CONSTRUCTING A SUSTAINABLE FUTURE APRIL 2023 THE SUSTAINABLE CONSTRUCTION MAGAZINE BY SAINT-GOBAIN Cliquez ici pour la version française
WHY THIS MAGAZINE? Constructing a sustainable future is far more than just a magazine. It is the starting point for a conversation we want to have with everyone involved in construction, all around the world. That conversation is necessary because the construction sector, which accounts for the use of 50% of our natural resources and 37% of CO2 emissions, is at the intersection of the great challenges of our time. The challenge of the increasing scarcity of resources, climate change, the energy crisis, and the acceleration of urbanization and population growth. So, it is our firm belief that constructing our future calls for sustainable construction. To achieve that, we need to take a multi-perspective look at the environmental impact of our buildings throughout their life cycles, from design to deconstruction — without forgetting how they are actually used, of course. From policymakers and industry leaders to developers, architects, urban planners, students, manufacturers and distributors of construction materials, builders, craftsmen, transporters and users, we are all responsible for building a more equitable and sustainable future. The stakes are clear, and we already have solutions. We now need to continue working, innovating, accelerating and pushing boundaries, and to do so together. Saint-Gobain We have also taken a sustainable approach to this magazine, from production to print, to minimize its environmental footprint as far as possible. Using vegetable-based ink and paper from recycled disposable coffee cups, the magazine was made by Pureprint, a pioneer in carbon-neutral printing. Cover artwork by Emily Forgot
Last year, the world’s population crossed the eight billion mark. It took the human family 125 years to get from one billion to two billion but only 12 years to advance from seven billion to eight billion. More than four billion of us live in cities today, with 1.5 million additional city dwellers added each week. This growth means greater diversity, infinite opportunities, and endless possibilities. However, we also face more challenges as cities contribute 70% of all carbon emissions. With resources quickly diminishing, we need to pause and re-think how we urbanize while taking care of our natural and built environment. The construction sector and professionals of the built environment that work for them play a key role in ensuring that we find solutions. Cities and city managers are at the frontline of crises: Covid-19, climate change, conflicts, and a lack of capital. We need to help them to make our habitat more sustainable and resilient. Not everything is doom and gloom, though. We see change happening. We simply need to accelerate it. Many construction companies, architects, and urban planners have started thinking about sustainability and resilience to climate change, focusing on more environment-friendly and energy-efficient designs. With one major ambition: creating a better quality of life for people now and for the generations to come. Collectively, we have also started to not only think about building more sustainable and resilient buildings but also adapting and rehabilitating existing structures – to make our houses more efficient and sustainable. It is important to look at regenerating neighborhoods and communities in our cities. And not only think about building new structures. EDITORIAL By Maimunah Mohd Sharif UNUnder-Secretary-General and ExecutiveDirector of UN-Habitat To overcome challenges and create better cities, we need a whole-house or whole-society approach. It is not enough to demand action from the construction sector alone. We need holistic solutions, from better policies and better building standards to designing and implementing better urban models. Then, we also need businesses to adopt and scale these models. And communities and people to embrace them. We also want to understand the current gaps. Once we know what we miss and what we need to do, we can act and support initiatives to make human settlements more environmentally and socially sustainable. It is our chance to create a better quality of life for the eight billion people currently living on our planet. And leave a better world for the billions yet to come. 3 CONSTRUCTING A SUSTAINABLE FUTURE
TABLE OF CONTENTS Building our future Carbon construction: where does the problem lie and who can act on it? Whether building or renovating, in the North or South, the city of tomorrow is taking shape today 31 Renovate the North 34 Europe’s Energy Efficiency Problem 36 Designs and renovations that will withstand the test of time are possible 40 Building a Global South 21 Decarbonizing across the entire value chain 27 Operational or embodied: changing perceptions about carbon 28 Renovation and the necessary mobilization of public authorities 07 The urgent need for sustainable construction 11 Construction’s carbon footprint 12 Designing the megacities of 2050 18 The social impact of poor-quality housing 19 The housing shortage accentuates inequalities 4 SAINT-GOBAIN
Sustainable Construction Observatory 78 Initial findings from the 2023 edition Giving investors the green light for carbonfree construction Sustainable construction: challenges and actions 47 Action 1: aiming for energy efficiency 50 « The city of tomorrow will be blue-green » 52 Action 2: acting across the entire value chain 55 Action 3: designing buildings differently 58 Action 4: integrating the principles of a circular economy 61 Action 5: opting for light construction 65 Action 6: taking care of people 69 Sustainable investment is profitable 71 Energy demand: two scenarios for 2050 75 Ensuring access to the most advantageous financing 76 « In the medium term, sustainable construction has a lower cost » 5 CONSTRUCTING A SUSTAINABLE FUTURE
