Category Archives: Energy Star

Definitions of Sustainability and a Steady State World

”…the world’s richest 20 per cent of the population consume 86 per cent of its goods and services, over half its energy and nearly half its meat and fish.”

Given how few buildings architects actually design in this country compared with the EU for example, I’m not sure how relevant the profession is to the topic of sustainability. However, I was curious enough to see what might be the official AIA word on the subject. I found this posting on the internet from the AIA Committee on the Environment.

“The linked domains of sustainability are environmental (natural patterns and flows), economic (financial patterns and equity), and social (human, cultural, and spiritual). Sustainable design is a collaborative process that involves thinking ecologically—studying systems, relationships, and interactions—in order to design in ways that remove rather than contribute stress from systems. The sustainable design process holistically and creatively connects land use and design at the regional level and addresses community design and mobility; site ecology and water use; place-based energy generation, performance, and security; materials and construction; light and air; bioclimatic design; and issues of long life and loose fit. True sustainable design is beautiful, humane, socially appropriate, and restorative.”

My first reaction to this lengthy, rambling definition was huh???!!! what the %$#@ does that mean? No wonder I hear quotes like “If it’s not beautiful, it’s not sustainable” from celebrity architects. Definitions like that, however well meaning are a license to do just about anything. So I thought maybe one of the leading schools of architecture would be more helpful and provide a definition with some substance. I found this posting on the Carnegie Mellon School of Architecture’s site.

“Sustainable design is a collective process whereby the built environment achieves new levels of ecological balance through new and retrofit construction, towards the long term viability and humanization of architecture. Focusing on environmental context, sustainable design merges the natural, minimum resource conditioning solutions of the past (daylight, solar heat and natural ventilation) with the innovative technologies of the present, into an integrated “intelligent” system that supports individual control with expert negotiation for resource consciousness. Sustainable design rediscovers the social, environmental and technical values of pedestrian, mixed use communities, fully using existing infrastructures, including “main streets” and small town planning principles, and recapturing indoor-outdoor relationships. Sustainable design avoids the further thinning out of land use, the dislocated placement of buildings and functions. Sustainable design introduces benign, non-polluting materials and assemblies with lower embodied and operating energy requirements, and higher durability and recyclability. Finally, sustainable design offers architecture of long term value through ‘forgiving’ and modifiable building systems, life-cycle instead of least-cost investments, and timeless delight and craftsmanship.”

Again, a long, rambling definition full of academic architectural jargon like “timeless delight”. Is this representative of the sustainable mind candy being fed to the future building designers of america? What about limits? What about carrying capacity? What about the huge energy drain, climate impact, and unsustainable ecological footprint of our existing building stock? Where is the call to action?

Looking for answers, I found the following on the Presidio School of Management’s “Sustainability Dictionary” website. Apparently in the academic world there are three different flavors or “criteria” of sustainability.

Social Criteria:

  • Socially desirable
  • Culturally acceptable
  • Psychologically nurturing

Financial Criteria:

  • Economically sustainable
  • Technologically feasible
  • Operationally viable

Environmental Criteria:

  • Environmentally Robust
  • Generationally Sensitive
  • Capable of continuous learning

Although I can sympathize with architectural profession’s emphasis on social criteria such as beauty and “timeless delight”, I don’t think it serves a world facing climate change and a looming carrying capacity crisis brought on by the “peak” production and supply of oil, gas, and coal. The AIA and Carnegie Mellon definitions allude to “environmental criteria”, but only in vague terms. What is needed is a sustainable building standard that addresses the very real limits to carrying capacity and our obligations to future generations. Unfortunately, LEEDS, Energy Star, or any other “green” standard falls far short of meeting such a standard.

In 1987 the U.N. World Commission on the Environment and Development [commonly known as the Brundtland Commission] set the table for the what has been a 20 year debate on the meaning of sustainability. The classic and oft quoted definition from the commission is:

“Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”

This definition is not far removed from the “seventh generation” philosophy of the Native American Iroquois Confederacy, a philosophy that put forth that chiefs should consider the effects of their actions and decisions seven generations into the future. However, as often as I’ve seen the commission’s definition quoted, I rarely see anyone expound on what the commission meant by their simple, elegant definition.

