Monday, March 28, 2011

Earthbag Construction

I added a new (small) section on Earthbag home construction here...

This was prompted by seeing a TV program on the home of Kelly and Rosanna Hart in Colorado.  Its an earthbag house that they constructed themselves over a three year period.  The house is beautifully done with with each room hand crafted for its purpose.

The home uses a lightweight volcanic rock for the bag fill in order to increase the insulation value.  I'm still not clear on what the actual R value of the walls/roof are -- anyone have a good source of information on this?
It would be nice to know how cold a climate this type of construction makes sense in.

The outer covering of the house (over the earthbags) is papercrete.  An interesting house to say the least.
Beautifully handcrafted interior.

Total cost of the house was $49,900 including land and a solar electric system!  Dirt cheap (sorry).

The and the Earthbag Building book that are listed are both quite good  -- lots of hands on material.  The website is run by Kelly Hart.

The TV program mentioned above is Offbeat America, season 3, episode 1 on The Travel Channel -- it has a nice 10 minute tour of the house.


Thursday, March 17, 2011

Cristian's Earth Sheltered Passive Solar Home in Romania

Cristian is an engineer in Romania, and has designed, built, and lived in this passive solar, earth sheltered house for two years. 

The house is very carefully laid out to make maximum use of space and and the solar heating and lighting opportunities.

 The house features:
  1. Earth sheltering on three sides with a carefully designed PAHS style insulation umbrella that uses the surrounding earth for thermal storage.
  2. Passive solar gain through the south triple glazed windows.
  3. Active solar through several Trombe walls integrated into the south wall.
  4. An extensive earth tube system that pre-heats incoming fresh air and recovers heat from outgoing stale air.
  5. A carefully designed back up wood heating system.
  6. Solar water heating
  7. Provisions for solar electricity.

The house has a very light and open feeling.
The house is located at 45 degrees north latitude and has a serious winter -- the total heating bill for the past two winters has been $70 worth of wood -- about 0.6 cords.

Cristian says it took about 50 versions to get to this final design, and I can believe it -- it shows a lot of careful design work.

This shows the PAHS type insulation umbrella being installed.  This
basically allows earth around the house to act as thermal storage for the house.
Diagram of the layout for the insulation umbrella, drainage tubes, and earth tubes.

 All the details on the design and construction of Cristian's home...

Thanks very much to Cristian for sending in this detailed description of the house!


Solar John in Wyoming with Automatic Solar Shutters

On the way back from Denver we happened to stop at a Rest Area in Wyoming along I25.   The rest area is one of 19 solar rest areas that Wyoming built quite a while back.
South glazing on solar Rest Area in Wyoming
Placard showing all the solar features of the rest area.

The rest areas have bunch of solar features (see placard just above),  but the one that caught my eye was the fully automatic thermal shutters. 

The automatic shutters.

It has always been a bit of a problem in passive solar homes with lots of south facing glazing that while the south windows pick up a lot of useful heat when the sun is shining, they lose a lot heat when its not shining.  While there is normally still a good net gain even with the large night time losses, its still a big improvment in performance if some kind of insulating shade or shutter can be used to reduce heat loss at night.  The problem is that many people are just not up for raising and lower shades or shutters twice a day.

These very simple and automated shutters would be one way to take care of the problem.  The shutters apparently use a set of two cylinders to do the work.  One cylinder is mounted on the sunny side of the shutter and the other on the shady side.  The two cylinders are connected by a tube.  There is some fluid inside the system that partially fills one of the cylinders.  When the sun is shining, some of the fluid in the sun facing cylinder vaporizes which drives the rest of the fluid from the sun side cylinder to the shade side cylinder.  The shutters are carefully balanced with their center of gravity very close to the point the shutters pivot about.  So, the transfer of the fluid from the sun side to the shade sides shifts the center of gravity enough so that the shutter pivot open.  When the sun goes away, the opposite happens.   Simple and clever.

A few more pictures and details here... 

Have you got any ideas for automated window insulating devices?  -- please leave a comment.


Monday, March 14, 2011

Solar Heated Stock Tanks -- Reducing Drinking Opening Heat Loss

The solar heated stock tank project has been a good success with quite a few people building them and reporting good results. 

A solar heated stock tank.
The one remaining problem is that there is still a significant amount of heat loss out the drinking opening, and when you get extended periods of no sun and lots of wind and cold, there can still be enough ice accumulation to be a problem.   BUT, it looks to me like Art has worked out a good solution to this problem.

Art uses canvas awning material to make a sort of shield that reduces heat loss from the large open water surface down to just the area of the drinking hole itself -- see the pictures below.  Art reports that with this technique the tank can go several days of sunless, cold, and windy Wyoming weather without a problem.  Ice still forms in the drinking opening itself, but the horses can easily push the ice out of the way and get to the water -- the canvas is soft enough and slick enough that the ice does not freeze to it.

Using canvas shield to insulate the water surface.