BUILDING OUR FUTURE By 2050, this planet will be home to another two billion human beings. To accommodate us all, we are going to need to build more housing and more infrastructure. It has been calculated that the equivalent of a city the size of Paris (105 km2) will crop up every day, particularly in the countries of the Global South1. Yet the housing challenge will be just as great in Western countries. To meet the demands of its current population, the United States would need to build the equivalent of three years’ worth of houses and apartments in the space of a single year. In the United Kingdom alone, 340,000 homes would need to be built every year until 2031 just to address the existing shortfall. The construction sector is responsible for 36% of the world’s energy consumption, 37% of greenhouse gas emissions, 40% of solid waste production, and 50% of natural resource use 2. So, we face an environmental, economic, and societal challenge that forces us to address a key issue: how to renovate and build faster and cheaper but, above all, more sustainably? 1. The term "Global South" designates countries classified by the World Bank as having a low or average income and being located in Africa, Asia, Oceania, Latin America, and the Caribbean. 2. World Green Building Council. SAINT-GOBAIN 6
The urgent need for sustainable construction Wherever humans go, we build. A lot. Everywhere. And we always have. Above all, we too often build to the detriment of nature. Our planet is no longer capable of absorbing the environmental cost of our constructions due to greenhouse gas emissions, the overexploitation of natural resources and energy inefficiency. Yet we need to continue to house an ever-increasing population. To meet this need, there is only one solution: sustainable construction. The essential conditions for human society to flourish are living in a healthy environment, where nature is protected, with ecosystems that are in perfect working order. Yet it is human activity that, century after century, has imperiled the equilibrium of our planet. For more than three hundred years we have continued to build, come what may, without any real awareness that the environmental impact of the construction of our cities would come to represent on a global scale 36% of the planet’s energy consumption. It also represents 37% of its carbon emissions (CO2), 50% of its resource use, and 40% of its solid waste production. > 7 CONSTRUCTING A SUSTAINABLE FUTURE
«Adirewarning about the consequences of inaction» The construction sector is not solely responsible for climate change, by any means. Nevertheless, Charles Kibert, Director of the Powell Center for Construction and Environment at the University of Florida, emphasizes that “activities linked to the building and construction sector and the completion of its projects constitute 60% of the climate change problem.” There is a substantial impact that can be seen throughout the lifetime of a building, including its construction and everyday use. Professor Kibert, who is also the author of the seminal publication Sustainable Construction: Green Building Design and Delivery, highlights that it’s imperative to take urgent action. As does South Korean economist Hoesung Lee, Chair of the Intergovernmental Panel on Climate Change (IPCC). The IPCC’s Climate Change 2022: Impacts, Adaptation and Vulnerability report is described by the economist as “a dire warning about the consequences of inaction.” The $2,004 trillion cost of climate-change related disasters According to Hans-Otto Pörtner, who co-chairs the IPCC Working Group II with Hoesung Lee: “Any additional delay in taking concerted worldwide action will be a missed opportunity to ensure a viable future”. The facts are there for all to see: the very survival of mankind is now at stake. According to the United Nations Office for Disaster Risk Reduction (UNDRR), the number of natural disasters has increased fivefold over the past 50 years, and the cost of these incidents has increased by 30% in 20 years. Between 2000 and 2019, the total economic impact of climate change-related disasters rose to $2,004 trillion, of which $1,206 trillion was linked to storms. Periods of intense heat have become increasingly frequent in recent years, and among the 197 member states of the United Nations, 168 have declared themselves under threat of desertification. Meanwhile, the number of floods has more than doubled in the past 20 years. As a result of these environmental disasters, 254 million people have been displaced in the past decade. According to the Internal Displacement Monitoring Centre (IDMC) of the United Nations Refugee Agency (UNHCR), 60% of the displaced resettle in urban areas. Is Jakarta about to disappear off the map? The world’s sea levels are rising and 40% of the Indonesian capital Jakarta is already below sea level, with the districts closest to the seafront sinking by 25-30 centimeters per year. The World Economic Forum has estimated that 95% of roads in this Southeast Asian megacity could be under water by 2050. In the face of this reality, the Indonesian parliament passed a law in early 2022 authorizing the creation of a new capital 2,000 km away, on the island of Borneo. It’s named Nusantara - which means “archipelago” in Indonesian. Bangkok, Thailand; Dhaka, Bangladesh; Lagos, Nigeria; and Alexandria, Egypt are other cities that, by the year 2100, could also find themselves with large stretches covered by water, rendering them uninhabitable. Cities occupy only 2% of the Earth's surface but emit nearly 70% of greenhouse gases. 8 SAINT-GOBAIN
A river delta in the Java Sea east of Jakarta, Indonesia. 95% of Jakarta’s roads could be under water by 2050. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + The impact of similar changes is also evident in the United States. A study in the Journal of the Association of Environmental and Resource Economists predicted that one in 12 Americans currently living in the southern half of the country will emigrate sometime in the next 45 years. They are set to move to areas including California, the Rocky Mountains region and the American Northwest for reasons linked to climate change. Experience with climate-related issues teaches us that the least optimistic hypotheses have the unfortunate habit of coming true. In its 2022 report, the IPCC observes that the increase in global > © Getty Images Mangiwau 9 CONSTRUCTING A SUSTAINABLE FUTURE
