Design for Adaptation: Living in a Climate-Changing World

Climate scientists have been speaking out for decades about the need to reduce greenhouse gas emissions in order to avoid a significantly warmer and less livable future. Now that climate change is finally part of the public discussion, the future is already here—and it’s only getting warmer. Designing energy-efficient buildings is an important step toward preventing more drastic warming. We need to redouble these efforts—the 2030 Challenge goal of carbon-neutral buildings by 2030 will be a difficult yet critical standard to meet. But by stopping there, are we turning a blind eye to the changes that scientists say are coming even if greenhouse gas emissions were turned off tomorrow?

More and more experts acknowledge that while we must continue to do all we can to slow greenhouse gas emissions, we must also begin designing buildings that will work in a changing climate. This article examines the science of global climate change and looks at how we can adapt the built environment to a world that will, by most accounts, be very different by the end of this century from the one we know today.

The Reality of Climate Change

Debate may continue in some circles about whether humans are causing climate change, or even whether it is happening at all, but the scientific consensus is overwhelmingly clear. A report issued in June 2009 by the U.S. Global Change Research Program (USGCRP)—which coordinates climate change research of 13 federal agencies and operated as the U.S. Climate Change Science Program from 2002 through 2008 under the George W. Bush presidency—estimates that global average temperatures have risen approximately 1.5ºF (0.8ºC) since before the Industrial Revolution and could rise another 2ºF–11ºF (1.1ºC–6.1ºC) by the end of this century, based on modeling of a variety of greenhouse gas emissions levels, mitigation efforts, and economic scenarios. “The reality of climate change is unequivocal—we see it in many aspects of the Earth’s climate system,” said Jonathan Overpeck, Ph.D., co-director of the Institute of the Environment at the University of Arizona and a co-author of the USGCRP report.

A matter of degrees

The question in the scientific community seems to be not whether we will see change but how much we will see. “The confidence that something is going to happen is exceedingly high,” said Stephen Schneider, Ph.D., professor of biology and interdisciplinary environmental studies at Stanford University and a leading proponent of climate change adaptation. “Where it gets a bit more speculative is with questions like how many meters of sea level rise we will see and what the changes in rainfall will look like,” Schneider told EBN. He suggests that the extent of change depends on a few primary factors, including the speed with which the climate responds to varying concentrations of greenhouse gases, or “climate sensitivity”; the ability of the oceans and land-based ecosystems to absorb carbon dioxide (CO₂) emissions; and the robustness of our efforts to curb the release of greenhouse gases into the atmosphere.

Some effects of the warming planet are already being felt, and further consequences are on their way. These changes will vary from region to region, but general trends include changing precipitation patterns and heavier downpours, even in areas where overall precipitation will decline; longer, hotter, and more frequent heat waves; rising sea levels due to melting glaciers and land-based ice sheets; loss of both sea ice and protective snowpack in coastal areas; stressed water sources due to drought and decreased alpine snowfall; and “positive feedback loops”—consequences of warming that cause further warming, such as melting sea ice decreasing the capacity of the northern oceans to reflect solar radiation back out of the atmosphere. (More information on the regional effects of climate change can be found at www.globalchange.gov.)

Alarmingly, a paper published in the Proceedings of the National Academy of Sciences by Susan Solomon, Ph.D., of the National Oceanic and Atmospheric Administration (NOAA), and colleagues in February 2009 reported that these changes to the earth’s systems due to anthropogenic greenhouse gas emissions will be largely irreversible for 1,000 years after emissions stop. The authors emphasized that if atmospheric CO₂ concentrations rise to anywhere between 450–600 ppm (from their current levels around 385 ppm), we will see permanent decreases in dry-season rainfall and “inexorable sea level rise”—between 0.4 and 1.0 meters (15–40 inches) if CO₂ concentrations reach 600 ppm, and 0.6 to 1.9 meters (24–75 inches) if concentrations rise above 1,000 ppm—the consequences of which would be catastrophic. Other scientists, including James Hansen, Ph.D., director of NASA’s Goddard Institute for Space Studies, believe that we must reduce CO₂ levels to below 350 ppm or risk “irreversible catastrophic effects.”

