On the Path to Passive Survivability

Creating a superinsulated building envelope is one of the key requirements with passive survivability. I saw this superinsulated home feature when I was in Sweden last year. Photo: Alex Wilson. Click for bigger. (More below.)

By way of background for those who haven't tracked this issue, here's the thumbnail sketch: In an age with more intense storms, terrorist actions against our energy infrastructure, potential petroleum shortages, and drought, we should be designing homes, apartment buildings, schools, and certain other public-use buildings so that they maintain livable conditions in the event of extended power outages or interruptions in heating fuel or water.

I had initially been proposing passive survivability as a smart design criterion. More recently I've been advocating that we mandate passive survivability through building codes. There are a number of developments along these lines:

Creating a superinsulated building envelope is one of the key requirements with passive survivability. I saw these superinsulated home features when I was in Sweden last year. Photos: Alex Wilson. Click for bigger.

Second, I'm participating in a committee that's providing input to the upcoming revision of New York City's building codes. We're trying to figure out what it will take to make the city's buildings and infrastructure more adaptable to climate change. I'm not sure where this will end up, but one of the ideas we're pursuing is to require dual-mode buildings. Dual-mode buildings would operate with conventional HVAC systems in normal conditions, but could be switched over to a passive operation mode during a power outage.

Third, I was recently in California speaking at a couple conferences — including on passive survivability at San Diego Green. Following the San Diego conference, I led a brainstorming meeting to address passive survivability. The group of a dozen or so individuals, including Bob Berkebile, Chuck Angyal, and Drew George, focused on three questions:

1. What constitutes "livable conditions"? We pondered whether a house would need to maintain 50°F in the winter to keep people safe (wearing coats), or if a house would need to be 55°F. How hot could a house get in the summer and not put its occupants at undue risk? We concluded that there's a significant body of knowledge out there to tap into on these questions — such as emergency management databases and ASHRAE technical committees on comfort.

2. How easy is it to model the "drift conditions" of buildings? I was surprised here to learn that our more sophisticated energy modeling software tools can do this without any modification — one only needs to vary the inputs. That's good news indeed.

3. Do we need "performance standards" for passive survivability or could "prescriptive standards" suffice? This is a tougher question. It's hard to deal with passive solar heating, daylighting, or cooling load avoidance on a strictly prescriptive basis, but we felt that having both a prescriptive path and a performance path would be ideal. We have a lot of work to do in answering this question and moving ahead with those prescriptive standards.

One of the new ideas that came out of the San Diego meeting was to come up with labeling of houses to indicate how they stack up relative to passive survivability — perhaps an A through F scale — and get insurance companies to buy in to preferential rates for the higher-ranked buildings. I continue to believe that the insurance industry could be a big driver of passive survivability.

Lake Mead, which supplies 90% of Las Vegas's water, is less than half full today. Maybe it's time we begin designing buildings to get by if water shortages or water rationing become a reality — not all that unlikely, especially with Scripps Institute scientists telling us there's a 50% chance that Lake Mead will be functionally empty by 2021. Photo: Ken Dewey. Click for bigger.

Finally, having just returned from Las Vegas, where I was attending the WaterSmart Innovations conference (about water efficiency and water conservation), I'm inspired to push harder to address water to a greater extent in defining passive survivability. In most cases, the idea with passive survivability probably won't be to create homes and other buildings that can be totally self-sufficient with water. Rather, we will push for buildings that can get by all right if water were to be rationed or only available intermittently for periods of time in the future.

If anyone wants to be part of this ongoing discussion about passive survivability, reply to this posting or e-mail me directly: alex@buildinggreen.com