The Europa building, headquarters of the European Council in Brussels. Its facade is made of a patchwork of wooden frames recovered from building sites across the European Union. temperature has become more pronounced. At the current pace, the threshold of a 1.5°C global temperature rise compared to preindustrial levels will, in all probability, be crossed at some point between 2021 and 2040. While this is a frightening prospect, experts believe there is still time for change. “Adapting to climate change is possible if global warming is limited to 1.5°C or 2°C [by the year 2100, as envisaged in the Paris Agreement signed in 2015 by 197 parties, including the European Union].” Taking immediate action So how can the climate change tipping point be avoided? By continuing our efforts to change our practices and by investing in adapting our built environment, so the world can avoid the need for much greater investment in the future. We need to accelerate action to protect the world’s populations from the effects of climate-related upheavals, while intensifying our efforts to address the root cause: the reduction of greenhouse gas emissions. This is an issue of the utmost urgency. Even if the objective of a maximum rise of 2°C now seems difficult to achieve, given that in 2022 the global temperature had already increased by 1.15°C compared to preindustrial (1850-1900) levels. We should act, but how? Well, within the context of an increasingly urbanized world, the actors within the construction industry have the power to design tomorrow’s buildings for a society that is more mindful of preserving the delicate equilibrium of the natural world. © Alamy Stock Photo/Santi Rodriguez 10 SAINT-GOBAIN
CONSTRUCTION’S CARBON FOOTPRINT Construction’s carbon footprint The emissions that make up the world’s energy-related carbon footprint come from a variety of industries. Of these emissions, 37% is produced by buildings and construction. Buildings and Construction 17% Residential buildings Direct emissions: 6% Indirection emissions: 11% 10% Non-residential buildings Direct emissions: 3% Indirection emissions: 7% 10% Construction industry 37% of total energyrelated C02 emissions + + 6% Other Energy-related emissions from agricultural practices or other small sources 23% Transport 10% Other construction industries* 23% Other industries Emissions from manufacturers, etc. Source: UN GABC 2021 Global Status Report for Buildings and Construction *Emissions from other materials used in construction (excluding brick, glass, concrete, aluminum and steel) CONSTRUCTING A SUSTAINABLE FUTURE 11
Designing the megacities of 2050 The number of cities with over 10 million inhabitants – known as megacities – will have doubled by 2050. Scores of new megacities will be created, mainly in Africa and Asia. This constitutes a stark environmental challenge, but also represents a real opportunity: the chance to build cities that are different and are sustainable, not only for the environment but also for inhabitants. Cities that avoid repeating the errors of the past and can offer residents better living conditions are the key to preserving social cohesion. Aerial view of Tokyo, Japan. © EyeEm 12 SAINT-GOBAIN
Source: United Nations Asia Mumbai (42 million) New Delhi (36 million) Dhaka (35 million) Kolkata (33 million) Tokyo (32 million) Karachi (32 million) Africa Kinshasa (35 million) Lagos (33 million) North America Mexico (25 million) New York (25 million) By 2050, 10 megacities will have over 25 million inhabitants each. > Since 2007, humanity has become predominantly urban. Of the world’s population, 55% live in cities and this number is estimated to rise to nearly 70% by 2050, which means the planet will have an additional 2.5 billion city dwellers. According to a global urbanization forecast by the United Nations Human Settlements Programme (UN-Habitat), the number of cities with more than 10 million inhabitants will rise from 31 today to 43 by 2050. Ten of these megacities will have more than 25 million inhabitants. Moving toward a «planetwide city» With Earth gradually changing into a ‘planetwide city’, it is becoming imperative to formulate a new, inclusive, and sustainable urban model that is more in tune with the planet’s natural ecosystem. Particular attention must be paid to the needs of the countries of the Global South, especially in Asia and sub-Saharan Africa, where over 1 billion people still live in slums and where urbanization is set to accelerate at the highest rate. UN-Habitat estimates that by 2070, the number of cities will increase by 76% in low-income countries, compared to 20% in high or medium-income countries. In the countries with the highest GDP per inhabitant, the number of cities is only predicted to increase by 6%. According to the Smart Sustainable Cities: Reconnaissance Study (2016), the urban population will rise from 40% to 56% in Africa, and from 48% to 64% in Asia. In Latin America, Europe and North America, growth will be slower. Nevertheless, with urban population percentages of 86%, 82% and 87% respectively by 2050, the challenge will still be considerable. The solutions proposed to respond to the challenge might vary between regions. However, the objective will remain the same: to provide future city dwellers with the best possible quality of life, aligned with their social, material and even food needs, without negatively affecting the environment. The burden of this exponential urbanization of the planet inevitably exhausts the Earth’s natural resources. Every year, millions of hectares of agricultural, natural or woodland is used to accommodate the expansion of urban areas. This damages biodiversity, reduces the area available for cultivation and weakens productivity and food security in certain countries. It is estimated that by 2030, Nigeria will have lost 17% of its capacity for 13 CONSTRUCTING A SUSTAINABLE FUTURE
Reykjavik, Iceland has also become one of the most ecologically conscious cities in the world. This city of 120,000 inhabitants has developed in close contact with the natural world, with green rooftops, parks, gardens, pedestrian and cycle lanes, and nearly 410m2 of green space per resident. Renewable energy production – including geothermal energy and hydroelectric dams – now supplies 100% of Reykjavik’s electricity needs. This is particularly impressive as, until the 1970s, the country depended almost exclusively on fossil fuels. In South Africa, the city of Cape Town is favoring climate-related progress. Between 10% and 20% of its energy production now comes from the gas produced by the burning of urban waste. This rapidly expanding African city, with over four million inhabitants, has also consolidated its public transport network, enabling it to reduce traffic, carbon dioxide emissions and pollution. Cape Town is also 100% of Reykjavik's electricity needs are met by renewable energy (geothermal, hydroelectric dams). Call this turning point whatever you like: a transition, a parting of the ways, a change of direction or a revolution. Whatever you call it, it is coming at us head-on and needs to be negotiated quickly. This is not an adjustment of the needle, it’s a complete change of model for the fabric of our cities. » « > 1. UN-Habitat - World Cities Report 2022: Envisaging the Future of Cities, 2022. