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by Al Hodgson, Co-founder and Research Director, Berkeley Analytical Associates

Total Volatile Organic Compounds (TVOC) has a long history as a metric for determining the acceptability of the emissions of VOCs from building products and furnishings. The first significant program to rely on a TVOC criterion was the Carpet & Rug Institute’s (CRI) Green Label Program that evolved out of the Carpet Policy Dialog between the carpet industry and the US EPA.The TVOC criterion was later incorporated into the U.S. Green Building Council’s LEED rating systems and was adopted by the commercial furniture industry. More recent VOC emission test method and acceptance standards have focused instead on individual VOCs that may pose health hazards to individuals at low concentrations. Examples of such programs in North America are the California Department of Health Services' Standard Practice (a.k.a. Section 01350), which recently was revised to Standard Method Version 1.1, and CRI’s Green Label Plus program. TVOC values are still reported, but pass/fail determinations are based on the emission levels of individual compounds of concern. There is an urgent need to expand such determinations of acceptability beyond a select number of individual VOCs to encompass the broader range of chemical emissions that may impact health. TVOC is again being proposed to fill this gap and may be appealing to many because of its presumed simplicity. In my opinion, we should avoid this temptation and move on the more difficult, but certainly achievable, task of focusing on the toxicity of individual compounds. The following are my primary arguments against the use of TVOC as a Pass/Fail metric.

TVOC measurements may be grossly inaccurate and therefore the TVOC concept is unsuitable as a PASS/FAIL metric.  Individual compounds' instrumental responses relative to toluene, the surrogate standard of choice, vary dramatically.  Some common VOCs have an order of magnitude lower response per unit mass than toluene. Other compounds have higher response ratios. Even within a class of compounds (e.g., alkane hydrocarbons) the response per unit mass can vary substantially depending upon their chromatographic retention times with early eluting compounds having lower response ratios than late eluting compounds.  Individual VOCs also are measured with very different levels of precision. Thus, there is no way to determine the accuracy and precision of TVOC measurements made across different mixtures of VOCs characteristic of the broad range of products and materials being assessed.  This problem with TVOC is well recognized by true experts.  In particular, ISO 16000-9, the emission test method most widely used in Europe and other regions outside of the US clearly states. "The sum of emitted compounds, TVOC, should be regarded only as a factor specific to the product studied and only to be used for comparison of products with similar target VOC profiles."  One of the big changes that is needed in the reporting of VOC emissions is to include estimates of uncertainty.  In fact, reporting of uncertainty is dictated by ISO/IEC 17025 quality management systems if requested by the customer.  The use of TVOC moves the process in the completely opposite direction toward unknowable uncertainty.

Product certification programs can, and should, be progressive with respect to public health concerns.  TVOC may be a useful tool for such certification programs.  For example, the monitoring of TVOC for a specific product over time (in keeping with the ISO 16000-9 precaution) may provide useful information on manufacturing variations within or among production facilities assuming the VOC profiles are similar.  However, this is not a substitute for assessing the potential impacts of the individual compounds comprising these emissions.  There are many different lists of toxic chemicals that can be used by certification programs as the basis for such assessments.  The fact that a publically available method and guideline document only contains a relatively short list of chemicals of concern should not be a limiting factor.  MBDC's Cradle-to-Cradle program is one example of a proactive certification program that considers the environmental and human health issues associated with chemicals used the in the manufacturing of products.  It should be noted that a significant downside to this particular program is the lack of transparency with respect to how the toxicology judgments are made.  It also might be argued that the success Greenguard's Children & Schools program in the marketplace is, in part, related to their use of an expanded list of individual chemicals of concern.

Assuming there was a more accurate and precise measure of the quantity of total VOCs emitted by a product, there still is a need to establish an acceptable level.  The Greenguard Indoor Air program uses a guideline of 500 µg/m3 modeled to a small room.  The Greenguard Children & Schools program uses a guideline of 220 µg/m3 modeled to a typical school classroom.  The 500-µg/m3 value has some historical precedence, but in reality these numbers are simply 'pulled out of a hat.'   The chemicals used in manufacturing products are undergoing rapid change.  When the TVOC metric was first implemented as a metric for the Carpet & Rug Institute Green Label program in 1989, the chemicals used in manufacturing included aromatic and chlorinated hydrocarbon solvents.  Today in the 21st century, most products do not use these traditional solvents because of concern regarding their toxicity.  Instead, we have an increasing emphasis on 'Green Chemistry' and widespread use of water-based solvent systems. Generally, these chemicals have lower toxicity than the solvents they are replacing but they also have lower vapor pressures.  Due to their low vapor pressures, the off gassing of these solvents occurs more slowly than for aromatic solvents, for example.  Thus, total VOC emissions will be higher, but in many cases toxicity can be presumed to be lower.  The use of a TVOC metric may, therefore, penalize products and inhibit government's and industry's efforts to switch to more sustainable chemistry.  These efforts are better served by focusing on the toxicity of the individual compounds.

