Seven-Plus Wonders of Sustainability

by Donella Meadows

— August 26, 1999 —


A couple of years ago, while I was doing something else, I heard snatches of a radio program in which Alan Durning, the director of Seattle’s Northwest Environment Watch, talked about the “Seven Sustainable Wonders of the World.”  Clever concept, I thought, but afterward I could only remember three of his wonders:

The bicycle — the most energy-efficient form of transport ever devised.  It doesn’t emit pollution, it runs on renewable energy, it makes its user healthier, it’s easy to repair, it requires little in the way of pavement or parking lot, and 80 percent of the world’s people can afford one.  (Only 10 percent of the world’s people can afford a car.)

The clothesline — even more affordable than the bicycle, runs on solar energy, no wires, no electricity, no pollution, and your clothes come out smelling sweet.

The ceiling fan — the air conditioner of the tropical world, which I fondly remember turning slowly and romantically in rooms all over India.  A fan makes a space feel 9 degrees F. cooler than it really is.  A typical ceiling fan draws no more than 75 watts, about as much as a single incandescent light bulb, only one-tenth as much as an air conditioner.  And it doesn’t make the air stale and clammy, the way air conditioners do.

Now what were those other four Sustainable Wonders Alan came up with?  I couldn’t remember.  I kept meaning, and forgetting, to call him and ask.  So I was delighted to see that he passed his idea on to a colleague, John C. Ryan, who has just put out a little book called Seven Wonders (Sierra Club Books, San Francisco).  Here are the other four:

The condom — protects against some of the world’s worst diseases, gives parents control over the size and timing of their families, helps control population growth.  “Those are big jobs for a flimsy tube of rubber,” says Ryan.  One sustainability problem with this item is that it’s discarded after just one use.  But it’s made from natural rubber, a renewable resource.

The public library — the written wisdom of the world at the fingertips of anyone with a library card!  The average American pays $20 a year in taxes to support public libraries and can save that much by borrowing instead of buying just one or two books.  A book that is loaned ten times cuts not only cost but paper use per read by a factor of ten.

Pad Thai — the highly seasoned Asian dish made of noodles, garlic, and vegetables, sometimes with bits of chicken or shrimp thrown in. Ryan doesn’t mean to celebrate that particular dish so much as the basic principle of “peasant” cooking around the world: start with starch, mix in veggies, add great seasonings, and use meat sparingly if at all.  Could as well be tortillas and beans, or curry and rice, or spaghetti and tomato sauce.  Healthy, cheap, do-it-yourself, easy on the planet, delicious.

The ladybug — constantly, without charge, without environmental damage, searching out and destroying plant pests.  Your average ladybug scarfs up 40-75 plant-sucking aphids a day.  Multiply that by 75,000 beetles per gallon, which farmers can order through the mail, and you’ve got one heck of an efficient pesticide.  Something like 98 percent of sprayed chemical pesticides never even hit a pest, but ladybugs zoom right in on the aphids and nothing but the aphids.

After I finished reading Ryan’s book, which is full of interesting facts about these wonders, I started seeing Wonders of Sustainability all around me.  There’s no reason to limit the list to seven.  Here are some more:

The root cellar — temperature controlled by the earth, a way of storing potatoes, carrots, onions, cabbage, squash, turnips, beets, apples, dahlia tubers and gladiolus corms (that’s what goes in my root cellar) without moving parts, canning jars, boiling or freezing.

The basket — someone once told me that no one has yet succeeded in mechanizing the making of baskets.  Whether or not that’s true, baskets, made all over the world by skillful hands out of renewable, biodegradable material, are lightweight, strong, beautiful, and reusable over and over.

The olive tree — it can live hundreds or thousands of years in dry, hot climates; like all trees it recycles carbon dioxide breathed out by us animals and turns it back into the oxygen we need; its roots hold the soil; its leaves break the impact of the rains; and it produces tasty, healthful olive oil.

The sari — and the sarong and the shawl, made of uncut, unsewn cloth colored and patterned as gorgeously as a butterfly, gracefully draped, comfortable, cool, adaptable.  You can suspend babies in it or melons or firewood.  You can hitch it up for wading, tuck it around your legs for bicycling or running, pull it over your face if you want shade or to be modest or to flirt.  Never out of style.  Easy to wash and dry.  One size fits all.

The compost pile.  The knitting needle.  The canoe.  This is fun.  I could go on with this list, and so, probably, could you.