Adaptation: ‘Not an either-or proposition’

Much of what we already do in green building is related to mitigating (preventing or slowing) our impact on climate change. But given the slow pace of climate policy changes and the still-contentious political climate, we cannot stop greenhouse gas emissions on a dime, which means we are looking at changes to the earth’s systems that could radically alter our way of life. The implications are clear: no amount of mitigation will prevent potentially devastating impacts; it’s necessary for us to adapt.

The human tendency to adapt reactively is well documented, as in the case of New Orleans, where the destruction of Hurricane Katrina laid bare the city’s vulnerability to extreme storms. But proactive adaptation will be necessary to avoid far more widespread impacts of climate change elsewhere. Some municipalities have begun to incorporate climate adaptation provisions into their long-range planning, and in August 2009 California unveiled the first statewide strategy to adapt to climate change.

These policy efforts have been slower than some climate scientists feel is necessary, and some of this may be due to a perception that adaptation initiatives will take time and resources away from mitigation programs. “What should be done about [climate change] is a legitimate debate,” says Schneider, but he argues that ultimately, mitigation and adaptation must complement each other. “The bottom line is that you’ve got to adapt to what won’t get mitigated—and unfortunately that’s going to be a few degrees—and mitigate what you can’t adapt to.” Jonathan Overpeck agrees: “Adaptation and mitigation are not an either-or proposition,” he told EBN.

Strategies for Adapting to Climate Change

There are many ways in which we can plan today for a changing climate. The strategies described below provide a sampling of ideas; this is not a comprehensive list. Many of these strategies make sense for other reasons, such as reduced operating costs, reduced emissions, and greater durability, but providing resilience to the effects of a changing climate may prove to be the easiest way to justify—or mandate—such changes.

Warmer temperatures

Increasing temperature is at the heart of climate change, and responding to this change is a critical component of any climate-change adaptation strategy. Longer, hotter, and more frequent heat waves raise demands for air-conditioning and increase heat-related deaths and injuries. Heat-adaptive strategies differ markedly by climate—what makes sense in Phoenix, where temperatures in the summer of 2009 have exceeded 115°F (46°C), will be very different from what makes sense in the Arctic, where melting permafrost is already affecting foundation design, according to John Davies, Ph.D., research director at the Cold Climate Housing Research Center in Fairbanks, Alaska.

Design cooling-load-avoidance measures into buildings. Use building geometries to limit solar gain on east and west façades, limit the area of east- and west-facing glazing, incorporate exterior shading devices above glazing, specify glazings tuned to the orientation (glass with a low solar heat gain coefficient on east and west façades), incorporate high insulation levels to reduce conductive heat gain, provide high-albedo (reflective) roofing, and provide optimized daylighting to minimize the use of electric lighting.

Design natural ventilation into buildings. In some climates, particularly those with low relative humidity, buildings can be designed to rely entirely on natural ventilation; in higher-humidity climates natural ventilation may be more practical as a backup cooling strategy that can be used during power outages as a passive survivability measure or during periods when bringing in outside air will not introduce excessive moisture.

Limit internal gains by specifying high-efficiency lighting and equipment. The higher the efficiency of lighting, office equipment, appliances, and mechanical equipment, the less waste heat is generated. In general, equipment choices are less important than design decisions since equipment is replaced more frequently.

Model energy performance with higher cooling design temperatures. With a climate that is projected to become warmer, cooling design temperatures used in energy modeling should be raised. This will help to justify higher investments in cooling-load-avoidance measures. (We’re still likely to see cold winters, so don’t raise the heating design temperatures.)