US Proponents of TVOC have repeatedly pointed to European product testing methods and certification programs as a precedent for the use of TVOC.  While it is true than many European programs do contain a TVOC requirement, the values are often considerably higher than the values the proponents would like to impose on the US.  The most widely used European assessment document, the German AgBB ( scheme, relies mainly on criteria for a list of about 190 individual chemical substances.  The AgBB TVOC criteria at 3 days is 10,000 µg/m3, or 20 times a proposed 500 µg/m3 value measured at 7 or 14 days (note that a direct comparison is complicated by different testing methods and modeling assumptions, but the magnitude of the difference is approximately correct).  Clearly the dominant European assessment criteria focus on individual VOCs, NOT on TVOC.

Proponents of TVOC argue that there are tens of thousands of individual chemicals emitted by building products and furnishings that may be affecting our health, and due to this overwhelming number only a metric like TVOC is practical.  This is far from the truth.  There are many hundreds of chemicals in petroleum distillate fractions, e.g., Stoddard solvent.  Over the years, there has been a shift away from these solvent mixtures to simpler, manufactured mixtures with better controlled volatility and elimination of compounds that are of particular concern because of their toxicity.  The true number of chemicals that are frequently emitted by building products and furnishings probably number several hundred.  If this universe of chemicals can be identified (not difficult), it is a much more manageable task to evaluate the toxicology data to see which chemicals are of real concern for the general population and at what levels.

Proponents of TVOC also argue that there are many potential synergistic relationships among VOCs and that, again, only the use of TVOC can guard us against this danger. Such arguments regarding synergism are not founded on fact.  For example, while the hedonistic value of odor response can vary depending upon the mixture of chemicals, odor receptors are very specific for particular chemical functionality and size.  The mammalian sensory perception system (Trigeminal) is much more generalized.  However, the effects for VOCs with low reactivity (i.e., most of the VOCs that are measured by conventional methods) have been shown to be additive in both animal and human studies.  If there is a highly reactive VOC in the mixture, the sensory response is controlled by the reactive chemical, not the mixture.

Al Hodgson, Co-founder and Research Director, Berkeley Analytical Associates

Cement is one of the most carbon emissions intensive parts of today’s buildings, and more often than not, one of the most widely used materials in pure mass per unit of floor area. Cement manufacturing is estimated responsible for 5% of global CO₂ emissions.

California has placed the reduction of carbon emissions from concrete high on its agenda to meet its ambitious CO2 emission reduction goals. Wouldn’t it be lovely if concrete could actually store CO2 instead of being responsible for so much CO2

Next to one of the largest fossil fuel-fired power plants in the United States, at Moss Landing on the Monterey Bay, Calera is capturing CO2 from the power plant and using it to make cement. Calera founder Brent Constantz claims that each ton of Calera cement contains half a ton of CO2 transformed into an essential ingredient of cement. Constantz says his process is probably the best carbon capture and storage technique available.

Calera bubbles the CO2 through seawater to make calcium carbonate. The resulting water has the calcium and magnesium removed, making it even more suitable for desalination. Local agriculture in the region around Moss Landing is responsible for overdraughting the groundwater to support local agriculture, so a desalination plant is also an attractive option in conjunction with the electric power and cement plants. A pilot plant is being built in nearby Santa Cruz to address water shortages during drought years.

As the plant produces only ten tons of cement daily and its product’s structural performance still must be tested, it is too early to say the climate crisis is solved. But the technology has the promise of contributing substantially to dramatic reductions in greenhouse gases attributable to buildings. Seventy percent of the electricity produced in the U.S. goes to buildings, and electric power production is responsible for more than half of all GHG emissions. It would be lovely if Calera’s process turns out to be as economically and environmentally attractive as it appears to be so far.


You can read more about Calera. It is featured in an August 7 on-line article on Scientific American’s web site, the promise of Calera cement is described in more detail. 

The idea that plants clean indoor air is a sad, continuing saga fed by bad science, commercial interests, and wishful thinking.

