Build-It-Solar Blog

Build-It-Solar Blog Moved to New Location

2010-04-28T00:39:02Z

Hi,

I've moved the Build-It-Solar blog to a new home:

www.BuildItSolarBlog.com

I was having a lot of trouble with the old blog creation software and with its subscribe function, and decided it was better to change than to fight it. The new blog software is the Google/BlogSpot offering, and just seems ever so much easier to deal with.

So, please reset your bookmark, and, if you were subscribed to the old one you will have to subscribe to the new one. Sorry about the hassle, but I think this will work out much better in the long run.

I was able to move all the old posts and comments over to the new blog, so all the history should be there.

Please let me know if you have any problems with the new one.

I will keep the old blog up for a couple months, but I won't be adding anything to it.

Best,

Gary

Test of 2 Thermosyphon Solar Water Heating Systems Using Homemade Collectors

2010-04-22T19:38:46Z

I've been doing some simple testing of thermosyphon solar heating systems that make use of our two homemade collector designs. The idea being to see how these collectors would perform in a thermosyphon system and just to learn more about thermosyphon systems.

For thermosyphon systems, the heated water storage tank is placed above the collector. The inlet of the collector is connected to the bottom of the tank, and the outlet of the collector is connected to the top of the tank.

As sun heats the water in the collector, it becomes less dense and rises out the top of the collector and into the tank. The water leaving the collector is replaced by cold water from the bottom of the storage tank. As long as the sun continues to heat the water in the collector, a circulation loop is setup in which water flows continuously out the bottom of the tank, through the collector, and then back into the top of the tank.

When the sun goes off the collector, the water in the collector cools, and circulation no longer occurs since the water in the collector is more dense than the tank water and naturally stays in the collector.

So, in this system, the circulation is all by natural forces -- no pumps needed. And, the control is automatic -- no controllers needed.

These systems are very simple and are widely used in some parts of the world.

The two collector configurations I tested include the collector that uses PEX tubing with aluminum heat transfer fins, and the configuration that uses copper tubing with aluminum heat transfer fins. Here is the performance log for the copper tube collector (click for full size):

All the details on the test are here:

Details for the PEX tube collector thermosyphon system...

Details for the copper tube collector thermosyphon system...

Please read all the details from the links above if you have an interest in this, and maybe you can help answer some of the outstanding questions.

But, the tentative bottom line appears to be:

- The collector that uses the PEX tubes is probably a bad choice for this thermosyphon application. The collector temperatures observed would likely result in a short life for the PEX tubing.

- The copper tube collector with the top/bottom manifolds and vertical risers worked well, and would likely be a good candidate for a homemade collector in a thermosyphon collector. There were some anomalies that showed up in the performance logging -- maybe you have an idea what is causing these?

Gary

April 22, 2010

Over/Around Window Solar Air Heating Collector -- Help!

2010-04-11T18:36:37Z

The Mother Earth News folks have a strong interest in a solar air heating collector that works in conjunction with a regular window. This is based on the long term popularity of the "Heat Grabber" collector that MEN published a number of years back. While the Heat Grabber has been popular and works well, it does suffer a bit from limited collection area and, also because it sticks out from the building, which does not fit some situations. So, the MEN folks are interested in anyone's ideas on how to improve the design.

The link below is my rough first prototype effort at a solar air heating collector that could be installed over a regular window. The idea is to use the existing window to get air into and out of the collector. This avoids any need to cut holes in the wall for vents. It also makes it feasible to just install the collector over the winter. Some design "challenges" remain.

So, have a look, and if you have any ideas to improve this design or have an alternative design, please leave a comment, or email them in.

Details on the prototype over/around window collector...

The first cut prototype over/around window collector.

The air ducting and screen absorber for prototype collector.

Gary

Solar Space & Water Heating -- With Folding Collectors

2010-04-01T14:55:42Z

Kenneth has incorporated some very nice and new features in his innovative solar space and water heating system -- including:

Folding collectors that allow more collector area for winter and less for summer
Some unique new tools for collector making, including a homemade "Tee Puller', and new designs for forming and clamping the collector fins to the collector tubes.
Use of a surplus stainless steel bulk milk tank for heat storage.

