Build-It-Solar Blog

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.



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

Solar Hot Water

Now 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.

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

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...

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

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

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

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

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

Tom sent in the final update on his new solar space and water heating system.  This update covers the storage tank, controls, heat exchanger and integration with the boiler.