Decarbonization is a new buzzword. It seems like it is replacing sustainability, a very ample, anthropocentric concept*, coined in 1987. Global and European policies are looking to ‘lower greenhouse gas (GHG) emissions’ by 2030 and 2050 . The ongoing COP26 in Glasgow was the best confirmation. We have seen big words and declarations, many times. In recent history, we have seen multiple events [img 01]. Probably the most influential one was the Roman Club Report in 1972 that clearly indicated the Limits of Growth. Many have heard about the Kyoto Protocol signed in 1997, a treaty that aimed to lower (!) GHG emissions. At the COP26 António Guterres, Secretary-General of the United Nations and former Portuguese Prime Minister, is urging to change the business as usual. Can we decarbonize the Portuguese building stock? How to do that?
*Its definition is focused on human wellbeing and future. As per Our Common Future, sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs.
But first, a small disclaimer. greenhouse gas emissions are not the only aspect of the actual crisis. We have only started to work with the most tangible aspect of the planetary crisis. Stockholm Resilience Center has clearly shown the complexity of the crisis and the domains we are crossing. [Image 02]. Climate change, which is closely related to GHG emissions, impacts the other limits, but as we can see in the diagram [Image 01], it is not the most urgent. Biogeochemical flows (pathways by which elements like carbon, phosphorus or compounds like water, flow in the environment) and biodiversity loss are two domains that are beyond the zone safe zone. If they cross the point of no return, we should expect disequilibrium of the system and unknown activities in other domains. Biodiversity loss is connected to the territory we occupy. It is an exponential relation: the level of biodiversity increases exponentially with the surface area of uninterrupted, natural land .
That is why we prioritise working within already-occupied areas, especially here in Portugal, where 97% of building stock requires renovation , the population rate is virtually not growing  (do we need more houses for fewer people?) and centres of major cities are low-populated . Also, denser walkable centres mean less carbon emitted during everyday commuting. Most of the relations between planetary domains are beyond the scope of an engineer, we can only act within our professional responsibilities. Everything is connected.
Decarbonization is a very demanding aspect. We at Dosta Tec are researching and prototyping solutions. We have been meeting industry champions and talking with Portuguese companies, and public authorities to understand what their approach is. Many questions popped up: How to lower the energy intensity of housing when we experience energy poverty? How to renovate for thermal comfort, low-energy consumption and simple maintenance? What kind of low-carbon materials can be used for insulation? Do we have them available in Portugal? Is hemp insulation brought from the Czech Republic still sustainable? Can we replace concrete with cross-laminated timber (CLT)? How will climate change influence thermal comfort and heating needs?
Since the EU imposed ESG (Environmental, Social and Government) certification for large companies, they have been asking for services of minimizing energy intensity, carbon emission, and renewables. Will policies help the transition? Are we not going to stack in carbon tunnel vision [image 03]? Well, this is another trap. Certification systems can help but many of them (like LEED or BREEAM) validate only the project. What if the operation of the building doesn’t reflect the project? Some studies  have shown that LEED-certified buildings do not outperform conventional ones.
As engineers, we are trapped between “weak sustainability” and “strong sustainability”. Two handy terms were coined by Robert Solow and John Hartwick . The first is focused on the technical solution and the second on policy-making; the first one is human-centred and the second is bio-centred, the first is business as usual the other is to innovate. As an engineering and technology company working in the field of architecture and construction, we are answering the clients’ and market’s needs, looking to be at the forefront of changes, trying to push from weak sustainability to strong. It might seem that weak sustainability is inferior to strong. Indeed it is, but it is also complementary, as it gives actual solutions that can be implemented almost immediately, and its prototypes and verifies regulations. Many of them have been already checked on the market and require further work.
The big issue is: how to decarbonize? In Portugal, we need local and verified knowledge, data, qualified policy-makers, clerks, engineers and architects, construction companies, a whole new collection of materials to replace concrete, steel and glass, and procurement schemes that favour low-carbon design. The challenge seems to be enormous and it might bring innovation and an exciting working environment for the next decade.
 Wilson E. O., Half-Earth: Our Planet’s Fight for Life. Liveright, 2016.
 Buildings Performance Institute Europe, 2017, Energy Performance Certificate Factsheet
 INE 2020
 Almeida M. A. P. de, “Fighting depopulation in Portugal: Local and central government policies in times of crisis,” Portuguese Journal of Social Science, vol. 17, no. 3, (Sep. 2018), pp. 289–309.
 Scofield J. H., “Efficacy of LEED-certification in reducing energy consumption and greenhouse gas emission for large New York City office buildings,” Energy and Buildings, vol. 67, (Dec. 2013), pp. 517–524. https://doi.org/10.1016/j.enbuild.2013.08.032