% of the world's population will live in cities, compared to 55% currently. This means that cities will tend to expand and densify and the real estate market will inevitably change. With the declared intention of major global metropolises and megacities - such as Paris, Seoul, or San Francisco - to achieve carbon neutrality by 2050, renovating the envelope is thus an essential tool for reaching this goal, influencing energy consumption, often from non-renewable and carbon sources, and representing the largest share of carbon in the building's carbon balance.
An Ally for the Health of Occupants
Designing an efficient envelope allows good moisture management, temperature regulation, and air circulation. All these factors are essential for the health of building occupants: poor air quality can cause respiratory problems, just as too low or too high temperatures can weaken the immune system and degrade the quality of life. Furthermore, the envelope is an effective protection against external noise nuisances, especially in urban areas where excessive noise levels can cause stress, sleep disorders, or decreased productivity.
The world is trending towards increased urbanization, a population always rising affected by issues such as atmospheric pollution, more intense heat waves reinforced by urban heat islands and more and more congested and noisy cities. The renovation of the existing stock, through an envelope renovation, is an effective barrier against these health risks.
How to Get There
Several tools and techniques allow the design and renovation of the building envelope to make it optimal:
Insulation and fighting thermal bridges: A well-insulated building is a building that consumes less as the best source of energy is the one we do not consume. By opting for triple-glazed windows, for example, the thermal and sound insulation of the building is improved. Also, innovative solutions exist, such as vacuum insulation panels and silica aerogel: they are up to 5 times more efficient than a traditional insulator and much thinner, thus allowing to gain additional space, increasing the property value. These are solutions to implement in areas not insulated due to lack of space.
Use of bio-based and geo-sourced materials: The carbon footprint mainly resides in the structure and envelope of the building, so it is important to use materials that reduce this. One could think of wood, cork or even hemp concrete which have similar or even superior properties to materials predominantly used today, such as cement or asphalt, and have a very high carbon footprint due to their manufacturing process. Bio-based and geo-sourced materials come from biomass and thus have a very low carbon footprint.
An "intelligent" envelope: An intelligent envelope allows, in addition to protecting the building from external conditions, to produce its own energy, for example. The Asca protective solar films, manufactured by the company Armor, are solar panels derived from a low-carbon process, tailor-made and flexible, compatible with a multitude of materials and produce solar energy once affixed to windows, protecting the interior from radiation and generating decarbonized electricity.
Finally, national regulations are effective tools, already implemented in over 80 countries worldwide, imposing strict standards for construction and renovation, reducing emissions from the real estate sector. With RE2020, France has one of the strictest regulations in the world for sustainable construction.
In conclusion, the renovation of building envelopes is one of the first steps to effectively improve energy efficiency, reduce the carbon footprint, enhance the health and comfort of users and create a resilient and sustainable real estate stock.
Do you have a building renovation project and want to improve its environmental impact? Contact us now to find the most suitable solutions for your needs!