The system is built using the Solar Shed concept, meaning its a separate building that acts as both a storage or garden shed, supports collectors and provides space for the heat storage tank.

A few hightlights below, and 5 pages of construction detail here...

Folding Collectors
The two pictures below show the folding collector feature.

The top photo shows collectors folded out for winter -- 8 active collectors.
The bottom photo shows collectors folded in for summer -- 4 active collectors (along with Kenneth).

Homemade Tee Puller
Kenneth made a tool for drawing a Tee out of a copper collector manifold part -- this allows the collector risers to be connected to the manifold without using reducing Tee fittings or brazing.

Bulk Milk Tank for Heat Storage
Kenneth used a 750 gallon surplus stainless steel bulk milk tank for heat storage.
The tank is mostly buried (to allow drainback from collectors) and insulated with 4 inches of polyiso insulation.

Gary

3 Ways to Save Energy That are a Bit "Out There"

2010-03-28T00:58:00Z

Here are three areas where significant energy might be saved in a home with fairly simple systems. One has to do with using some of the heat in the hot air up in your attic, and the other two have to do with recovering some of the heat we waste in showering.

Regular showers are a major waste of energy. Typically we spend about 3 KWH heating water for a shower, and then send about 85% of that energy right down the drain. It amounts to about 300 KWH for a family of 4 per month.

Using The Heat In Your Attic
This page looks at some of the ways that all that heat up in the attic might be used productively. This includes recovering heat for domestic water heating, space heating, pool heating, and cloths dryer air preheat.
Some of these look fairly practical (to me).

I've been logging the temperatures up in my attic for about 6 months and the plot of these temps is included. We live in a very cold climate, and it still looks like there is some potential.

Details here...

Recovering Heat From Shower Water Drain Pipes
This page looks at all the energy we send down the drain when taking a shower, and in some of the ways that are currently out there to recover some of that energy.
It considers one (as far as I know) new method, which is basically to rearrange the drain plumbing to retain the shower water in the homes heated envelope long enough to recover the heat in the water for space heating.
Some ways of doing this, the resulting energy saving, and a small test to examine the potential of this method are discussed.

It may seem like there is not really much potential here, but for heating climates, the potential energy saving for a family might be of the order of 1200 KWH a year.

Details ...

A Very Energy (and Water) Efficient Shower Design
This is a look at a shower design that was looked at for potential use on very long range commercial jet airplanes. It is a very efficient design both from a water use and energy point of view. It may not be for everyone, but have a look.

Details...

So, I'm particularly interested in whether you think any of these ideas have some merit and are worth pursuing (or not).
Or, maybe you have some of your own "Out There" ideas you would like to share?

UPDATE: Turns out Kenneth has built and uses a recirculating shower...
Kenneth's interest were more in getting long showers with very high flow (6 shower heads) without breaking the bank on energy use. Its a nice simple design.

Note that Kenneth has also done a very nice Solar Shed project that does both solar space and water heating -- hope to have the details on this up soon.
Thanks Kenneth!

Gary

New Content on Build-It-Solar

2010-03-20T15:58:07Z

Pop Can Collector From Sweden
A very nicely done aluminum pop/beer can collector. Lots of attention to detail, and lots of good assembly pictures. In Swedish, but the pictures plus Google translator make it quite readable.
Pop can solar air heating collectors force room air through connected columns of black painted aluminum soda cans. The sun heats the pop cans and the heat is transferred to the air. The even distribution of airflow and large heat transfer area should make them efficient collectors.
Details here...

Update on Chad's Solar Heating System
Chad has made a number of changes to his solar water and space heating system. He has also logged and measured the performance of the system.

All the details and performance graphs...

Efficient Inflation System for Double Skin Poly Greenhouses
Many poly skinned greenhouses use two layers of poly with a small blower inflating the space between the layers. This gives you cheap double glazing, and reduces heat loss.

