Entrepatios Las Carolinas is the first ecological co-housing built in the city of Madrid, nearly-zero energy building which operates with the Right of Use of the dwelling, but not ownership of it. It is a nearly zero energy residential building consists of 17 houses, CO2 zero and made of wood, under the Right of Use regime in the Community of Madrid.

Ongoing: from 2018 (date of the first building finished) to now 

Several working committees drive the activities of decision-making, providing the members of the cooperative with the necessary information to take decisions. An Assembly was organized among future inhabitants of the co-housing and members of the cooperative to co-design and manage the building.

Entrepatios Las Carolinas is a nearly-zero energy residential cohousing, composed of 17 houses that are combined with common spaces (3.313 m2). The project is developed with the latest advances in ecological architecture under criteria of high energy efficiency, life cycle analysis, bio-construction, water management, geo-environmental analysis and bioclimatic design.

The buildings' carbon footprint is offset by reforestation programmes, making it a CO2 zero building. The structural spruce wood used (400 m3) is sustainable and certified FSC (Forest Stewardship Council). Recycled wood has also been used for the false ceilings. The use of wood is a paradigm shift, because it is a renewable and circular material.

Regarding the water management system, there are low water consumption taps and toilets with dual flush cisterns, aerators, etc.. Rainwater and grey water are recycled for subsequent use in the irrigation system in the courtyard garden, paddocks and roof, as well as in the toilets. This system is expected to save 750,000 litres of water per year.

The cohousing is 100% electrified with energy from renewable sources, by contracting and by producing photovoltaic energy in the building itself. 

• Entrepatios Las Carolinas achieves the maximum possible degree of Nearly Zero Energy Consumption Building concept according to the European Directive 2010/31/EU, in addition to other advanced strategies in terms of green architecture: bioclimatic design, high energy efficiency, life cycle analysis, bio-construction, water management, and geo-environmental health. The ECOMETRO tool has been applied, based on the UNE-EN 15804 (product) and UNE-EN 15978 (building) standards for the evaluation of the environmental impact of the construction process and use of the building (extraction and manufacture of materials, transport to the construction site, installation, maintenance and use: heating, cooling, lighting and consumption of household appliances).
  
• New regulation for co-housing at municipal level in some cities in Spain (Barcelona, Alicante, Asturias, etc.).
  
• There is also a future link with the European Energy Regulation (EU Directives 2018/2001 and 2019/944) related to co-production practices and the new legal figure in the energy supply chain: the "citizen energy community", translated into the Spanish regulation (PNIEC, 2021-2030) as Local Energy Communities (Comunidades Ciudadanas de Energía) and Renewable Energy Communities (Comunidades de Energías Renovables). 
  

Entrepatios Las Carolinas is the first ecological co-housing built in Madrid, nearly zero energy building, CO2 zero and made of wood. It is also the first cohousing management under the Right of Use regime in the Community of Madrid.  This means that the ownership of the co-housing building is cooperative and not private. The Right of Use regimen is an intermediate ownership model between renting and buying that advocates the management of the commons. The inhabitants of the cohousing do not own their home, but have a right of use over it and overthe common areas of the building throughout their lives. The right of use can be indefinite in time, transmitted and inherited.

The project is a non-speculative and non-profit model funded by ethical banking, as well as loans and donations from those seeking to promote a new housing model. The cooperative members enjoy indefinite use of the housing through a fee or 'soft rent'. To this is added another fixed fee to enter the project, paid in the beginning and refundable in the event of leaving the cooperative. As a collective project, a reserve fund is envisaged that could cover the non-payment of the entire cooperative for three months. The transfer of land by the public authorities means that the purchase of land does not make the project more expensive.

Finally, sAtt is the first B Corp architecture and construction company in Spain.

Entrepatios Cooperative, promoted by sAtt Arquitectura Abierta Studio (SME). 

