A survey of North American cities by the American Council
for an Energy Efficient Economy (ACEEE) and the Global Cool Cities Alliance
(GCCA) finds that confronting the challenges of extreme weather, adapting to a
changing climate, and improving the health and resiliency of urban populations
are driving cities to develop and implement strategies to reduce excess urban
heat.
Nearly
two thirds of the cities surveyed cited local extreme weather events as a key
reason for initiating urban heat island mitigation strategies. U.S. cities are
waking up to the growing threat of urban heat and employing a number of innovative
approaches suited to their location and priorities," said ACEEE researcher
and report author Virginia Hewitt
ACEEE
and GCCA surveyed 26 cities in the U.S. and Canada representing all of the
major climate zones, geographies, and city sizes. Despite the diversity of the
respondents, several common themes emerged.
Local
governments are "leading by example" by requiring use of
"cool" technologies, such as reflective roofs on municipal buildings,
lining city streets with shade trees, and raising public awareness.
Additionally,
more than half of the cities have some kind of requirement in place for
reflective and vegetated roofing for private sector buildings. Almost every
city had policies to increase tree canopy and manage storm water.
"Our
report finds that by addressing their urban heat islands, cities are more
effectively delivering core public health and safety services, making them
attractive places to live, work, and play," said Kurt Shickman, executive
director of the Global Cool Cities Alliance.
The
report includes case studies on how several cities have responded to urban
heat, demonstrating the variety of strategies employed. In response to a study
that found that Houston's roofs and pavements can reach 160
° °F,
the city now requires most flat roofs in the city to be reflective. Washington
D.C. has instituted a wide suite of programs such as Green Alleys, which helps
residents manage excess stormwater by replacing pavement with grass and trees,
and requiring reflective roofs on all new buildings.
The
survey also found that most city governments are not acting alone to reduce
excess heat. States, neighboring jurisdictions, utilities, developers,
contractors, and local building owners are collaborating to create incentives
for communities to reduce urban heat and mainstream these practices.
Cities
surveyed in the report include: Albuquerque, NM; Atlanta, GA; Austin, TX
Dallas,
TX; Houston, TX; Las Vegas, NV; Los Angeles, CA; Louisville, KY; New Orleans,
LA; Phoenix, AZ; Sacramento, CA.
Many
of these are broadly similar to north Australia in summer, especially those in
the SW of the USA. With climate
modelling for Australia predicting major heat issues in north Australia in
coming years that will impact on living in the region it is prudent to examine
options that will minimise the heat island effects.
A
recent scientific journal article clearly showed a 2C effect now in the city of Phoenix in
Arizona caused from night time use of air conditioners, and the heat emanated
as waste heat was the cause.
What
are we now doing here in Darwin? Yes, we
do have vegetation, but there has been little use of reflective roof coatings
to mitigate heat gain, nor little use of green roofs.
And
nothing seems to have been mandated in building codes for this region, a
location where it is always hot, and buildings need cooling [never heating!].
Cool
Policies for Cool Cities: Best Practices for Mitigating Urban Heat Islands in
North American Cities, visit: http://aceee.org/research-report/u1405
The
survey is available on the Cool Roofs and Pavements Toolkit: http://www.coolrooftoolkit.org/knowledgebase/cool-policies-for-cool-cities/
NOTE
- The Global Cool Cities Alliance is a non-profit organization works with
cities, national governments, and other stakeholders to advance policies and
actions that reduce excess urban heat in order to cool buildings, cool cities,
and to mitigate the effects of climate change through global cooling.
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