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Posts Tagged ‘energy efficient’

Windcatchers have been employed for thousands of years to cool buildings in hot climates. The windcatcher is able to chill indoor spaces in the middle of the day in a desert to frigid temperatures.

Windcatchers have been employed for thousands of years to cool buildings in hot climates. The windcatcher is able to chill indoor spaces in the middle of the day in a desert to frigid temperatures.


The following list includes dozens of low tech, low cost ways to cool buildings in hot climates passively without electricity or machinery, i.e., passive cooling or natural cooling. This list is in addition to the 11 or so simple passive cooling techniques that I talked about in my video the other day. Altogether there are over 50 practical methods for cooling your home sustainably. Despite all these wonderful methods, most people – at least in North America – live in poorly insulated boxy houses with costly, wasteful air conditioners. This is one example of “ignorance is not bliss”.
– night cooling: open the windows at night to let in cooler, fresher air.
– roof vents for improved ventilation. This could include a ridge vent and cupola.
– gable vents on gable end walls
– adequately shaded clerestory windows
– smaller windows on the east and west to prevent overheating (if the walls aren’t shaded)
– louvers and vents
– well located doors
– 50-100% more or larger windows on the leeward side than the windward side to help hot air to escape
– earth berming with moist vegetation such as grass
– keeping vegetation moist around the house to help cool the breezes (the yard)
– planting trees to funnel air toward your house
– plant trees that don’t block breezes
– wing wall to direct cool breezes into the home
– building on stilts
– stack effect: multi-story designs can be very effective at encouraging natural convection
– open plan living areas that encourage air circulation
– narrow floorplans
– orientation to catch breezes more effectively
– location: breezy locations near lakes, etc.
– outdoor living areas
– porches/verandas that shade the walls
– shaded, high thermal mass walls such as earthbags, adobe, etc.
– windscoop/windcatcher (with possible addition of a water element)
– evaporative cool wall such as double terra-cotta brick walls (low fired brick) filled with moist sand
Venturi effect
– solar chimney: chimney designed to heat air and draw air from the house
– atrium or sunroom: can act like a solar chimney if properly designed
– basement: upper floors draw cool air upwards from the basement
– cool pantry and rootcellar
– well, open air cistern or underground water canal in the basement
– earth tubes in dry climates where mold is not a problem and digging is fairly easy
– roof insulation and reflective roof insulation
– fly roof (secondary roof over the main roof)
– green roof/living roof
– soffit vents and baffles between rafters to improve roof ventilation
– light roof color that reflects sunlight
– manmade water feature such as a lily pond on the windward side
– awnings (if you don’t have large roof overhangs)
– inner courtyard/open atrium
– pergolas and trellises to shade walls
– minimize sun reflection and re-radiation from surrounding environment: plants versus gravel or pavement
– blinds: close if sunlight is entering window
– avoid skylights unless openable and tinted
– smooth plaster reflects more light than textured plaster

Note: This is just a list of practical cooling strategies. There are plenty of ‘yeah, buts’ you should be aware of to prevent problems. There isn’t time or space here to cover everything. A fair amount of research is required to learn the details so you can optimize the passive cooling design for your home and building site.

Image source: Wiki – Windcatchers (good info on windcatchers)
Good reference with more details: Passive Cooling at House-Energy.com

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Chest fridge that consumes about 0.1 kWh per day or about $5 worth of electricity per year.

Chest fridge that consumes about 0.1 kWh per day or about $5 worth of electricity per year.


I saw this fridge a few years ago on Build it Solar.com. It’s a great site like I keep saying with hundreds of practical projects. Several years later and now I’m asking the same questions as the author below. Why haven’t more people made the switch to this super energy efficient fridge?

“Using vertical doors in refrigeration devices is an act against the Nature of Cold Air. Understanding and cooperating with Nature rather than acting against it leads to much better efficiency.