Provide landscaping to minimize cooling requirements. Trees, vines, annuals, and green roofs can all help control heat gain and minimize cooling demands on a building. Carefully designed landscaping can also help to channel cooling breezes into buildings to enhance natural ventilation. Involve landscape architects or designers at the earliest stage of planning with a new building so that existing vegetation can be preserved to aid in these uses.

Address urban heat islands in building design and landscaping. It is not unusual for urban heat islands to maintain temperatures 6°F–8°F (3°C–4°C) above that of surrounding rural land, according to Lawrence Berkeley National Laboratory. Urban heat islands increase cooling requirements and produce localized smog. Specific measures to reduce urban heat islands include tree planting, installation of green roofs on buildings, roofing with reflective membranes or coatings, and installation of light-colored (higher-albedo) pavement and walkway surfaces. Neighborhood participation and policies that address urban heat islands will help communities achieve the greatest benefit, as these strategies are most effective with widespread implementation.

Plan for termite ranges extending north. Termite ranges are extending north, so measures to exclude or control these insects should be implemented in the northern U.S. and parts of Canada (see EBN Sept. 2000).

Drought and water shortages

Changes in precipitation patterns are an expected outcome of climate change, so designing for drought is a high priority in many regions. Even in places that receive relatively high levels of precipitation, such as the southeastern U.S., drought can occur, as we learned in 2007 when Lake Lanier, the Atlanta area’s primary water source, shrank to historically low levels. Places that have not traditionally had to deal with drought are less prepared to respond. Emergency water-use restrictions are commonly imposed during drought, but there are design- and planning-related measures that can reduce the risk and lessen the difficulty or long-term impacts of response.

Avoid new development in the driest regions. An obvious, but remarkably rare, response to expected water shortages and drought is to restrict new development in areas most likely to be affected. California has a provision requiring developers of large projects (over 500 housing units) to demonstrate that there will be an adequate water supply for 20 years before a building permit is issued. It is likely that much broader building moratoriums will become necessary in many areas in the future, and it makes sense for municipalities to establish procedures today that will enable such measures to be instituted when and if they become necessary.

Specify water-efficient fixtures and appliances. Most water fixtures and equipment are replaced relatively often—many cycles within the lifespan of a typical building—but this doesn’t mean you shouldn’t install state-of-the-art water-conserving products when any new building is constructed or an existing building is renovated. Building owners should ensure that any replacements are state-of-the-art as well.

Plumb buildings with water-conserving fixtures in mind. In homes, structured plumbing (sometimes referred to as “home-run” systems), in which individual piping lines (PEX tubing) run to each fixture or appliance from a central manifold, allows smaller-diameter lines to feed water-conserving fixtures. For example, if a water-saving, 0.5 gallon per minute (1.9 lpm), lavatory faucet is supplied by a 3⁄4" (19 mm) pipe, there will be a long wait for hot water. The wait time (and water waste) can be significantly reduced by running a 3⁄8"-diameter (10 mm) line to this feature.

Plumb buildings for graywater separation. Even if graywater collection is not permitted today, it makes sense to plumb wastewater lines to simplify the installation of a graywater system in the future. (See EBN May 2008 for more on graywater.)

Harvest rainwater. In many climates, rainwater can be collected and stored for outdoor irrigation, toilet flushing, and, with proper filtration and treatment, potable uses. By addressing rainwater harvesting during design, it may be possible to locate cisterns high on the building to facilitate gravity distribution—which can be critically important during power outages or emergency situations. Rainwater collection is still illegal in some states, particularly in the West, but that is changing as water shortages become a reality.

Plant native, climatically appropriate trees and other vegetation. Conventional turf requires about 40 inches (1 m) of rainfall per year, distributed evenly over the growing season, and such turf is being planted from Arizona to Maine. Similarly, the same few dozen trees and shrubs are being planted nationwide, no matter what the climate—often locking building owners into decades of watering. When drought emergencies are imposed, such vegetation often dies, unable to survive without irrigation. A better and lower-risk approach is to plant vegetation that is adapted to the local climate and able to survive periodic droughts. Such practice is often referred to as xeriscaping. Areas of turf needed as play areas or for aesthetic reasons can be irrigated with harvested rainwater or graywater as local regulations allow.

