“Solar paths will supply energy to entire cities.” It is not science fiction, but the headline that informs about an ambitious project developed by the small North American company Solar Roadways . His plan consists of the installation of surfaces for streets and highways that, through special panels, produce solar energy. Developers claim that establishing these “solar trails” across the country would produce more renewable energy than the entire United States needs.

The debate on what should be the sustainable city model that we have to build has been intensified in the last decade. A challenge in which engineers, architects and urban planners play a key role. A majority current of these professionals assume efficiency as an attribute linked to the quality of the constructions. They are specialized professionals who have wanted to channel their work towards environmental protection, designing ‘smart’ buildings that can be self-sufficient.

«There is a false model, which is disguised under the sustainable label, which is expensive. But if it is done right from the beginning -optimizing materials and using natural resources- it does not have to be, “explains Luis De Garrido, director of the National Association for Sustainable Architecture (ANAS).

Something as simple as taking advantage of the resources -our own and unlimited- that nature offers us. without devastating it And lowering the energy bill.

But there is another price – that of climate change and resource depletion – that we cannot afford to ignore. Buildings are responsible, worldwide, for almost half of total energy consumption and 15% of water consumption. «In Spain it is necessary to rehabilitate existing buildings because 30% of the energy consumed comes from the expenditure of the real estate park», clarifies the architect De Garrido.

Housing does not have to be solely intended to provide shelter. Now, structures can be designed to respond to natural phenomena, underground conditions, permeability of materials, and energy consumption. The benefits are multiple: apart from ‘almost zero’ energy consumption and greater economic profitability, the useful life of buildings is extended, since self-sufficiency is analogous to durability.

The function of architecture and design is not limited to the iconographic. Its role as a transforming agent in social and labor relations can be key. This is the case of La Vela, the architectural symbol of the new headquarters that BBVA is building in Las Tablas, Madrid. This elliptical-shaped tower, 93 meters high and with 19 floors, has been designed by the prestigious Swiss architects Jacques Herzog and Pierre de Meuron.

«The buildings have to be seen, in the future, for something else. They must be open to change. If architecture does not fulfill this function, focused on reuse, sustainability and service to the citizenry, it will be a failure”, Herzog pointed out during a recent visit to Spain on the occasion of the presentation of this project.

To raise La Vela, the ecological criteria necessary to achieve the LEED Gold certificate , the most demanding sustainable construction standard, have been followed. The materials used have a low environmental impact and the buildings are designed so that remote monitoring of energy consumption can be carried out. A part of the energy needs of the complex –La Vela is only the main building of a set of 114,000 square meters of offices and services, among them: a restaurant area, a convenience store, a gym, a physiotherapy center and a nursery– supply thanks to their own renewable sources, such as thermal or photovoltaic solar panels and closed-loop geothermal energy, which will take advantage of the stable temperature of the subsoil. “All this will allow savings of 7.6% in CO2 emissions and 8.3% in energy consumption, which will mean savings of many millions of euros”, explains Susana Lopez, engineer and director of the Ciudad BBVA project.

In addition, gray water reuse systems and 100% rainwater collection systems are being installed on the roofs of the buildings for use in irrigation, as well as in the sinks and showers, from where it will flow into the cisterns. The estimate is that the cost of water is reduced by half. Points will also be located for the recycling of 100% of the waste generated, which will replace individual bins. The same idea is thought for the centralized area of ​​printers, which will memorize the files sent but will not print them until the employee presses a button on the machine. This avoids the waste of paper that characterizes workplaces. The building envelope is one of the most unique aspects of the project. The complex will have49,000 square meters of glass façade, protected by more than 2,800 prefabricated slats whose orientation meets criteria of insolation and thermal efficiency. All office areas will have exterior views: the greatest distance that we could find ourselves from a window would be only 8 meters. «The idea is to encourage interaction between employees and promote the exchange of knowledge at all levels, creating open spaces that avoid isolated groups and favor agility in decision-making. It is a venue designed for people”, adds Susana Lopez.

Hammarby Sjostad is a neighborhood on the outskirts of Stockholm, Sweden. Construction began in 1996, when the city opted to become an Olympic city, and has become a benchmark on how to obtain energy through waste. Here, 50% of the heat and water consumed comes from recycling. The secret of this neighborhood, a former industrial dock, lies in its design. All the houses have solar panels, the inhabitants deposit their garbage in an underground collection system, which allows separating the organic materials with which the biogas is produced, which is later consumed by the kitchens. In addition, those materials that are not reusable are burned to generate electricity.

Transport is, for its part, key to favoring sustainability. Paco Segura, state coordinator of Ecologistas en Accion, warns of “the influence of cars on pollution problems, lack of space, noise and accidents.” In Hammarby Sjostad, thanks to a transport system of free train, bike lanes and car sharing, the neighborhood’s CO₂ emissions are 50% lower than those of other conventional cities.

2014 is a representative year for sustainability. Demography is growing, the effects of climate change are worsening and ” the need to create sustainable communities is  more important than ever“, according to the UN, which has chosen ‘Green Cities’ as this year’s motto. The campaign focuses on the development of sustainable technology and public policies that invest more in energy efficiency and the formation of a committed citizenry.

«Our administrations bet very little -says the architect Herzog- but society is sometimes more solid than the institutions in terms of innovation». For this reason, in addition to political will, a more determined citizen involvement is also needed, which gives the environment the importance it deserves.

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