The erection, operation, and maintenance of our built environment are responsible for half of the natural resources used and waste produced worldwide today. Architects, planners, developers, and engineers need to prioritise resource efficiency and green solutions. However, with even our most banal consumer habits deceptively marketed as green, it comes as little surprise that the words "environmentally friendly," "green," and "sustainable" have lost their ability to rouse and to captivate. To truly evaluate a building's sustainability, we must abandon our number-crunching crutch and accept that some criteria, such as the social, aesthetic, and even long-term energy and economic performance of a building, may be less quantifiable than others.
In 2003, the Holcim Foundation for Sustainable Construction defined a series of "target issues" that evaluate sustainable construction in terms of environmental performance as well as by its economic and social impact, developed together with experts from the Swiss Federal Institute of Technology (ETH Zurich) and other partner universities. These issues are set out here.
To truly evaluate a building's sustainability, we must ... accept that some criteria, such as the social, aesthetic, and even long-term energy and economic performance of a building, may be less quantifiable than others
1. Progress: innovation and transferability
The first target issue, innovation and transferability, evaluates the significance, applicability, and scalability of innovations in sustainable construction.Regardless of scale, these must be transferable to a range of other usesand applied to the entire process of construction,from the design and siting of a project to its construction, maintenance, and lifespan.
One example is the Station Z Memorial by HG Merz and Werner Sobek, a temporary monument on the site of a former concentration camp. Its main driver is the concept of reversible construction: that the structure should be as easy to disassemble as it was to assemble and that it should therefore be completely salvageable. This requires thinking about recycling early and throughout the entire design and construction process, particularly in regards to how different materials are joined together.
In the Station Z Memorial, the structure is covered on the inside and outside with a transparent membrane of glass fibre. This membrane, quite remarkably, is not conventionally fixed to the structure, but holds on to it exclusively by virtue of a vacuum seal maintained by a small pump powered by eight square meters of photovoltaic cells. If you ever want to dismantle the membrane, all you need to do is switch off the pump, and the membrane slips off. And since the structure and the membrane are neither glued nor bolted together, the memorial's 1,000 tons of steel and 500 kg of fabric can be easily disassembled and recycled once the vacuum is released.
This novel approach to jointing is clearly transferable and has already been applied on different scales. For instance, Sobek's house, R128, is bolted and jointed by mortice and tenon, making the materials entirely salvageable, just like the Station Z Memorial.
2. Planet: environmental quality and resource efficiency
The second target issue is to incorporate material efficiency and long-term environmental concerns into the design and construction of the built structure. Construction has been so obsessed with technological progress over the last century that it has overlooked simple but smart local methods of construction. In Addis Ababa, Ethiopia, the Ethiopian Institute of Architecture, Building Technology and City Development in conjunction with the ETH Zurich proposed an alternative to the Western building systems currently used to build housing for the masses (i.e.concrete pillar and slab). The first level of their double-story Sustainable Urban Dwelling Unit (SUDU) was built using rammed earth technology and for the second floor, locally produced loam stone bricks were stacked with very little connecting mortar or cement. The roof, a vault tiled system, was sealed using mortar made of prickly pear cactus juice, salt, lime, and loam soil. This efficient solution to waterproofing and passive cooling had been used for centuries in Mexico before it was replaced with corrugated metal sheeting, which transfers the heat from the desert sun almost directly to the interior of the house.
3. People: ethical standards and social equity
The third target issue refers to projects that create positive change in their communities. Within this criterion, architects, planners and engineers are expected to address critical issues of the general public, design socially viable environments, and support social equity for laborers and residents at all stages of the project.
A building that is powered exclusively through solar energy, but that fails to create a lasting relationship with its immediate community, is not sustainable ...
Good design is created through collaboration; the more stakeholders involved in the decisions that shape their built environment, the better. When BeL Associates set out to explore how to lower the income threshold for purchasing a home in their Allotment House in Hamburg, they worked with different stakeholders at different scales. The project also involved residents as the design allowed to use their construction skills as sweat equity.
The first units will be completed this fall, but already the project has extended homeownership to a demographic usually excluded from the real estate market. And it has helped create a discussion on how to house the urban poor in Germany in a way that consolidates, rather than gentrifies, existing neighborhoods.
4. Prosperity: economic performance and compatibility
The fourth target issue, the economic feasibility of a project, is especially pressing today. It assesses on the one hand the way a project's budget is resourced, as in the case of BeL's privately financed affordable housing project, and on the other hand, how they choose to allocate a given budget.
The Nantes School of Architecture by Lacaton & Vassal Architects is a compelling example of how to make the most out of a limited budget. The use of industrial construction processes and prefabricated greenhouse building systems dramatically reduced construction costs to such a degree that leftover capital could be reinvested into making its spaces even more generous. Cost-efficiency as a strategy to build more space provides an ingenious model for architectural financing. And to boot, these additional spaces naturally cool and heat the school, eliminating costs associated with the installation and operation of mechanical systems.
5. Proficiency: contextual and aesthetic impact
So far, we've discussed the environmental, social, and financial aspect of sustainable construction-but what about its aesthetics? This largely suppressed aspect of sustainable buildings that they should be as beautiful and generous as any other is the final target issue. Like all the aforementioned projects, most successful examples of sustainable construction approach sustainability holistically by tapping into each of the five target issues. They are innovative, resource efficient, socially viable, economically feasible, and last but not least, beautiful.
This is because energy self-sufficiency alone does not make a building sustainable. A building that is powered exclusively through solar energy, but that fails to create a lasting relationship with its immediate community, is not sustainable, just as building technologies, methods, and materials completely foreign to a local context are not financially feasible in the short and long terms.
The targeting of all five issues benefits the discourse on sustainability by simultaneously broadening and honing in on the definition of the term. It addresses issues previously overshadowed by a discourse focused almost exclusively on energy savings and numbers, like the social and aesthetic dimensions of a project, while also raising the bar for sustainable construction.