I published an article in the Indoor Air Bulletin on the subject in 1992 (available on this web site) that provides some details.

Take home message:

1.   Don't use plants to improve IAQ. They don't. If anything, they pose risks to good IAQ.

2.   There is no credible scientific evidence that plants improve IAQ. The planting media has been hypothesized to be responsible for pollutant removal in some studies. The planting media alone can be expected to contribute to a limited reduction in some airborne chemical concentrations.

3.   Most advocates of indoor plant use have been funded by or are themselves providers of plants or supporting systems.

4.   If plants are used indoors for aesthetic reasons, there should be extra care to avoid moisture problems or problems with fertilizers and pesticides, all known sources of indoor air quality and health problems.

If you do have plants indoors, don't do it to improve indoor air quality. The pollutant removal effect is negligible and, as far as the science has shown, is not due to the plants but is due to adsorption on the soil and, possibly, uptake by the organisms in the root area of the plant. So, you could just put the planting mix in the space and use fans to move air through it. In one study, charcoal was added to the planting mix with fans moving the air, demonstrating that it was not the plants but the planting mix that was doing the removal.

The rate of removal by plants, even if you use the data from the one NASA research project ever done on it, is smaller than the removal of pollutants through the air exchange that takes place in a very tight building due to leakage through the envelope. If you will fill a house with three layers of the plants recommended by the advocates, the removal rate would be equal to 1/10th of an air change per hour (ach). Buildings with mechanical ventilation generally have a minimum ventilation rate of 0.5 air changes per hour. Offices using typical ASHRAE design values have about 0.8 ach.

The one. often-quoted NASA research project was done in static chambers, sealed chambers with no air exchange rates. This is not a scientifically sound way to investigate the removal rate of pollutants. A dynamic test involving an air change rate equal to those in real buildings and achieving steady state conditions is a far more relevant test. In a static chamber, a test over the time period in the NASA study would be dominated by the sink effects, removal from the air by adsorption to surfaces of the chamber and the plants. This does not give any idea about the removal rate obtained by plants in a real environment or even in a chamber over a normal period of on-going occupancy.

More recently published studies have been characterized by the use of static chambers or carelessness in the measurements of the environmental parameters. A paper presented at Indoor Air 2008 in Copenhagen last month actually showed a decrease in research subjects' task performance when plants were present.

The use of plants indoors, especially the "living wall" concept or other extensive use requiring periodic addition of moisture, creates substantial risks of moisture, mold, and bacteria problems in the air. There is a substantial risk of moisture-related problems including but not limited to mold in buildings with extensive plantings. The scientific evidence points more strongly to moisture than to mold as the relevant association in buildings with higher rates of asthma or allergy among the occupants. There are also risks from the use of fertilizers and pesticides, if required, in the indoor environment. We generally try to steer people away from plantings that require frequent irrigation, fertilizer, or pest control immediate around buildings, especially if there are operable windows.

Most of the favorable publicity around the use of plants comes from folks whose business it is to provide plants and/or the systems to support them. Try to check out your sources and the sources of funding for any study that they cite.

You can read a more extended discussion of plants and indoor air quality in an article posted on this web site under articles, "Can house plants solve indoor air quality problems?" It was originally published in my old newsletter, Indoor Air Bulletin, in 1992.

Because of the financial interest providers of the plants and supporting systems have, there continue to be many individuals innocently advocating the use of plants to improve indoor air quality. This is a problem that doesn't seem to go away because of the appeal of indoor plants and the myth that everything natural is good. Remember that many chemicals found in nature are poisonous, that many plants are poisonous and even deadly (e.g., digitalis) to humans and other living beings.

Natural insecticides such as those derived from chrysanthemums (pyrethrins) are allergenic to many people and are toxic to insects and, it appears likely, to humans.

The Wikipedia listing for pyrethrin says: "In humans, pyrethrin irritates the eyes, skin, and respiratory systems, and it may cause other harmful effects. One study suggested a link between maternal pyrethrin use and autism in children.

The study indicated that mothers of autistic children were twice as likely to have washed a pet dog with a flea shampoo containing pyrethrin while they were pregnant."

By the way, I have a few plants around me as I sit here typing,  but they are mostly orchids and cacti, not intended to or expected to clean the air. I tend to underwater them and rarely fertilize them. Of course they don't bloom as often as I'd like, but that's the trade-off for ensuring better IAQ.

