Building codes aren’t climate ready, but changes are coming
The world’s climate is changing more quickly than building codes are being updated, putting lives and structures at risk, according to panelists at the Building Innovation 2023 conference in Washington, D.C., last week.
In fact, only about a third of the U.S. is covered by disaster-resistant codes, according to panelist Daniel Bass, an architect with the Federal Emergency Management Agency. Although climate risks interact with each other, building and zoning codes are not meshed accordingly and vary by locality. Wildfires, for example, must be addressed at a community and neighborhood level, since a fire at one building threatens all the structures around it.
This holistic thinking is vital because sometimes climate mitigation efforts conflict with each other. Bass gave an example from the 2021 Marshall Fire in Boulder, Colorado, where grass-filled drainage canals, built to deal with stormwater runoff, inadvertently created “fire superhighways” that spread flames directly into the hearts of towns and subdivisions.
For the most part, buildings in the U.S. are not designed for future conditions or even current climate change-fueled extreme weather, and growing flood and fire activity is forcing residential and commercial insurers to leave coastal states like California, Florida and Louisiana.
Plus, people increasingly live in high-risk areas — both because threats are growing and because people choose to build in and move to risky areas. For instance, at least 10% of the U.S. population lives in 500-year floodplains, according to NYU Furman Center, which now flood much more frequently than historically predicted. Wildfire threat is growing as well, including in areas once deemed low-risk.
As data and knowledge of these threats evolve, building codes and standards must as well, said panelist Chad Berginnis, executive director for the Association of State Floodplain Managers. For example, the National Flood Insurance Program minimum standards, the basis of flood codes across the country, have not been updated in 45 years, making it difficult to design truly resilient buildings. The U.S. also lacks consistent flood design standards for infrastructure, he said.
Another key issue is that building codes don’t address multiple extreme weather events, especially within a relatively short period of time, said panelist Paul Totten, building enclosures practice leader with Montreal-based contractor WSP. Building codes typically address resilience to a single disaster, not two or three in a year, which is an increasingly common pattern.
Climate-aware codes in the works
More accurate codes and projections are coming. The newest edition of the ASCE 7, the most widely used professional standard guide used by engineers, for the first time includes a supplement that addresses how climate change is impacting flooding and sea level rise, according to panelist Dan Cox, professor of civil engineering at Oregon State University, who worked on the update.
The new standard ties load standards to risk categories and now bases them around the 500-year floodplain rather than the 100-year benchmark. Structures with low impact to human life, such as parking garages, still use the old standard.
The ASCE/SEI 7-22 supplement also includes for the first time a flood-mitigation planning requirement relative to sea level rise over the service life of a structure. For now it’s based on historic rates of sea level rise, rather than projections that show this metric is likely to accelerate in coming decades, according to Cox.
The guide also has first-ever criteria for tornado-resistant design, another form of extreme weather increasingly occurring outside historical boundaries. This new information is set to be included in the 2027 International Building Code update, and upcoming editions will have an entire new chapter for future conditions that address flooding, ice, wind and more.
The National Oceanic and Atmospheric Administration is updating precipitation projections in its Atlas 15, which will include trends in historical observations and as well as future climate models. These estimates will provide critical information to support infrastructure design in a changing climate, and will be available by 2027, per the agency. It’s the first time NOAA’s atlas will account for climate change, thanks to funding from the Infrastructure Investment and Jobs Act.
FEMA is currently working to update its flood maps, and is evolving its flood hazard data from binary to graduated risk, according to panelist John Ingargiola, lead physical scientist with FEMA. The agency is also working on a new rating methodology for flood insurance. Its Future of Flood Risk Data initiative can look at multiple risks and scenarios at once, and its IIJA-funded National Initiative to Advance Building Codes priorities include matching climate resilience with energy standards, equity and other criteria.
Even once a new code is written, state and local lawmakers must adopt them into laws that inspectors will use to measure the safety of buildings.
Land use is largely ignored
Even with the best of building codes, in some cases it’s simply not sustainable to build in high-risk locales. Yet new construction is happening in parts of the country that are likely to be partly underwater in the coming decades or that will otherwise become uninhabitable.
Most new housing in the U.S. is built in subdivisions on greenfield lots, but developers rarely take into account the massive fire threat in many of those areas, nor consider whether they should be planned differently or built somewhere else entirely, according to Bass.
Part of the problem is that officials don’t comprehensively know where these risky areas are — that’s why it’s so critical to update flood and other risk maps, said panelist Tim Judge, senior vice president of climate analytics at Fannie Mae. Only about a third of people living in flood-prone areas know it, said Judge, and they often don’t know what to do about it once they’re aware.
Building industry stakeholders must have more conversations about land use and zoning standards and their role in hazard reduction, said Berginnis.
“We pay a lot less attention to the land use side of this than we need to be,” said Berginnis. “We can have the greatest building standards and the greatest technology standards, but if land use doesn’t follow, we are still fighting a losing battle.”