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + rice production and 12% of its capacity for corn production as a result of urbanization. Egypt could lose 40% of its rice and 60% of its corn1. The cities of the future will therefore need to be denser. We need to limit urban sprawl, which necessitates the construction of more and more buildings, infrastructure, and transport networks. However, housing that is affordable, healthy, and accessible will also still be needed. Model cities all over the world Across continents, traditional cities are taking steps to change and are progressively turning into sustainable cities. In a single decade, Vancouver, Canada – which boasts nearly 700,000 inhabitants – has become one of the greenest cities on the planet. To achieve this, the city appealed to the green conscience of companies. The training of professionals in low-carbon construction techniques has led to new buildings with smaller carbon footprints, as well as a 2% annual reduction in energy consumption. The policy of ’greening’ has resulted in the creation of thousands of parks all over the city, while composting areas and gardens perched high on skyscraper rooftops have sprung up. The city’s economic performance has benefited from this boom as jobs related to the green economy have increased by 20% in 10 years. Christine Leconte, architect, and Sylvain Grisot, urban planner, Réparons la ville ! (Let’s Repair Our Cities!), published by Apogée, 2022. 14 SAINT-GOBAIN
Borja Bonaque CONSTRUCTING A SUSTAINABLE FUTURE 15
Housing is a major challenge because it is the point of entry for economic, social, and cultural inclusion. It must be intrinsically sustainable, which means it must be constructed in such a way as to provide stability and dependable living conditions for the long-term. » Christophe Lalande, Housing Unit Leader at UN-Habitat « developing many sustainable construction projects, including the distribution of a dedicated guide. As a result, projects are flourishing. That includes The Fynbos, the first biophilic apartment block in Africa, due to be completed by late 2024. Its objective is to create an authentic natural environment within an urban context by relying on the natural properties of plants and air and light circulation. Equally sustainable, and accessible to low-income groups, is the Sandbag Houses project by MMA Architects. The project involved the use of sandbags, locally sourced material and the manpower of future inhabitants, and led to the creation of 10 houses with a sale price of just over $5,000 each. The model city is no longer a utopia The city of Curitiba, Brazil, has been committed to environmentally friendly policies since the 1980s. This city of two million inhabitants has long been considered ahead of its time and is often referred to as ’Cidade Modelo da América Latina’ (‘the Model City of Latin America’). The city sorts 70% of its waste through an ingenious exchange system that allows residents to swap garbage for baskets of vegetables or bus tickets. Curitiba has also planted over a million trees along the edges of its highways and has created more and more green spaces – totaling 60 m2 per inhabitant. All these results are very encouraging. To construct or modernize cities capable of offering citizens better living conditions – ensuring the preservation of social cohesion – there must be innovation in construction projects. That is the case whether they are individual houses, apartment blocks or public buildings. This transformation of urban areas must also encourage inclusiveness, ensuring everyone not only has access to housing, but also to healthcare, employment, and public services. Cities redesigned in a sustainable way represent an investment in the future for urban centers that are safer, more affordable, more humane, better for inhabitants’ wellbeing and with a less harmful environmental impact. 16 SAINT-GOBAIN
Curitiba, Brazil: 'The Model City of Latin America'. © GettyImages 17 CONSTRUCTING A SUSTAINABLE FUTURE
The social impact of poor-quality housing Aerial view of a township in South Africa. The World Health Organization (WHO) is clear about the subject. Living in sub-standard accommodation can have detrimental psychological consequences including anxiety, depression and loss of self-esteem... The organization attributes 130,000 deaths every year in Europe to inadequate housing conditions. The University of California, Berkeley has also established that living in unhealthy housing with dampness and mold leads to a 50% increase in the risk of developing asthma, allergies or infections And that’s not all. Poor acoustics in a home can disturb sleeping patterns, cause fatigue and stress and reduce learning ability. In the longer term, noise disturbances can also lead to hormonal irregularities, high blood pressure and a significantly increased risk of developing cardiovascular disease, the WHO has concluded. The organization estimates that people in Western Europe lose around 61,000 years of healthy life every year. An estimated one sixth of the world’s population struggles to keep a roof over its head. In the countries of the southern hemisphere, the problem is even more acute: 597 million Asians and 238 million Africans face a shortage of housing. Many live in homes that are unsafe, unstable, and even unhealthy – without running water, sewage systems, electricity or access to public transport. This can lead to social problems, adding to the health and environmental issues already created by the poor-quality buildings. This cost is an additional burden on the community. © EyeEm/Tim Wege 18 SAINT-GOBAIN
