It is absolutely irrational to think that the issue of sustainability may be solved only by looking at a building(s) as is thinking that the architect can only affect in the building itself. It is true that building account for a big part of the CO2 emissions, land loss through urbanization, water use, etc. yet a building must be understood as part of a bigger picture. There are two scales that have to be seen to understand this; the building inside a system and the use of a building by its dwellers.
Cities, towns, villages, and any of the kind contains and belongs to a system. A building for instance is part of the built environment system of a city, which in turn relates to the transit system, park system, infrastructure system, social system, information system, and so on ans so forth. Hence, the understanding of a city should be approached as an ecosystem itself. This work is beign done by biologist Salvador Rueda, who has been studying different cities and the parameters that make it a “healthy” ecosystem. Out of his work it is very interesting to understand the importance of density and available services. The best example would be Barcelona city, that given it’s density (along with urban design) only 30% of the trips done inside it are done by car. So in conclusion, the architect when designing a building should look at all this other systems and the parameters that rule over healthy urban ecosystems for it to respond and help make the system better.
Second scale to understand is the dweller. This is much simpler and can be summarized in one question: who pollutes more, a person who lives in an energy inefficient building who consumes little energy or a person who lives in an energy efficient building but consumes a lot of energy? ┬áIt all drops down to the dwellers behaviour inside the building. It doesn’t matte how efficient the building is if the dweller wants to have beach weather inside his house in the middle of winter. To be energy efficient, water efficent, waste efficient, and whatever other efficiency regarding a building the dwelles have to modify their behaviour and understand that resources are limited and you someteimes have to balance your comfort levels to help the world survive.
In conclusion, yes, we have to design sustainable buildings yet a building is not sustainable unless it relates to the systems surrounding it and the people inhabiting it.
As for developers, the main issue is that they do business in an “touch and go” manner, meaning that they put money in and want it back as soon as possible. In terms of sustainability of buildings, the return is slower than that expected by the developers, so the ones recieving the economic savings are the managers of the buildings, which are the ones that keep the building for longer. So it needs a shift in the way buildings are financed, by making the developers percieve the economic savings of the buildings by running them for longer periods of time. It would require laws to make the building property of the developer for 20 or so years or make the developers manage the buildings themselves.