My chest fridge (Vestfrost freezer turned into a fridge) consumes about 0.1 kWh a day. It works only about 2 minutes per hour. At all other times it is perfectly quiet and consumes no power whatsoever. My wind/solar system batteries and power-demand-sensing inverter simply love it.

It is obvious that a truly energy efficient fridge does not cost any more money than a mediocre one. It actually costs less. It also has amazing food-preserving performance because temperature fluctuations in its interior are naturally minimized.

So – WHY mediocre food-spoiling fridges are being made? WHO makes decisions to manufacture them? Who awards them “stars” and other misleading awards? Why people continue to buy and use energy wasting and food-spoiling devices? Does anyone care about understanding anything?

Nearly every household on Earth has a fridge that totally wastes at least 1 kWh of energy a day (365 kWh a year). How much reduction in greenhouse emissions can we achieve by banning just ONE inefficient household device in just ONE country? How many politicians debating for how many years will it take to achieve such a ban?

Rather than waiting for someone to do something I would like to volunteer to supply modified chest freezers and/or freezer modification kits to environmentally conscious people of Australia. Let’s do something in the right direction right now.”

Source: Mt. Best.net (lots more good info on this site)
You can read the full article here.
How to Convert a Chest Freezer to a Fridge

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Underground houses by Vetsch Architektur

Underground houses by Vetsch Architektur


Modern, sustainable underground home

Modern, sustainable underground home


Hebridean Earth House

Hebridean Earth House


“Underground living refers simply to living below the ground’s surface, whether in naturally occurring caves or in built structures.

Underground homes are an attractive alternative to traditionally built homes for some house seekers, especially those who are looking to minimize their home’s negative impact on the environment. Besides the novelty of living underground, some of the advantages of underground houses include resistance to severe weather, an exceptionally quiet living space, an unobtrusive presence in the surrounding landscape, and a nearly constant interior temperature due to the natural insulating properties of the surrounding earth. The greatest draw for most, however, is the energy efficiency and environmental friendliness of such houses. Because of the stable subsurface temperature of the Earth, heating and cooling costs are often much lower in an underground house than in a comparable above-ground house. When combined with solar design, it is possible to eliminate energy bills entirely. Initial building costs are also often exceptionally low, as underground building is largely subtractive rather than additive, and because the natural materials displaced by the construction can be recycled as building materials. However, underground living does have certain disadvantages, such as the potential for flooding, which in some cases may require special pumping systems to be installed.”

Source: Wiki
Image source: Erdhaus
Image source: Home-02
Image source: Hebridean Earth House

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Earth covered farm homes in Keldur, Iceland. These were built in 1193, and are supposedly the oldest buildings in Iceland. (click to enlarge)

Earth covered farm homes in Keldur, Iceland. These were built in 1193, and are supposedly the oldest buildings in Iceland. (click to enlarge)


Earth-sheltered home

Earth-sheltered home


Earth-sheltered home

Earth-sheltered home


“Earth sheltering is the architectural practice of using earth against building walls for external thermal mass, to reduce heat loss, and to easily maintain a steady indoor air temperature. Earth sheltering is popular in modern times among advocates of passive solar and sustainable architecture, but has been around for nearly as long as humans have been constructing their own shelter.

The expression earth-sheltering is a generic term, with the general meaning: building design in which soil plays an integral part.

Definition of earth-sheltering: A building can be described as earth-sheltered if its external envelope is in contact with a thermally significant volume of soil or substrate (where “thermally significant” means making a functional contribution to the thermal effectiveness of the building in question.)

There may be said to be three forms of earth-sheltered building:
– earth-covered
– earth-bunded [I call this earth bermed.]
– subterranean

The benefits of earth sheltering are numerous. They include: taking advantage of the earth as a thermal mass, offering extra protection from the natural elements, energy savings, providing substantial privacy, efficient use of land in urban settings, shelters have low maintenance requirements, and earth sheltering commonly takes advantage of passive solar building design.

