While energy efficiency measures will not end the serious global climate change challenge, adopting such measures would buy time to further the development of alternative low-carbon energy resources. White roofs can cool buildings, cities, and even the planet. Implemented worldwide, cooler cities could bring the world 5 percent closer to avoiding future climate disaster.

2011 Global Energy Prize recipient and Distinguished Scientist Emeritus at Lawrence Berkeley National Laboratory, Rosenfeld, spoke at Carnegie about the impact of the energy efficiency concepts around the world and the potential of white roofs to slow global warming. Carnegie’s Adnan Vatansever moderated.

The Global Energy Prize

The Global Energy Prize was instituted in Russia in 2002. Rosenfeld received Russia’s pre-eminent Global Energy Prize for his pioneering work in energy efficiency. He shared the award with Professor Philipp Rutberg of Russia.

  • Russia’s changing attitude: Rosenfeld suggested that granting this award to two scientists whose work focuses on energy savings and alternative energy sources is a sign of Russia’s changing attitude toward the use of energy resources in the context of global climate disruptions.

    • In 2009, President Medvedev issued an executive order to reach significant improvement in energy efficiency by 2020.
    • President Medvedev established a new Russian Energy Agency.
    • Over the past decade, Russia has greatly reduced its energy intensity due largely to its transition to a market economy.

Rosenfeld said that the devastating forest fires in 2010 and their coverage in Russian media also contributed to this change in attitude. However, he cautioned that even after the fires, the government in general may not share Russian academia’s outlook on climate change or President Medvedev’s apparent concerns for climate issues.

Global Impacts of Energy Efficiency Measures

To illustrate the success and widespread impact of increased energy efficiency, Rosenfeld presented examples from China and the United States:

  • California: The combination of a mild climate, a limited access to indigenous coal, and early adoption of energy efficiency standards has enabled California to bring per-person electricity consumption to levels far below the national average. Per capita electricity consumption in California has remained relatively stable in the past four decades while continuing to grow in the US overall. Californians spend less on electricity than residents in other states, despite higher electricity prices in California, Rosenfeld said.
  • Wider United States: While the average size of U.S. refrigerators has almost tripled since 1947, the energy use per unit, as well as the price of refrigerators, has declined significantly due to greater energy efficiency.
  • China: Energy savings from appliances sold in China, which are subject to the country’s energy efficiency standards, will amount to $50 billion per year by 2020, Rosenfeld added.

White Roof Global Cooling Potential

Rosenfeld explained that roofs and roads comprise the majority of surfaces in urban areas worldwide, absorb over 80 percent of incoming sunlight, and create urban heat islands due to the fact that most roofing and paving materials are a dark color. Summertime temperatures in downtown areas can be up to nine degrees Fahrenheit above the ambient air temperature. He said that white roofs reflect up to 80 percent of sunlight, which helps reduce the heat island effect. In addition, white roofs have a number of other environmental, economic, and health benefits:

  • Air conditioning: White roofs reduce air conditioning needs by about 15 percent in the summertime, saving consumers both energy and money.
  • Lower temperatures: White roofs lower temperatures on the top floor of a non-air conditioned building by two degrees Fahrenheit, a potentially critical difference during the summertime, when heat waves can make living in a non-air conditioned apartment underneath the roof lethal.
  • Offsetting global warming: A 1,000 square foot patch of white roof can offset the global warming potential of ten tons of carbon dioxide (CO2) emissions, roughly equivalent to taking a family car off the road for a year.
  • A global effect: Converting every roof and pavement surface in Boston and Chicago would cool the world by one-tenth of one degree Fahrenheit, not an insignificant amount, Rosenfeld said.
  • Widespread application: Whitening all urban flat-roofs worldwide would be equivalent to an annual offset of 1.2 Gigatonnes of CO2 emissions.

Rosenfeld admitted that national acceptance of energy efficiency concepts has been rather slow. But increased corporate interest in the potential financial benefits of adopting energy efficiency standards makes him hopeful. Like all good ideas, Rosenfeld believes that this concept will eventually be applied universally.