Passive Solar Home Using Below Floor Soil Heat Storage

Josh built this very unique passive solar home in Missouri. The house incorporates the usual south glazing to gather solar heat and good insulation to reduce heating requirements.  But, it also has a unique heat storage capability using the soil under the main floor.  And, a unique cooling system that makes use of the same soil heat store.

Passive solar home with under floor heat storage

 The home has a 2 foot deep earth heat storage bank under the slab floor of the house.  During sunny periods, solar heated air from the main floor is circulated through ducts embedded in the heat store in order to store heat for use during the evening.  This has the added benefit of reducing the chance of overheating the main floor as sometimes happens on passive solar homes.

To provide cooling in the summer, cool well water will be circulated through pex tubes embedded in the under floor heat store.

Solar heated air is circulated through these under floor ducts to add heat to the heat store.

All the details on this unique design here...

Thanks very much to Josh for providing information on this unique design.

Rain Harvest Calculator

Darrel sent in a note on the Rain Harvest Calculator that he has developed and made available free of charge on his website.  Its a dandy.

Its a very good Rain Harvest tool that provides a lot of flexibility -- you have control over all of the following:

• Location -- specify your location and the calculator looks up the average monthly rainfall.
• Collection area
• Collection efficiency
• Water usage by month
• Water storage available
• Supplementary water available by month
• Specify years with less or more than average rainfall

The calculator provides very nice graphic output that makes it very clear what your rain harvest and water supply situation is and makes it very easy to do what if studies on collection area, storage, usage, ...

Well worth having if you are planning a rain water harvesting system.

Thanks Darrel!

Gary

David's DIY drainback solar water heating system

David has designed and built a very nice solar water heating system for his energy efficient home. It is a drainback system that uses an EPDM lined, non-pressurized wood tank for heat storage.

Some of the highlights of Dave's system...

• Tank design suitable for limited height crawlspaces.
  
• Nice tank frame design using half lap joints for the corners
  
• Used new old-stock commercial collectors at a very good price
  
• Efficient heat exchanger installation
  
• Using used and recycled materials kept the cost of the system down

David with his three drainback collectors

David's system consists of three collectors mounted vertically on the south wall of his house. The heat storage tank for the system is in the crawl space under the collectors. Its a drainback system, so for freeze protection, the water in the collectors drains back to the heat storage tank when the pump turns off.

The collectors were obtained on Craig's list as "new old-stock" for a very good price.

The heat storage tank is a non-presurized, wood framed, insulated with polyiso rigid foam, and then lined with an EPDM liner - this is a design that has been used on quite a few Build It Solar projects, and works well.

David with heat storage tank in his 29 inch deep crawl space.

The heat exchanger uses a 300 ft coil of pex pipe that has been used successfully on several Build-It-Solar projects. The scheme that Dave used to support the pipe coil and space the coils out is very nicely done and likely provides a worthwhile gain in heat transfer efficiency. One nice thing about this style of heat exchanger is that it stores several gallons of fully preheated water right in the coil.

PEX coil heat exchanger with nice coil separation and support scheme.

See all the details here...

Gary

January 13, 2018

An Experimental Trickle Down Solar Water Heating System

Lu has designed and built a solar water heating system with several innovations.

The system includes a collector based on the the Thomason trickle down design with some new wrinkles.

Innovative features include:

• The unique trickle down collector.
• A storage tank with a new liner design.
• An innovative version of a copper heat exchanger.
• A PV powered diaphragm pump.

Lu provides full construction details as well as measured performance...

Innovative, Energy Efficient, Solar Heated, Cost Effective Home in Montana

I recently got the chance to see a very innovative solar home being built near Bridger Montana by Andrew Ray of Rational Design/Build.

Andrew (and his frequent conspirator Clint Wicks of CW2 Construction) have been building homes for fifteen years, with Andrew getting his start with Steve Loken in Missoula.  But, this time its a really special home in that its for his own family. He is a very innovative builder and careful planner, and on this home he has taken out all the stops and included all of the best energy efficiency, solar, and material saving features he has used and studied over the years. Its a fascinating home.