Facade d’un bâtiment résidentiel. The housing shortage accentuates inequalities In the majority of Western countries, housing is scarce and expensive, usually between two and four times more than the original construction cost. In The Housing Theory of Everything article published in Works in Progress, Sam Bowman, John Myers, and Ben Southwood, explain: “In the 1960s, it was commonplace that a middle-class single-earner American or British family would be able to afford a comfortable home.” This is no longer the case, and not only in the United States or Great Britain. In the past forty years, average house prices in the New York metropolitan area have increased 706%. House prices in San Francisco have gone up 932% – making them 326% higher than American salaries. In the same period, house prices have increased 800% in Dublin, Ireland; 1,450% in Sydney, Australia (compared with a 480% increase in hourly pay); and 2,100% in London (1,500% more than local salaries). In France, the financial pressures are such that it is almost obligatory to combine two salaries to be able to buy a home. Today, 62% of buyers are couples with both partners working. In 1990, this was the case for only 35% of buyers. In the words of Christophe Lalande, Housing Unit Leader at UN-Habitat: “Housing is a major challenge because it is the point of entry for economic, social, and cultural inclusion. It must be intrinsically sustainable, which means it must be constructed in such a way as to provide stability and dependable living conditions for the long-term.” A residential building facade. ©iStock/Nongnuch Pitakkorn 19 CONSTRUCTING A SUSTAINABLE FUTURE
CARBON CONSTRUCTION: WHERE DOES THE PROBLEM LIE AND WHO CAN ACT ON IT? Let’s shift the paradigm. Our homes, offices, schools and hotels can emit less CO2 throughout their life cycle. Materials, industrial processes, transport, use and, ultimately, demolition: at each stage, our choices can reduce the carbon footprint of the built world. And this is why, faced with climate challenges, everyone must act sustainably and responsibly. SAINT-GOBAIN 20
For a long time, the environmental challenge in construction has been approached solely by means of improving the thermal and energy performance of buildings. And for good reason: of the 37% of greenhouse gas emissions emitted by buildings1, 27% comes from energy consumed by heating, cooling, ventilation, and lighting. Energy efficiency, therefore, remains an indisputable priority. But it is also essential to deal with the remaining 10% – the carbon emitted throughout the life cycle of buildings and not just while they are being used. From operational to embodied carbon The Paris Agreement, which is aiming for net-zero carbon emissions by 2050, leads the way to building standards that further light and eco-friendly construction. Reducing operational carbon, i.e., the carbon emitted during the building’s operating phase – such as lighting and energy – remains a priority when undertaking renovations. But it is also essential to consider the carbon footprint of a building over its entire life cycle, from the extraction of raw materials to transport, and the recovery of materials at the end of its life. The reason is simple: all these steps generate CO2 to a greater or lesser extent. Therefore, embodied carbon, which often goes undetected, must be scrutinized. Decarbonizing across the entire value chain By 2050, seven billion of us will be living in urban areas, creating a demographic challenge. Coupled with climate disruption and increasingly rare resources, it will require us to consider the entire life cycle of buildings, from design to use, to ensure all real estate projects are truly sustainable. > 1. UN - "Emissions from the building sector have reached an all-time high” 21 CONSTRUCTING A SUSTAINABLE FUTURE
In France 46 million tons of construction waste is produced each year, but only 31% is recycled. It is critical to address the carbon emitted throughout the life cycle of buildings. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + SAINT-GOBAIN + In terms of ‘carbon tracking’, it all starts at the beginning of the project, when a building is designed. A decarbonization effort requires comprehensive thinking and constant attention. It starts with the extraction of the raw materials needed to manufacture building materials, a process that produces a steady source of greenhouse gas emissions. And when we talk about extraction, we are also talking about the logistics of transport, often over long distances – by truck, boat or plane – which will obviously contribute to the carbon balance. Tracking carbon includes looking at industrial sites where raw materials are transformed into building materials. Energy-intensive high-temperature industrial processes involving fossil fuels or the use of petroleum-based materials, such as plastics, can generate significant CO2 emissions. For example, concrete, a critical material in the building and public works sector, is reported to be responsible for around 8% of global greenhouse gas emissions, according to the leading scientific journal Nature. In addition to generating too much carbon, not enough building material is recovered during the management of a building site or during its demolition. Of the 46 million tons of waste produced by the construction industry in France each year, only 31% is recycled. This is a waste of resources and reusing or recycling them would make it possible to reduce greenhouse gas emissions. So, what can we do to improve things? Shifting from the linear to the circular In the world of carbon neutrality, nothing is lost: everything is transformed. Inspired by chemist Antoine Lavoisier, eco-design focuses on all stages of a product’s life cycle in order to reduce its environmental impact. As opposed to the "takemake-dispose” approach of a traditional, linear economy – which wastes enormous amounts of material – a circular economy encourages the use of lower-impact materials. This includes materials with a high level of recycled content. Designed to recover materials, this low-carbon model promotes the reuse and recycling of construction waste. This is a double win for the sector, which preserves virgin resources while securing its supply lines by using secondary raw materials. Saint-Gobain is implementing this circular approach at its Aniche-Émerchicourt plant in France. Since May 2022, the Group has operated the world's first low-carbon production of flat glass there. Its secret? 70% cullet and 100% green energy. 22
