Let the sunshine, let the sunshine in, the sunshine inLet the sunshine, let the sunshine in, the sunshine in
Let the sunshine, let the sunshine in, the sunshine in
Oh, let it shine, c’monNow everybody just sing along
Let the sun shine in
Open up your heart and let it shine on in
When you are lonely, let it shine on
Got to open up your heart and let it shine on in
And when you feel like you’ve been mistreated
And your friends turn away
Just open your heart, and shine it on in
~The 5th Dimension(Words by James Rado and Gerome Ragni: Music by Galt MacDermot)
What is Passive solar? How does it differ from active solar technology? What are the benefits of passive solar technologies? Read on to find out.
By the way, this weekend marks the National Solar Tour by the American Solar Energy Society. You can check to see if there are any tour events in your area here
Here are some answers from Wikipedia, which explain and define the general principles:
Passive solar technologies convert sunlight into usable heat, cause air-movement for ventilation or cooling, or store heat for future use, without the assistance of other energy sources. Technologies that use a significant amount of conventional energy to power pumps or fans are classified as active solar technologies. Some passive systems use a very small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, and use.
Passive solar technologies include direct gain and indirect gain for space heating, solar water heating systems based on the thermosiphon, use of thermal mass and phase-change materials for dampening indoor air temperature swings, solar cookers, the solar chimney for enhancing natural ventilation, and earth sheltering.
Passive solar systems have little to no operating costs, often have low maintenance costs, and emit no greenhouse gases in operation. They do, however, need to be optimized to yield the best performance and economics. Energy conservation reduces the needed size of any renewable or conventional energy system, and greatly enhances the economics, so it must be performed first. Passive solar technologies often yield high solar savings fractions, especially for space heating; when combined with active solar technologies or photovoltaics, even higher conventional energy savings can be achieved.
Why should we consider going solar? For myself, living in the desert it just makes common sense. Even if you live in the North where days of sunshine are more limited you can still harness the sunlight and heat and put it to good use, both to save money and to reduce your carbon footprint. Here are some factoids about energy use that give justification for cutting back our consumption of energy from the traditional grid system.
· Though accounting for only 5 percent of the world’s population, Americans consume 26 percent of the world’s energy. (American Almanac)
· In 1997, U.S. residents consumed an average of 12,133 kilowatt-hours of electricity each, almost nine times greater than the average for the rest of the world. (Grist Magazine)
· Worldwide, some 2 billion people are currently without electricity. (U.S. Department of Energy)
· Total U.S. residential energy consumption is projected to increase 17 percent from 1995 – 2015. (U.S. Energy Information Administration)
· World energy consumption is expected to increase 40% to 50% by the year 2010, and the global mix of fuels–renewables (18%), nuclear (4%), and fossil (78%)–is projected to remain substantially the same as today; thus global carbon dioxide emissions would also increase 50% to 60%.
· Among industrialized and developing countries, Canada consumes per capita the most energy in the world, the United Sates ranks second, and Italy consumes the least among industrialized countries.
· Developing countries use 30% of global energy. Rapid population growth, combined with economic growth, will rapidly increase that percentage in the next 10 years.
· The World Bank estimates that investments of $1 trillion will be needed in this decade and upwards of $4 trillion during the next 30 years to meet developing countries’ electricity needs alone.
· America uses about 15 times more energy per person than does the typical developing country.
· Residential appliances, including heating and cooling equipment and water heaters, consume 90% of all energy used in the U.S. residential sector.
· The United States spends about $440 billion annually for energy. Energy costs U.S. consumers $200 billion and U.S. manufacturers $100 billion annually.
General Passive Solar Design
This is a great guide to the introduction and principles to passive solar design if you are considering building a new home or retrofitting an existing one. Passive Solar Design Sourcebook
Again, I resort to the blockquotes, because they explain it better than I could.
Solar energy is a radiant heat source that causes natural processes upon which all life depends. Some of the natural processes can be managed through building design in a manner that helps heat and cool the building. The basic natural processes that are used in passive solar energy are the thermal energy flows associated with radiation, conduction, and natural convection. When sunlight strikes a building, the building materials can reflect, transmit, or absorb the solar radiation. Additionally, the heat produced by the sun causes air movement that can be predictable in designed spaces. These basic responses to solar heat lead to design elements, material choices and placements that can provide heating and cooling effects in a home.
