When Stefan Behnisch set out to build his practice, he was preoccupied with one key question: how to construct high-quality buildings that use minimal natural resources – not just in construction, but over the course of that building's lifetime.

Why care? Well, for many reasons, but chiefly for this one: Buildings emit up to 40% of the greenhouse gases the world produces each year. Reducing those emissions would go a long way to curbing the impact of global warming.

"It became obvious in the late '80s and early '90s that we had a big problem," Behnisch says over the phone from his satellite office in Cambridge, Mass. "Now, for me, it is just another one of the disciplines we have to work with – an essential part of value engineering."

The exhibit Ecology.Design.Synergy gives a flavour of what Behnisch Architekten, together with long-term collaborator, German climate engineering firm Transsolar, is working towards in this field. Divided into sections, the exhibit frames each project through a particular sensory experience: light, sound, air, temperature and materials. "We wanted to do something different," says Behnisch. "We didn't want to just show buildings, buildings, buildings. We wanted to give people an idea of how people would perceive and be affected by the temperature, air and light in the building – all the things that use energy."

Take the theme of "temperature." In the exhibit, it's illustrated by models and drawings of the Sensity complex, an as-yet-unbuilt project currently being considered for a desert near Dubai. The complex consists of a park complex in a depression, overshadowed by a canopy of flower-like structures.

"At an elevation 8 meters below grade, the temperature in the desert is a constant 18 degrees Celsius; it's very stable," explains Behnisch. "All the halls and spaces would be under a mountain of sand." Salt water would be pumped constantly from the sea nearby to run over the flower “petals” and evaporate, cooling the air – and precluding the need to air condition the built spaces.

This exhibit runs to October 3 at Harvard University. It then moves to Yale through October and on to Pittsburgh in the new year, where one of the newest projects in the exhibit, the Riverparc mixed use residential and retail development, is to be built. "Riverparc is all about the public realm," says Behnisch. "We won that competition because we were looking at the project not only in terms of its energy use, but also for the way it promotes spaces for a certain kind of social fabric."

The complex consists of a series of structures for retail and cultural use, mixed with condo towers and town homes, and interconnected with walkways and public squares. Energy saving moves include geothermal slabs to heat the buildings, and natural ventilation to cool them. The architects also took care to ensure there is sun in the public spaces in winter, and shadow in summer. "The climate in the spaces is configured to work with the light and the seasons," says Behnisch. "It's nothing new – old Italian cities were always built this way. But it's new for this context."

Behnisch first got interested in sustainable design in the 1970s. "It was a generation thing, and a German thing," he says. "The Green Party had formed as part of the anti-war movement, it was in the air." The first "sustainable" building Behnisch worked on was the IBN Building, a structure commissioned by the Dutch government in 1996. It featured roofed interior gardens controlling the climate inside. In winter, the gardens acted as insulation and a heat source; in summer, they functioned as a sun break. The gardens bolstered the structure's level of thermal insulation to such an extent that it was possible to make 65% of the area of the office wing outer walls of clear double glass, reducing the amount of artificial lighting needed for the offices.

Behnisch has since fought several battles to stand by his firm's principles of always building green. "Sustainability is a weaker force than cost," he says, "so we have to strengthen it."

Take the complex that Behnisch Architekten is currently building for Harvard University in Allston, a district of Boston across the Charles river from the school. "It's a Harvard project: the university wants it to be sustainable, the president is dedicated to sustainability," says Behnisch. "But again, the cost issue comes up, and the sustainable parts of the design are what the project manager goes to cut first."

So what does one of the world's foremost sustainable architects advise, when a developer quibbles over the cost of building green? "Make sustainable design an integral part of your architecture," he says. "Could you imagine, asking Frank Gehry to design a square building? This is the same thing. Integrate it right into the design. Make it a non-negotiable."

By Rachel Pulfer

For more, see www.behnisch.com, www.treehugger.com