Climate change is leading to warmer and more extreme weather, including more severe droughts and more powerful storms such as hurricanes and cyclones. This more extreme weather is having a profound effect on the built environment.
Heat waves and drought worldwide are becoming more severe. Record high temperatures have been set in countries all over the world this year, including Urimitia, Colombia at 42 degrees Celsius, Madrid at 39.7 degrees Celsius, and London at 36.7 degrees Celsius. India suffered through a May heat wave that killed approximately 2,500 people and saw the temperature spike to 47 degrees Celsius at Titlagarh in Odisha. Pakistan’s heat wave killed more than 1,200 people and saw high temperatures reach 44 degrees Celsius. California’s four-year drought is a historic record. According to NASA, “The 10 warmest years in the 134-year record all have occurred since 2000, with the exception of 1998. The year 2014 ranks as the warmest on record.”
In Australia, The State of the Climate 2012 report, prepared by CSIRO and the Bureau of Meteorology, says average temperatures will rise by one to five degrees Celsius by 2070. That amount of warming will have a huge effect on water use and energy use, and will require some changes to the status quo of the built environment.
The good news is that a variety of design features can address the functionality of all buildings with regard to energy use, water use, and resilience. These design features enable occupants to live comfortably and safely, and enable structures to withstand extreme weather such as hurricanes.
Water conservation is crucial, and green buildings, such as those certified by Green Star and LEED, make remarkable cuts in water use. Green Star, for example, has certified more than 640 buildings since launching in 2003. A 2013 report by the Green Building Council of Australia, The Value of Green Star - A Decade of Environmental Benefits, notes that, “On average, Green Star buildings use 51 per cent less potable water than average buildings.”
In addition to conservation, Australia’s Millennium Drought resulted in a host of new schemes to ensure adequate water supplies, including desalination plants, the unpopular North-South Pipeline, and water recycling.
California, like Australia, has experienced recent drought and water shortages. Years of profligate water use, supported by expensive schemes that pull water from sources hundreds of kilometres away, have led to the current crisis. This drought has been decades in the making, but highlights that even a wealthy state that wastes water is heading for trouble, as the current rationing scheme has made clear. Governor Jerry Brown has ordered cuts to average 25 per cent, with steep fines possible for people who don’t comply.
The city of San Francisco has taken it a step further by mandating on-site water recycling in certain new developments. New construction projects of more than 40,000 square feet will be required to include water recycling systems that supply water for non-potable uses such as toilet flushing, irrigation, and street cleaning.
Supervisor Scott Wiener, author of the ordinance, told the San Francisco Appeal that water savings would total 7.5 million litres per year in a 46,000 square metre building.
Building design has a massive impact on energy use. According to the report The Value of Green Star - A Decade of Environmental Benefits, “On average, Green Star certified buildings use 66 per cent less electricity than average Australian buildings, and 50 per cent less electricity than if they had been built to meet minimum industry requirements.”
With the advent of ubiquitous air conditioning systems, many structures have been built that ignore established design features, such as orienting buildings to capture prevailing breezes, and building generous overhangs that shade the windows below, minimizing solar gain. Those features make sense in a warming world. In addition, high-performance glazing with a low solar heat gain coefficient minimizes solar gain through east- and west-facing windows, and exterior sunshades and awnings can be used wherever needed.
Reflective and light-colored exterior walls and roofs can also lessen heat gain, and increasing insulation levels will minimize heat conduction through walls and roofs.
Outside the structure, landscaping can provide shade, lower air temperatures, filter air pollution, and buffer excess water levels from storms. According to advocacy group American Forests:
- A tree can absorb as much as 48 pounds of carbon dioxide per year, and can sequester one ton of carbon dioxide by the time it reaches 40 years old.
- One large tree can provide a supply of oxygen for two people.
In addition, the US Department of Agriculture Forest Service says, “Trees properly placed around buildings can reduce air conditioning needs by 30 per cent and save 20-50 per cent in energy used for heating.”
Another wise tactic is upgrading building codes to withstand likely storms. Erik Rancatore, director of communication for the Portland Cement Association, made the case for enhanced building codes in an article in The Huffington Post.
In addition to decreasing the number of human casualties, Rancatore wrote, decreasing the impact of disasters saves money.
“According to a National Institute of Building Sciences Multi-Hazard Mitigation Council study, every dollar spent on reducing the potential impact of disasters saves society an average of $4," he wrote.
Leapfrogging over existing minimum codes to the national model codes published by the International Code Council “augments economic viability, addresses societal issues, and helps communities to minimize negative environmental impacts."