It also makes it possible to optimize construction practices, supply strategies and logistical challenges – as well as encourage refurbishment and the reuse of materials. The good news is that, beyond environmental optimization, digitizing the building sector could save up to 20% on the total cost of a project, according to Boston Consulting Group. Austria and Norway are setting an example, since these two countries now require the use of BIM for all public projects. France is following suit with its ambitious “Plan BIM 2022,” which aims to make the use of digital modeling widespread among craftsmen and small businesses. In Singapore, BIM has been required for all projects of more than 5000m2 since 2015. > The Aniche factory (Saint-Gobain) achieves zero-carbon production of flat glass, a global first. ©ChristelSasso_CAPA This empowering approach must involve all stakeholders, starting well before construction, with architects and urban planners committed to imagining the post-carbon city and infrastructure of tomorrow. Buildings, in particular residential buildings, have an average lifespan of 70 to 100 years. For the professionals involved, this means imagining the city of the future a century in advance, considering the adaptability of uses and the modularity of places. It also includes looking at how buildings might be adapted and transformed over time – into offices, housing or business spaces – while anticipating their environmental impact Digital technology serves sustainable construction The use of digital technology – including one of its more powerful tools, building information modeling (BIM) – makes it possible to test different hypotheses. 23 CONSTRUCTING A SUSTAINABLE FUTURE
Geoffroy de Crécy SAINT-GOBAIN 24
> Buildings have an average lifespan of 70 to 100 years. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + The entire value chain needs to be assessed for society to move towards a less carbon-intensive circular economy with a positive impact. To make this happen, all stakeholders must be committed. Both large and small companies have a role to play in training their teams in the use of new technologies (smart sensors, smart buildings and BIM) to effectively manage their production lines and transform buildings into true ‘connected platforms’. Decarbonizing industrial tools Another major challenge is industrial manufacturing facilities, the transformation of which must also be accelerated. Acutely aware of this need to transform, the construction sector has several options available to optimize its processes, which are mainly powered by fossil fuels. Some manufacturers are now turning to the electrification of their production lines, relying on energy sources derived from biomass, biogas and other renewable, lowcarbon sources of energy. Others focus on recovering waste heat (unused heat generated by a process whose main objective is not energy production) to transform it into energy. For their part, cement manufacturers are updating their processes through the development of new cement formulations. Produced from ‘wasterials’ (waste materials) such as blast furnace slag or fly ash, these neo-cements open up new avenues for decarbonization. A shared policy approach Only a collective approach, supported by real political will, can drive change. To this end, the European Union seems to agree on the adoption of common carbon reduction targets for all Member States. Finland, Denmark and Sweden are leading the way on this and plan to integrate carbon reduction requirements into their regulations. In France, RE2020 is strengthening previous legislation by adding environmental requirements that take the entire building life cycle into account. But political will alone is not enough to change minds. Fiscal or financial incentives are vital to supporting low-carbon efforts. Several countries have taken such steps, including France with its Plan de Relance (Recovery Plan) and the United States, with President Joe Biden’s Inflation Reduction Act2, partly inspired by the European Green Deal. 2. The European Green Deal contains a series of measures to make the European Union climate-neutral by 2050. 25 CONSTRUCTING A SUSTAINABLE FUTURE
The city of Copenhagen hopes to become climate neutral within the next decade. SAINT-GOBAIN © Alamy Stock Photo/Oliver Förstner For the construction sector, it is important for green financial incentives to make it possible to fund the refurbishment of old housing in a low-carbon manner. As a cornerstone of the decarbonization strategy, energy efficiency renovation with improvements to the envelope and the building, is amajor lever – acting on two levels. On the one hand, there is operational carbon (see page 27), incorporating housing-related energy optimization (water, gas, electricity) and better tracking of energy consumption. On the other hand, there is embodied carbon, including insulation that helps with energy savings. Refurbishment may often be seen as the preferred option, with a lower carbon impact than demolishing and rebuilding. But regardless of whether it is a new or refurbishment project, measuring the carbon impact of its activities should help the construction sector drive transformation, growth, and opportunities. 26
Operational or embodied: changing perceptions about carbon Today it is impossible to talk about decarbonizing the construction sector without making the distinction between two types of CO2 emissions: operational carbon and embodied carbon. In the past few years, there has been a great deal of effort to reduce operational carbon emissions related to building use: such as heating, cooling systems, and lighting. With the introduction of new technologies and increasingly stringent legislation, new constructions emphasize their low-energy consumption attributes, asserting themselves as ‘passive’ or even ‘positive’ because they produce their own energy. But much remains to be done to reach zero-carbon. Reducing operational carbon is an important first step, but it’s not enough to create zero-carbon buildings. The focus should not only be on the use of the building, it should also include all the CO2 emissions the building has generated. From the extraction of raw materials and the production of building materials to the recovery of building site waste and the demolition of the building. This is the principle underlying the concept of embodied carbon which represents nearly 50% of a building’s CO2 emissions. This intrinsic carbon takes into account the entire life cycle of a construction. That ranges from the origin of the raw materials – which sometimes require long journeys – to the production of the materials, all the way to the end of the building’s life. Unlike operational carbon – which can be addressed throughout the life of the building, especially through energy retrofitting – embodied carbon emissions are an indelible part of the building’s envelope (especially insulation) and its equipment. This leads to a need to envision each step of a construction from the ’net zero emissions’ viewpoint, assessing emission inputs and outputs. That is the challenge currently facing the industry. It is a global challenge that requires construction stakeholders to start thinking in a circular, rather than linear manner, including being proactive in the sourcing of raw materials with a low carbon footprint. In this Copernican revolution towards a construction world that is finally fully decarbonized, the sector will have to improve building design and production processes to make them more efficient, with fewer CO2 emissions. 27 CONSTRUCTING A SUSTAINABLE FUTURE
