Gordon's Deep Energy Retrofit - After 5 Years Report

Back in 2009 Gordon and Sue did a full deep energy retrofit of a 1963 brick schoolhouse making it into a very energy efficient home.

The retrofit include R40 Larsen Truss walls, triple glazed R6 windows, a passive solar window scheme, a new solarium, solar water heating, and a hand crafted masonry heater.

The new solarium

They have been in the home for five years now and this full report describes on how things have worked out along with a well kept record of energy savings -- all the details after five years here...

The whole retrofit project is described in detail here...

The Larsen Truss Walls

Thanks very much to Gordon and Sue for providing the update.

Gary
February 27, 2014

A Solar Heated Loo

Michael has developed this simple and elegant solar heated version of Arbor Loo that has many advantages as well as offering a little more comfort on those cold mornings.

The Arbor Loo provides a efficient and sustainable solution to the poop problem, saving thousands of gallons of water a year and providing useful tree planting compost.

I really like the nice simple space heating system.  It is a drain back system with the collector nicely integrated with the roof.  An IBC container is used for heat storage.  And, by leaving the insulation off the parts that face the "living space", the IBC also provides the heat distribution.

The only moving part is the pump -- no controller, no antifreeze, no heat distribution controls or pumps -- very simple.

I think that this kind of design could be applied to other simple space heating needs.

The loo under construction with the IBC container at the back (providing a heated backrest for the toilet seat).   I like the way the structure integrates the standard size door, collector, IBC and toilet seating area with no wasted space.

Full details on the build and performance of Michael's solar heated loo ...

Thanks very much to Michael for providing this material!

Gary

DIY Ground Source Heat Pump + PV Array -- No Heat Bills!

In this very ambitious project, Jerry goes through all the details on installing a 5000 watt PV system and a 2 ton Ground Source Heat Pump. Together they provide all of the space heating and cooling and hot water.  

No heat bills and very low emissions.

The ground loops for the Ground Source Heat Pump

Jerry started by installing a 5000 watt PV system on his garage roof.

5 KW grid tie PV array on garage roof.

The PV system is grid tied and uses an Aurora 6000 watt grid tie inverter to produce house power and to interface with the grid. Jerry is paid 14 cents per KWH generated via the net metering agreement with his utility and is also able to sell SRECs to the utility to allow them to meet their renewable energy generation requirements with the state of NJ.

The 6000 watt grid-tied string type inverter for the PV system.

Once the PV system was installed, Jerry installed a Ground Source Heat Pump to efficiently use the PV generated electricity to both heat and cool his house. The GSHP installation involved digging a 300 ft long 8 ft deep trench, laying out the ground loops in the trench, installing the 2 ton heat pump.

The 300 ft long trench for the three GSHP ground loops.

The 2 ton ClimateMaster water to air heat pump.

In addition to installing the 2 ton heat pump, Jerry also designed and installed a duct system to distribute heating and cooling to the house.

All the details on the DIY GSHP + PV system in a 26 page pdf...


Gary
January 22, 2014

Building Large Cylindrical Tanks for Solar Heat Storage

Alan Rushforth of Rushforth Solar provides detailed information on building large cylindrical water tanks for storing heat. These tanks are commonly used to store heat generated by an array of solar collectors in space and water heating applications.

One of Alan's tanks

The tanks that Alan makes typically range from a thousand gallons up 4000+ gallons, but the design could certainly be used for smaller tanks that would be typical of residential solar applications.

This design is very structurally efficient, light weight, and material efficient.

The tanks consist of aluminum  sheet wrapped into a cylinder, which is then lined with rigid foam board insulation.  

The outer aluminum sheet wall with layers of insulation inside.

An EPDM liner is then installed to contain the water.

The EPDM tank liner being installed

Alan also includes some very helpful material on building heat exchangers for these large tanks.

Thanks very much to Alan for providing this material!

Stainless steel pipe coil heat exchanger.

Alan's full description on building these tanks ...

Gary

Home Power Digital Subscription Deal

I don't usually do deal announcements, but could not pass up this one.

Home Power Magazine is doing 50% off their digital subscription rate for a while.  So, a 3 year digital subscription that also includes access to 20+ years of back articles is now $11.95 -- what a deal!!

https://www.homepower.com/subscribe-and-save?template=subscribe

If you are not familiar with Home Power, its probably the best source out their for detailed articles on DIY solar and other renewable energy projects -- aside from Build-It-Solar of course :)

Gary

Backup Heating for the $2K Solar Space and Water Heating System

Our $2K solar space and water heating system provides solar water heating and also space heating to part of our house.  Until recently the backup heat for this part of the house was a propane forced air furnace that came with the house.  But, last winter the furnace died and the replacement cost was $6000.  So, instead of replacing the furnace, we added a backup heat system that just adds heat to the large solar heat storage tank when there is not enough sun to keep the solar tank warm.  This approach cost about $300 (pretty good saving), and has the advantage that we no longer have a noisy and potentially unsafe gas furnace hung from the floor just below our bed.

The new backup heat system is pretty simple.  Its just an electric hot water heater that sits next to the solar tank with a small pump to circulate hot water from the electric tank to the solar tank when the solar tank temperature drops below a setpoint.  The heat is distributed to the room above by the same radiant floor pex tube system as before.