Most of blowers are set up to run 24/7, but this article shows a way to cut down the run time dramatically using a small pressure switch and a very simple check valve. With the check valve, the blower runs only when enough air leaks out to the point of needing reinflation.

Details here...

Facebook Page
I've put up a page for Build-It-Solar on Facebook.
Basically I have no clue how this all works, so if you have any ideas for the Facebook page, please let me know.

We just broke 500 fans today, so have to be doing something right :)

The Facebook page...

!! Happy Spring Equinox !!

Gary March 20, 2010

Massachusetts Zero Energy Challenge Winning Home

2010-03-14T16:11:56Z

This is a very impressive less than zero energy home. It uses a combination of reasonable size, excellent thermal envelope, very efficient appliances, some passive and some active solar heating, and a PV driven mini-split heat pump for additional heat and cooling.

The end result is a true zero energy house that can be built within a reasonable budget.

I cover a few of the highlights below, but all the details on the house are in the article here...

Performance
The monthly performance chart below speaks for itself. For the year 2009, the house produced significantly more energy than it used.

Highlights
Double stud, R42 walls insulated with cellulose insulation.
R100 cellulose attic insulation.
Triple glazed R5 windows with R7 interior thermal shutters.
Very good infiltration sealing.
Emphasis on south windows for solar passive gain.
Concrete slab floors for heat storage thermal mass.
Solar water heating
Solar air heating collector to for additional space heating.
Exceptionally efficient appliances and lighting.
Heat recovery ventilation system.
Efficient mini-split heat pump for heating and AC.
4.9 KW grid-tied PV array supplies all electrical power and then some.

Double stud R42 cellulose insulated walls

Total cost of the house without land is $180,000.

Altogether, and exceptional house.

Thanks very much to Doug and Tina for providing this material.

Gary

Spring Solar Projects

2010-03-07T16:16:15Z

Solar Hot Water

HTML clipboardNow is a good time to study up on, and start building a solar water heating system, so you can get it in this summer.
There are several high quality DIY designs that cab be built for inside of $1000.

Many solar water heating downloads

Solar Greenhouse or Sunspace

A place to grow some plants, produce some free heat for the house next winter, or just a nice place to sit and have a cup of coffee with the newspaper.
Many Solar Greenhouses and SunSpaces -- ranging from $20 to $200,000.

HTML clipboard
Passive and Low Power Cooling

Here are many ways to keep your house cool, and at the same time save money and reduce Greenhouse Gas Emissions. Shading, whole house fans, landscaping, earthtubes, insulation and sealing, reflective and garden roofs, ...
Lots of ideas here.
Passive (and efficient active) Cooling

Solar Pool and Hot Tub Heating
HTML clipboard
Solar pool heating is arguably the shortest payback solar technology. Take the chill off the pool, and be easy on the planet at the same time.
Solar pool heating information
My favorite quote on solar pool heating from Tom Lane in the Home Power Article Pool Heating Article:
"Three gallons of oil refined and burned provides 400,000BTU ... Once. Three gallons of oil, made into a 4 by 12 foot solar collector, can provide over 10 million BTUs per year ... year after year"

How about a Summer Outdoor Solar Shower?

This is a very simple solar project to get started with. It can save energy and reuse shower water for plant watering while providing a nice outdoor shower experience!

How to build info for several outdoor solar showers...

Build Your Own Solar Electric System

Solar electric systems have become much easier to self install over the years. If you are careful about the safety issues, and have done some home wiring, you may want to give this a try. Plan it this spring, and build it this summer.

Details on my self installed system...

More on DIY PV...

Do a Water Conservation Project

Spring is a great time to get started on an outside water conservation project.
Dozens of projects described in detail here -- rainwater harvesting, greywater reuse,
rain water gardens, ...

All the details on water conservation projects...

Any other ideas --- make a suggestion.

Gary

Collector Absorber Fins from Tom

2010-03-05T16:49:41Z

Tom Sullivan built a couple large water heating solar collectors. To reduce the work involved in making the heat absorbing fins that go on the collector tubes, Tom built a very nice press to stamp out fins.

