Environmental Building News Calls for "Passive Survivability"

In an age of increasing concern about natural disasters, terrorism, blackouts, heat waves, and fuel supply interruptions, all houses and school buildings should incorporate "passive survivability" features. This is the key message of a December, 2005, editorial in Environmental Building News (EBN), by BuildingGreen president and EBN executive editor Alex Wilson.

Wilson uses the term passive survivability to describe a building's ability to maintain critical life-support conditions in the event of extended loss of power, heating fuel, or water, or in the event of extraordinary heat spells, such as the one that killed over 700 people in Chicago in 1995. "It's an idea that really gelled for me during work on several charrettes related to reconstruction in the Gulf Coast region following Hurricane Katrina," says Wilson. "This wasn't the first natural disaster to cause widespread, prolonged loss of critical energy and water services, and it certainly won't be the last." says Wilson.

An ice storm in eastern Canada in January, 1998 left 4 million people without power--many for a period of weeks--and forced 600,000 residents from their homes. Hurricane Katrina caused massive power outages in the Gulf Coast region; power has still not been restored in some areas more than three months later and some homes that are now reoccupied are without natural gas heat. The Blizzard of 1978 left tens of thousands of New Englanders without power. And a circuit overload in the Midwest in 2003 resulted in a widespread blackout throughout much of eastern Canada and the northeastern U.S., leaving roughly 50 million people without power (one-seventh of the U.S. population and one-third of the Canadian population). Note that with nearly all heating systems, a loss of power means that the heating system will not work--losing power means losing heat.

Along with natural disasters is the growing risk of terrorist actions that could sever power or fuel delivery to large regions. And in the longer term, many experts believe that we will soon be entering an era of declining availability of fossil fuels (natural gas and petroleum) that could result in supply shortages.

"All this points to the need to design buildings to protect their occupants passively," according to Wilson. The highest priorities are houses, apartment buildings, schools, and other public buildings that could be used as emergency shelters.

Passive survivability should include such features as cooling-load avoidance, natural ventilation, a highly efficient building envelope, passive solar heating, natural daylighting, and onsite water collection and storage. "Most of these design strategies make good sense from economic and environmental perspectives," says Wilson. "The survivability aspect provides another way to justify these measures."

In terms of building performance, the goal isn't to maintain temperatures within the accepted threshold of comfort (typically 68° to 81°F), but rather to maintain conditions in a building that will not threaten the lives of their occupants. After Hurricane Katrina, temperatures in the New Orleans Superdome rose as high as 105°F, and in the Chicago heat wave, many apartments remained above 90°F even at night. A building designed for passive survivability would not reach such dangerous conditions. Natural daylighting in a school will enable that building to be used during the daytime hours even if power is lost--that can be critical, especially when schools are designated evacuation locations or emergency shelters.

The conventional solution to power-supply interruptions is to provide back-up generators and adequate fuel to carry a building--or at least the critical functions in that building--during outages. Indeed, generators need to be part of the answer in some situations (such as hospitals), but passive solutions are preferable in most situations for various reasons: unless very large, generators are rarely able to provide air conditioning, general or task lighting, or even heating or ventilation during outages; storing significant quantities of fuel on-site to power generators during extended outages has its own inherent environmental and safety risks, particularly during storms; and back-up generators are expensive, both to buy and to maintain.

Renewable energy systems can be an important component of passive survivability. Photovoltaic (PV, or solar electric) power systems, when coupled with on-site battery storage can provide electricity when the grid loses power (though utility-approved disconnect equipment is needed for any PV system that is configured to normally feed power into the utility grid). Solar water heating systems can protect homeowners from loss of hot water in the event of a heating fuel or electricity interruption.

Passive survivability measures are so important that it may make sense to incorporate them into building codes, though this could affect affordability. "Most--but not all--passive survivability features will add some cost to a building," according to Wilson, "so the impact on affordability needs to be considered if such measures are to be required by code, but it's time to at least begin this discussion."

More information on passive survivability can be found in the just-published New Orleans Principles, the outcome of a three-day charrette held at the U.S. Green Building Council's Greenbuild Conference in Atlanta in early November. To learn more about this report or to download a copy, visit http://green_reconstruction.buildinggreen.com.

BuildingGreen, Inc., has been providing the building industry with quality information on sustainable design and construction since its founding in 1985. Publications include Environmental Building News, the GreenSpec® Directory of green building products; and the integrated, online BuildingGreen Suite. For information, visit www.BuildingGreen.com or call 802-257-7300.

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