The backup heat source electric hot water tank

The TopsFlo pump that circulates water between the backup tank
and the solar tank is at the bottom of the picture -- only 15 watts.

Diagram of the new backup heat system -- really simple.

I've added a new page that describes the backup system here...

And, updated a few pages for the project to reflect the new backup heat system...

There is also some discussion of other alternative backup heating systems -- I'd be interested in hearing any ideas on a better way to do it.

Gary

The Passive Solar Bird Bath is Back

We lost Jim's very nice passive solar bird bath for a while, but is back now.

The passive solar bath provides some unfrozen water in the winter for the birds to drink.  Its a nice simple design that is easy to build and has worked well for Jim.

Thanks very much to Jim for documenting this project!

The solar collector on the bottom heats the drinking dish on the top.

If you have any ideas for improvements or any questions, or have a design of your own that you would like to report on -- please use the Comments section on this page...

All the details on Jim's passive solar bird bath...

Gary

Backdraft Dampers for Solar Air Heating Collectors

Solar air heating collectors provide a nice stream of heated air during the day when the sun is shining on them, but at night, the flow often reverses and brings unwanted cold air from the collector into the room.

Backdraft dampers are added to prevent this reverse flow of cold air.  There are several types of dampers -- both DIY and commercial.

I've added a section that lists the ones I know about -- if you know of others, please let me know.

New section on backdraft dampers for solar air heating collectors...

A example DIY backdraft damper

PV Powered Pool Pump Installation

When Bruce looked at where his electricity was going, he found that about a quarter of his total electricity use was to run his pool pump. He decided to install a new pump that would be run from PV modules.

Bruce's report gives details on the design and installation of the new pump, and on how the economics is working out. The drop in PV module prices in the 6 years since the system was installed, the payback period would now be substantially shorter.

Two 170 watt PV panels in series drive the DC motor pool pump

The installation is simple consisting of only the two 170 watt PV panels (above), a controller, and the DC powered pool pump itself.  Given the efficiency of DC pumps and the minimal losses its a very efficient setup.

The new pool pump -- the controller is visible on
the wall behind the pump

An alternative to Bruce's approach would be to retain the existing AC pool pump and add a grid-tie PV system for the whole house that would power both the pool and the rest of the house loads.  This is appealing in that one system does both jobs, but the low efficiency of typical AC pool pumps appears to require a much larger PV array (perhaps a 3000 watt PV array just to drive a 1.5 hp AC pool pump 8 hours a day).  So, the dedicated PV array to drive the DC pool pump appears to be the more cost effective solution -- do you agree?

Two speed AC pool pumps run for longer periods at lower speeds also appear to offer a larger saving in electricity at a modest initial cost.

I've added a small section on powering pool pumps efficiently that includes Bruce's PV powered pump as well as some other ideas on efficient pool pumps.  If you have any other ideas or thoughts, lets hear them.

Gary

Our Low Thermal Mass Sunspace Project in Home Power Magazine

I did an article for Home Power on the Low Thermal Mass Sunspace concept -- its in the Dec 2013 issue, which is just coming out.

William's Minnesota LTMS 

I'm a big fan of the Low Thermal Mass Sunspace (LTMS).  In a nutshell, this is an attached sunspace in which the design is optimized for providing maximum heat to the attached house.  The main design characteristics are:

• Double glazing with tilt angle optimized for winter collection
• Unglazed surfaces in the sunspace are dark in color to absorb sun well
• Unglazed surfaces are well insulated to reduce heat loss
• Unglazed surfaces are low in mass so that they don't suck up heat you want to go to the house
• A high capacity fan/duct system delivers heated air to the house as fast as the sunspace makes it

Some of this may seem strange at first compared to the usual sunspace design guides, but its all aimed at maximizing heat production and in getting as much of the heat as possible to the house. 

It turns out that if you follow these design guides, the LTMS will produce heat for the house just as efficiently as a good commercial collector with the same glazed area -- AND it will give you all the benefits of a sunspace as well.  Benefits include: great place to have cup of coffee in the sun, great playroom or family hangout, all season clothes line drying, wood drying, ...  

About the only downside of the LTMS is that when the sun goes down it goes cold quickly, so its not a space to hang out in after sunset, or go grow plants in cold climates.

The performance is impressive.  My test LTMS with 200 sf of glazing produced 200K BTU of heat for the house on one sunny winter day -- equivalent to nearly 3 gallons of propane burned in a typical furnace.

The test LTMS under construction.

I also tested the performance of my test sunspace when it was closed in, but not insulated and with a dirt floor -- in this configuration it only delivered 1/3 of the heat to the house than the finished sunspace with insulated low mass surfaces.

The finished test LTMS

I've done a section on LTMS's that goes into quite a bit of detail on on the design, performance testing, and includes some great LTMS examples contributed by Mike, Nick, and William. 

Mike's example LTMS -- heating the house and solar drying clothes!

Nick's 3 story LTMS that provides most of the heat for his
very difficult to heat old home.

The Home Power article covers everything in the LTMS section in one place and the Home Power editors have worked it into something that is clear, easy to read, and still quite detailed.

Gary
November 9, 2013