Digging into the actual report I found that even 20 years ago the commission was deeply concerned about the impact development and population growth was having on the world’s carrying capacity with respect to several important environmental criteria.

  • Global Warming
  • Ozone Depletion
  • Species Loss
  • Desertification
  • Deforestation
  • Air, water, and soil pollution

In making it’s case for sustainable development, the commission’s report would define carrying capacity as:

“The population that can be supported indefinitely by an ecosystem
without destroying that ecosystem”

Although not generally part of our awareness, it is no secret that various regions and country’s of the world compete for carrying capacity and the so called developed world imports a large portion of it’s own carry capacity at the expense of other country’s and peoples. The commissions report states that:

“The Earth is one but the world is not.
We all depend on one biosphere for sustaining our lives.
Yet each community, each country, strives for survival and prosperity with little regard for its impact on others.
Some consume the Earth’s resources at a rate that would leave little for future generations. Others, many more in number, consume far too little and live with the prospect of hunger, squalor, disease, and early death.”

Carrying capacity is not just a function of population. The actual population that can be supported by the earth’s ecosystem is also a function of the average standard of living or level of consumption of that population. Lower consumption levels allow the support of a larger population, and conversely higher consumption levels will support proportionally less population

Today we find ourselves in a world of 6.6 billion people in which the world’s richest 20 per cent of the population consume 86 per cent of its goods and services, over half its energy and nearly half its meat and fish. Another 1.4 billion people in China and India (nearly 5 times the population of the U.S) are rapidly growing their economies and as they begin to approach the developed world’s level of consumption and energy density, their rising demands on the earth’s carrying capacity is driving up energy, commodity, and food costs around the world. As the world’s collective economic growth rapidly depletes non-renewable resources such as oil, gas, and coal we will soon be faced with a carrying capacity crisis in a post peak world in which countries desperately complete for resources in a limited ecosystem. The commission’s report predicted this condition twenty years ago when it stated that:

“The ultimate limits to global development are perhaps determined by the availability of energy resources and by the biosphere’s capacity to absorb the by-products of energy use. These energy limits may be approached far sooner than the limits imposed by other material resources. First, there are the supply problems: the depletion of oil reserves, the high cost and environmental impact of coal mining, and the hazards of nuclear technology. Second, there are emission problems, most notably acid pollution and carbon dioxide build up leading to global warming.”

Many informed people in and out of government are painfully aware of this impending carrying capacity train wreck. Unfortunately, it is the nature of governments to only respond to an immediate crisis. Another problem, one that the Brundtland Commission omitted from their report, is our almost religious belief in economic growth. Even modest rates of growth mathematically become exponential, so that in the context of a closed ecological system, “sustainable growth” and “sustainable development” are eventually rendered oxymorons. In order to survive, at some point in time we will have to respect our planet’s limits in terms of carrying capacity. This will mean the acceptance of limits to our population size and to our levels of consumption and waste, and the transition to a steady-state economy.

The following definition of steady-state economics is from the Encyclopedia of Earth

The phrase “steady state economy” originated from ecological economics, most notably the work of Herman Daly, but its roots are in classical economics, most notably the “stationary state” by economist John Stuart Mill. The steady-state economy is often discussed in the context of economic growth and the impacts of economic growth on ecological integrity, environmental protection, and economic sustainability. Therefore, use of the phrase “steady-state economy” requires a clear definition of economic growth.

Economic growth is an increase in the production and consumption of goods and services. For distinct economic or political units, economic growth is generally indicated by increasing gross domestic product (GDP). Economic growth entails increasing population times per capita consumption, higher throughput of materials and energy, and a growing ecological footprint.

Theoretically and temporarily, a steady state economy may have a growing population with declining per capita consumption, or vice versa, but neither of these scenarios are sustainable in the long run. Therefore, “steady state economy” connotes constant populations of people (and, therefore, “stocks” of labor) and constant stocks of capital. It also has a constant rate of throughput; i.e., energy and materials used to produce goods and services.