Determining whether a building is sustainable requires a benchmark based on scientific knowledge of the earth’s carrying capacity. Environmental budgets or targets can be used to evaluate or compare building designs or performance. We propose a method for deriving targets based on global population projections through the year 2100 to allocate resource consumption and pollution emission budgets equally to all the earth’s inhabitants.

This article appeared in the newsletter from the Committee on the Environment, American Institute of Architects, AIA COTE notes, Summer 2006.

By Hal Levin

We propose a method for developing budgets based on calculation of fossil carbon emissions, an indicator of carbon equivalents greenhouse gas emissions, contributors to climate change. We use scientists’ calculations of the capacity of the earth’s atmosphere to balance the heat entering and leaving the atmosphere as a result of all forces including but not limited to human activities. The overwhelmingly dominant human contribution to climate change appears to be the human impact on the global carbon dioxide concentration. For 400,000 years before industrialization, the global average concentration never exceeded 300 ppm. Since industrialization, it has risen from 285 parts per million (ppm) CO2 to approximately 380 ppm, with a steep climb in the past few decades. Climate scientists predict that our present rate of growth in carbon emissions will result in a global average of 700 ppm CO2. Most climate scientists agree that we should stabilize the concentration between 450 and 550 ppm by the year 2100 in order to limit global average temperature to a 2 degrees Celsius increase above current climate. A substantial amount of science is available regarding the potential impacts of this amount of warming, and the consequences appear rather significant but are hoped to be tolerable. In fact, a recent European Commission report says that even limiting global CO2 to 450 or 550 ppm will result in a 25 to 75 percent risk that global average temperatures will increase by more than 2 degrees Celsius.

Some experts argue that we can’t wait until 2100 and that we should shoot for 2050 or sooner to stabilize atmospheric CO2. From a practical perspective, that does not appear to be achievable at present. Neither the United States nor the developing countries are signatories to the Kyoto Protocol. The extremely rapid diffusion of technology in many developing nations and their substantially higher rate of population growth compared with the developed countries suggest that they will have to radically alter their current path. But until developed nations set an example and develop the necessary technology and the policy instruments necessary to effect the change, it is difficult for leaders of developed countries to request that developing countries curtail their growth in the distribution of higher standards of living through appliances, automobiles, and other consumption that is energy intensive. The prudent approach is to reduce anthropogenic carbon emissions as much as possible as quickly as possibly—probably considerably faster than contemplated under the Kyoto Protocol and the most advanced current planning in Europe.

The approach proposed here involves a number of assumptions that are either subject to revision as we obtain new and better data in the next decade or two. It also involves some choices that warrant further discussion and revision to improve their fairness to all affected parties as well as their feasibility. The basic approach was first described in 1992 report by the Dutch government agency Advisory Council for Research on Nature and Environment (RMNO). The report, Ecocapacity as a Challenge to Technological Development, was borrowed and applied in reports produced by the Friends of the Earth Netherlands that also estimated the carrying capacity of the Netherlands that became a model for several European countries and finally for a report on Sustainable Europe. These reports translated “budgets” for resource consumption and pollution emissions into national targets against which national reporting could be compared. These activities contributed significantly to the current model for carbon emissions trading that has become widely accepted in Europe and that functions in the marketplace the way emissions trading of various air pollutants operates in the United States.

The Process
There are five simple steps in the process as follows.

Define the capacity of the resource or sink in question. In the case of fossil carbon emissions, this is based on the best available models of the impact of carbon emissions on global climate and uses the assumption of a 450 to 550 ppm global average CO2 concentration.

Translate the total emissions that are believed “sustainable” into a per capita budget. In the case of carbon emissions, to achieve 450 to 550 ppm global average CO2 concentrations would allow emissions of 1 to 2 kilograms of carbon per person per day (kg C/p-d) by the year 2100 with an expected population of about 8.5 billion people—the latest UN population projection. Compare this to the current global average of 3 kg C/p-day and the U.S. average of around 17 kg C/p-d. Of course various sources of energy have different implications, with electricity from coal emitting roughly twice that derived from natural gas. Hydropower is closer to carbon neutral, although there are some emissions related to the development and maintenance of hydropower electricity sources. Solar photovoltaic can also be close to zero on a life cycle basis.

Calculate the portion of total emissions attributable to buildings. Using the latest Department of Energy data on the distribution of energy consumption by sector and our own data on components of building-related energy attributed to industry, transportation, and agriculture, we estimated that building related energy consumption (including “plug loads”) is about 40 percent of total energy consumption. Thus, each individual’s emissions must be 0.4 to 0.8 kg C/d-p as a “sustainable” budget. Currently 5 to 7 kg/p-d are associated with building energy use. This estimate could be refined but is not likely to change more than about 5 to 10 percent. It includes construction, use, operation, maintenance, renovation, and demolition or recycling of buildings.