Renovation and the necessary mobilization of public authorities For the past fifteen years, Peter Sweatman has advised on urban planning policies all over Europe. As Chief Executive Officer of Climate Strategy & Partners and an expert on energy efficiency strategies for the construction sector, Peter is convinced that public authorities have a pivotal and rewarding role to play in the improvement of individual housing, which covers nearly 70% of the European real estate stock. Peter Sweatman believes that without resolute private and public action, there will be no real change towards a sustainably built world. Even if “European policymakers understand very well the urgent need to save energy; they are all in agreement that the real estate stock is really behind,” and have a major interest in making it less energy consuming, he says. But as long asmany property owners have neither the means or expertise to access tools and technology that makes it easier to reduce energy consumption, how do we encourage them to renovate? Peter Sweatman CEO & Founder of Climate Strategy & Partners, a consulting firm specialized in decarbonized energy strategies for theconstructionsector 28 SAINT-GOBAIN
For the energy efficiency specialist, the first argument is clear: housing that is brought up to standard has a higher market value. Studies have shown that homes with high energy performance sell more quickly, and for between 5% and 11% more. They also rent for 1.9% more than housing without major energy qualities1. “And that is why politicians must present renovation to homeowners as a long-term investment, even though it represents an average cost of between €20,000 and €40,000,” Peter insists. But he warns that: “This invisible energy debt must be well signaled to individuals who are unaware of the additional renovation investment to come when they buy an existing home with a low energy performance.” According to Peter, public authorities are key actors that can provide homeowners with a package of assistance to make it easier to carry out the necessary work to improve the insulation and energy efficiency of their properties. This support will also have to promote the resources, materials, and processes with the lowest carbon impact. This is the case in Germany, for example, where the Energy Agency has partnered with the German state bank KfW to create a new certified occupation: supervisor specialized in major home renovation. This expert, who can be an architect or engineer by training, supports property owners who renovate throughout their projects. 1. Boosting Building Renovation: What Potential and Value for Europe?” European Parliament, 2016 The involvement of public authorities is vital to build robust renovation supply chains. Energy efficiency investments are a safety belt to protect consumers from energy shocks like the one we are experiencing. » « They establish a work plan, manage the complex supply chain of building materials, help choose the providers and, finally, cosign the loan with the owners. These professionals should also take into account the social circumstances and vulnerability of their customers. Today in Germany, there are no fewer than 11,000 accredited professionals who work with homeowners on a daily basis to combat greenhouse gas emissions. For Peter, the trajectory is clear: “Mayors and local elected officials must now take the plunge and turn the need for the massive energy renovation of housing into a real political strategy. After all, what could be more rewarding for them than providing solutions to improve the homes of their constituents?” Peter Sweatman 29 CONSTRUCTING A SUSTAINABLE FUTURE
WHETHER BUILDING OR RENOVATING, IN THE NORTH OR SOUTH, THE CITY OF TOMORROW IS TAKING SHAPE TODAY While the challenge of sustainability exists from the Global North to the Global South, the responses are not the same. In particular because the existing structure differs depending on whether we are on one side of the globe or the other. Europe has to deal with its existing buildings, of which 97% do not meet the criteria needed to combat climate change. Meanwhile, the Global South, where more than a billion people still live in slums, has to provide housing to accommodate the population explosion. The needs therefore differ, but so do the means and the qualifications of construction professionals. So, should we build or renovate? Below are some responses. SAINT-GOBAIN 30
Renovate the North > The Western world, and more generally all developed countries, is very built up and has been for centuries. Its city centers are unique: often dense, sometimes historic and are the result of a succession of architectural layers. But today, these ancient cities and the newer suburban areas that have developed around them, are no longer able to meet the demands of modern comfort let alone climate change and energy crises. So, what do we do? Knock everything down and rebuild? Or renovate extensively? In Europe, around 200 million buildings built before 2001 will still be standing in 2050. As many as 97% of existing buildings are considered energy inefficient and too dependent on fossil fuels. The European Parliament estimates that buildings account for 40% of the final energy consumption of the European Union, 36% of CO2 emissions and 55% of electricity consumption1. In the United States, the situation is no better. The International Energy Agency estimates that the 111 million buildings on American soil are responsible for around 41% of the total energy consumption of the United States, 40% of CO2 emissions and 70% of electricity consumption2. There is, therefore, a clear need to achieve a building stock aligned with the requirements of the Paris Agreement adopted in 2015 by 196 parties. By 2030, existing buildings will have to reduce their energy intensity by 35% compared to 1990 to reach around 95 kWh per square meter3 (compared to around 150 kWh per square meter today, a figure unchanged for three years). They will also need to become more energy efficient to fully meet the target of a 55% reduction in CO2 emissions by 2050 (compared to 1990 levels). 1. "Boosting building renovation: What Potential and Value for Europe?" — European Parliament, 2016 2. "Energy Efficiency in the North American Housing Stock” — International Energy Agency 3. "Tracking Report, Buildings 2022 " — International Energy Agency, September 2022 31 CONSTRUCTING A SUSTAINABLE FUTURE
