The real estate sector's green future. Rethinking sustainability.
The real estate sector is striving for greater sustainability. But what does sustainability actually mean? A professor from the Swiss Federal Institute of Technology proposes a new definition. In addition, three projects reveal how sustainable construction could be implemented.
Real estate sector needs to rethink its definition of sustainability
The real estate sector is facing a paradigm shift. That is the opinion of Guillaume Habert, a professor at the Swiss Federal Institute of Technology in Zurich (ETHZ). "Our lives are still heavily governed by the logic of longevity," says the Chair of Sustainable Construction at ETHZ. In this way of thinking, sustainability is equated with energy efficiency. Buildings are therefore designed to use as little energy as possible, and are highly insulated, equipped with numerous building systems, and extremely complex. According to Habert, this mindset is not wrong, but it is outdated.
That is because it assumes that energy itself is not sustainable – that is, renewable. Moreover, it ignores a major factor: embodied energy. Concrete, for example, is a carbon-intensive material. Roughly 15 million cubic meters of concrete are used in construction every year in Switzerland. "We are affecting the climate of the future by constructing buildings that are not designed with that future in mind," warns Habert. He adds that it is impossible to predict the future.
The logical conclusion is that we need flexible buildings that can be adapted to different circumstances. Habert is convinced that the term "sustainability" will someday be used to mean adaptability.
trees take one year to offset the carbon emissions produced by one cubic meter of concrete.
(Source: University of Stuttgart)
Flexible design makes this high-rise building a model of sustainability
Adaptability is not a problem for the Pergamin II office building in Zurich. At a height of 40 meters, it and its sibling, Pergamin I, form the gateway to the Greencity redevelopment, where different housing options for more than 2,000 residents are combined with office space for some 3,000 people. During construction of Pergamin II, emphasis was placed on both the flexibility of the design and its social components, which were studied, evaluated, and certified.
This sustainable approach to construction makes Pergamin II the first building ever to be awarded Gold status under the revised criteria of the greenproperty quality seal. To earn this certification, real estate is assessed based on the following five dimensions of sustainability: use, infrastructure, CO2/energy, materials, and life cycle.
Greater urban sustainability through densification
The advantages of the Greencity redevelopment support the idea of urban densification. As Guillaume Habert points out, density is one of the crucial aspects of sustainable real estate. The ETHZ professor argues not only for repurposing unused sites, but also for a "parasitic transformation" of cities. The idea is to add on to existing structures and avoid demolition as much as possible, because a great deal of energy is concealed in the existing buildings. Thus, demolition would inevitably lead to the release of CO2.
The project of adding stories to the LOKwerk shopping mall in Winterthur is in keeping with this "parasitic" principle. Architectural firm "fsp Architekten" is planning a new, three-story structure with 60 apartments on the roof of the mall, which features a striking brick facade that is protected as a landmark. The existing structure will remain largely untouched throughout the construction. As an added benefit for the environment, the entire roof will be covered with a photovoltaic system. Thanks to its shared use with the shopping mall, almost all the independently generated electricity can be used locally.
Once the project is completed in 2023, the hope is that it will meet the requirements for both the greenproperty quality seal and the Minergie label.
Sustainable construction: We have entered the century of wood
For reasons of structural stability, wood was the only material suitable for building additional stories on top of the LOKwerk. The Erne AG Holzbau company has calculated that the prefabricated roof elements, which combine the advantages of wood and concrete, are 60% lighter than a roof made entirely of concrete. Erne AG Holzbau is using spruce and fir from the European market to produce these elements.
Urs Huber from fsp Architekten states, "Today's timber construction is so good that you don't even recognize it as such." Moreover, contrary to people's preconceptions, it no longer differs from traditional construction in terms of soundproofing. Wood also has another thing going for it: As a renewable resource, it stores CO2. After a century of concrete, experts are predicting that the 21st century will be the century of wood.
Sustainability and single-family dwellings are not necessarily a contradiction
What do these insights mean for single-family dwellings, which have a poor reputation when it comes to energy consumption and footprint? "Many people want to have a house in the country, so this is not something that we can simply ignore," says Fredy Hasenmaile, a real-estate analyst at Credit Suisse. He favors taking a pragmatic approach. In the future, he says, we need to provide incentives for people "to at least install a photovoltaic system or a heat pump." And perhaps to build with wood instead of concrete and to use straw rather than polystyrene for insulation.
One structure serving as an example of what the future of single-family dwellings might look like is the "House with a Tree" in Basel. In 2013, the architectural firm Sauter von Moos collaborated with Pierre de Meuron to renovate and expand the classic single-family home, which was built in 1930. The architects considered it important to leave the structure of the existing building largely unchanged and avoid affecting its stability. When adding on to it, they used sustainable building materials, including recycled slats of fir. Energy is provided using a heat pump and photovoltaic system.
This example demonstrates that individual structure measures, even small ones, can help protect the environment. As real estate expert Fredy Hasenmaile puts it: "At Credit Suisse, we believe that everyone can make a contribution in some way."