Low Thermal Mass Sunspace (LTMS) -- provides high solar fraction solar space heating with better control and more efficiency that conventional passive solar heating.

The Low Thermal Mass Sunspace provides 213 sqft of glazing optimized for solar space heating.

Inside-out Mooney Wall -- provides an R34 with near zero thermal bridging. A low cost, high performance wall.  The walls are also very efficiently framed with continuous top of wall header and with metal bracing in lieu of sheathing.

The inside-out Mooney Wall with metal bracing instead of sheathing, and continuous top header.

Crawl Space Plenum -- serves as a well sealed plenum to distribute the heat from the Low Thermal Mass Sunspace and the wood burner to the house.  It is constructed from Insulated Concrete Forms with a unique integrated footer design that requires no forms.  

Sealed crawl space that serves as plenum to distribute solar heat from LTMS

The house uses many innovative techniques to minimize material use and labor.  There are only eight sheets of OSB used in the entire home!

Note the minimal framing that reduces material use and thermal bridging.

While the home has about half the heat loss of an conventional construction home, the cost is no greater than conventional construction.  

All the details on this solar efficient home...

A lot to be learned from this house.

Gary

Ian Woofenden's Renewable Energy Workshops

I just want to give people a heads up on some excellent DIY renewable energy workshops provided by Ian Woofenden.

These workshops cover practical, standalone systems on solar electric, solar thermal, wind power, small hydro power and energy efficiency.

Ian's workshops are known for a practical and realistic approach to DIY renewable energy -- they are based on Ian's decades of real experience in designing, building and consulting on actual systems and decades of living in an off grid home. Expect to leave one of Ian's workshops with actual hands on knowledge and experience that will get you ready to build a practical system of your own.  Just as important, the workshops will provide you with the knowledge and tools to determine if a renewable energy system is a good choice for your situation.

Ian is also a senior editor and author for Home Power Magazine -- search their archives for his many hands on, practical and honest renewable energy project articles.

Ian's next workshop will be in Costa Rica and will be on Solar Electricity for the Developing World. This is the overview for the up coming workshop:
"Learn about solar electricity for developing world in the developing world! This workshop provides an introduction to stand-alone solar-electric (PV) system design and installation, with a focus on small, rural systems.  The workshop combines classroom sessions with a strong emphasis on real-world projects in the community, along with hands on labs.  You will have the opportunity to understand, design, and install lighting and cell phone-charging systems that can dramatically improve the living conditions of the local people.  This is an experimental program, with real-world focus.  Come and learn the basics of simple stand-alone solar-electric systems for rural people by doing, sharing, and experiencing on projects in the developing world."

You can find out more about this and his past and planned workshops at his website Renewable Reality.

Thanks to Ian for providing these excellent workshops.

Gary

A 35 mpg RV Setup

Mike and Nancy have come up with this unique and very efficient camping arrangement.  They pull a tear drop trailer behind their Honda Insight hybrid.  They achieve an amazing 35 mpg and have full sleeping and cooking facilities — they even have a shower!

Honda Insight and Little Guy teardrop trailer.

The Honda Insight is a standard 2001 with the addition of a custom trailer hitch made by Mike.  A transmission cooler has also been added.

The teardrop trailer is a "Little Guy" that provides a full sized bed for two and a small kitchen accessed via the back hatch on the trailer as is usual for teardrop trailers.  The Little Guy weighs only about 500 lbs.

They have even added a solar heated shower enclosure they can set up to take hot showers.

Shower enclosure with pressure tank water system.

Without the trailer attached, the Insight gets 50+ mpg and with the teardrop trailer attached and going the full speed limit plus it gets 35 mpg -- pretty amazing for a full function RV.

The Little Guy teardrop and added Air Cond and Heating unit.

While Honda does not advise towing with the Insight, Mike says it works well and has not seen any adverse effects.

More here...

Its great to see teardrop trailers becoming popular again.