Art's tank
More details...

Thanks very much to Art for sending this in!


Sunday, March 13, 2011

Solar Powered Transporation for Disasters

I got a very interesting email from Terhesa about transportation in emergencies such as the earthquake in Japan.  She brought up some good points about the advantages of having a solar powered form of transportation for this type of disaster.

She pointed out that  the delivery and dispensing of gasoline depends on electricity at many stages.  This means that many of the people in the area effected by the Japan earth quake and similar disasters are unable to use their gasoline powered vehicles.  In some areas, it seems likely that this will be the situation for quite a while.

Most of us live in areas that are subject to natural or man made disasters that could result in extended periods without electricity, and since the gasoline delivery infrastructure depends on electricity, we would also be without the use of our cars.  In times of emergency, not having transportation could be more than an inconvenience -- for example not being able to evacuate a hazardous area. Having some form of independent transportation could also be very important for procuring supplies during an extended natural disaster.

Terhesa suggested that buying a solar powered scooter or bicycle not only gives you a good, low cost, green form of transportation for normal times, it also provides a means of transport that keeps working in case of disaster -- even extended disasters.  I think this is a great idea.

There are quite a few commercial and DIY electric vehicle projects listed here...

I like for a good rundown on the possibilities bikes to scooters to small E-Cars...


Thursday, March 10, 2011

Improving the Efficiency of an Older Wood Burner

Scott has a 1981 wood burner that was built before the EPA regulations for wood burners came into effect.  The wood burner (like many others of that time period) is still in very good shape, but not very efficient.

Scott worked out a couple ways to improve the efficiency:

1- Adding an air supply to support secondary combustion.  This improves combustion efficiency and heat output, and reduces pollution.
The added air supply to support secondary combustion.

New piping to supply preheated air for secondary combustion near
the top of the firebox.

2 - Retrofitting a catalytic combustor which goes into the flue to burn the remaining burnable stuff in the smoke.  This also improves the combustion efficiency and heat output, and further reduces pollution.
Close up of the catalytic combustor (on right) and the bypass
damper to allow the cat to be bypassed.

Shows the new catalytic combustor installed just
above the stove in the flue.

Scott provides a lot of detail on how he built the two devices and also goes through a nice, simple and inexpensive way to measure wood burner efficiency with just an anemometer and a thermometer.

All the details on Scott's wood burner efficiency project...

More projects and information on wood burners and biofuels...


Sunday, March 6, 2011

Giving LEDs a Try

We decided to give LEDs a try for our overhead kitchen lights -- thought I would pass on what we learned since some of it was not what we expected.

We had six overhead R30 track lights in the kitchen that we had converted from incandescents to CFLs  sometime back.  The CFLs worked out pretty well, but they did have a shorter life than you would expect from a CFL.  This is probably because the lights are turned off and on a lot, and that is not good for CFL life.  The lights are also very awkward to replace as the ceiling is 13 ft high, and its hard to get a ladder in the right place.  These are also the most used lights in the house, so that seemed like a good place to start.

Our new R20 track mounted LED lights.

We found that getting the right LED is a bit more complicated that just buying a bulb used to be.  The LEDs are expensive (as in $20 to $40 ish each), the quality is not yet consistent for all manufacturers (perhaps an understatement), and there are light quality and color issues that need to be understood.  And, given that the lights may last the rest of your life, you will live with any mistakes for quite a while.

The link below goes over all the details, but after some homework we were able to find a good LED for our situation, and we are very happy with the result.  The LED we selected is an R20 (instead of the R30's we had).  The new LED uses only 8 watts as compared to the 15 watt CFLs we had, which replaced the orginal 65 watt incandescents.  We also found that we could eliminate one of the lights.  So, we went from the original 390 watts in incandescents down to 90 watts of CFLS, and now 40 watts of  LED lights -- quite a saving -- about 500 KWH a year and over 800 lbs of CO2 compared to the original incandescent lights.

The R20, 8 watt LEDs we chose -- $22 each.

And, the lighting is very nice.  A definite improvement over the CFLs inspite of the fact that on paper the LEDs have substaintially less  total lumen.  In addition, the LEDs come on instantly, and I will never have to go up that ladder again!

The link below goes into some of the issues involved in finding the right LED and in deciding which of your current lights might be good candidates for replacement, and figuring out the dollar and carbon saving.  But, in a nutshell, it looks to us like at the current prices and performance the LEDs pay very well compared to incandescents, and also make sense as CFL replacements in some cases.

All the details on our first LED project...

Anyone have any interesting/helpful experiences in LEDs to pass on?

Light trivia -- did you know that the "R" in R20 means its a reflector light, and that the "20" means that the light diameter is 20 eighths of an inch (2.5 inches)?
An PAR38  is Parabolic Aluminized Reflector light that is 38*1/8 = 4.75 inches in diameter.
An A19 is the traditional Edison household light bulb shape that is 19*1/8 = 2.4 inches in diameter.

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