Cool Roofs – Melvin Pomerantz


In Berkeley, we are fortunate to have such events as Science at the Theater, where Lawrence Berkeley National Lab researchers give talks on their work at the Berkeley Repertory Theatre. The lectures are free and get a pretty sizeable audience.

On Monday, October 11, I was in the audience as researchers from Lawrence Berkeley National Laboratory (and the beloved Art Rosenfeld) gave a presentation titled “Cool Roofs, Cool Cities.” The post below consists of Part 1 of my record of the presentation – Melvin Pomerantz gives an introduction to the heat island effect and cool roofs. All portions are included in chronological order.

An ellipsis (…) indicates that I was not able to capture the words or thoughts skipped. The presentation is transcribed as accurately as possible – punctuation choices are mine. I also added any images.

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What I’m going to talk about is a very familiar experience to a lot of you – when you go into the center of a city, it’s a lot warmer … That effect, namely the temperature … tends to be anywhere from 5-7 deg F warmer in the city than outside the city …

Image Credit: Wikimedia Commons

The heat has not only an effect of causing discomfort, but has economic effects, too … Looking at some SMUD data … went up to about 107 degrees that day … As the day goes on, it gets hotter and hotter, and the demand for electricity gets higher and higher … finally it cools down and people turn off their air conditioners a little bit. … To get this power, you need about 5.5 power plants, but the power used in January is much less, so the power company has to have in reserve all these power plants. So there is capital involved in having these in reserve … And the ones in reserve are generally the oldest, most polluting plants … so it’s an unfortunate effect …

Another effect that goes on is that when things are very hot, there are actually deaths … Chicago in 1995, there were 739 deaths attributed to the heat wave – almost all occurred on the top floor of buildings with black roofs …

So what can we do about it? … How is the air heated in the first place? The sun does not heat the air directly … Sunlight travels very well through the atmosphere … There are opaque surfaces – the light comes in from the sun and strikes a surface … some stays in the surface and heats the surface, then the air comes along and touches the surface and heats up … The surface is acting as a converter, so if we can modify the surface, we can get a handle on it … If you have a building underneath a roof, that heat travels into the building, then you have to run on the air conditioning. …  Also pavements suffer if it gets too hot … the pavement needs to handle the deterioration that the heat causes … …

One way to look at this is to look at the solar reflectance … If you have no light coming out, it’s black … if it all comes out, it’s very bright. If the light is not all caught by the material, it has a higher solar reflectance, and it’s cooler … If you decrease the solar reflectance, the temperature can rise 80-90 degrees F over the ambient air – and you don’t want that … …

There’s another feature, which is that once the surface is warm, it radiates … there are gases in the air which absorb this thermal radiation, and it’s like a blanket. It’s blocked by the gases in the atmosphere… this is the atmospheric greenhouse effect. If we can affect the light from sticking in the surfaces, we reduces the greenhouse effect, too, and keep the planet a bit cooler …

Image credit: Wikimedia Commons

What can we make cooler? … Looking again at Sacramento … about 39% of what we could see from the sky was pavements … … … If we reflect sunlight, it mostly passes back out of the atmosphere without heating the air…

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Part 2 is posted here. Part 3 is posted here. Part 4 is posted here.

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The Difference Between the CEC and CPUC


I know what you’re thinking – a really exciting topic. But this question has actually come up in conversation a remarkable number of times in the last couple of weeks. This is not intended to be a definitive guide, but just to start the delineation between the organizations.

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Photo Credit: Wikimedia Commons

The Basics

The CEC is California’s primary energy policy and planning agency.

The CPUC regulates privately owned electric, natural gas, telecommunications, water, railroad, rail transit, and passenger transportation companies.

This post will focus only on the energy aspects of the CPUC’s role.

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The California Energy Commission (CEC)

The five CEC commissioners are appointed by the California governor and must be approved by the Senate. Terms are five years. Commissioners must represent the following specific areas of expertise: law, environment, economics, science/engineering, and the public at large.

The CEC’s responsibilities include:

  • Forecasting future energy needs and keeping historical energy data.
  • Licensing thermal power plants 50 megawatts or larger.
  • Promoting energy efficiency by setting the state’s appliance and building efficiency standards and working with local government to enforce those standards.
  • Supporting public interest energy research that advances energy science and technology through research, development, and demonstration programs.
  • Supporting renewable energy by providing market support to existing, new, and emerging renewable technologies; providing incentives for small wind and fuel cell electricity systems; and providing incentives for solar electricity systems in new home construction.
  • Developing and implementing the state Alternative and Renewable Fuel and Vehicle Technology Program to reduce the state’s petroleum dependency and help attain the state climate change policies.
  • Administering more than $300 million in American Reinvestment and Recovery Act funding through the state energy program, the energy efficiency conservation and block grant program; the energy efficiency appliance rebate program and the energy assurance and emergency program.
  • Planning for and directing state response to energy emergencies.

The CEC is located in Sacramento, CA.

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The California Public Utilities Commission (CPUC)

The five CPUC commissioners are also appointed by the California governor and must be approved by the Senate. Terms are six years.

The CPUC regulates investor owned utilities (IOUs) that distribute electricity and natural gas, including Pacific Gas & Electric Company (PG&E), Southern California Edison (SCE), San Diego Gas & Electric Company (SDG&E) and Southern California Gas Company.

The CPUC does not regulate municipal utilities, such as the Sacramento Municipal Utility District (SMUD).

The CPUC’s mission is the following:

  • The California Public Utilities Commission serves the public interest by protecting consumers and ensuring the provision of safe, reliable utility service and infrastructure at reasonable rates, with a commitment to environmental enhancement and a healthy California economy.  We regulate utility services, stimulate innovation, and promote competitive markets, where possible, in the communications, energy, transportation, and water industries.

The CPUC has a number of different divisions; the Energy Division assists Commission activities in the electricity, natural gas, steam, and petroleum pipeline industries. Energy Division handles the regulation and Commission approval of official rates and terms of service for energy IOUs.

Because the regulated California utilities are so large, and their programs reach so many customers, CPUC energy policy decisions and goals have wide influence in California. The CPUC touches programs in energy efficiency, demand response, low-income assistance, distributed generation, and self-generation, among others. It has a role in California climate policy. It is overseeing the CA utilities’ switch to Smart Grid technologies. The CPUC regulated electric generation and procurement, electric rates and markets, gas policy and rates, and electric transmission and distribution.

CPUC headquarters are in San Francisco, CA.

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Stimulus Money for Energy Efficiency


The Sacramento Municipal Utility District (SMUD) will receive $20 million from the federal stimulus funds designated for California. The money will launch a Home Performance Program, which will offer HERS audits and energy upgrades to about 15,000 homes in SMUD territory. Because the program is expected to increase demand for trained contractors and auditors, SMUD will be working with the Sacramento Employment and Training agency and Los Rios Community College to develop training programs – via SMUD.

The California Energy Commission also approved $8 million for the County of Los Angeles, $3 million for the County of San Diego, and $1.9 million for the City of Fresno from Recovery Act Energy Efficiency Conservation Block Grants for residential energy retrofit programs – via Imperial Valley News.

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There’s a cool map of hotspots where water and energy are coming into conflict around the world –  IEEE Spectrum.

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There’s a new study from Arizona State University that analyzes the life cycle impact of swimming pools in nine cities in terms of their consumption of chemicals, water, and energy – via Environmental Science & Technology.