“Decarbonize” means to stop depending on carbon dioxide emissions – hence the word decarbonization – to produce the goods and services that satisfy our needs, such as food, clothing, electronic devices, transportation, or buildings. We emit a lot of CO₂ in these processes, because the main source of energy we use – more than 80% of the total – for this production are fossil fuels: oil, gas and coal. Getting energy from these materials means burning them, and doing so emits carbon dioxide into the atmosphere.
Carbon dioxide -CO₂ in its chemical formulation- is a gas that promotes the greenhouse effect in the Earth’s atmosphere, that is, it is transparent to the solar radiation that reaches the surface of the planet but makes it difficult for the radiation to escape towards the planet. space. “The more greenhouse gases the Earth’s atmosphere has, the higher the planet’s surface temperature must be to be able to return energy to outer space. For this reason, the increase in the amount of greenhouse gases in the atmosphere produces what is called global warming, that is, the increase in the Earth’s temperature,” explains Greta Tresserra, sustainability member of the Col legi. d’Arquitectes de Catalunya.
This global increase in temperature produces large changes in the climate of different regions. This implies very important and very rapid alterations in the ecosystems of the biosphere, which see the conditions in which they develop altered – including those controlled directly by man, such as agricultural plantations, forests or pastures. Climate change is already causing major alterations that affect a very important and growing part of the human population. And if the average temperature of the planet’s surface rises more than 2 C compared to the temperature prior to the systematic use of fossil fuels, the costs of climate change will be unaffordable and the damage irreparable.
Using fossil fuels as the main energy source is at the basis of industrialization, of the productive model that feeds the quality of life of modern societies. The Industrial Revolution was based on the use of coal as an energy source, and since then the evolution and extension of our modern society has also been supported by oil and natural gas. Everything we produce and transport around the world uses energy that, for the most part, comes from fossil fuels. Therefore, decarbonizing society is a major challenge: “it means changing the energy model of our production and consumption system, changing the basis of our model of life,” says Tresserra.
This change in the energy model is based on two fundamental strategies. The first, change fossil energy sources towards so-called renewable energies. Solar energy and wind energy are the sources relied on for the change in model. But the photovoltaic panels that transform solar energy into electrical energy, as well as the windmills that do it with the wind, require very specific materials that are found in low concentration in the mines, and large amounts of energy are needed to separate them from the minerals that contain them. Building the infrastructure required by an energy system based on renewable energy requires a lot of energy and, of course, the energy we have now is essentially energy from fossil sources. Thus, building a renewable future implies extra consumption of fossil fuels and may not be available to meet current energy demands. This is what is called the energy trap.
That is why the second strategy is essential: reduce the amount of energy necessary to produce what we need and, at the same time, adjust our needs to those that are possible in a decarbonized world. Energy efficiency in a sustainable model. An essential social change that does not follow the line of the current model of continuous growth in production fueled by the energy system based on energy from fossil sources.
Thus, the satisfaction of needs must be redefined in a sustainable world, considering basic needs, such as food, health and housing, priority. It is interesting to look at the challenge posed by the decarbonization of our buildings as an example of the complexity of the global decarbonization challenge.
In Europe, the energy used in buildings accounts for 40% of carbon dioxide emissions. If it is necessary to decarbonize our society, it is essential to decarbonize buildings. And this involves several tasks. The first is knowing how to build buildings that are very efficient in the use of energy – energy efficiency – and that the little they need comes from renewable energy captured by the building itself. Even the building captures more energy than it uses and can become a supplier to cover the rest of social needs. This is already possible today and, from 2030, European regulations will require all new buildings to be like this. But this does not solve the problem.
We have a huge built park that has not been built in this way, but uses energy – mostly fossil – without much efficiency to generate comfort and shelter activities. In Spain there are more than 23 million homes – 18 of them main homes – and 2 million service buildings – offices, commercial, educational, etc. – in operation. According to Greta Tresserra, “if we do not significantly improve its energy efficiency, we will not be able to decarbonize our society. That is why it is necessary to carry out important rehabilitation policies for the stock of existing buildings that allow them to be decarbonized -high energy efficiency and the little energy they require is renewable and as local as possible- in 2050.” Do we have enough? Not yet.
The manufacturing of the materials with which we build new buildings and rehabilitate existing ones today involves the emission of significant quantities of CO₂. Like the entire industrial system, the production of construction materials depends on fossil fuels and it also needs to be decarbonized before 2050. This is a great challenge, and the main materials – cement, steel, aluminum, ceramics – already propose decarbonization trajectories that, we hope, can be effective. But the sector can also recover traditional materials that require little or no emissions and help reduce these emissions.
In short, the building sector shows us the path towards decarbonization: high energy efficiency and use of renewables as a model, transforming the existing one towards this objective, and a change in material culture that allows us to reach that essential future. A process of change that forces us to redefine our way of living.
Content developed in collaboration with the College of Architects of Catalonia (COAC)