Aerial view of ancient buildings in Lisbon (Portugal). Old buildings largely «amortized» To meet this challenge, Western countries need to renovate extensively — at a rate of about 10 million homes per year, according to the International Energy Agency. Thedecisiontorenovate isbasedonanumber of factors. These buildings, which have been in use for decades or even centuries, have generally ‘amortized’ the carbon cost of their construction — both in terms of emissions associated with the manufacture of the materials used to create them and those produced during the construction itself. There is no official amortization threshold for a building and the range of 20 to 80 years commonly mentioned is quite wide. The actual duration depends on several factors, such as the quality and durability of materials, maintenance, usage and local weather conditions. Nevertheless, inmost cases, destroying an ‘amortized building’ and replacing it with a new one would lead to a negative energy balance. "For every squaremeter built, 1.5 tons of eqCO2 are emitted for 50 years," says the team at the Pavillon de l'Arsenal, Paris's center for urban planning and architecture, in the book Conserver Adapter Transmettre (Conserving, Adapting and Handing Down).4 "One half comes from materials, the other from energy (…)," they explain. What is the most carbon-heavy element in a construction? The primary structure: the framework and the floors. Conversely, "reusing an existing building can significantly reduce embodied carbon," says Joy Gai, Asia Pacific Programs Head at theWorld Green Building Council (see our article "Operational or embodied: changing perceptions about carbon," page 27). It can generate an estimated saving of 250 kg eqCO2 per square meter. And beyond the carbon cost, "demolishing to rebuild involves more time, more labor, more transportation. By renovating, we can minimize all these items," adds Joy Gai. 4. "Conserver, adapter, transmettre" (Conserving, Adapting and Handing Down) — Éditions du Pavillon de l'Arsenal, 2022 ©EyeEm/Martina 32 SAINT-GOBAIN
> Reusing an existing building can significantly reduce embodied carbon » « Joy Gai, Asia Pacific Programs Head at the World Green Building Council Old buildings, champions of energy optimization Furthermore, in Europe, the age of buildings, particularly urban buildings, may well prove to be an asset rather than a disadvantage. Admittedly, in most cases it will be necessary to make thermal adjustments: changes to joinery or to internal or external insulation, where possible. But according to the General Directorate of Urban Planning, Housing and Construction in France, old buildings, provided they are well maintained, can boast better hygrothermal behavior than some more recent buildings. That is to say, better regulation of the temperature and humidity of the air. This is particularly the case when their orientation has been optimized in relation to the sun, wind and rain, and they are built of cut stone, wood or clay. They then allow the water vapor to pass through better. Made from mostly recyclable materials, these old European buildings could be an interesting model of sustainable construction. In addition, during renovation, old buildings are often densified, improved or even raised. This makes it possible to house more people in the same place and to contain urban sprawl, also containing the artificialization of the soil in the process. This logic has been in place in many European countries since 2011 when the Net Zero Artificialization protocol was signed. What is the aimof this? To limit any increase in the area of occupied land by 2050 and to compensate for any new artificialization of land by equivalent renaturation. Finally, the buildings of these old cities sometimes hold centuries of history. From the quintessentially Parisian Haussmann buildings to the workers' housing developments of the interwar period, right through to the medieval style or the colorful wooden houses typical of Scandinavian countries. Even if their value is not always architectural, these constructions tell a story that must be passed on to future generations. Suburban areas, poor land tenure and opportunities for renovation Admittedly, the architecture found in the outskirts of major Western cities does not necessarily boast the same heritage value. Whether it is high or low-rise buildings or single-family homes, we tend to see many more standardized constructions that are often not particularly energy efficient or made of high-quality materials. The houses in housing developments, also known as ’tract housing’, were often built quickly and cheaply between 1950 and 1980, to bring the comfort of modern life to a rapidly growing population5. The most emblematic example of this standardized post-war suburban architecture is Levittown in Pennsylvania (USA). This giant housing development, considered the first of its kind, consists of 17,311 single-family homes, designed in the style of one of six different models and built according to an industrialized prototype in 26 stages. Would it be necessary to knock them all down to reconstruct new buildings, as often happens in Japan, after 20 or 30 years6? The answer is no. Faced with an endless housing crisis – goods that are too rare or too expensive – these apartment buildings, disused industrial sites, dilapidated public buildings, or even unused parking lots are excellent candidates for redevelopment. They even represent real opportunities to densify peripheral urban areas that are still too sparse. And in order to achieve this while limiting the carbon cost of the renovation, architects can now rely on the qualities of the building: its layout, volume, structure and materials that can be preserved or even reused elsewhere. They can also look to light construction methods that save considerable time, while ensuring high performance. 5. 10 Architectural Sins Committed in Suburbia — Architizer 6. Raze, rebuild, repeat: why Japan knocks down its houses after 30 years — The Guardian 33 CONSTRUCTING A SUSTAINABLE FUTURE
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