Passive solar energy means that mechanical means are not employed to utilize solar energy.o 1.1 Passive solar systems rules of thumb:
o The building should be elongated on an east-west axis.
o The building’s south face should receive sunlight between the hours of 9:00 A.M. and 3:00 P.M. (sun time) during the heating season.
o Interior spaces requiring the most light and heating and cooling should be along the south face of the building. Less used spaces should be located on the north.
o An open floor plan optimizes passive system operation.
o Use shading to prevent summer sun entering the interior. The Center for Renewable Energy and Sustainable Technology (CREST) has an online lesson on calculation of Sun Angles and overhang calculations.
Solar Hot Water
One of the least expensive and easiest to self construct passive solar technologies is the solar hot water heater.
This is a photo of a simple outdoor solar shower I helped build up in the Northwest. Actually it was in a solarium attached to the house, not totally outdoors, but close. My budgies loved to hang out up there and sing to me and on occasion poop on me while I was in the shower.
This site’s El Paso Solar Energy Association guide to Passive Solar technologies has simple to build plans for making a solar hot water heater. (Other links on this site provide plans for making your own Solar still, cooking oven and food dryer.)
The passive solar water heater is known today by many names; PSWH, Batch Heater and Bread Box are the most common and then there is the very technical; Integrated Collector and Storage System (ICS).
The PSWH of today usually starts with a 40 gallon, glass lined tank. These tanks come disguised as ordinary electric water heaters, which are stripped of their appliance shell and insulation. Painted flat black, with high temperature engine or barbecue paint and they’re ready for solar.
Here is another on line guide: How to Build a Solar Hot water system
And if you want to buy one already fabricated, here is a good supplier: The Solar Store
Other Resources/Links:
Solar Technologies Program, US Dept of Energy, Energy Efficiency and Renewable Energy. This site addresses active solar technologies such as photovoltaics. It also has a useful glossary of solar terms here
17 comments
Skip to comment form
Author
by any means, but I can try to answer any questions.
Anyone else here have any experience building and using passive solar technology? If so, please share.
Have a great weekend everybody.
back in the late 1970s, just after my birth, my parents built not one but two passive solar homes on a white birch filled lot in rural maine – the first for our family, the second for friends of my parents. i spent the first five years of my life in that house and still look back fondly at its beauty and function. sadly, both of my folks have passed away so i only have a slight sense of why and how they did it. obviously there were environmental concerns. my father, a fine arts/architecture student in the mid-to-late-sixties, had a hippy sensibility like my mother, a feminist activist. but i also think there were economic concerns. let’s face it, it costs a shit-ton to heat a house in maine. we lived with a single cast-iron stove that heated about 2,000 sf. in fact, my very first words were “OUCH-HOT”, learned while trying to avoid the stove in the middle of the living room.
Author
I’ve got a bunch of errands to run and will be out till early evening. I’ll check in then in case there are other comments.
Also, this will probably be the last of this series, or perhaps the series will shift to less often since my free time is going to become far more scarce after next week.
Anyone interested in filling in, go for it.
Ciao bellas…
out the passive solar home concept on a small cabin before I go ahead and build the big version.
It should help me figure out the structural issues and window placement.
The design will be the double-walled style I mentioned earlier. Most passive solar homes have a slanted window area/solarium. Is this an advantage or disadvantage in colder climates? Because I was thinking of a straight design, outer wall mostly glass, inner wall regular window spacing.
Many homes in the Middle East have a water tank on the roof which supplies all the water used in the house or apartment. In summer the water can get too hot, so you need to have some buckets of cool water on hand to mix with the extra-hot solar heated water.
I’ve been learning how to make “raw” bread, where the heat is kept below 120 degrees F. Starting with sprouts which contain infinitely high levels of nutrition (plant adolescence, if you will), one sunbakes the bread.
It IS delicious. My favorite author/cookbook is Juliano whose recipes in his “uncook book” can be “cooked” with sunlight. I highly recommend his “real toast” recipe.
this series of essays rocks….
it is great to see the things that I threw myself at in the seventies finaly return…..
keep it up I am glad that you are commited to the conservation of life….
I made it out of a cardboard box that something I bought came in.
I didn’t get a chance to use it yet, and I think it isn’t very practical for my upper midwest latitude.
It would work great for purifying water in a place with lots of sun near the equator — and probably in Iraq, a place where much of the water is contaminated and the US is restricting the import of chlorine.