Does Saving Historic Buildings Really Save Energy? – A Response
In a recent posting on BuildingGreen.com, “Does Saving Historic Buildings Really Save Energy?” Tristan Roberts pointed out a number of benefits that may be realized by the adaptive reuse of older buildings; however, he dismissed the notion that there is value in the energy embodied in these structures. While he is correct in his assertions about the cultural and urban value of historic buildings, he misses the point, or at least part of the point of the value of the energy embodied in those buildings. Despite the fact that there is no way to “recover” the embodied energy in old buildings, if their reuse offsets the need to build replacements, the energy that would have been embodied in those new buildings is saved – avoided cost.
Of course, there will almost certainly be some construction, and therefore some energy commitment, required to extend the useful life of older buildings including implementation of measures to significantly improve performance. The net avoided energy cost will be less than the total energy cost on the new building. Nonetheless, the new energy that must be “embodied” into the existing building will typically be 1/3 to 2/3 that of starting from scratch. Additionally, there is that much less debris sent to landfill and that much more “embodied” culture carried forward.
This is not to say that saving older buildings will always be the best choice for the environment, nor is it saying that one should only consider saving important historical buildings if their continued existence can be justified through energy savings or other environmental benefits. The considerations will be based on a sliding scale. At one end, there are the truly significant historical and cultural artifacts that must be preserved at all costs. At the other end, there are the purely utilitarian structures whose continuance will be determined by quantifiable, pragmatic concerns. In the middle is that vast majority of buildings that make some contribution to the understanding of history and sense of place, and whose reuse will offset some portion of the embodied energy that would otherwise by required for new construction. These are buildings that are neither historically and culturally indispensable, nor clearly justified by environmental imperatives. In some cases, the positive attributes embedded in these structures will be outweighed by benefits that can only be achieved through new construction.
Decisions regarding adapting and reusing instead of demolishing and replacing should be informed by multiple factors; some environmental, and some, as Roberts noted, cultural. What is critical, however, is that all significant considerations be included. This is particularly true for those middle ground buildings for which no single criterion is likely to prove decisive. While it’s true that embodied energy itself is not a recoverable resource, it is a valuable asset that can offset the need to expend new energy resources. And, while it’s unlikely that the energy offsets inherent in building reuse will be the sole determining factor in deciding whether or not to save a building, it is a real consideration that may push the eventual decision in one way rather than another. To exclude this asset from the equation is to neglect a readily exploitable and relatively benign resource. To knowingly neglect such a resource at this point in history would be irresponsible.