The “growing ecological footprint” of economic growth only becomes problematic as we begin to push up against the limits to carrying capacity. This can occur locally in an “island” economy or globally as we are beginning to experience today. Getting back to architecture and the massive ecological footprint of our building stock, our homes are but a subset of years of unsustainable development that are pushing the limits of carrying capacity. This is especially true when we consider the energy consumption and climate impact of both residential and commercial buildings. My personal definition of sustainable building design is:

Sustainable building design meets the needs of the present without compromising the ability of future generations to meet their own needs for shelter. In order for our built environment to be supported indefinitely by the earth’s ecosystem without destroying that ecosystem, sustainable building design must be based on a net zero energy standard. A net zero energy standard, in no way constrains designers from creating buildings that are socially desirable, culturally acceptable, and psychologically nurturing.

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The Road to Energy Zero Homes – Metrics

“All healing is essentially the release from fear.”- A Course in Miracles

If you’ve been my reading previous posts you know that I believe that “sustainable” in the context of “home”, can only mean “net zero” or “energy zero” construction. What that means in practical terms, is that the thermodynamics of the building design (insulation levels, window performance, tightness, solar gain, etc.) must be good enough to allow the reasonable application renewable resources like solar or wind power to render the building a net zero energy consumer. By net zero, I mean that the home may have PV system that uses the grid as a storage device and although it may draw power from grid at times, on average the home delivers at least as much power to grid as it consumes.

The HERS Index is a good metric to help quantify the design performance required to meet this standard. I my opinion, the design of the home prior to the application of renewables, to be “good enough”, must have a HERS Index score of 25 or better to be “net zero ready”.

HERS Index

Unfortunately of the million or so homes built every year, my guess is that less than a thousand (perhaps less than 100) meet this standard. These are the hardy souls that build Earth Ships or are determined enough to find the few professionals who know how it’s done, regardless of the climate or any bias toward a specific building system. But in the long run it’s not the new homes that will be the challenge, it’s the over 100 million existing homes that grace the HERS Index scale from 130 to 150+. Some of these will of course be lost causes, economically not worth the effort, however the vast majority can be reasonably retrofitted, if not to 25 threshold, at least to below 50.

Stay tuned, I’ll be writing a series of “Zero Energy Home” posts that will cover the thermodynamic basics and strategies for retrofitting our existing housing stock.

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Energy, Carrying Capacity, and Sustainable Building

“By their own follies they perished, the fools.” – Homer, The Odyssey

The growth of civilization has been intimately linked to our ability to harness energy since man’s discovery of fire. Our reliance on biomass (wood) and eventually, the wind and hydro power of mills would limit our growth until the use of coal and the invention of the steam engine would launch the industrial revolution. However, it was the discovery of energy dense, crude oil in 1859 that would catapult us into a whole new age of growth, mobility, and abundance.

What is “sustainable” is based on carrying capacity, and every human advance in the use and amount of available energy would serve to increase both the population and economic carrying capacity of the earth. The shear abundance of cheap oil over the last 150 years would change the face of architecture and our built environment. Architects and building designers no longer had to consider local climate conditions, they could let their imaginations and ego’s run wild (or lazy) and rely on brute force heating and cooling to save the day. Architects like Phillip Johnson would build their design fame and fortune with glass homes in Connecticut and glass skyscrapers in Houston. Buildings that reply for their very existence on cheap and abundant energy.

Phillip Johnson Glass House

Phillip Johnson – Glass House Connecticut

Phillip Johnson Houston Skyscraper

Phillip Johnson – Houston Skyscraper

Mass housing in the U.S. would follow a similar path. Not only would the buildings themselves be inefficient statements of style over substance and function, but the sprawling pattern of development based on cheap oil and the automobile, would create a formula for maximum energy consumption.

The OPEC engineered “oil shock” of the 1970’s would bring about some much needed building energy standards, but vested interests continue to play the “politics of energy codes” and keep us far from anything remotely sustainable. The recent Green movement is a positive step, but new standards such as Energy Star and LEED for Homes do nothing more than tweak the status quo in the direction of sustainability.

