What is a Resilient Home?
In the aftermath of Hurricane Sandy, we've been writing quite a bit about the concept of resilience, and specifically how the Home Performance industry can step in and increase the resilience of our buildings in order to minimize risk from future disasters. While we're rebuilding anyway, it only makes sense to "rebuild better" so that we're better prepared for extreme weather events in the future.
Resilience is a concept that's gaining increasing traction, both in the building science community and in the sustainability/green community more broadly. As Andrew Zolli writes in The New York Times:
"Among a growing number of scientists, social innovators, community leaders, nongovernmental organizations, philanthropies, governments and corporations, a new dialogue is emerging around a new idea, resilience: how to help vulnerable people, organizations and systems persist, perhaps even thrive, amid unforeseeable disruptions. Where sustainability aims to put the world back into balance, resilience looks for ways to manage in an imbalanced world."
What is a Resilient Building?
But what makes a resilient building, and how do we go about rebuilding better? We think these are important questions, and ones that deserve some thought moving forward so that we can come up with some reliable, measurable standards that will help ensure the safety of our friends and families down the road.
In this post, we don't go into extensive detail about what makes a resilient building (ACH, specific heating requirements, etc.), as so much of what makes a resilient building depends on factors including climate, topography, etc. We do attempt to itemize a list of requirements that a resilient building should meet: requirements that are real, tangible, and achievable.
As you're reading through the list, keep in mind that we'd love to keep this discussion going, so feel free to chime in with any comments, questions, or arguments; we'd be happy to hear them.
Criteria of a Resilient Building:
We think that resilience is just as much about the aftermath of the storm as it is about the storm itself. It's not enough for a building to remain standing after a hurricane: it should be functional to the point that you can stay alive and remain in relative comfort for a reasonable period of time after the extreme weather event.
Depending on climate zone, it's possible to insulate and air seal homes to the point that they don't require any heating system at all, and still maintain a comfortable living temperature (Passive House). While this may be a little extreme for our limited requirements of a resilient building, it seems plausible to dfine resilience as a building air tight and well-insulated enough that it can stay at a livable 45 degrees indefinitely, without heating input.
Ideally, a building designed to be resilient has some passive solar capacity, increasing its ability to acquire and retain heat during periods of extended power outage. Of course, it's not always easy to retrofit an existing building to take advantage of passive solar heat, but in the case of new construction, its incremental cost is often very low, and its advantages are huge.
Backup Power Generation or Storage
It's critical that there is some way for a home's vital electricity-powered elements to stay functional in the aftermath of a disaster (some basic lighting and cooking capacity as starters). This could be provided by a gas generator, or by a renewable energy source such as a solar PV system or a small wind turbine. Ideally, this could also come from stored energy, possibly from the big battery in that electric car in the garage. (Hat tip Alex Wilson.) If the home is energy efficient (as it should be, if it is resilient), the home won't need a lot of electricity, and a small generator or renewable installation should suffice.
Even if your home has a backup power supply, which helps to ensure access to clean drinking water, it's hard to be sure that the water entering your home is clean: floods are notorious for contaminating drinking water supplies. While it may not satisfy all of your water needs, a rudimentary rainwater collection system is a low-cost, easy way to ensure that you have access to at least some water.
Protection from High Wind / Debris
One of the key tenets of a resilient building would be that it remain standing throughout an extreme weather event such as a hurricane. While this certainly can't be guaranteed (you can't build an "unsinkable ship"), steps can be taken to increase the chances that the building survives the storm. This might include roof tie-downs and/or shutter systems to keep the building in-tact, the roof on, and the windows and doors in place, but I'm sure our engineer friends can recommend other intregral approaches.
A resilient home is one that has at least minimal protection against stormwater damage. This can be accomplished in a number of ways -- from keeping the home out of a flood plain in the first place, to using flood-resistant building materials and methods (such as raised foundations, air-tight construction, hydrophobic insulation, etc.).
A wet building can kill you. Having a resilient home in the wake of a hurricane means being able to control the moisture in the home at least to the point where it's safe -- where structural damage is minimized, and where indoor air quality is kept in a safe zone. This means keeping the building dry as far as possible (with an air tight building envelope), and incorporating the ability to deal with any moisture issues that may inevitably arise. Many of the newish, advanced air tight but vapor open wall structures enable insulation to wet and dry. Dehumidification, ventilation, and a sump pump to deal with bulk water accumulation are also good ideas.
For more information about resilient building, check out the Resilient Design Institute. The Margate Residence, designed by Zero Energy Design, is also a great example of a home designed for resilience on the New Jersey shore in the wake of the hurricane. For more on how the home performance industry can best help implement resilient building features during the rebuilding process, check out our webinar on Home Performance in the wake of Hurricane Sandy.
Do these seem like reasonable criteria to you? What did we miss?