Addressing the challenge of ecological limits to economic growth and protection of the commons has been the central focus of scholarly research and policy debate in the world of EDE over the past two decades. Notable progress has been realized on a number of fronts but big challenges remain. Advances in the theory and practice of sustainable development, moving away from income measures such as GDP and promoting inclusive wealth as the right indicator of change in wellbeing and sustainability for the evaluation of economic performance and associated progress with the development and use of natural resources and environmental accounts represent one major example. Another important example is the ecosystem services (ES) approach of the millennium ecosystem assessment that has now become the main framework widely adopted as the basis for the characterization, valuation and evaluation of tradeoffs among the multiple services of ecosystems impacted by the pursuit of economic growth. Together with progress in the science and economics of addressing climate change, these advances moved the EDE focus from micro- to macro-environmental economics management issues. Major manifestations of progress on these fronts include: the emphasis on the green economy for ‘the future we want’ at Rio+20 and the intended move beyond the millennium development goals (MDGs) to redirect future efforts of the international community towards new sustainable development goals (SDGs) and targets; global consensus and support for establishing an Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES); and efforts to better define planetary boundaries.

The competition between wind and buoyancy forces acting on a naturally ventilated building with one upwind and one downwind opening and a distributed heat source can lead to multiple steady states. This study considers the impact of a second downwind opening on the existence of these multiple steady states. It is found that if this new opening exceeds a critical area, then the multiple steady states are eliminated, and the transition from buoyancy to wind dominated flow is continuous. This critical area is shown to be a function of the relative heights of the three windows. The predictions of the model are in accord with new laboratory experiments, and the implications for building design are discussed.