If we assume cheap and abundant energy will be with us forever, then the critical constraints to the carrying capacity of our current way of living and building are environmental degradation, water, and global warming. Observing the behavior of many our politicians and policy makers this would seem to be case. Unfortunately, because these issues are hard to economically quantify and the consequences can be conveniently be passed on to future generations, actions tend to come in tepid half measures like raising the CAFE standards to 35 miles/gallon over several years.

But what if cheap and abundant energy will NOT be with us forever? What if the critical constraint to the carrying capacity of our current way of living and building where the peaking and eventual depletion of fossil fuels like oil, natural gas, and coal? What if this constraint was not off in some nebulous, non-renewable resource future, but was now or very close to now? What if this where the eleventh hour? How would this change the way we build?

Based on data published by the Energy Information Administration (EIA) the worldwide production of conventional crude oil peaked in May of 2005 and is currently in an undulating plateau. If we add unconventional sources (deep water, oil sands, etc.) worldwide production peaked in February of 2006 and is also stuck in an undulating plateau. Matthew Simmons, advisor to the Bush administration, author of “Twilight in the Desert”, and investment banker to the energy sector, says that “Serious peak oil analysts all agree that peak oil is 0 to 10 years away.“

ASPO Peak Oil Projection

The U.S. production of conventional easy-to-get natural gas peaked in the early 70’s and we have only just been able to keep our supply versus demand heads above water with imports from Canada and Mexico and the aggressive exploration of unconventional, hard to get sources like shale and coal methane gas.

The International Energy Agency (IEA) projects that we will be facing a supply crunch sometime in 2010. Big oil executives, speaking in “peak oil code”, are now stating publicly that the “era of cheap oil in over”. There have been more than a half dozen Peak Oil related documentaries released since 2003 and Leonardo DiCaprio’s The 11th Hour documentary debuts this month.

Peak oil changes everything. It is a hard limit to carrying capacity to both population and economic growth. As consumption and depletion widens the gap between supply and demand, we will become supply constrained and as supply declines economic growth must follow. Building design will be climate driven and zero energy buildings will soon become a matter of necessity, not choice. Not in some nebulous green future, but by the end of this decade. This is the eleventh hour.

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Facing a Painful Future Reality of Sustainability

“People cannot stand too much reality” – Carl Jung

I’ve been musing lately about exactly what it means to be sustainable in the context of residential building. Since words are the symbols blogger’s use to communicate, I checked my American Heritage dictionary and found that “sustainable” in today’s lexicon means “capable of being continued with minimal long-term effect on the environment” as in “sustainable agriculture”. That didn’t quite do it for me. It’s the kind of feel good definition that allows people to build 10,000 SF homes with bamboo floors, dual flush toilets, and a HERS index of 85 and call themselves “green”. So I continued looking and found that one of the definitions for “sustain” is “to support from below; keep from falling or sinking; or to prop.” Since our built environment has been “propped” up and shaped by cheap oil for about a 100 years, I found that definition more on the mark.

Getting back to our friend Dr. Jung, our not so sustainable residential lives are about to be turned upside down by three major reality checks. At the risk of being labeled as a “crazed and raving doomsdayer”, let’s just say, it is going to be painful.

Reality Check #1 – Global Warming

“When applied to material things, the term “sustainable growth” is an oxymoron.” – A.A. Bartlett

Thanks in part to an “Inconvenient Truth” global warming has already penetrated our collective consciousness, and for the 20% of the population that’s in denial it is already “too much reality”. American is responsible for about 25% of the green house gases [GHG] that contribute to global warming. Buildings in America account for about 42% of that total and our homes contribute about half of that total or 21% of this country’s GHG emissions. But that’s just part of the story, because of the sprawling suburban pattern of WHERE we build our homes, our automobile lifestyle compounds the problem. According to the Energy Information Agency, in 2001 107.4 million households logged 2.3 trillion miles commuting, shopping, and schlepping the kids to school, consuming 113.1 billion gallons of gasoline and diesel fuel in the process.

Fortunately for our Jungian psyche’s, global warming is a slow moving water torture kind of crisis that we can safely ignore until Disney World Orlando is an underwater attraction.