More intense storms, flooding, and rising sea levels

According to some experts, the most visible and imminent effects of climate change will likely be the increasing severity of storms. As water temperatures rise in the South Atlantic, tropical storm systems will pick up more energy, resulting in higher-magnitude hurricanes on the Gulf Coast and Eastern Seaboard. Elsewhere, changing precipitation patterns are expected to deliver more rainfall in intense storms that result in river flooding. To complicate matters, development has made our landscapes less able to absorb rainfall, says architect Don Watson, FAIA, who is writing a book on “design for resilience.” “We’ve taken away all the absorptive capacity of our landscapes,” Watson told EBN. Adapting to climate change will require making our buildings more resilient to storms and flooding. In the longer term, we need to prepare for rising sea levels and restoring the ability of our land to absorb water.

Avoid building in flood zones. Flood zones are expanding—often faster than revisions to zoning regulations, meaning that simply following the law relative to the siting of buildings may not be enough. Instead of designing to 100-year floods, consider designing to 500-year floods, seeking civil engineering or surveyor assistance as needed.

Expand stormwater management capacity and rely on natural systems. More intense storms will strain the capacity of standard stormwater management infrastructure in some areas. Provide larger stormwater conveyance and detention basins, and try to rely on natural features, constructed wetlands, and other ecologically based systems to manage stormwater. “Restore the ecological services of the landscape,” says Watson.

Design buildings to survive extreme winds. The Miami-Dade County Hurricane Code has done a great deal to lessen storm damage in Florida. This sort of code should be adopted much more widely (not just in hurricane-prone areas) to protect buildings from the more severe storms that are expected. Examples of specific measures that impart good wind resistance to a building include installing impact-resistant windows (compliant with Miami-Dade Protocols PA 201, PA 202, and PA 203) or exterior shutters; installing outward-opening doors that are less likely to be pushed inward in intense wind; designing walls to resist uplift using hurricane strapping and other metal fasteners that provide a continuous load path from foundation to roof (see photo above); anchoring walls properly to foundations or frost walls; designing walls to resist shear and lateral forces using engineered wall bracing or shear panels for frame walls and proper use of re-bar for masonry walls; designing roof geometries (such as hip roofs) that are less prone to wind damage than gable roofs; installing continuous roof underlayment; properly installing high-strength roof sheathing (such as 5⁄8" plywood) that will resist uplift; and specifying roofing that has been tested to ASTM standards for wind resistance.

Raise buildings off the ground. In flood-prone areas—even where flooding is only remotely possible—raise buildings or living spaces above ground level to minimize damage in the event of flooding. With any type of pier foundation, use great care to ensure that energy performance and airtightness are not compromised; raised floors are notoriously difficult to insulate and seal.

Specify materials that can survive flooding. Especially in locations where flooding or hurricane damage is likely, use materials that can get wet and then dry out with minimal damage. Such materials include preservative-treated sills and wood framing (choosing environmentally friendly treatments like sodium silicate and borate), fiberglass-faced rather than paper-faced drywall, and tile or resilient flooring rather than carpeting.

Install specialized components to protect buildings from flooding or allow flooding with minimal damage. Breakaway wall panels on pier foundations in flood-prone areas can allow floodwaters to pass under a house without destroying it. Flood vents (permanent openings in foundation walls) allow floodwaters to escape. Specialized flood barriers, such as products made by Savannah Trims (www.floodbarriers.net), can keep rising floodwaters out in certain situations.

Elevate mechanical and electrical equipment. To minimize damage—and danger—from flooding, elevate mechanical equipment, electrical panels, and other equipment above a reasonably expected flood level.

Install check valves in sewer lines. These prevent floodwaters from backing up into drains in a building—which can occur when sewers or combined storm sewers are overloaded.