What do all these wonders have in common?  Well, their kindness to the earth and to human health is what qualifies them for a sustainability list.  They are accessible to anyone, inexpensive to obtain and maintain.  Many of them serve not only practical but also esthetic needs; they satisfy the eye, the palate, or the soul.  Most are old in concept, though they may have modern variations.  Something like them has evolved in many different cultures.  Most are objects you can buy, but usually from a local maker, not a multinational corporation.

Maybe that’s why we don’t much appreciate the humble, sustainable wonders around us.  Their value is too obvious to need touting.  You only have to spend billions “marketing” something if its worth is in doubt.


Copyright Sustainability Institute 1999

What Does Solar Cost?

After 10 years of working in the solar industry, the question that we hear most often is, “What is the cost of solar?” To answer this, we must first consider a few factors. We look to see if solar is a viable option for your property. Aspects of your property that increase the efficiency of a solar system include a south/southeast facing roof with little to no shade. If you believe that your roof may not be available option or are simply opposed to having panels on your roof, you can explore other options. Ground or pole mounted systems (providing that you have the available space) are viable options and in some cases, we can build a unique structure just for solar. After determining viability for solar on their property, we will then determine what that individual’s goals and expectations are for their solar project.

If a person is seeking to reduce the cost of their electricity bill or potentially make a profit on their solar installation, we would recommend a grid-tie system. A grid-tied system involves having a solar system installed that feeds back into the power grid. All of the energy produced by this system is sold back to your local power company. In most cases, the power company will credit your bill for the kilowatt energy produced, so depending on the size of your system, you can reduce or, completely cancel out your bill. Added value occurs when you produce more energy than you consume and receive a check in the mail in place of your power bill. If a person mentions to us that they are interested in generating and storing their own energy, we would recommend an off-grid installation. With off-grid installations, you become independent of the power company, choosing instead to go with a reliable combination of solar and a battery backup system.

After determining which project style fits your energy needs, we can start to get a better idea of cost. Factors to consider include; your energy usage, material cost, city permit fees, local power company fees, labor fees, and travel cost. A rough estimate for a solar installation can be determined through the regions avg. price per watt cost towards a new system. The avg. price per watt found in our area is generally between $3.00-$4.00 per watt. For example, a 10kw (or 10,000w) grid-tie system, which could off-set a large portion of the average utility bill, would run between $30,000-$40,000 (with a buffer zone on each end of $5,000). The life expectancy of that system is between 20-40 years, paying itself off around the first 8-12 years. This means that you have the potential to see up to 20 years of profit from your system. Combining this with the current 30% federal tax credit on solar installations, you can see why it is a sound investment. Depending on certain factors, many additional incentives may be available to use with that federal credit. Additional benefits include an increase in property value and of course reduced overall environmental impact. To quote a local realtor, “If there are four equal valued homes for sale on the same street, the one with solar panels will always sell first.”

If after reading this you would like to know more about solar and see what options you may have with solar energy, please give us a call at 423-535-9350 or write in through our website at!

The summer solstice is coming! Here’s what to know

by Melissa Breyer (@MelissaBreyer)
Science / Natural Sciences


The 2017 solstice falls on June 20 or June 21 depending on where you are … celebrate with a crash course in curiosities about the longest day of the year.

It’s hard to believe that a mere six months ago, those of us in the Northern Hemisphere were grimly facing the shortest day of the year – and now suddenly, the sun is setting at bedtime and the unofficial first day of summer is upon us! How did that happen?! To be honest, the winter and summer solstices sometimes feel out of whack with the seasons they represent – shouldn’t the longest day of the year be the hottest and occur at the height of summer? Answers to that curiosity and more explained below.

(Note: For the Southern Hemisphere this is all reversed, thanks to our topsy-turvy world.)

1. First things first, the when of it all
In North America this year we can revel in longest period of sunlight on Wednesday, June 21 at 12:24 AM. EDT. This is the precise moment when, basicly, the sun stands still at its northernmost point as seen from Earth. Its zenith doesn’t teeter north or south, but sits patiently at the Tropic of Cancer before switching directions and heading south again. This is where the word solstice comes from; the Latin solstitium, from sol (sun) and stitium (to stop).

Since this happens at a specific moment in the heavens, it happens at the same time across the time zones – which means that for some, it falls on June 20.

CDT: June 20, 11:24 PM.
MDT: June 20, 10:24 PM
PDT: June 20, 9:24 PM

2. There will be SO MUCH SUNLIGHT
Get your sunglasses out, bare your shoulders, put on the sunscreen! The weatherman willing, we will have oodles of sunlight. In New York City, we will have a soul-affirming 15.05 hours of daytime. (You can check your day length at the Farmer’s Almanac sunrise and sunset calculator, to see what to expect in your neck of the woods.)