Tom has decided to make these fins available as a product from his UP Truck Center business. He is offering fins to fit 1/2 inch and 5/8 inch tubing in lengths from 24 inches to 34 inches. He also offers a sort of super fin option that achieves more wrap of the fin around the tube. The prices are very reasonable, and I think this is a good option for anyone wanting to save some time on building the fins.

Here is the web page describing all the options and some notes on how best to install the fins...

Tom is a long time friend of Build-It-Solar, and has sent in detailed descriptions of some of his very well done solar projects... Thanks Tom!

Gary

Some New Stuff

2010-03-02T23:04:03Z

This is just a collection of some interesting (at least to me) items added tot he site over the last week or so....

Harvesting Fresh Water From Fog
Areas with regular daily fogs (e.g. some coastal areas) can harvest impressive amounts of fresh water from the fog. Nets catch the fog and then channel droplets from the fog into a catch basin.

Details...

Booklet on "Hot Water From Your Woodstove"
This is a good 45 page booklet from Lehman's describing a couple systems for adding a heat exchanger coil to the firebox in your woodstove to heat water. Good detail on both thermosyphon and pumped systems, and lots of information on troubleshooting and doing the installation safetly.

Details...

Skysails -- Kites for Towing Ships
These are large kites that can be deployed under favorable wind conditions to reduce fuel consumption. With favorable winds, fuel consumption can be reduced as much as 50%.
Operation of the Skysails is largely automatic.

Details...

Homes From Cylindrical Grain Storage Bins
A collection of links to homes made from cylindrical steel grain bins. These homes offer a thermally efficient shape, and some options for good insulation thickness -- plus and interesting look.

Details...

Gary

UAZ Students Help Local Businesses to Reduce Energy and Water Consumption

2010-02-26T16:39:00Z

I thought this was a great program to get students involved with renewable energy and also help local businesses with energy and water costs.

Students from the UAZ Free Enterprise team identified two local Tucson businesses in need of some help on energy and water use, and then worked out and implemented a program to help the businesses reduce energy use, water use, and carbon emissions.

Here are the details on what the team did -- there is contact information at the end if you want information on starting a similar program ...

I have to brag a little here and mention that my granddaughter Kelly was one of the team members :)

Gary

Making, Buying, Designing, Evaluating Fins for Solar Collectors

2010-02-22T18:27:02Z

Many of the homemade collectors shown on this site use aluminum fins to collect the incoming solar heat and transfer it to a tube that carries the heat transfer fluid.

The fins need to transfer heat efficiently, and need to have a good thermal connection with the tube carrying the heat transfer fluid.

Copper tube with heat absorbing fin being installed.

This article goes over several fin designs, several ways of making the fins, some of the types of fins you can buy and where to get them.

The new article also provides calculated fin efficiencies for some of the homemade and commercial designs. I'm sure you are dying to know Which fins do best? Does steel work as a fin material? Are those big, thick, extruded fins worth the extra money? ...

All the details on fin design, fabrication, purchase, and performance here...

Some fin designs that people have sent in...

Kevin's two layer fin

Matt's bicycle powered fin former.

Tom's most impressive fin press

Got any ideas on fin design or fabrication?

Update March 11 -- I've added a couple more entries that have been turned in since this blog entry was written -- all on this page:

All the details on fin design, fabrication, purchase, and performance here...

Gary

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The fins need to transfer heat well, and need to have a good thermal connection with the tube carrying the heat transfer fluid.

This article goes over several fin designs, several ways of making the fins, some places you can buy the fins. It also provides the calculated fin efficiency for several of the designs.

This blog entry has a few highlights, but all the gory details are here...

Some fin designs that people have sent in...

Kevin's two layer fin

Bob's Solar Ice Fishing Shack

2010-02-20T19:00:44Z

This is a really simple but very effective solar heating collector that Bob uses to heat his ice fishing shack.