Begin planning for rising sea levels in coastal areas. Some of our largest population centers and a number of resort developments are located in low-lying coastal areas that are vulnerable to rising sea levels. Considerable planning will be needed to protect buildings and infrastructure in such places—ranging from construction of levees and flood walls to reconfiguring entire coastal landscapes in ways that minimize risks from rising sea levels. In some areas, it will be necessary to move entire cities and towns. We need to begin planning for such monumental efforts in a serious way.

Wildfire

In certain climates and ecosystems, climate change will increase the risk of wildfire—particularly in the West but also in other areas where it is not common today. The concern is exacerbated by development that has sprawled into chaparral areas that are managed by periodic fire. Most homes that are ignited by wildfires catch fire from airborne embers (firebrands) that may extend ahead of a wildfire by a mile or more. Measures described here largely concern residential buildings, which comprise most of the structures being built in wildfire-prone areas.

Specify Class A roofing. The roof is the most vulnerable component of a house to wildfire, according to the Center for Fire Research and Outreach at the University of California, Berkeley. Standard tile roofs are particularly vulnerable to wildfire, because wind-blown embers can enter attics through gaps in the tile. To reduce risk, a Class A “assembly rating,” for roofing, which addresses both the roofing and underlying components, should be specified (based on ASTM E-108 testing). Complex rooflines with dormers, valleys, and other architectural features increase risk because pine needles and other debris accumulate in these places and can catch fire from blowing embers.

Eliminate gutters or design and maintain them to minimize fire risk. Embers can quickly ignite pine needles and other debris caught in gutters, which can then impinge on the roof-edge assembly. Both metal and vinyl gutters are problematic—noncombustible metal gutters stay in place when burning, thus exposing the roof edge to fire, while vinyl gutters typically melt and fall off but continue burning on the ground, exposing siding to fire. Eliminating gutters and providing moisture management in some other way is one option in fire-prone areas. If gutters are used, screening and other features can help keep gutters free of debris, though some trap debris above the gutter. Diligent cleaning of gutters by homeowners is of paramount importance.

Avoid vented roofs or protect vents from ember entry. Embers entering a roof through soffit vents are one of the leading causes of home ignition during wildfires. The best option is to design—and carefully build—an unvented (or hot) roof; great care is required to control air leakage and moisture entry. Where vents are used in wildfire areas, maximum 1⁄8" (3 mm) screening should be used, but even this can admit some embers. Specialized soffit venting products are available to minimize risk. While some wildfire design guides suggest limiting roof overhangs (soffit depths) because they can trap pockets of heated air, this conflicts with moisture-control benefits of deep overhangs, and the Berkeley Center for Wildfire Research and Outreach recommends maintaining deep overhangs.

Install high-performance, tempered windows. Window glass breaks from thermal stresses during a fire, allowing fire to enter the house. Double- and triple-glazed windows are less prone to breakage during a fire than single-glazed windows, and tempered or reinforced glass further helps prevent breakage.

Choose deck materials carefully. Plastic and wood-plastic composite decks are fairly vulnerable to fires. Solid wood decking is surprisingly resistant to wildfire, though some treated decking products, such as TimberSIL (www.timbersilwood.com), offer significantly better fire resistance. Generally more important than the decking materials is the management of the deck area and keeping combustible vegetation and other material away from it. Patios provide a safer alternative to decks.

Install noncombustible siding. While siding is less often the point of home ignition in a wildfire than the roof, windows, or vents, it can be the weak point if these other components are particularly fire-safe or if an adjacent structure catches fire. Non-combustible options include fiber-cement siding, metal siding,three-coat stucco, and brick. Wood siding can be made “ignition-resistant” by treating it with an exterior fire-retardant chemical.

