White Roofs Seen as Part of the Solution

Many people head for the thermostat to cool things down indoors when it gets hot outside.  The problem is, running our air conditioner only makes the problem worse by adding to the strain on an already overworked energy grid, and increasing the amount of carbon in the air.  This is especially true during extreme heat events.  And for vulnerable populations without access to air conditioning, extreme heat could be – and often is – life-threatening.

That’s why cities are looking at other ways to naturally reduce the urban heat island effect.  White roofs, reflective surfaces, and planting trees all add up to cooler temperatures as we deal with the increasingly real effects of climate change.

Read more about the problem in northern climates, and see what Toronto is doing about it.

Cool Surfaces and Social Justice

Heat kills more than 1,500 people in the U.S. each year – more than any type of other natural disaster.  In many cities around the world, it’s not uncommon to find that people in the most disadvantaged neighborhoods are often the most vulnerable to heat.

New research highlights just how vulnerable poor and minority communities are to urban heat.  Cities such asToronto and Washington, DC have identified opportunities to improve environmental and social justice by mitigating their urban heat islands.

Partnership with C40

GCCA has partnered with C40 Cities of Climate Leadership (C40) to build the Cool Cities Network (CCN). CCN cities work together with technical experts to design, implement, and measure solutions-oriented approaches to promote sustainability by lowering urban temperatures.

The Cool Cities Network focuses on opportunities for cities to reap the economic, energy, health, environmental, and social benefits of reducing risks posed by heat waves and urban heat island effect through:

  • Tools and resources to identify the causes and impacts of heat waves and urban heat islands and to support design and launch of successful cool surface programs (such as cool roofs and reflective pavement)
  • Support development of city-specific action plans
  • Peer-to-peer and expert knowledge exchanges to share best practices, proven strategies, and data

The C40 Cities Climate Leadership Group
C40 was created in 2005 by former Mayor of London Ken Livingstone to reduce carbon emissions and increase energy efficiency in large cities across the world. Since then, C40 has grown from eighteen megacities to sixty-three members, who are working together to address the risks and impacts brought on by climate change both at the local and global level. C40 is committed to implementing meaningful and sustainable climate-related actions locally that will help address climate change globally. Their global field staff works with city governments, supported by their technical experts across a range of program areas.

CCN Cities
The CCN’s most active city participants include: Athens, Austin, Chicago, Changwon, Dhaka South, Houston, Los Angeles, Lima, Melbourne Mexico City, New Orleans, New York, Paris, San Francisco, Seattle, Seoul, Singapore, Tokyo, Toronto, and Washington DC

What are the Network’s Areas of Focus?
Drawing directly upon the expressed network objectives from participating cities, the CCN has developed the following network work streams:

  1. Measuring and mapping heat and UHI – Sharing heat wave and UHI modeling and mapping methods amongst cities including mapping health and other effects
  2. Technology solutions to mitigate heat – Sharing of technology solutions and tools to determine best fit for conditions including specifics to climate zone, industry vs. residential, historic preservation, and integrated solutions (cooling + solar PV + green + stormwater)
  3. Green infrastructure and biodiversity – Sharing programs to use green infrastructure for cooling (in addition to co-benefits) and biodiversity strategies for cooling and species resilience in face of heat
  4. Integrating heat mitigation into long term planning, codes and regulations – Mainstreaming, making the political case to prioritize heat-related planning, and building heat mitigation strategies into plans, building and infrastructure codes and regulations
  5. Financing heat mitigation activities : Developing a replicable cost/benefit analysis for private property owners and policy makers to install or implement cooling on their property.

Global Superior Energy Performance Partnership (GSEP)

The Global Superior Energy Performance Partnership was launched by then Secretary of Energy Dr. Steven Chu as part of the Clean Energy Ministerial and the International Partnership for Energy Efficiency Cooperation (IPEEC). GCCA manages GSEP’s Cool Roofs and Pavements Working Group for DOE.