Determine the portion of total building use attributable to each building type. Again, based on DOE data on the shares of total energy used by each building type, we used the present share of each building type and allocated it to each. This allocation could be refined by analysis of the degree of conservation and efficiency already applied and the amount of further reductions deemed reasonably feasible and achievable in each type. Energy per square foot consumption represents a wide range with health care and food retail at the high end and public safety, public assembly, and storage on the low end.

Finally, to derive a target for a specific building, the budgets of its users are applied. For example, for a school, divide the number of students, teachers, and staff who study or work at the school by the total number at all schools at the same grade levels in the country. For offices, the value could be based on workers or work stations, for a library it could be based on daily average users, for a retail establishment on the number of customers or customer hours etc.

The proposal presented here is to compare modeling data for building designs or data from monitoring of built structures with the carbon emission budget targets to determine their “sustainability” with respect to carbon emissions. Similar budgets can be prepared, as was done by the Dutch in the reports mentioned above, for consumption of various renewable and non-renewable resources as well as for various pollution emissions and for land encroachment. Targets are set for biodiversity loss, ozone depletion, copper consumption, cadmium releases, etc.

An elaborated version of the derivation and a number of relevant references are part of a paper I presented in Tokyo last September at the Sustainable Buildings 2005 conference and two papers presented at Healthy Buildings 2006 in Lisbon, Portugal, in June 2006. These papers can be downloaded from

Other resources include:
EnergiePortal: Climate change:

ASHRAE web site pages for sustainability:

An article appearing in the American Journal of Public Health describes a number of approaches to dealing pandemic flu outbreaks including the devastating global pandemic of 1918, as well as some more recent ones. It praises the approaches of placing diseased patients in “open air” environments, focusing on the benefits of exposure to plentiful fresh air and sunlight, without ignoring the importance of “scrupulous standards of hygiene” and the use of reusable face masks. As the H1N1 infection spreads now, the advice is not without relevance.

The article is available on line at

Our sources suggest that the sunlight may be important for the synthesis of Vitamin D, often lacking especially during the darker portion of the year due to a lack of sunlight exposure. Some suggest that in northern latitudes there simply is not enough sun intensity for the necessary exposure. Recently published findings are now suggesting that Vitamin D may important for proper immune system functioning and could play a role in resistance to infections such as the influenza virus.

Hobday RA and Cason JW: The Open-Air Treatment of Pandemic Influenza. AMERICAN JOURNAL OF PUBLIC HEALTH: 99;S236-S242; SUPPL. 2, 2009.

ABSTRACT: THE H1N1 "Spanish Flu" outbreak of 1918-1919 was the most devastating pandemic on record, killing between 50 million and 100 million people should the next influenza pandemic prove equally virulent, there could be more than 300 million deaths globally, the conventional view is that little could have been done to prevent the h1n1 virus from spreading or to treat those infected; however. There is evidence to the contrary. Records from an "open-air" hospital in Boston, Massachusetts, suggest that some patients and staff were spared the worst of the outbreak A combination of fresh air, sunlight, scrupulous standards of hygiene, and reusable face masks appears to have substantially reduced deaths among some patients and infections among medical staff We argue that temporary hospitals should be a priority in emergency planning Equally, other measures adopted during the 1918 pandemic melt more attention than they currently receive (Am J Public Health 2009;99:S236-S242. doi 10.2105/AJPH.2008.134627)

If outdoor ozone levels are related to SBS symptom prevalence in a building, would it be wise to install filters to remove the ozone entering the building? If using synthetic fiber filters further increased SBS symptom prevalence as outdoor ozone levels increased, would you want to use some different material for your building's particle filters?

Recently published research on the results suggest that it may reduce SBS symptom rates if you reduce ozone remove ozone from outdoor air. Researchers at Lawrence Berkeley National Lab (LBL) have published two papers linking outdoor ozone concentrations with SBS symptom rates in the EPA's BASE study of 100 office representative of U.S. office buildings in various climates and parts of the country. They also found that the effect of outdoor ozone levels was dramatically increased when synthetic fiber filters were used as particle filters in the buildings studied.

You can learn more about it from a Scientific American piece on their web site or by reading the two papers themselves.