Reality Check #2 – Peak Oil

“The time when we could count on cheap oil… is clearly ending.” – David O’Reilly, Chairman, Chevron, 2005

Peak Oil has yet to enter our collective consciousness, in fact most people don’t even know what it means. Peak Oil is the date when the peak of the world’s (crude oil) production rate is reached. After this date the rate of production will enter a long, painful and terminal decline. Peak oil in the U.S. was reached in 1970 and in N. America sometime in the early 1980’s. There is a growing consensus that global Peak Oil either already occurred (as early as 2005) or will happen sometime between now and 2010. Does that mean that production will fall off a cliff and there won’t be any oil? No, but it does mean that demand will very shortly exceed supply and that there will be shortages, rationing, and major economic upheaval and other changes to our “cheap and plentiful oil” lifestyles.

Oil Discovery Gap


“It’s no secret anymore that for every nine barrels of oil we consume, we are only discovering one.” – British Petroleum Statistical Review of World Energy

“…we don’t have to run out of oil to start having severe problems with industrial civilization and its dependent systems. We only have to slip over the all-time production peak and begin a slide down the arc of steady depletion.” – Howard Kunster The Long Emergency (2005)

“Such a peak would require sharp reductions in oil consumption, and the competition for increasingly scarce energy would drive up prices, possibly to unprecedented levels, causing severe economic damage. While these consequences would be felt globally, the United States, as the largest consumer of oil and one of the nations most heavily dependent on oil for transportation, may be especially vulnerable .” – 2007 GAO (U.S. Government Accountability Office) Peak Oil Report

“The U.S. food system consumes ten times more energy than it produces in food energy. This disparity is made possible by nonrenewable fossil fuel stocks.” – Dale Allen Pfeiffer, Eating Fossil Fuels, 2003

ASPO Peak Oil Projection

Source: Association for the Study of Peak Oil & Gas

Since only 9% of our housing stock is heated directly by oil, the most painful impact of Peak Oil on our residential lifestyles will be on our one car, one person commutes.

  • Expect a major increase in walking, bicycling, carpooling, telecommuting, the use of public transportation and an end to suburban sprawl and strip malls.
  • Expect globalization to take a backseat to localization.
  • Expect some people and governments to behave badly.
  • Expect “victory gardens” in the front and back yards of suburbia.
  • Expect 10 to 20 years of unrest while we make the painful transition to a new world order

Unlike Global Warming, Peak Oil will be an “in your face” crisis, impossible to ignore or deny.

Reality Check #3 – Peak Natural Gas

“It seems obvious to most viewers the [U.S.] future production will decline in a cliff in the near future…” – Jean Laherrere, ASPO Berlin, 2004

As if Peak Oil were not enough “reality”, we also have to get our Jungian heads around Peak Natural Gas. According to Energyfiles Ltd., natural gas will peak in N. America about 2010 and globally between 2030 and 2035.

Unfortunately, natural gas is different animal from oil. Oil is a nice viscous, not very volatile liquid that can be easily shipped around the world and processed locally into to gas, diesel, fertilizer and other products. Natural gas however, must be refrigerated to minus 260 degrees Fahrenheit to convert it to Liquid Natural Gas (LNG) and shipped in very expensive container ships that amount to small nuclear bombs. Because the global LNG infrastructure (ships and docking facilities) is relatively undeveloped, the impact of Peak Natural Gas is basically confined and defined locally by a geographical network of pipelines. For us that network includes Mexico and Canada, and our “reality” is that we may be facing shortages by the end of this decade or sooner.

So how bad is this new energy reality? How does energy flow into our homes, and how will shortages affect our lives? Let’s first take a look at electrical generation in the U.S. Unfortunately, just about every power plant built after 1980 was designed to run on natural gas, so we’ve spent the past 25 years adding to the problem.

Electrical Generation by Energy Source

Source: U.S. Energy Information Agency 2005

The good news is that thanks to venerable coal, Peak Oil & Natural Gas only impact about 22% of our current electrical generating capacity. The bad news is that is more than enough to cause brownouts, blackouts, and rationing, especially during the summer when air conditioning loads peak.