The Earth’s mass absorbs and retains heat. Over time, this heat is released to surrounding areas, such as an earth shelter. Because of the high density of the earth, change in the earth’s temperature occurs slowly. This is known as ‘thermal lag.’ Because of this principle, the earth provides a fairly constant temperature for the underground shelters, even when the outdoor temperature undergoes great fluctuation. In most of the United States, the average temperature of the earth once below the frost line is between 55 and 57 degrees Fahrenheit (13 to 14 degrees Celsius). Frost line depths vary from region to region. In the USA frost lines can range from roughly 20 inches to more than 40 inches. Thus, at the base of a deep earth berm, the house is heated against an exterior temperature gradient of perhaps ten to fifteen degrees, instead of against a steeper temperature grade where air is on the outside of the wall instead of earth. During the summer, the temperature gradient helps to cool the house.

The reduction of air infiltration within an earth shelter can be highly profitable. Because three walls of the structure are mainly surrounded by earth, very little surface area is exposed to the outside air. This alleviates the problem of warm air escaping the house through gaps around windows and door. Furthermore, the earth walls protect against cold winter winds which might otherwise penetrate these gaps.”

Source: Wiki
Image source: Wiki
Image source: Earth-sheltered Homes (good summary of earth-sheltered homes)
Image source: Earth-sheltered Homes

From Earth-sheltered Homes by Rob Roy:
“Back in the ’70s, earth-sheltered housing enjoyed great popularity, thanks in part to the energy crisis resulting from the 1973 oil embargo. Adventurous builders and researchers explored various forms of earth-sheltered building, from underground excavated spaces to surface-level buildings with earth piled in berms against their walls. People searching for alternatives to conventional building showed that sheltering a building with earth could reduce energy costs for both heating and cooling by half or more — at little or no increased expense… An earth-bermed house can reap about 95 percent of the energy advantages of a fully underground home, and adding an earth roof, or living roof, further promotes planetary health by “greening” the house’s footprint.”
Read the full article at Mother Earth News

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Montague Urban Homestead, Massachusetts

Montague Urban Homestead, Massachusetts


Montague Urban Homestead floorplan (click to enlarge)

Montague Urban Homestead floorplan (click to enlarge)


I was browsing Build it Solar.com, one of my favorite websites, and found the Montague Urban Homestead zero energy home pictured above. I was initially attracted to the home design by its simple lines and potential for do-it-yourself owner-builders (the focus audience of our blog). But then I saw the $180,000 price tag and was immediately put off. That’s not affordable to most. I started to leave the site but then realized how some of the good ideas in this design could be merged with natural building materials to create very low cost zero energy homes.

The Montague Urban Homestead was the winner of the Massachusetts Zero Energy Challenge 2009, and also the NESEA Zero Net Energy Building Award for 2010.

The goal of the design: “To eliminate dependence on the dirtiest/most harmful energy sources – coal, nuclear, oil, electricity from biomass – and meet our housing and energy needs with as little health and environmental impact as possible, in an economically-affordable, low-toxic, sustainable home.
The Montague Urban Homestead is a single-story, single-family detached dwelling of 1152 square feet, with three bedrooms and one bath. It also has an attached insulated but unheated mudroom of 96 square feet.

It has an audited HERS rating of -8 and a Platinum (highest level) LEED rating. The house is close to German “passive house” standards – a “Power House”, or “Below Zero Energy” house that is also free of many of the typical toxins used in building.”

A lot can be learned by studying award winning designs. Study enough of them, mix and match features you like, combine with low cost building methods such as straw bale, earthbag, pole building, earth floors and plaster, etc. and you can have a zero energy home that costs substantially less than contractor-built projects if you build it yourself. You can take existing designs like the one above to the next level. We know X, Y, and Z work (ex: insulated slab, solar water heater and heat recovery ventilator) and then it’s just a matter of using these ideas in a house made with more affordable, sustainable materials.