The collector uses the whole south wall of the shack.

The collector is a very simple thermosyphon air heating collector that uses 2 layers of black insect screen as the flow through absorber, and 6 mil poly film as the glazing.

Bob took the time to insulate and seal up the ice shack before installing the collector, which is key to making it work. On a sunny day, it heats the inside of the shack up to very comfortable temperatures.

All the details from Bob...

If Bob can heat his ice shack with solar, you can surely heat your home, or chicken coop, or barn, ... with solar!

Gary

Zero Energy Homes for the Rest of Us

2010-02-18T22:52:23Z

While visiting St George Utah recently, we found that we were in town during the parade of homes, so we looked at a few of them. One of the display homes was a very efficient home built by Sun-Savvy Inc. I was very impressed by this home and the other homes they offer.

Their design combines a very good and very tight thermal envelope, heat recovery ventilation, passive solar, solar thermal and PV arrays, and efficient mini-split heat pumps to make a home that should be able to achieve net zero energy use in the southern Utah climate. The display home has a LEED Platinum rating.

Even more impressive to me is that these are very nice and very "normal" looking homes. These homes appear to be very easy for the homeowner to live with. While the energy efficiency does add some cost, the homes appear to be cost competitive with ordinary construction homes. In other words, these are net zero or near net zero energy homes which should have a very wide appeal to ordinary home buyers -- you don't have to be an eco-freak (like me) to like these homes.

We took the full tour, got a lot of pictures -- all the details here...

Much more on solar homes here...

Clerestory windows -- great daylighting. These open automatically when a set temperature is exceeded.

The energy recovery ventilation unit -- an earthtube is used to precondition the intake air to the ventilator.

It seems like a lot of the "net zero" energy homes you see are a long ways out of the mainstream -- they tend to be architecturally unique (some would say strange) and come with an acre of PV panels that would add $100K+ to the cost of the house were it not for some very very generous (and perhaps questionable) rebate programs. I don't see this type of near zero energy home ever catching on and becoming widespread. On the other hand, a design like the Sun-Savvy homes seems like it could have very wide appeal. I hope it turns into a trend.

Gary

Solar Articles from the Fine Homebuilding Magazine Archives

2010-02-12T03:20:28Z

I've been going through the newly available DVD archive of all of the past issues of Fine Homebuilding Magazine. Fine Homebuilding has been published since the late 70's and has carried some very good articles on solar and energy efficient home construction. I've added links to my picks of the best articles dealing with energy -- these are listed in New Content on the Build-It-Solar home page, and in the list below.

Here are the articles I liked the most from 1995 up to the end of 2009:

Six Proven Ways to Build Energy Smart Walls,
Bruce Coldham, Fine Homebuilding,
Dec 2009

Spray Foam -- What Do You Really Know?,
Bob Yagid, Fine Homebuilding, June 2009

Power House,
Bill Heigis, Hobie Guion
Fine Homebuilding issue 203, summer 2009

Attic Insulation Upgrade,
Mike Guertin, Fine Homebuilding, January 2009

Design a Home That Keeps You Cool, Naturally,
William Hoffman, Fine Homebuilding August 2004

Airtight Attic Access,
Mike Guertin, Fine Homebuilding, July 2002 issue 148

Rainwater Collection Systems,
Peter Pfeiffer, Fine Homebuilding, Nov 2001 issue 142

Thick Walls and a Great Room,
Jan Wisniewski, Fine Homebuilding, summer 2000 issue 131

Insulated Concrete Forms,
Andy Engel, Fine Homebuilding, issue 128

Off the Grid in Tucson,
Gale Prososki-Marsland,
Fine Homebuilding, June 1997

Building a Straw-Bale House,
Janet Johnston and John Swearingen,
Fine Homebuilding, June 1996 - issue 103

You can get access to back issues of Fine Homebuilding in several ways...
Probably the simplest way to get access to the articles is to do a one month online subscription -- this is inexpensive, and should gain access to most past articles.

I'll go through the 70's to 90's as time allows.

Gary