Scientific American is running a piece on the BASE Study ozone/BRS papers in their online site (see below for link). This article is based on two new LBNL papers and material Mike Apte sent as well as a lengthy interview. Apte says he wishes the writer would have listened to his cautions about the need for replication and the pitfalls of over interpreting statistical analyses. But it’s hard to get the media to take such cautions seriously. Hopefully this media attention will spur more interest in ozone-related environmental health issues.

But the case for a link of outdoor ozone to health effects has been made very strongly for increased mortality, and there are many good reasons to believe that increases in outdoor ozone can contribute to other effects such as building-related symptoms (SBS).

For more on indoor ozone and health, read Charles J. Weschler's excellent analysis in the journal Environmental Health Perspectives. You can read it  on line, Ozone’s Impact on Public Health: Contributions from Indoor Exposures to Ozone and Products of Ozone-Initiated Chemistry.


Click here to read Smog Can Make People Sick, Even Indoors

There are also links to the LBNL versions of the papers published in the Indoor Air journal. The papers are also available on the Indoor Air journal's web site.

The LBNL versions of the papers are currently available online here.

The references are Apte M.G., I.S.H. Buchanan, and M.J. Mendell. 2007. “Outdoor Ozone and Building Related Symptoms in the BASE Study,” in press, Indoor Air. LBNL-62419.

Buchanan I.S.H, M.J. Mendell, A. Mirer, and M.G. Apte. 2007. “Air Filter Materials, Outdoor Ozone and Building-related Symptoms in the BASE study,” in press, Indoor Air. LBNL-62508.


For more on indoor ozone and health, read Charles J. Weschler's excellent analysis in the journal Environmental Health Perspectives. You can read it  on line, Ozone’s Impact on Public Health: Contributions from Indoor Exposures to Ozone and Products of Ozone-Initiated Chemistry.

Do you want to know the potential for solar energy to solve our energy needs as well as eliminate greenhouse gas emissions? Bill McDonough closed his keynote lecture at GreenBuild 2006 in Denver with a comment about our (Earth’s) own nuclear power plant, 93 million miles away. Yes, of course it’s the sun.

A downloadable primer, well-written and illustrated, places the potential of the sun in perspective relative to our energy use and needs. It gives details not only of the potential applications of solar energy but also of the limitations. It places solar energy and its use on Earth in great perspective. Here are some excerpts from the article:

"The San Francisco 1906 earthquake of magnitude 7.8 released an estimated 1017 joules of energy, the amount the Sun delivers to Earth in one second."

"Earth's ultimate recoverable resources of oil, estimated at 3 trillion barrels, contains 1.7 x 1022 joules of energy, which the Sun supplies to Earth in 1.5 days."

"The amount of energy humans use annually, about 4.6 x 1020 joules, is delivered to the Earth by the Sun in one hour."

"The enormous power that the Sun continuously delivers to Earth 1.2 x 105 terawatts dwarfs every other energy source, renewable or nonrenewable. It dramatically exceeds the rate at which human civilization produces and uses energy, currently about 13 TW. "

The article nicely describes the potential for photovoltaics to satisfy our energy needs without greenhouse gas emissions. It discusses the various processes now being developed to increase the efficiency and lower the cost of photovoltaic energy, now far more costly than fossil fuels [ed: by human economic standards]. It also discusses the conversion of solar energy by plants and the potential use of the resulting “biofuels.”

For the scientifically inclined, the article is a thorough discussion of the fundamental physical processes involved. No resource we know of does such a nice job of putting solar energy in perspective. You can download the article for free from


Reference: Crabtree, G., and N.S. Lewis, 2007, Solar energy conversion. Physics Today, March 2007, 37-42. The article is available for free download here

By Kofi Annan, Former Secretary General of the United Nations


I thank the government and people of for hosting this international conference. You have warmly welcomed thousands of people into your midst, and created excellent conditions for the crucially important work on our agenda. Thank you for yet another strong show of support for the United Nations.

All of us in this hall are devoted to the betterment of the human condition. All of us want to see a day when everyone, not just a fortunate few, can live in dignity and look to the future with hope. All of us want to create a world of harmony among human beings, and between them and the natural environment on which life depends.

That vision, which has always faced long odds, is now being placed in deeper jeopardy by climate change. Even the gains registered in recent years risk being undone.

Climate change is not just an environmental issue, as too many people still believe. It is an all-encompassing threat.

It is a threat to health, since a warmer world is one in which infectious diseases such as malaria and yellow fever will spread further and faster.

It could imperil the world’s food supply, as rising temperatures and prolonged drought render fertile areas unfit for grazing or crops.

