U.S. Window Sales History
Low-E Sales and Financial Benefits
Low-E Energy Savings and Environmental Benefits
Lives Saved With Low-E
Energy Consumption for Heating and Lighting
Deaths From Fossil Fuel Pollution
Costs of Climate Change
Weather Panel Energy Production and Lives Saved


Some of the data and extrapolations in this section are approximations because rigorous, complete data is not yet available, especially regarding deaths from diseases caused by fossil fuel pollution. Some of the numerical conclusions may only be accurate to a factor of, say, 2. However, the ethical and financial actions they validate would not change if they were incorrect by a factor of 10.







Europe and Japan were about 5 and 8 years behind this schedule, and the third world is about 15. Industrial world markets are saturated, leaving market growth to semi-industrial countries like Brazil, Russia, and India. Low-E windows have gone through the usual cycle for successful products from hot and profitable to ubiquitous commodity.


U.S. sales of Low E in 2000 were 750 million square feet per year, when they reached 95% market saturation. (1) This level of sales was reached 18 years after Low-E's market entry, so that the amount of Low-E which was sold in the U.S. until 2000 is approximately:
18 years x 750 million sq ft per year x 1/2 = 6.8 billion sq ft. After 2000, sales were:
8 years x 750 million sq ft per year = 6 billion sq ft,
for a U.S. total sales of approximately 13 billion sq ft.

The rest of the industrial world's glazing markets are approximately 3 times larger than U.S. markets. However, Low-E sales in these markets started 5 to 10 years after the U.S., although they also reached saturation in 2000. Thus overseas sales are: 10 years x 750 million sq ft per year x 3 x 1/2 + 8 years x 750 million sq ft per year x 3 = 29 billion sq ft. Total world sales are: 13 billion sq ft + 29 billion sq ft = 42 billion sq ft, or 1,600 square miles of Low-E windows have been sold to date, discounting sales in the semi-industrialized world.

Since they had an average incremental installed sales price of $0.20 per square foot, approximately $8.4 billion of the Low-E coating has been sold.

Low-E's energy savings drove the doubling of window area, as a percentage of floor area, in new construction. By tripling the insulating value of double pane windows, it also drove their replacing single pane windows. This conversion nearly doubled windows installed cost per square foot. Thus, Low-E has more than tripled the size of the entire U.S. window industry to approximately $100 billion.

(1) Lawrence Berkeley National Window Laboratory; U.S. glass industry study. Statistics that are not referenced are readily available on the web.


The thermal conductivity of a single pane window is 1.3 BTU/sq ft °F hour, and that of a Low-E window is 0.4, so that a Low-E window conducts: 1.3 - 0.4 = 0.9 BTU/sq ft °F hr less heat. However, a Low-E window is warmer than a non-Low E window, thus increasing the mean radiant temperature of the room and allowing the air temperature to be reduced, and the thermostat turned down. This effect, which also saves cooling energy, doubles Low E's energy savings.

New York City has a typical heating and cooling climate, with 6,000 degree days per year for heating. Thus, over one year, each square foot of Low-E window replacing a conventional window reduces the heating load by:
0.9 BTU/sq. ft °F hr x 24 hrs/day x 6,000 degree days/year x 2 = 2.6x105 BTU/sq ft year. The amount of heating energy now being saved by Low-E is:
2.6x105 BTU/sq ft year x 42 billion sq ft sold to date = 1.1x1016 BTU/year. The air conditioning energy saved by Low-E is approximately 1/4 that amount, but it takes 3 times that amount of fossil fuel energy to generate the electricity for air conditioning, which, with an air conditioner c.o.p. of 2.5, gives:
1.1x1016 BTU/year x 1/4 x 3 ÷ 2.5 x 2 = 6.6x1015 BTU/year cooling energy being saved. The total savings is 1.76x1016 BTU/year.

In the U.S., heating oil costs $16/million BTU, coal $10, natural gas $12, and propane $41. A conservative use-weighted average price is $13/million BTU. (2) The rest of the world pays approximately 2 times as much for energy, and consumes 3/4 of the world's energy, so the world average price for heating energy is approximately:
$13 x 1/4 + $13 x 2 x 3/4 = $23/million BTU. Thus:
23 ÷ 106 $/BTU x 1.76x106 BTU/year = $770 million per year is saved by Low-E. And since Low-E lasts for 40 years: $770 million x 40 = $31 billion will be saved by the Low- Emissivity window now installed. World energy consumption is approximately 4.75x1017 BTU per year, so Low-E is now saving 3.7% of world energy consumption. Since there are 6.7 billion people in the world, Low-E is saving approximately as much energy as 250 million people are using.

