by Steve Moddemeyer
I am attending Stockholm Water Week which is a venerable water event each year. This is my first year to attend. There is some very sophisticated thinking being presented on adaptation to climate change. Most memorable so far was a presentation by Paul Kabat. He talked about the idea that designers design buildings and infrastructure to operate within certain parameters of performance . Just beyond the edges of performance are “reasonable” extremes or “failures”. Here’s how I think of it: in Seattle only 15% of homes have air conditioning. Living without air conditioning is only seen as a “failure” a few days of the year, so the price of putting it in every home is too much. But if we were in Phoenix, then it would be irresponsible to not have air conditioning. However, due to the accuracy of global climate prediction models, no one can really say if any of us are being reasonable any more. So we continue to design buildings and systems with the known climate in mind – all the while knowing that we don’t know if this building will really perform as we had hoped. Will there be four weeks of “failure” in Seattle if buildings don’t have air conditioning? Due to the uncertainties from climate change, we can’t say any more.
People who invest in infrastructure and buildings would prefer a better prediction than that. They say, “Tell me as closely as you can what I can expect so I don’t over-compensate or under-compensate.” But there is no one that knows. The climate models just do not “downscale” with enough accuracy to be very useful. (In fact, Kabat predicts it will be 20 years or more before this information gets helpful.) So what to do?
Two things, according to Kabat:
1st design to a “plausible extreme”. So if a few days of air conditioning failure is OK but four weeks of failure is not, what is the plausible likelihood on the high side that will happen within the life of the infrastructure or building? So basically design to that.
2nd is to run multiple scenarios of how to achieve the desired performance where you keep your flexibility and options open. So that when and if new information comes in, you have not foreclosed timely and cost effective adjustments. So in my air conditioning example, it might turn out that optimizing the buildings for natural ventilation is the most cost effective near term design option. But you should probably save room in the basement to add air conditioning in the future if that is necessary to keep the place from unacceptable failure. Or in the case of as commercial campus, it might only make sense right now to run a hot water district system and just do air conditioning building by building. However, try to keep open the option to easily retrofit a cold water system if the changes in climate warrant it.