As we painfully replace a 20% plus shortfall over the coming two decades, expect phenomenal growth in nuclear, coal, solar, wind, and geothermal power plants.

The next chart shows the relative residential energy consumption by energy source. Since over 55% of our homes and some 70% of new homes are heated by natural gas, shortages caused by Peak Natural Gas are going to be a major problem!

Residential Energy Consumption

Source: U.S. Energy Information Agency 2005

Given this new energy reality, homes built to our current energy code or even to an Energy Star or LEED standard amount to nothing more than rearranging the deck chairs on the Titanic. The energy train wreck we face demands that we only build and retrofit homes to a Net Zero Energy Standard. Homes that can be completely served on-site by wind, solar, hydro or geothermal power sources. This will require a new energy standard based on a HERS index of better than 25%, well below the current Energy Star/LEED minimum standard of 85%.

“We’ve invented the system that has given us this rise in life; now we begin the descent. We’ll either have to invent our way out of it, or go back to the way it was before.” – Byron King, Agora Financial Symposium, 2007

”We don’t inherit the Earth from our ancestors; we borrow it from our children.” – Antoine de Saint-Exupery

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Life, Liberty, and the Pursuit of Net Zero Energy

A large part of the collective dynamic that shapes our environment is embedded in the American culture of the individual. A culture enshrined in the words of Thomas Jefferson, “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty, and the pursuit of Happiness.” As a result, our American built environment has been largely shaped by the opposing forces of our individual “pursuit of happiness” no matter what the environmental or social cost and the countervailing forces of our communal needs for health and well-being.

Today we find ourselves directly in the cross-hairs of those opposing forces. Global warming has reached a tipping point of no return and we can now only mitigate the longterm effects, not reverse them. Peak Oil, declining worldwide production, and the point at which demand exceeds supply is expected within the next decade. With 120+ million housing units in the U.S. contributing 21% of our greenhouse gas emissions and consuming over 35% of our electricity, our “individual pursuit of happiness” has to be trumped by the needs of “our communal health and well-being”.

The way we build (and finance) housing in this country is no longer sustainable. Our model energy codes are still a triumph of the individual (lobbyist) over community, and Energy Star and LEED for Homes merely tweak the status quo in the direction of slightly better energy efficiency.

The truth is that truly sustainable homes (even net zero energy homes) are economically feasible. The cost premium for homes that exceed our current energy standards by 75% or more is only 5 to 15%. At that point (given a sunny climate) it only takes another 10% to reach “net zero”. If you consider that average new home sizes have increased 20% (400SF) to 2,434 SF since 1990, then rolling back average sizes to a very comfortable 2,000SF more than pays for a truly sustainable energy standard. Roll that back to a comfortable 1,800SF and the cost to have a net zero energy home becomes FREE!

Too much of a sacrifice? By comparison, the average home in Japan is 1,000 SF, 930 SF in Ireland, and 815 SF in the U.K.

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Energy Star Qualified Homes, Brands, Politics, and Vested Interests

“To impact the energy use of all new homes and prevent the resultant environmental degradation due to ever-increasing home sizes and escalating urban sprawl, the US Environmental Protection Agency (EPA) began its new homes initiative in 1995.”

The Energy Star for New Homes program is a voluntary program aimed at promoting energy efficient construction in the residential sector through the strength of the Energy Star “brand”. Since it’s inception in 1995, the program has attracted more than 90 utility partners, 2,900 builders, and 360 providers and rater (verification) organizations.

There is no question the the Energy Star New Homes program has been a huge success. According to conservative estimates, the program could save 0.70 quads of electricity by 2010 and forty billion pounds of CO2 could be prevented from entering the atmosphere if only 10% of US homes were able to meet Energy Star’s guidelines for new construction.

All of this has been accomplished on the strength of Energy Star’s “brand”. A brand which is widely known in the marketplace is considered to have acquired “brand recognition”. When brand recognition builds up to a point where a brand enjoys a critical mass of positive sentiment and trust in the marketplace, it is said to have achieved the status of a “brand franchise”. Energy Star has clearly become a brand franchise with strong recognition within the American buying public. Consumer’s have come to trust the Energy Star label to mean that they are getting the best in energy efficiency.

