Making Houses Resilient to Power Outages
The ice storm a week-and-a-half ago illustrated, all too clearly, the vulnerability of our homes. Hundreds of thousands of homes in New England lost power in the storm, which deposited up to an inch of ice on trees the night of December 11th, and tens of thousands were still without power a full week later, despite heroic efforts by utility crews. This illustrates why all houses should be designed and built to achieve “passive survivability,” an idea that, nationally, I’ve been advancing for the past three years.
Let me back up and provide some context. Three years ago, in the aftermath of Hurricane Katrina, I was part of a design team working on guidelines for more sustainable reconstruction in the Gulf Coast. I had observed that New Orleans residents were evacuated to the Superdome and then had to evacuate the structure when it got too hot inside—the building wasn’t designed to function without air conditioning. In the French Quarter of New Orleans, where homes were not flooded but nonetheless lost power, the older homes that were built in the early 1900s were livable, while newer ones were not. Those older homes had been built using climate-appropriate “vernacular architecture”—with wrap-around porches that shaded windows and design that channeled cooling breezes through the houses—while modern houses were built to rely on air conditioning.
Without electricity the modern houses got too hot.
Something seemed wrong with this picture. We argued that in rebuilding the Gulf Coast, the houses should achieve passive survivability, which we defined as “maintaining livable conditions in the event of extended loss of power or interruptions in heating fuel.”
The idea applies not only to hurricane-prone coastal areas, but everywhere—for a number of reasons. Scientists predict that global climate change will result in more intense storms, which in turn will cause more frequent flooding and wind storms that will knock out power.
Beyond climate change, many experts (including a past director of the Central Intelligence Agency, James Woolsey), argue that terrorists could target our energy infrastructure—power plants, electrical distribution systems, transformer stations, natural gas pipelines, oil pipelines, and refineries. This would cause devastating, long-term power interruptions or fuel shortages. There is even new evidence that “cyberterrorists” could cripple our energy production and distribution systems by hacking into the controls.
And in the not-too-distant future—well within the lifetime of homes being built today—there may be actual shortages of heating fuel. Some “peak oil” experts think that shortages, or prohibitively high costs, will occur within the next decade, as supply fails to keep up with demand.
Given all these reasons, we should be designing homes and apartment buildings to maintain livable conditions in the event of power outages or interruptions in heating fuel. What would this design for passive survivability look like for us in New England? It would mean extremely good energy performance. Such a house in our area might have R-40 walls, R-60 ceilings, triple-glazed windows (with two low-e coatings), airtight construction (with a heat-recovery ventilator(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. ), and passive solar design. During a power outage or if the heating oil runs out, the house would never drop below about 50 degrees. Homeowners would remain safe (by staying bundled up), and pipes would never freeze.
Such a house would cost more to build, but it would cost almost nothing to heat—so the “life-cycle cost” would be lower, an important consideration if (when) energy costs go back up. The house would be so energy efficient that a small woodstove or propane heater would maintain it at comfortable temperatures were power to be lost. Such a house could also be made “carbon-neutral” by adding rooftop solar panels.
Water availability is also an issue. Storing water in the building is a short-term option. For homes with their own water systems, hand pumping can be an option for shallow wells or springs. For deeper wells, a PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.-powered pump and battery storage may be required.
When I first proposed the idea of passive survivability three years ago, I suggested it as a smart design criterion that we should implement because it made sense. More recently, I’ve argued that requirements for passive survivability should be incorporated into building codes—they should be mandated for life-safety reasons.
While there is bound to be resistance, I have so far received considerable interest, including by the City of New York, which is working on modifying its building codes to prepare for climate change. (I’ve been part of a committee established by Mayor Bloomberg to recommend changes to the city’s building codes, and passive survivability is a big part of that discussion.)
With existing homes, achieving passive survivability is much more difficult and more expensive, but significant improvements can be made with superinsulation retrofits—a topic for another column.