Renovate more, build better

Maquette du projet Habitat symbiotique © LAST / Timothé Beuret

Maquette du projet Habitat symbiotique © LAST / Timothé Beuret

The journal TRACES has just published an article on work carried out at the Laboratory of Architecture and Sustainable Technologies (LAST) as part of the Symbiotic Housing research project funded by Innosuisse, the Swiss Innovation Agency. Entitled “Rénover plus, construire mieux” and co-written by Prof. Emmanuel Rey and Ulrich Liman, the article proposes a novel modeling framework based on a prospective and statistical approach to estimate – quantitatively and spatially – housing needs with a view to a low-carbon society.

In the current climate and housing crisis, positions are polarizing across Switzerland: some are calling for 50,000 new homes a year to cope with the shortage, while others are advocating limiting construction to preserve the environment. The “Symbiotic Housing” project offers a nuanced approach, proposing a new model for estimating - quantitatively and spatially - housing needs from the perspective of a low-carbon society, and developing symbiotic architecture for the emergence of new housing types.

The model estimates actual housing needs by cross-referencing demographic data, occupancy rates, and accessibility to public transport. It reveals an under-occupation of the existing stock, with a theoretical additional capacity of between 14% and 28%. By targeting areas well served by public transport and where growth is expected, it becomes possible to intensify the use of existing buildings while limiting mobility-related emissions. If we fail to implement this strategy, we run the risk of generating between 500,000 and 700,000 new commuters, mainly using private vehicles for lack of alternatives.

The results show that if we follow a scenario that intensifies occupancy, only 16,500 housing units/year would be needed by 2050 - a third of the current rate. This approach would make it possible to combine the ecological transition with a response to the housing crisis.

In line with these results, a strategy of four priority actions will enable us to better meet housing needs, while reducing the carbon impact of construction and promoting sustainable mobility:

1. Intensifying housing occupancy: making the most of under-utilized space by facilitating moves to housing adapted to household size, and encouraging roommates and exchanges within the existing stock.

2. Accelerating the renovation and transformation of buildings: adapting buildings to meet the needs of smaller households, improving their ecological performance and enhancing the value of our built heritage.

3. Converting commercial buildings into housing: transforming offices or other vacant premises into housing, a practice already emerging in Switzerland, with great potential in terms of quality.

4. Creating low-carbon housing for the remaining balance: Design new housing with a low environmental impact, using bio-sourced materials and limiting the carbon footprint associated with construction, operation and mobility. The Symbiotic Housing project proposes a housing scheme using bio-sourced materials, renewable resources and short cycles, including local wood, photovoltaic facades, rooftop greenhouses and shared spaces. It has a favorable life cycle assessment, can be implemented today and is already in line with future requirements.

This approach offers a middle way, reconciling the enhancement of existing buildings, environmentally-friendly construction, demographic change and low-carbon mobility.

Funding

Financial support from InnoSwiss for the Symbiotic Housing research project (Innolink: 101.837 IP-EE)