Source: Build it Solar.com (very good website)
Full plans “as built” also at Build it Solar.com
Zero Energy Earthbag House plans

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Cody Lundin’s energy efficient, sustainable home

Cody Lundin’s energy efficient, sustainable home


No heating or air conditioning, and yet Cody’s house stays around 72 degrees Fahrenheit. Cody’s website and book explain how he built his ferrocement house. You could build a house like this with earthbags on the sides and ferrocement on the roof.

“It’s winter in the high desert as I write this, and last night the thermometer outside read 9 degrees F (minus 13 degrees C), a bit colder than typical and, ironically, part of the same storm system that left 500,000 people without power in the Midwest. Regardless of single-digit temperatures, my home remained a cozy 72 degrees F (22 degrees C), and it did so without using any conventional energy resources. I have no heating bills of any kind and I don’t burn wood. My home is heated entirely by the free clean energy of the sun, a phenomenon commonly referred to as “passive solar.” Along with orienting my home solar south, I have the proper square footage of windows to match the square footage of my home so that it doesn’t under- or overheat. These windows let in shortwave radiation from the sun that soaks into my stone floor during the day. At night when outside temperatures dip, the stone floor, which is a great conductor of the sun’s energy, re-radiates the stored sunshine, or heat, as long-wave radiation that keeps the house warm. Insulation and thermal mass help retain the heat throughout the night. The process starts anew the next day. Even though my home is dependent on the sun for heat, it’s designed to retain this comfort for several days of cloudy weather or storms.”

Full article at Cody Lundin.com

Note: Cody’s house design works in part because he is in a very mild climate. As Kelly Hart points out, the ground temperature in his area is about 70 degrees, so it takes very little solar gain to keep the house warm in winter. This design would need to be modified for extremely cold and hot climates.

Cody is a world famous survival expert. Search YouTube for Cody Lundin survival videos.

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There’s a huge groundswell of interest in living more lightly on the earth. On the one hand, conscientious homeowners want to pollute less and protect natural resources. But they also want to save money on construction and energy costs and still have a beautiful, safe and comfortable home. Whether you call it natural building, green building or sustainable building, the eco-friendly building techniques outlined here meet all of these goals and more.

In designing your dream eco-friendly home, perhaps the most important consideration is affordability. This requires a realistic evaluation of individual and family wants and needs. Building small and simple, only what you need, will save money and headaches every step of the way, including reduced long-term energy costs and maintenance. Building small and simple means fewer resources are consumed, resulting in a smaller energy footprint for your home. That’s good for you and the planet.

Building affordably requires discipline and the right mindset. All too often people get swept away with ideas from home design magazines and luxury home tours. To build affordably and avoid budget creep during the building phase, put everything in writing and stick to the budget. Make a list of materials and then shop and compare prices. This one step alone, just a couple hours of effort, can easily save you $1,000 on a small home.

Do your research and plan meticulously. Every hour spent on planning will reduce problems (and unnecessary costs) later. Keep a careful eye on every detail. Even professionals make mistakes, so allow for delays and cost overruns. If you’re not a professional builder, be doubly careful. It is heart wrenching tearing out mistakes and doing things over. There are thousands of small steps in building a home and many of them must proceed in a certain sequence. Being your own contractor and building your home as a do-it-yourselfer is a good way to cut costs, but again, do your research, learn as much as you can and plan judiciously.

Going low-tech is one of the easiest ways to save money. We’re constantly bombarded with advertising claims that will supposedly improve our lives, when in reality they often complicate them. Scrutinize every product, every material that goes into your home. You may want to prioritize items that quickly pay for themselves. For example, we added vents in the gable end wall of our kitchen. (It’s a hot climate, year-round.) Everyday hot air rises to the top of the cathedral ceiling and flows out the vents … for free. Our kitchen stays cooler, the air is fresher and the refrigerator doesn’t work as hard. And soon, we’ll be enjoying our outdoor kitchen that will keep most of the heat outside. [Outdoor kitchen is now finished.] These are but a few examples of working with nature to improve the design of your home.

You can read the entire article for free at Civil Engineer Group.

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