the gold standard of evidence is the randomized clinical trial (Chow and Liu, 2004; Friedman et al., 1999; Katz, 2006). In the case of systems, performance-based measurement provides evidence that supports continuous improvement (Gawande, 2007; IOM, 2000; Smith, 2005) . With respect to economic outcomes, careful analysis of costs and benefits can provide the evidence base for wise decisions (Brent, 2003; Donaldson et al., 2002 ; Drummond et al., 1997).

Similarly, the move to green health care should be supported by evidence. Simply claiming that something is green, without demonstrating empirical benefits for human health and well-being, the environment, and economics,

is not enough. Although anecdotal accounts of success and case studies are useful in advancing green health care, a robust evidentiary base for the practice is needed. Many endpoints might be studied—patient health outcomes, staff turnover, the psychological comfort of visitors, the magnitude of the waste stream, the use of water, and the cost of energy, to name a few. An important goal of the workshop was to discuss some of the lines of research that, if carried out, could help guide the transition toward green health care.

Healthcare institutions, like any complex systems, do not change easily or quickly. Many factors drive change, including the evolution of new external demands, the emergence of new data, the reframing of questions about a healthcare institution’s operation, the influence of visionary leadership, and the reconciliation of competing interests within the institution. In the case of green health care, each of these may play a role; indeed each may be indispensable. Advocates of green health care need to understand the institutional dynamics, including the strengths and weaknesses of particular institutions and the opportunities and threats both at the institutional level and in the larger operating environment. Green healthcare success stories are useful in illuminating what works and what can go wrong.