Preservation & sustainability:: The case for ‘realistic' evidence-based design policy

In recent years, partisans of historic preservation have begun arguing "the greenest building is the one already built.” Often voiced in response to a narrowly conceived idea of building envelope energy performance, the statement nevertheless assumes away a proper research agenda. The underlying values appear incommensurate, and the differences between practitioners has appeared in a variety of public policy controversies ranging from conflicts over local preservation and sustainability ordinances, to government building energy performance contracting, to sufficiency of USGBC LEED standards for addressing issues of historic buildings. The potential question for the architectural researcher addressed here, is how to best frame the underlying research question. What metrics and data are relevant to policy and building level analysis? As a means of answering this question, this paper attempts to step-back from the tit-for-tat of the usual arguments by elaborating on how an evidence-based research program might address the problem. Specifically, the paper briefly discusses the genesis of evidence-based decision making in healthcare, and its ensuing extension into both building design and public policy making. The case is made that a discussion occurring among another group of scholars - those in public policy - is directly relevant to how designers might begin to more explicitly address what constitutes evidence in policy setting, as opposed to a more open-ended notion of data. The relevance of this as applied to sustainability and preservation lies in an urgency expressed by preservation advocates such as the National Trust for Historic Preservation and its recent call for "data to make our case.” This reference to data assumes that this will bring about agreement and supportive policy. However, the literature on evidence-based policy is more circumspect of simplistic relationships. It is interested in program logic (why we think an intervention will have the effect we think it will) and causation (how and through whom the effect will be carried out). While this paper addresses methodological issues in research, its abstractions are grounded in particular examples and ongoing dilemmas in the relationship of preservation to sustainability. These examples will be used to illustrate the more abstract points