When burned, each gallon of oil produces 139,000 BTU and 23 pounds of carbon dioxide, the principle global warming emission. Coal produces 2 times as much C02 per BTU as oil. We conservatively assume coal to be equal to oil. Thus, Low-E is preventing more than:
1.76x1016 BTU/year ÷ 139,000 BTU/gallon of oil x 23 lb C02/gallon of oil ÷ 2,000 lb/ton = 17 million tons per year of global warming C02 emissions.



We assume that a BTU of fossil fuel used for heating or generating electricity to light buildings produces approximately as much pollution (particulate plus non-particulate) caused disease as when that BTU is used for transportation or electricity. The predominant use of highly polluting coal for generating electricity and, outside the U.S., for heating, makes this assumption conservative.

since 9.4 million people die each year from fossil fuel pollution, and since Low-E has reduced world energy consumption by 0.37%: 9.4 million lives/year x 3.7% =350,000 lives per year are being saved by the Low-E. Since it lasts for 40 years: 40 years x 350,000 lives/year =
14 million lives have or will be saved by the Low-E windows now installed


The International Energy Agency of the European Union has developed the most complete and accurate statistics available on energy use. Although their statistics are just for the EU, they can be accurately extrapolated to world energy use because the proportions of energy consumed for different purposes is very similar throughout the world, and because 2/3 of energy is consumed in the industrialized world.

Jens Laustsen is in charge of evaluating energy used in buildings for the IEA. In a recent e-mail, he stated that:

"According to the latest energy statistics and the Energy Technology Perspectives of June, 2009, which was published here, the building sector is responsible for 2,900 Mtoe (mega tons oil equivalent), or 38 % of the worlds final [at the source] energy consumption. This includes appliances installed in these buildings and it includes both residential and commercial buildings. Residential buildings are responsible for 80% - 85 % of the energy used for heating. Based on these energy statistics and the models that I use to estimate, consumption in buildings is approximately 2000 Mtoe for heating, cooling, ventilation, and hot water. An approximate estimate is that heating alone is responsible for 1500 Mtoe globally." (3) 1500 Mtoe equals or 17,500 TWh per year, or 1.75x1013 kWh, or 6x1016 BTU.

Since 2,900 Mtoes is equal to 38% of the world's energy consumption, and since heating buildings consumes 1,500 Mtoe, then: 1,500 Mtoe ÷ (2,900 Mtoe ÷ 38%) = 20% of world energy is consumed for heating buildings.

Paul Waide is the author of "Lights Labors Lost", the IEA's report on energy used for lighting, which states that:

"650 Mtoe is used for all lighting, minus 66 Mtoe for fuel based lighting, minus 47 Mtoe for vehicle lighting, which gives 537 Mtoe for electrical lighting in buildings". (4) Thus: 537 Mtoe ÷ (2,900 Mtoe ÷ 38%) = 7% of world energy is used for lighting in buildings.

(3) Jens Laustsen, Senior Policy Analyst for Buildings, International Energy Agency, World energy statistics are available in: Energy Technology Perspective 2008 at:
(4) Lights Labors Lost, p176 and 180; available at:


Science, one of the most prestigious scientific journals, states that: "Deaths from air pollution have been ranked as one of the top 10 causes of disability by the World Health Organization" of the United Nations. (5)

A research report by the World Health Organization and the World Resources Institute states that 700,000 lives could be saved per year from the diseases caused by particulate matter emitted by fossil fuels if their consumption were reduced by 18% in developed nations and by 9% in the developing nations. They also state that 2/3 of fossil fuels are consumed in developed nations.(6) This results in a: 18% x 2/3 + 9% x 1/3 = 15% reduction in total fossil fuel use, which means that: 700,000 lives ÷ 15% = 4.7 million people die each year from particulate pollution from fossil fuels.