3. The longest day isn’t the hottest
Given that the sun passes directly overhead on the solstice – and it’s the day with the most sunlight – one wouldn’t be off-base to think it might claim the highest temperatures as well. But no. As NOAA explains, in the US, temperatures continue to inch up into July. “The temperature increase after the solstice occurs because the rate of heat input from the sun during the day continues to be greater than the cooling at night for several weeks, until temperatures start to descend in late July and early August.” The map below, based on 30 years of data, is a few years old but still gives a good indication of what to expect where.

warmest day© NOAA

4. The north gets short-changed on summer sun
While it certainly may not feel like it, in the Northern Hemisphere’s summer we are actually farthest from the sun thanks to the planet’s tilt; we get 7 percent less sunlight than the Southern Hemisphere does during their summer. Something we’ll be grateful for in a few billion years (see #8).

5. The constellation of Cancer steals the spotlight
The Tropic of Cancer is so-named because waaaay back when during the ancient naming of these things, the solstice sun appeared in the constellation Cancer. Due to subsequent shifting of Earth’s axis, explains Discovery, the Tropic of Cancer is now misnamed. This year on the June solstice, the sun will actually be moving from constellations Gemini to Taurus.

6. Lots of sunlight, but a dark day for science
According to legend, Galileo was, rather ironically, forced to recant his theory that Earth revolves around the sun on the summer solstice of 1633.

7. It’s a day of celebration
The solstice has been such a vastly important day throughout history that it would be impossible to list all the significant celebrations here. From Stonehenge on, the day is more-so-than-not marked by revelry – including no shortage of libations, nudity, dancing in the woods, costumes, parades, bonfires and general merrymaking.

8. The future of the summer solstice is bright. Really, really bright
The gifts of the sun have been a cause for celebration for millennia – and as it turns out, based on models of stellar evolution, the sun is about 40 percent more luminous today than it was when the Earth was born some 4.5 billion years ago. And it doesn’t look like it’s going to slow down. Scientists estimate that in another 1 billion to 3 billion years, the sun’s looming intensity will “boil away Earth’s oceans, turning our planet into an endless desert,” notes Discovery. In which case, the winter solstice will surely become the day to frolic naked in the forest…

How many solar panels do I need for my home?

by Energy Sage

Determining the size of your solar energy system starts with a simple question: how many solar panels do I need for my home? As most people want to produce enough energy to completely eliminate their electricity bill, the first step is determining what size solar system will produce enough power to meet your household consumption levels. Ultimately, you will be calculating how many kilowatt hours of power you will need and finding the correct system size and number of panels to power your house.

How many solar panels do I need?

If the average household consumes 11,000 kWh per year and we assume 250 watt solar panels, we can use the high and low panel production ratios to calculate an average. Thus, the typical homeowner will need 28 – 34 solar panels to cover 100% of energy usage (dependent on location and roof size).

For those wondering how we estimated those numbers for energy consumption and required number of solar panels, here’s the breakdown. When you want to understand how much power you’ll need, start by looking at how many kilowatt hours (kWh) of electricity you use in a year. Most utilities provide you with your total power consumption for the last twelve months on your monthly bill. To offer some perspective, one kWh is 1,000 watts of power being used in an hour. So, if you have 20 lights in your home and they all use 50-watt bulbs, having every light on in your house for one hour would use up one kWh of electricity. According to the latest data from the U.S Energy Information Administration, in 2013 the average American household used 909 kWh per month. Said differently, the average American household consumes just under 11,000 kWh per year.

In order to find a range for number of solar panels, we compared Arizona and Maine’s solar panel production ratios, 1.31 and 1.61, the highest and lowest in the U.S.. We then took 11,000 kWh and divided it by the respective ratios and then divided that number by 250 (the typical panel wattage). That calculation gave us high and lows for the average number of panels a homeowner will need.

How many kWh can your solar panels produce?

The amount of power (kWh) your solar energy system can produce depends on how much sunlight exposure your roof receives. The amount of sunlight you get in a year depends on both where you are in the country, and what time of year it is. California has more sunny days annually than New England. But in either location, you’ll be able to produce enough power to cover your energy needs! If you live in an area that gets less sun, you’ll just need to have a larger system installed at your home.