The official members of the working group are the national governments of India, Japan, Mexico, South Africa, and the U.S. In addition, industry and academic representatives from each country are very active, making the Working Group a true public/private partnership.

Member countries generally commit to an action plan to accelerate the deployment of cool roofs and pavements that includes:

  1. Analyzing the energy savings, GHG reductions, and economic payback of deploying cool roofs and pavements.
  2. Developing standards for cool surface performance and testing procedures and infrastructure. These are usually voluntary at first, with long term goals to move the standards into mandatory building codes.
  3. Capacity building for technical experts, policymakers, and others.
  4. Demonstration projects
  5. Most importantly, the creation and support of local working groups to achieve the goals of the action plan.

Progress to date

  • Mexico launched its action plan in May 2012. Since then, they have launched a local working group led by industry, published a national impact study, drafted a voluntary industry standard, attended cool surface testing and policy workshops in the U.S., and hosted a series of awareness raising conferences and meetings. A testing facility for cool surfaces is currently entering the accreditation process.
  • South Africa joined the working group in January 2013. They have adopted an action plan, launched a local public/private cool surfaces organization (SACSA), and initiated an impact study based on the Mexico model.
  • India has developed two projects to demonstrate the thermal comfort benefits of cool surfaces on low-income homes.

Can I just paint my roof white?

Unfortunately, installing a white roof isn’t quite as easy as opening a can of paint. Most roofing material manufacturers (including manufacturers of asphalt shingles) will not extend their warranties to roofs that have been painted or covered in some way. Many low-sloped (i.e. almost flat) roofs are covered with elastomeric coatings that are specifically designed to withstand weathering. These coatings can be painted on, which is why you see pictures of people painting their roofs with rollers.

Where do I find cool roof suppliers or contractors?

Energy Star and the Cool Roof Rating Council both provide useful resources for finding highly reflective roofing materials.

Additionally, Lawrence Berkeley National Laboratory has a directory of suppliers of cool roofing materials.

Are cool roofs more expensive than normal roofs?

It depends. On low-sloped roofs (typically found on commercial or high-rise residential buildings), installing a white roof is often a matter of simply choosing the right color coating. If the building needs a new roof anyway, there is no additional cost. If the roof is retrofitted ahead of schedule in order to install a cool roof, there will be some incremental cost. Depending on the kinds of materials used, the incremental cost of choosing a cool roof over a more traditional dark roof for a commercial building is approximately US$0 to US$2.20 per square meter (US$0 to US$0.20 per square foot). When factoring energy savings into the equation, the incremental cost can be fully recovered in many applications over a period of zero to six years.

On steep-sloped roofs (typically found on residential buildings), changing the reflectivity of the roof is usually not as simple. Because most people do not like the aesthetics of a white roof (which would be visible thanks to the sloped nature of the roof), increased reflectivity is best gained through highly reflective shingles that can come in any color. Currently, these roofing materials do cost more than standard materials, but as the market grows, the price is likely to come down.

There are also important non-cost factors to consider:

    Comfort: In unconditioned buildings, cool roofs can maintain cool indoor temperatures.
    Durability: Cool roofs may degrade slower and last longer than similar non-cool roofs, but more research is needed to prove this.

I live in a cold climate and use more energy heating my building in the winter than cooling it in the summer. Are cool roofs still a good idea?

One of the primary values of cool roofs is their ability to lessen the cooling demands of a building thanks to their higher reflectivity. In climate zones where the energy required to cool the building in the summer is greater than that required to warm the building in the winter, white roofs are valuable both to residents and to utilities.

Many people believe that the converse effect is also true; that white roofs increase the heating requirements for buildings in northern climates, the so-called “winter penalty.” There is sound evidence that the winter penalty is non-existent or minimal, since the sun is at a low angle in the winter months and heating loads are more pronounced in the evenings, especially in residential buildings. White roofs will still provide a higher albedo surface in these areas, creating a climatic benefit, even if the cost savings to the building inhabitants are minimal.

Visit the US Department of Energy’s Roof Savings Calculator to estimate what your energy and cost savings would be if you installed a cool roof.