• Entrepatios Las Carolinas Cooperative: Inhabitants of the cohousing with multiple roles: user, developer and participant in the co-design process (less than 1000 persons)
  
• Entrepatios Cooperative, promoted by sAtt Arquitectura Abierta Studio (SME): Initiator (66 cooperative members with the support of Lógica'Eco, a manager of collective initiatives, and sAtt, an architectural process studio)
  
• Companies involved in the construction of the cohousing Las Carolinas: Experts on construction and structures design, water management, geo-environmental health timber installation and manufacturer (7-10 people: Técnica ECO, Daniel Pascual, Miguel Nevado, Madergia, Ismael Caballero, Fernando Pérez y Pascual Pérez)
  
• Local public sector: Cession of land for the construction of cohousing
  

• Economic: 30% cheaper than new developments in the district (total construction cost: 708 euros/m2; final sale price: 2,295 euros/m2). It generates a model of use whose cost does not exceed 10euros /m2 for each housing unit.
  
• Social: social acceptance and growing demand; 13 participatory workshops with future tenants to make certain collective decisions, specifically design with technicians and managers; innovation in the Right of Use regime (i.e., an intermediate ownership model between renting and buying that advocates the management of the commons. The inhabitants of the cohousing do not own their home, but have a Right of Use over it and over the common areas of the building throughout their lives). 
  
• Technical: technical capacities in bioclimatic design and green building among the SME partners networks.
  
• Legal: there are no external promoters, the group itself is set up as a cooperative that will be maintained throughout the life of the cohousing; Open source prototyping and innovation project.
  

• Political: Among the measures that would guarantee a greater accessibility to the model, the main one is the transfer of land by public administrations (as in the case of BarcelonaCity Council with the La Borda cooperative), which means that the purchase of the land does not make the project more expensive and the initial payment is reduced. No institutional financial support (subsidies, bonuses) has been obtained, except for the photovoltaic system, which has been subsidised at 50% for the first 3 years.
  
• Legal: There is a need to modify a local water regulation (Ordinance on the Management and Efficient Use of Water) in the City of Madrid, which only allows the use of grey water for irrigation, but not for toilets (a change to this ordinance is planned). A reduction in property tax (IBI) for green buildings could make the model cheaper (this is a municipal tax).
  
• Economic: Niche market growing, but still has a niche scale; the transport of the FSC wood used, which came from Switzerland (400 m3), emits pollutants on its long journey
  
• Technical: No local wood market  
  

Pro:

• Growing social demand generates a space for community coexistence with a social action perspective, both internally (among the members of the community itself) and externally (from the community towards the neighbourhood and the nearby urban and social context).
  

Con:

• Pollution caused by the transport of imported timber by road fromoutside the country. This could be minimised by promoting the local timber industry in Spain in the face of a future increase in demand. 
  

Entrepatios Las Carolinas ecological co-housing is a social innovation reference case for climate neutrality. The ecologic co-housing model of Las Carolinas is being applied in a new cohousing nearby, in PIRITA. Negotiations are underway to build a third and fourth building nearby. And the promoters (Entrepatios) are working on the design of a future energy community in a rural area near Madrid, in the valley of the Tiétar river. This demonstration shows how climate innovation at a niche scale could generate a bigger impact in the growth of the green building market. 

Main positive lessons/opportunities identified:

• There is a growing social demand for such projects
• The Right of Use regime is a factible model for housing. This regime is an intermediate ownership model between renting and buying that advocates the management of the commons. The inhabitants of the cohousing do not own their home, but have a right of use over it and over the common areas of the building throughout their lives.

Main failures/barriers identified:

• There is a need to modify a local water regulation (Ordinance on the Management and Efficient Use of Water) in the City of Madrid, which only allows the use of grey water for irrigation, but not for toilets.
  
• The local timber industry is still too small in Spain, there is still a need for imported timber and transport to Madrid by road.
  

• Number of people/families involved in the first cohousing “Las Carolinas”: 58 people (17 families) co-living in Entrepatios-Las Carolinas
  
• Objective in the long-term: 2/3 cohousing buildings per year