Two comparably sized households in California and Massachusetts consume the average amount of electricity for an American household, about 11,000 kWh annually. The California household needs a 7.0 kWh system to cover 100% of their energy needs. By comparison, the comparable household in Massachusetts needs a 8.8 kWh systems to cover their energy needs. Solar panel systems in California are smaller than the solar panel systems in Massachusetts, but are able to produce the same amount of power because they’re exposed to more sunlight each year. Homeowners in less sunny areas, like Massachusetts, can make up for this disparity by simply using more efficient panels or increasing the size of their solar energy system, resulting in slightly more solar panels on their rooftop!

In order to offer comparison data on how many panels and how much power you will need, we’ve compiled a table that compares average annual energy need to estimate the number of panels required to offset typical energy demand. We looked at data for the 6 most common system sizes that we see active in the EnergySage Solar Marketplace. In order to calculate the below data, we averaged annual kWh production in the top 12 solar states and assumed standard 250 watt panels in order to calculate how many panels you would need. The average system size in the U.S. is 5kW (5000 watts) so you can use that as a benchmark if you’re unclear on what your power needs will be.

How many solar panels will I need? System size comparison table

System Size Average Annual KWH production Estimate number of solar panels
3.5kW 4,954 14
5kW 7,161 20
7kW 9,909 28
10kW 14,165 40
12kW 16,987 48
15kW 21,234 60

The table above assumes that you’re using standard-efficiency panel. However, the number of panels you need to power your home, and the amount of space that your system will take up on your roof, will change if you’re using lower-efficiency economy panels or high-efficiency premium panels. Below is a table that will give you a sense of how much space your system will take up on your roof, whether you choose economy, standard, or premium panels.

How many solar panels can I fit on my roof? System size compared to square footage table

System Size Economy Panels (sq ft) Standard Panels (sq ft) Premium Panels (sq ft)
5 kW 306 254 224
10 kW 612 508 448
15 kW 918 763 672
solar panel system size infographic

The average size of 5, 10, and 15 kW solar panel systems using standard panels.

Perhaps one of the most difficult aspects of sizing a solar panel system is estimating annual energy usage for your household. A number of larger consumer products or add-ons can significantly change your annual kilowatt hour requirements and thus can greatly impact how many panels you will need. For example, if you’ll be running central air conditioning or powering a heated swimming pool in your backyard, the size of your solar panel array could be drastically altered. To get a feel for the energy impact of various products you may have or may be considering for your home, check out this table comparison.

How many solar panels will I need for common household products?

From reviewing the various kWh requirements for everyday household appliances and products, one thing is clear: certain add-ons will dynamically change monthly energy use and solar panel system size. For example, pairing your electric vehicle with solar panels is a great way to reduce carbon emissions and improve energy efficiency, however, it should be planned accordingly considering it could potentially double the size of your pv system. Though it is certainly possible to install a solar system and then add more panels later on to accommodate increased energy needs, the most pragmatic option is to size your system as accurately as possible based on your expected purchases such as an electric vehicle, swimming pool or central air system. Asking yourself “how many solar panels will I need for my refrigerator, my hot tub” and etc is a great habit for any new solar homeowner.

The Facts of the Paris Agreement

The Paris Agreement is a 2015 agreement between 147 countries with the goal of reducing global carbon dioxide emissions to prevent a global temperature increase of 35.6 degrees Fahrenheit (2 degrees Celsius) above the pre-industrial level. The agreement requires each country involved to work towards this goal through NDCs (Nationally Determined Contributions), such as, “domestic mitigation measures, with the aim of achieving the objectives of such contributions.” As of June 1st, the United States have announced that we will be backing out of this agreement.

The US is the 2nd largest carbon dioxide producer globally, contributing to 17.89% of the carbon dioxide produced by countries. To put this in perspective, the third largest contributor is India with 6.81%. The US not participating puts much more pressure on other countries to clean up a mess that we helped create in a major way. However, even though we are backing out, a group of 30 mayors, 3 governors, over 80 university presidents, and over 100 corporations have all agreed to abide by the regulations of the Paris Agreement regardless of how the US proceeds.

The main threat presented by global warming is the melting of land ice in areas like Greenland and Antarctica which each. This additional water is causing the sea levels to rise at an average rate of 1.8mm/yr. Currently, around 700,000,000 people live in areas less than 30 feet above sea level. The rising sea level is already causing devastation in flat countries like Malaysia, destroying fields and homes, driving people into cities that are not built to maintain the population increase. At the rate we our going, more communities at sea level, such as Miami, will be engulfed by the ocean. This will lead to hundreds of billions of dollars in property damage and resource loss in the united states alone. To learn more on this I highly recommend watching this documentary, available for free on YouTube.