Gary
June 27, 2016

FlipFlic - An Innovative Energy Saving KickStarter Project

The developers of a new KickStarter project called FlipFlic gave me a heads up about their idea.  I was impressed with their design's simplicity, cleanness, low price and its potential to save energy and increase convenience and decided to pass the idea on here.

FlipFlic is a Smartphone controlled device that automatically opens or closes blinds based on the time of day, or temperature, or light level.

Some of the nice features:

• Easy to install.
• Smartphone controlled.
• Blind open/close can be based on time of day, temperature, or light levels.
• Solar powered.
• Low price.

The FlipFlic compact motor unit replaces the existing wand on the blinds.

It is solar powered, so no batteries to replace or wires to run.

Use your Smartphone to set up the times, temperatures, or light levels
that control the opening and closing of the blinds.

The initial offering works with either horizontal or vertical slat style blinds.  Kseniia tells me that the team has it in their plans to develop version that will also work with cellular shades, which,  I think, offers an even greater potential for energy saving due to the greater insulating value of these blinds.

Link to the KickStarter page with full details...

Our house uses lots cellular shades with side tracks to reduce winter heat loss and reduce summer heat gain.  They work great and have a large energy saving and short payback period.  But, the twice a day ritual of raising and lowering the shades can get to be a hassle.  I'm really looking forward to this device to have more control with less hassle.

More window related energy saving ideas on Build-It-Solar...

Gary

A Unique Straw Bale Arch Home Design

I really like this new straw bale home design by Brian Waite.  Its not very often you see a completely new home design that is energy  efficient, sustainable, AND well suited to being built by the home owner, but this one is all of the above.

Brian's new design straw bale home prototype

The design uses a number of identical prebuilt arches for the main structure of the house. The arches are spaced one straw bale apart so that the bales can be stacked between the arches with no trimming.

Arches being set up.

 The arches are light enough to be erected by one person with the aid of a hand winch.  In fact, the entire house was built by Brain with only common tools.

Straw bales install snugly between arches.

 The straw bales are stacked from the floor up to the peak in one continuous stack.

Because the arches provide all of the structural support for the roof, all of the interior walls (if used) are non-structural and would be easy to move over time.

The house has a  number of other unique features, including a means to secure the straw bales without settling, and a passive vent system that keeps the straw bales dry.

Another unique feature that Brain is testing is a quad glazed window design that is made from two standard double glazed glass units.

Quad glazed window made from two standard double glazed units.

 It seems to me that this is a simple design that is well suited to owner builders while offering an R value up toward US 6.

All the details here...

I want to thank Doug alerting me to this fine new design.

Gary
April 3, 2015

The Kume Shade: Simple, Homemade, Low-cost Insulating Curtains

The Kume "family" in Chile has come up with a new design for thermal shades that I think is very interesting and may be a good solution for you if  you are looking for thermal shades.

The Kume shade if various states of rollup

The Kume shades fit in the window frame and roll up to stow in a built in catch at the top -- the rollup only takes a few seconds.

The shades use four layers to provide better insulating value.

Layer 1 is a front insulating (and decorative) material, 2 is a moisture barrier, 3 and 4 are wood batten spacers, and 5 is the back insulation panel.

IR picture shows the Kume shade in action

The shade materials are relatively cheap and the shade is easy to build.  The instructions are very complete.

Good, detailed build instructions

The room facing layer can be a decorative insulating fabric, so the shades can be very nice looking.

One thing this shade appears to address is the problem of condensation on the window and frame that can occur the room air is humid, the outside temperature is cold, and the shade does not prevent room air from circulating behind the shade.  This design's combination of fabric that seals against the window frame and a moisture barrier address this problem.

I'd be very interested in hearing from anyone who build these shades on how well they do.

The Kume "family" is a group of friends and relatives living in Chile who are working together on projects that will have a positive effect on climate change.

For complete details on the design and build ...

For lots more on other thermal shade and window insulating techniques...

Gary
March 7, 2015