Tuesday, May 29, 2012

Greg's Near Zero Energy Solar Upgrade of a New Mexico Home

Greg used a well thought out combination of insulation upgrades and a solar space and water heating system to cut his space and water heating energy use of his all electric home to nearly zero.  
Greg's NM near net zero remodel -- collectors to left.
The house has been foamed and then plastered over the entire exterior.
This project shows that you can live within the limitations of an existing home and still make dramatic reductions in energy use within a reasonable budget.

Greg did most of the work himself, and goes through the details of planning and installing the upgrades.

The 2000 gallon heat storage tank stores heat for a couple days of cloudy weather.

Greg used a balanced approach consisting upgrades to the home's thermal envelope to reduce heat loss, and then the addition of a solar heating system sized to meet the remaining heat loss.

The thermal envelope upgrades consisted primarily of adding external foamed in place insulation, adding attic insulation, and  thermal window treatments.  These upgrades reduced the home heat loss to the point where a reasonable size solar heating system could heat the house.

The solar heating system consists of four large ground mounted solar water heating collectors.  The solar collectors provide heat to to a large and very well insulated fiberglass tank that is sized to store heat over cloudy periods.  Both the collectors and tank have been carefully added in such a way as to preserve the good looks of the home.

A hydronic heat distribution system was added to distribute the stored solar heat to the home as required.  The hydronic systems replaces the electric baseboard units that came with the all electric house.
Four large solar water heating collectors provide space and water heating.

With the insulation and solar heating upgrades, the home is now totally self sufficient on space heating and water heating energy use.

Greg plans to add a PV array on the roof to meet the remaining small electrical demand.  When the PV array is completed, the house will be a net zero energy home.  Net zero energy use is very difficult to achieve even for new construction homes, so it says a lot about Greg's design that he was able to achieve this zero energy use on a remodel and within a reasonable budget.

Central control.

Thanks very much to Greg for taking the time to document and send in the project!


Saturday, May 26, 2012

Solargraphy, Windmill Water Pumpers, and Solar Air Floor Heat

Just catching up on  a few new entries at Build-It-Solar.

New Solargraphy pictures from Kevin
Kevin's Solargraphy "cans" have been taking pictures for the last few months with some really nice results.

A 4 month exposure Solargraphy picture

All the details on how to do your own Solargraphy pictures...

Some Ways of Distributing Solar Heated Air to Floors
Most solar air heating collectors just distribute the solar heated air directly to the living space, but here are a couple ways to do radiant floor heating with solar heated air....

Scheme for heating a slab floor with solar heated air.

Updates to the Windmill Water Pumping Section
Added a link to the very nice Ainsworth site on water pumping windmills as well as a link to the Vintage Windmills News -- a good newsletter on restoring wind pumpers.
From Vintage Windmills News

Also added a link for the  Airlift Windmills -- on these windmills, the wind turbine drives a compressor which provides compressed air for a bubble pump.

If you have not taken the time to look at some of the pictures in this section of the beautiful old wind pumpers, you are in for a treat!

The windmill water pumping section...


Monday, May 14, 2012

Using PV Panels for Shading Structures

I've added a small new section on using PV modules that both generate electricity and provide shading.

The main entry is an article sent in by Amy and Dennis Heidner which describes in good detail how they went about designing and building a deck canopy that provides shading for the deck and for the living space in the house behind the deck.
Shading structure using PV panels.

One of their concerns was that it would be too dark under shading surface made with PV panels.  They describe how they were able to take light meter readings behind a variety of PV modules and find a module that had enough open area to provide the lighting the wanted.  They also included small glazed areas above and below the PV modules that also let in light.  In the end, they got just the light level they were looking for.

Incorporating small glazed areas to get the right light level below the canopy.
The new PV module shading section also includes the use of bifacial PV modules for shading.  Bifacial PV modules accept light from either side and do not have the opaque layer behind the silicon cells that regular PV panels have -- this means that they are semi-transparent and this works out well for some shading situations.

There are also links to a variety of projects that use PV modules for shading just to show some of the unusual and creative ways people have come cup with.

All the details on PV modules for shading structures...

A shade umbrella using PV panels


Saturday, May 12, 2012

How Large a Solar Collector Do You Need to Heat Your Hot Tub?

This is a pretty good method to determine how large a solar collector is needed to heat your hot tub. 

The size of the collector needed to heat a hot tub depends on a lot of things: volume of the tub, how well its insulated, how good the cover is, what your climate is like, how hot you keep it, ...   Its not easy to take all that into account to get a good idea what size collector you need.  But, I ran across the method detailed below in "More Other Homes and Garbage" that uses the temperature drop of the hot tub over 24 hours to determine the daily heat loss for your hot tub in your climate and for the way you use it -- it seems like a good approach to me.

By the way  "More Other Homes and Garbage" is a terrific book written the 80's, but full of good ideas, good analysis, and written in a style that won't put you asleep -- and, its only $8 used!  Better get one before they all disappear!

Given that hot tubs are the biggest energy users in most homes that have them, its not a bad idea to do the test on your hot tub to see how the heat loss looks, and even if you can't do a solar heater, things like more insulation and a good cover can make a lot of difference.


Saturday, May 5, 2012

Night Air Thermal Mass Cooling Using Water Barrels

This is a scheme that I am experimenting with to cool my shop.  It basically blows cool night time air over a collection of 50 gallon barrels filled with water to store "coolth" in the water. 

The idea is to cool the barrels down during the night hours, and then use the stored "coolth" in the barrels for space cooling during the daytime.  This requires a climate in which the night temperatures drop down to low levels even though the daytime highs are uncomfortably warm -- this is true for much of the western US.

While I am using the scheme in my shop, it could be used to cool any interior space.  Note that we use a variation on this cooling scheme to cool our house ...  The basic question is: does it make sense to use a fan forced flow of cool night air over thermal mass to store "coolth" for later use in daytime cooling?

Logger plot of water barrel storage and shop temperatures
with fan forced outside air flow over barrels at night.

This is definitely a work in progress, and I'm looking for any ideas people might have to make it work better.  I think that it has the promise to deliver good cooling performance for near negligible energy consumption (SEER 150 ish).   

This scheme only works for climates in which the night time temperature drop to relatively low levels even when the day temperatures are hot -- typical of a lot of the US west.

All the details and questions on night air cooling of water barrel thermal mass...

Water barrels for storing night time "coolth"

Rough prototype cooling tunnel to direct fan forced night time
airflow over the water barrels for good heat transfer.
In this particular scheme, the same water barrels are used to both store heat in the winter and store "coolth" in the summer!

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