It could endanger the very ground on which nearly half the world’s population live - coastal cities such as Lagos or Cape Town, which face inundation from sea levels rising as a result of melting icecaps and glaciers.

All this and more lies ahead. Billion-dollar weather-related calamities. The destruction of vital ecosystems such as forests and coral reefs. Water supplies disappearing or tainted by saltwater intrusion.

Climate change is also a threat to peace and security. Changing patterns of rainfall, for example, can heighten competition for resources, setting in motion potentially destabilizing tensions and migrations, especially in fragile States or volatile regions. There is evidence that some of this is already occurring; more could well be in the offing.

This is not science fiction. These are plausible scenarios, based on clear and rigorous scientific modelling. A few diehard sceptics continue to deny global warming is taking place and try to sow doubt. They should be seen for what they are: out of step, out of arguments and out of time.

In fact, the scientific consensus is becoming not only more complete, but also more alarming. Many scientists long known for their caution are now saying that global warming trends are perilously close to a point of no return.

A similar shift may also be taking place among economists. Earlier this month, a study by the former chief economist of the World Bank, Sir Nicholas Stern of the , called climate change "the greatest and widest-ranging market failure ever seen." He warned that climate change could shrink the global economy by 20 percent, and cause economic and social disruption on a par with the two World Wars and the Great Depression.

The good news is that there is much we can do in response. We have started using fossil fuels more cleanly and efficiently. Renewable energy is increasingly available at competitive prices. With more research and development - current levels are woefully, dangerously low - we could be much farther along.

Spurred by the Kyoto Protocol, international carbon finance flows to developing countries could reach $100 billion per year. Markets for low-carbon energy products are expected to grow dramatically.

But we need more "green" approaches to meet surging energy demand. And we need to put the right incentives in place to complement the constraint-based efforts that have prevailed to date.

The climate challenge offers real opportunities to advance development and place our societies on a more sustainable path. Low emissions need not mean low growth, or stifling a country’s development aspirations.

So let there be no more denial. Let no one say we cannot afford to act. It is increasingly clear that it will cost far less to cut emissions now than to deal with the consequences later.

And let there be no more talk of waiting until we know more. We know already that an economy based on high emissions is an uncontrolled experiment on the global climate.

But even as we seek to cut emissions, we must at the same time do far more to adapt to global warming and its effects. The impact of climate change will fall disproportionately on the world’s poorest countries, many of them here in Africa . Poor people already live on the front lines of pollution, disaster and the degradation of resources and land. Their livelihoods and sustenance depend directly on agriculture, forestry and fisheries.

Think, for example, of the women and girls forced to forage for fuel and water in the absence of basic energy services. Or of the innumerable African communities that have suffered climate-related disasters in recent years. The floods of , the droughts in the Sahel and here in , are fresh in our memories. For them, adaptation is a matter of sheer survival. We must make it a higher priority to integrate the risks posed by climate change into strategies and programs aimed at achieving the Millennium Development Goals.

The message is clear. Global climate change must take its place alongside those threats - conflict, poverty, the proliferation of deadly weapons - that have traditionally monopolized first-order political attention. And the United Nations offers the tools the world needs to respond.

Regional and national initiatives have their value. But the UN Framework Convention is the forum in which a truly global response is being formulated.

The Kyoto Protocol is now fully operational, and its Clean Development Mechanism has become a multibillion-dollar source of funding for sustainable development.

This mechanism is an outstanding example of a UN-led partnership linking government action to the private sector in the developing world.

I am pleased to announce that six UN agencies have launched, at this conference, the "Nairobi Framework," a plan to support developing countries, especially in Africa , to participate in the Clean Development Mechanism. I encourage donor countries to help make these efforts a success.

I am also pleased to note that today, UNDP and UNEP are embarking on an initiative to help developing countries, again including in Africa, to factor climate change into national development plans - so-called "climate proofing" in areas such as infrastructure.

UN agencies will continue to bring their expertise to bear. But the primary responsibility for action rests with individual atates - and for now, that means those that have been largely responsible for the accumulation of carbon dioxide in the atmosphere. They must do much more to bring their emissions down.

While the Kyoto Protocol is a crucial step forward, that step is far too small. And as we consider how to go further still, there remains a frightening lack of leadership.

In developing countries, meanwhile, emissions cannot continue to grow uncontrolled. Many of them have taken impressive action on climate change. Rapidly growing economies, like , have been increasingly successful in decoupling economic growth from energy use, thereby reducing the emission intensities of their economies. But more needs to be done.