Manage vegetation around homes. In wildfire-prone areas, fire-safe landscaping around a home is very important. Recommended practices include keeping dry grasses, brush, and dead leaves at least 30 feet (10 m) from the house (more on a slope); maintaining firefighter access around the house; selecting drought-tolerant, high-moisture-content plants; pruning trees to maintain at least 10 feet (3 m) between branches and the roof; and pruning lower branches of trees near homes to eliminate “fire ladders” that allow fires to reach tree canopies. Some homeowners go so far as to keep all vegetation away from a home, maintaining instead a barren “mulch” of crushed stone; such an extreme measure should not be required in most places. See references, including Firewise.org, for more recommendations.

Power interruptions

Some of the likely impacts of climate change, such as intense storms and flooding, can cause power outages directly. Drought can also cause power outages indirectly if lack of cooling water for power plants results in rolling blackouts or brownouts. Adapting buildings to climate change should include measures that will make those buildings less affected by power outages. This is one of the key tenets of passive survivability, detailed in EBN May 2006.

Design buildings to maintain passive survivability. Homes, apartment buildings, schools, hospitals, and certain other public buildings should be designed to maintain livable conditions in the event of loss of power or heating fuel, or shortages of water—a design criterion known as passive survivability. Specific strategies include an extremely high-performance building envelope (high insulation levels, triple-glazed windows in cooler climates, etc.), cooling-load-avoidance features, natural ventilation, and passive solar heating.

Provide dual-mode operability with high-rise buildings. Look into designing tall buildings that will operate in normal mode when utility power is available, and in an emergency passive mode during power outages or when site-generated power is used. In the passive mode, electricity flow would be limited to critical needs such as elevators, ventilation fans, heating system pumps and fans, fire suppression systems, critical lighting, and so forth, so that the building could maintain limited functionality rather than having to be evacuated.

Design mechanical systems to operate on DC power. If mechanical systems are designed with DC-powered pumps, motors, and fans, they can be more easily switched to non-grid power, which could be provided by backup generators or renewable energy systems.

Provide site-generated electricity from renewable energy. Incorporate photovoltaic panels into buildings or link buildings with other nearby renewable energy sources such as stand-alone wind turbines or small hydropower facilities.

Provide solar hot water. Install solar water-heating systems. Especially appropriate are systems that can operate passively or that rely on integral photovoltaic modules to operate pumps so that functionality is maintained during power outages.

In urban and suburban areas, maintain access to the sun. Site-generated electricity and solar-thermal energy will become increasingly important with climate change, and being able to retrofit buildings for solar electricity, water heating, space heating, and absorption or evaporative cooling will depend on solar access. Solar access should be mandated by zoning and other provisions.

Plan and zone communities to maintain functionality without power. Incorporate measures for ensuring mobility, access to key services, and general functionality during power outages or gasoline shortages through effective municipal planning and zoning. Providing high-density, pedestrian-friendly, mixed-use communities surrounded by farmland and open space should be a high priority among planners.

Looking to the Future

Most of these strategies for adapting buildings to the effects of climate change are relatively straightforward—and eminently doable. It makes sense to incorporate these into our design palette today. There are other challenges that are likely to be far more complex, requiring significant cultural and economic shifts if we are to adapt to a future that is not only warmer but must function without petroleum. Alternate transportation systems, new agricultural practices and food systems, more localized economies, and stronger neighborhood and community networks will make us more resilient to changes and uncertainty in a way that simply building better buildings cannot. The adaptive measures addressed here give us something we can think about and act upon today. The good news is that many of these measures also help to mitigate climate change—and quite a few reduce building operating costs or improve durability, benefiting building owners as well as the future of the planet.

For more information:

Federal Alliance for Safe Homes (FLASH)

Tallahassee, Florida

877-221-7233

www.flash.org

Federal Energy Management Agency (FEMA)

Washington, D.C.

800-621-3362

www.fema.gov

Center for Fire Research and Outreach

University of California, Berkeley

Berkeley, California

firecenter.berkeley.edu

U.S. Global Change Research Program

www.globalchange.gov