Builders (usually large builders catering to a large suburban market) have signed on to the program because they want the marketing power of the Energy Star brand to help them sell homes. They also want to do and spend the minimum required (with notable exceptions) to win the Energy Star label. As a result, because the EPA is subject to politics, the Energy Star New Homes requirements tend to get watered down by the lobbying power of vested interests which includes the builders. The end result is undeniably positive, but it is not the “best in energy efficiency” that consumer’s think they are getting.

Green building specifications like Energy Star come with about a 2 to 3% cost premium and merely tweak the status quo by reducing energy consumption over existing U.S. code requirements by a minimum of 15%. By contrast, European green standards like PassivHaus in the UK and Germany come with a 5 to 10% premium and if applied in the U.S. would reduce energy consumption by more than 80%. (see chart for a graphic comparison)

Energy Star vs PassivHaus

My point is that consumers having been lulled into complacency by their trust in the Energy Star brand and are blissfully unaware of what’s truly possible.

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Low-e Glass … A Nation Divided

Low-e glass, first introduced in 1979, has transformed window energy performance. Low-e glass is manufactured with a microscopically thin and transparent layer of metal or metal oxide that reflects infrared “heat” energy back into the home, greatly enhancing the thermal performance of the window.

In the simplest of terms, there are basically two kinds of Low-e glass:

  1. Low-e glass with a low Solar Heat Gain Coefficient (SHGC) that also reflects and keeps much of the Sun’s heat energy out of the home. This is the best choice in climates dominated by cooling.
  2. Low-e glass with a high Solar Heat Gain Coefficient (SHGC) that allows the Sun’s heat energy into the home. This is the best choice in climates dominated by heating or for south facing windows in climates with a mix of cooling and heating requirements.

All this seems pretty straight forward until you actually attempt to purchase a window with Low-e glass. But before I get into that let’s take a look at the climate zones in the U.S. used by Energy Star to determine the qualification criteria for windows and skylights in an Energy Star rated home.

Energy Star Climate Map

The Northern zone is the perfect candidate for a Low-e glass with a high SHGC and the North/Central and even the South/Central can greatly benefit from high SHGC Low-e glass on southern exposures. Unfortunately, even though the average American family spends far more on heating than air conditioning, both Energy Star, LEED, and the International Energy Conservation Code (IECC) seem to be color blind when it comes to space heating and the benefits of Low-e glass with a high SHGC.

Energy Star requirements for SHGC seem to be all about cooling as the following requirements for SHGC for each climate zone indicates. The IECC is no better, only requiring a SHGC of ≤ 0.40 for any residence with less than 3,500 Heating Degree Days (HDD). LEED only takes the cooling bias further by requiring even lower SHGC’s in the South/Central and Southern climate zones.

Energy Star Window Criteria

As an unintended consequence of the regulatory bias in favor of cooling, window manufacturers have all but abandoned Low-e glass with high SHGC’s. The result is a nation divided, with more than half of the country left out in the cold without ready access to high performance windows that take advantage of the free solar energy that strikes our windows everyday. With very few exceptions you just cannot find a window manufacturer willing to give you the glass options we need and require in heating dominated climates.

So what’s the consequence of the current regulatory bias? First of all it makes no sense, according to the U.S. Energy Information Administration’s (EIA) 2001 Residential Energy Consumption Survey, Americans consume more than 7 times more energy for space heating than for air conditioning. To get an estimate of what’s on the table for high SHGC, Low-e glass in terms of the potential energy savings I assumed a 10% improvement in heating costs for homes in the U.S. with more than 4,000 Heating Degrees Days. Based on the same 2001 EIA Survey, that would amount to an annual savings of 0.362 quadrillion(1 followed by 15 zeros) Btu’s per year. In monetary terms, that’s about $475 billion dollars worth of natural gas!

When the government gets serious about Global Warming maybe they’ll fix the cooling bias in the regulations, but until then here’s where to go to get a Low-e windows with a high SHGC:

Just want a source for the glass? Try Pilkington North America.

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