Business, too, can do its part. Changes in corporate behavior, and in the way private investment is directed, will prove at least as significant in winning the climate battle as direct government action.

And individuals too have roles to play. A single energy-efficient light bulb placed in a kitchen socket may not seem like much; but multiplied by millions, the savings are impressive.

Voting power could be similarly compelling, if people were to make action on climate change more of an election issue than it is today and individuals, through their purchasing choices, can put pressure on corporations to go green.

There is still time for all our societies to change course. Instead of being economically defensive, let us start being more politically courageous.

The Nairobi Conference must send a clear, credible signal that the world’s political leaders take climate change seriously.

The question is not whether climate change is happening or not, but whether, in the face of this emergency, we ourselves can change fast enough.

Roughly 70% of all workers in the United States travel to work in single occupancy motor vehicles. It seems to me that this is one of the lowest hanging pieces of fruit on the tree of opportunity. Perhaps the only lower one is the wastefulness of energy use in buildings.

For example, while California has been a model for stabilizing total energy consumption for the past 30 years in spite of its population growth, there is still only something on the order of 12% market penetration of compact fluorescent lamps in the residential market. The reason frequently given when I raise this point is ‘color rendition.’ This may have been the case at some point in the past, but a wide range of color rendition is available in CFLs now. Go to a good lighting specialty store where they display the range of CFLs available and you will be able to see this. When an investment of $2.50 to $5.00 results in a lamp lifetime saving of $40 to $50, it is hard to explain. Potential electrical energy saving — huge!

Now for the really big one — passive solar. Why do we restrict the minimum size and amount of opening area of windows and yet let people put windows on any side of a building regardless of compass orientation? Passive solar is the invisible low-hanging fruit. Use overhangs and properly oriented and sized windows and you can save half the heating costs for a house in most North American climates, far more in sunnier, warmer locations like nearly the entire west coast and southwest. Get a clue! Heating is nearly half of residential energy use, therefore, nearly 1/3 of building energy use and nearly 15% of all U.S. energy use.

Let’s pick the biggest, lowest hanging fruit first — no new technology is required.

Anybody out there know how to do this?

At the U.S. Green Building Council's annual conference, Greenbuild 2007, Bill Clinton presented the keynote address focusing on green buildings and climate change.

What I heard was an unequivocal statement that addressing climate change through changed business practices including but not limiting to reducing carbon emissions attributable to buildings would be good for the economy and was an untaped opportunity with abundant profits available. The conference was attended by almost 23,000 people, up from 14,000 last year and 9,000 the year before. It has become clear that this is not just a movement, it is a tsunami.

President Clinton said: "This is the biggest economic opportunity that our country has had to mobilize and democratize economic opportunity since World War II," he said.

You can see the CNET coverage of Clinton's speech at:

Here is a selective summary of some of the highlights of Clinton's talk:

* Challenge / opportunity that is going to create jobs and businesses to create a sustainable planet to leave to our children and grandchildren.
* World is plagued by persistent economic inequality except in the countries that are going to meet their Kyoto targets.
* In Denmark, they grew their economy 50% without an increase in their GHG emissions. Wages are raising and inequality is falling.
* In Europe wages are rising without increasing inequality because of energy transformation.
* The UK is meeting their Kyoto targets.
* 75% of GHG come from urban areas. About 70% of those come from buildings. In NY , where the Clinton Foundation is headquartered,  it’s 80%.
* Clinton Foundation is in partnership with 40 cities to retrofit buildings; using energy services companies to save energy and money, and to use the savings to pay off the cost of the retrofits.
* The value of a couple of blocks of downtown Chicago is $5B. This capital is enough to finance the retrofits of a large fraction of downtown Chicago to take advantage of the opportunities provided by the inefficiency of the existing stock, the cost of energy, and the coming cost of carbon.
* Announced a program with the worlds biggest building – McCormack Place Convention Center.
* GE Real Estate -- $71B worth of real estate in their portfolio throughout the world. Now committed to retrofitting their holdings in partnership with the Clinton Foundation.
* Prove through economies of scale that this can be done, others will follow your lead.
* 20% of population goes to school in America. Greening schools is another opportunity awaiting. Operational savings more than pay for the cost of retrofit in green schools.
* We have to keep score. Several years down the line, when people ask us what we did, we have to keep score so we can tell them what we did. We need to measure the baselines of performance and track our improvements over time.
* Staggering economic opportunity – greening for the benefit of the American dream, as well as to save the climate.