This report further states: "Because the study followed a conservative approach, the benefits may be far greater than those estimated. For example, estimates include only avoidable deaths among adults more than 30 years old and infants less than one year old. In addition, by focusing only on deaths that could be avoided by reducing particulates, the study did not estimate health benefits less dramatic -- but much greater overall -- such as avoidable illness and days lost from work. Nor did it consider deaths associated with pollutants other than particulates." [italics added]

We assume that an approximately equal number of years of life are lost due to non-particulate fossil fuel pollutantion as are lost due to particulate pollutantion. These non-particulate pollutants include: nitric and sulfuric acids and oxides, ozone, carbon monoxide, hydrocarbons, etc. We assume that an equal number of people die from non-particulate pollution or die between the ages of 1-30, then approximately: 4.7 million x 2 = 9.4 million people die each year from fossil fuel pollution.

(5) Science, August 17, 2001, p.1257-9, referring to: C. J. L. Murray, A. D. Lopez, Editors, "The Global Burden of Disease: A Comprehensive Assessment of Mortality and Disability from Diseases, Injuries and Risk Factors in 1990 and Projected to 2020", Harvard University Press, Cambridge, MA, 1996. (6) This Working Group included collaborators from the U.S. Environmental Protection Agency, the U.S. Agency for International Development, Harvard University, and the University of California, Berkeley. Their report, "The Hidden Benefits of Climate Policy: Reducing Fossil Fuel Saves Lives Now", is available at: This study refers to: "Short-Term Improvements in Public Health from Global-Climate Policies on Fossil-Fuel Combustion: an Interim Report", in the Lancet, (the most prestigious medical journal), vol.350, pp1341-1348.


The carbon dioxide emitted by fossil fuels does not cause disease directly. However, it does cause global warming, which causes climate change. Diseases are now following the movements of the climates for which they are adapted and are moving into non-immune populations of people and crops. This is the cause of most of the recent dramatic increase of epidemics of both old and "new" diseases, especially in and from the third world. Epidemiologists studying specific cases of these effects have a consensus that, although not yet quantified, they will cause many times the deaths caused directly by fossil fuel pollution, and will increasingly cause plagues.

Climate change's most familiar effect is increasingly violent weather. The insurance industry has made studies of the financially catastrophic cost of predicted increasingly frequent and violent Katrinas, rising seas, etc. SwissRe, the world's largest insurer, has refused insurance to board members of corporations with no financial plan to deal with climate change.

The greatest long-term damage from climate change will be massive crop failures that are already greatly increasing the price of grains, causing in poor nations widespread famine and food riots that are only a hint of the future.

Other victims of climate change are the many species that are unable to adapt to sudden new weather patterns, and so face extinction, along with the network of plants and animals linked to them, including crops.

The scientific community and its increasingly accurate computer models of climate have, for the last decade, agreed that we are now experiencing only the mild early warnings of what's to come, which is too devastating to imagine or, unfortunately, to inspire corrective action from the usual institutions.

Of course, the greatest and most obvious cost of not using renewable energy is the many millions of innocent peasant families slaughtered by war over the last 50 years because they were born near oil.


Most heating energy is consumed in cold, cloudy winters, where, until the Weather Panel, solar heating was not practical. Nearly all heating energy is consumed in small buildings because they have much more exterior surface area for a given amount of floor area. In fact, large office buildings in northern cities use only their electric lighting for heat in the winter. Most small buildings are 1-3 stories. 1-3 story buildings in cold, cloudy winters is exactly what the Weather Panel roof is designed for. It therefore addresses most of the heating market. Based on these factors, approximately 70% of heating energy can be supplied by the Weather Panel, even though they can be used on only a much smaller percentage of total floor space. Since 20% of world energy is used for heating: 20% x 25% = 14% of world energy can be supplied by heating Weather Panels.

Because they transmit a constant amount of diffuse illumination, even when outdoor light varies greatly, illuminating Weather Panels make daylighting economically competitive, for the first time, with electric lighting. But Weather Panels can illuminate the only top story, and only during the day. Due to these restrictions, we assume that they can provide 25% of building lighting energy.

Adding the energy provided by heating and illuminating Weather Panels gives: 14% + 2% = 16%, or one sixth of world energy can be supplied by the Weather Panel.

Since the Weather Panel can supply 16% of world energy, and since approximately 9.4 million people die each year from fossil fuel pollution: 9.4 million lives x 16% = approximately 1.5 million lives per year can be saved by the Weather Panel at market saturation.