Building today in stone by means of load-bearing or semi load-bearing walls, starting from an environmentally friendly extraction and processing process, is an interesting solution for the ‘decarbonization of construction processes’, as demonstrated by our participation in the project ‘Îlot Fertile – Eole Evangile,Paris 19, Premier quartier zéro carbone de Paris’ where our Albamiel stone has been selected to execute the stone section of part of the project due to the low CO2 emission of the product throughout its life cycle, despite the transport, recognized by the FDES and DAP report. The project is being executed by the company Bouygues.

The ‘decarbonization of construction processes’.

To what extent are building materials important in the energy balance of a house? Let’s imagine a 222 m2 single-family house located in Zaragoza, which is where Aragonese engineer Ignacio Zabalza places it in a study published in the scientific journal Building and Environment. If the data of this hypothetical house is introduced into a simulation program that complies with the current building energy certification regulations(RD 235/2013), the result obtained is that it is going to generate about 1.6 tons of CO2 per year, which corresponds to a class B. Now, this is taking into account only the use of the house over 50 years of life (spending on heating, air conditioning, hot water, lighting …), if we analyze the materials used in its construction, then we would have to add another 57 tons of CO2.

These 57 additional tons would represent 41% of the total emissions generated by the house over 50 years or, in other words, it would take 35 years for the emissions produced by the use of that house in Zaragoza to equal those of its construction. Paradoxically, they are not taken into account by the regulations that evaluate the energy efficiency of that house, when their impact is much greater than that of other factors that are given much greater importance. As Zabalza explains, a great opportunity is being wasted to act on the efficiency of houses from the very choice of materials for their construction.

Building in stone today: Load-bearing and semi load-bearing walls as a possible solution

The construction style we propose for Low Carbon Construction is the construction in stone ashlars and in exceptional cases in claddings of at least 8 cm thick.

The reference in this type of construction, in addition to historical buildings, obviously, in modern architecture, is Fernand Pouillon (1912-1986) who carried out most of his new construction projects between 1950 and 1960. A lover of stone, he argued that respecting prices and the quality of construction allowed two goals to be achieved: giving access to the luxury of living to the lowest paid and ensuring excellent preservation of the neighborhoods while avoiding their degradation.

In the middle of the last century, massive stone construction, the name given to solid stone construction in English and French, served other purposes: social and economic development, the importance of reducing carbon emissions in the construction process had not yet been realized, but all these purposes are still valid today.

Today Gilles Perraudin is the star architect in massive stone construction, but it is interesting to know that he started in architecture with André Ravéreau, in understanding the relationship between architecture and climate or how men manage to survive in extreme conditions and how to build houses where comfort is achieved with almost no energy expenditure, both in construction processes and maintenance.

Perraudin worked in the new town of Cergy Pontoise with the Lyon school of architecture on buildings full of environmental concerns, but still without discovering stone. He considered himself at this time a prisoner of the dominant building culture, from which he reflects that ‘architects have a difficult escape and are asked less and less to be thinkers of construction to be creators of gleaming and abracadabrante forms’.

In his words: ‘it was a fabulous and founding experience, because I discovered a material, its possibilities, its interest and its capacity at the same time; I discovered an architectural writing that has allowed me to find myself in the fullness of my function as an architect, which is not to invent forms that end up being thoughts’. He also invites us to start, as he does, from an ethical and social vision, since architecture is not like the other arts, such as music, which we have the right to listen to or not, architecture imposes itself on everyone.

With stone, Gilles Perraudin has discovered a rigor in architectural writing. He can think about the material from beginning to end, while most architects use products already invented and prefabricated by industry. Without mastering either production or design, they ‘assemble’ industrial products.

Gilles Perraudin found gaps in legislation regarding the use of massive stone for construction. In Spain the same thing happens, there is no specific law and sometimes it is complex to adapt the existing one. This is a dramatic point and indicative of a total loss of building culture; despite the fact that most of our heritage has been built in massive stone, everything has been forgotten! Building legislation has been invented for the use of new materials and this is a clear disadvantage, even though in recent years much progress has been made mainly in our neighboring country, France.

Why stone is low in CO2 emissions? environmentally friendly extraction and processing process

As a reminder, Raquel Galarza of the company Eurovertice, who served as a headline in Murcia Diario last August 18, said, ‘If there is no commitment of companies to sustainability, there will be no future’.

In our business project, ISO 14001 certified since 2005, to date:

• The various stone wastes are reused, revalued and ultimately returned to their place of origin and used for the restoration of the affected natural areas.
• Other wastes, whether hazardous or not, are treated by authorized waste managers,
• We have Photovoltaic Solar Energy and we acquire Green energy,
• We have begun to switch the company’s fleet of internal vehicles to electric power,
• In quarrying, we cut dry, avoiding the high consumption of water resources, for other primary and secondary cutting processes carried out with water, we recycle the process water, with the only losses caused by evaporation or irrigation of roads and squares in the hottest season to avoid atmospheric pollution, we do not make any discharge to public watercourse,
• We have conducted preliminary soil studies, resulting in uncontaminated soils.
• We mainly regulate the temperature in our facilities by means of massive stone constructions and regulation of air currents, providing, if necessary, heating by means of biomass,
• We control atmospheric emissions and have the qualification of type C industries, for low emissions,
• We have two Ecosystem Restoration Projects underway, approved by the competent administration,
• We have had a CO2 emissions reduction project in place since 2016,
• We have agreements for intensive, flexible and teleworking working hours, to facilitate the reconciliation of family and professional life, we care for those who care.
• For years, we have been offering our employees spaces for the creation of vegetable gardens and animal care.
• We respect the wildlife of the environments we inhabit, sharing spaces.
• We are a family-owned company, founded in 1985, the management positions in the company are managed equally between men and women without discrimination based on gender, sexual orientation, religion or any other cause.

Results of our efforts to decarbonize our company’s production processes

Our corporate sustainability journey has been reinforced by the selection of our material for the supply of one of the buildings of the first zero-carbon district in Paris. In order to certify this journey, we embarked on a study of Greenhouse Gas emissions throughout the life cycle of the requested products (ashlars for massive construction in load-bearing walls of approximately 80x50x30 cm and semi load-bearing walls of 8 cm thickness). This study has been carried out in France because they demanded it and because we must say that the neighboring country has already opted for this use of massive stone in construction.

Catalina Sánchez Robles

CEO Rosal Stones