Tuesday, August 28, 2012

Prince Edward Island Passive Solar Bermed ICF Home on a Budget

This is Tracey's very nice home on Prince Edward Island, CA.   Its a passive solar home that uses earth berming on the winter wind sides, and uses ICF (Insulated Concrete Forms) for the walls.

The home has large south facing passive solar gain triple glazed windows for winter heat gain, along with roof overhangs that shade the house from unwanted summer heat gain.

South windows provide lots of solar gain to the heat storing floor.

The long east-west layout of the house and use of Solatubes to provide lighting in some areas makes for a very pleasant and bright interior.

The 1285 sqft floor plan.
Probably the most amazing thing is that the home was built on a very manageable budget.

Tracey provides lots of detail on the house including a book on the whole process of designing and building a  very efficient solar home within a budget.

All the details here...


Saturday, August 18, 2012

Home Heat Loss Calculator -- Updates

Our Home Heat Loss Calculator gets used several hundred times a day, so I thought it would be good to make a few small updates.

The calculator lets you estimate the heat loss, yearly energy use, fuel cost, and greenhouse gas emissions that result from heating your house.  It estimates losses for ceilings, walls, windows, and floors and losses due to  air infiltration.  Its easy to use, and some examples are provided to get you started.

Probably its biggest value is giving you some idea where the major heat losses are in your home, which is the first step in identifying which areas will give the most bang-for-the-buck for improvements.  It also lets you try various improvements and see the resulting saving in dollars and CO2.

So, I cleaned up the forms, added a plot that shows at a glance how the heat loss from ceilings, walls, ... compare to each other, added some printing pagination, ...

The new plot
If you use the calculator now, be reassured that no algorithms have been harmed in this update -- it gives the same answers it always has.  The one small number change is that CO2 emissions for electric fuel were lowered from 2.2 lbs/KWH (typical of coal generators) to 1.5 lbs (average US generation).

Some parts of the calculator:
The inputs look like this -- basically define your climate, pick a heating fuel, and enter Rvalue and area for ceilings, walls, ...    Mercifully, there is only one page of inputs to fill in.
You just enter your numbers in the blue boxes.

The summary output looks like this -- yearly energy, cost, and CO2 for your house as well as coldest temperature hourly loss rate.

This is a simple calculator -- it uses the usual Loss = (Area)*(deltaT)/Rvalue for each component.  It uses Heating Degree Days for your climate to estimate yearly losses.  There are fancier calculators available that give more details and probably more accuracy, but this one is fast and easy to use and appears to do pretty well -- and its FREE :)

Give the Home Heat Loss Calculator a try ...

If you have any thoughts on improvements, let me know.


Wednesday, August 15, 2012

Using Your Lawn Sprinkling Water to Cool the House

This is a unique way of providing some free space cooling for your house.

Rick runs the water that he is using for lawn watering through a heat exchanger first and extracts some "coolth" from it before it goes out to the yard.

Rick's current test setup.
His current test setup uses a 20 by 20 inch water to air heat exchanger with a fan that blows air through the heat exchanger to cool it.  In this current test setup, it cools the airstream about 10F and provides about 5000 BTU/hr of cooling -- about a half ton of cooling.

The energy use is very low -- the COP appears to be about 29 (SEER 125!).

Side of HX with water connections.

All the details on lawn water for cooling here...

Thanks very much to Rick for sending this in.


Tuesday, August 7, 2012

Calling all Sunspace Owners

I think that home attached sunspaces may be the most cost effective and sensible approach to adding solar to your house -- attached sunspaces offer:
  • Space heating for the house 
  • Additional living space that can be very pleasant
  • A place to grow plants
  • A place to hang the laundry for solar drying
  • A good place to locate a solar water heater
While direct gain to the house through south facing windows can be an effective solar heating scheme, the direct gain approach has the not so good feature of quite a bit of heat loss on cloudy days and at night through the large windows.  Sunspaces allow you to harvest the same heat through their large, south facing glazing, but the susnpace can be closed off from the house at night or on cloudy days to avoid the big glazing heat losss.
A nice sunspace
Compared to traditional active solar space heating (with collectors, tanks, pumps, ...) sunspaces can be better looking and more cost effective (when you consider all of the benefits).
Doug's sunspace
For space heating, low thermal mass sunspaces collect heat quite efficiently, and it is relatively easy to transfer this heat to the house.  A good writeup on the low thermal mass sunspace design...

While having a sunspace to hang laundry in bad winter weather may seem like a small thing, clothes dryers are are the largest single electricity use in many homes -- on average about 900 KWH a year!  Even more when you consider that the dryer is pulling in cold outside air as it vents its hot air outside.  The sunspace gives you a good, sheltered, efficient place to dry clothes.

Sunspaces make a good, protected enviroment to add a solar water heater to -- the water heater will be more efficient because it does not see outside temperatures, and may need less or no freeze protection.

I've got a section on Sunspaces, but it has few examples of good, attached sunspaces used as described above.

Sooooooooooooooo, I would REALLY like to hear from folks with sunspaces -- how well do they work for you?  What's good?  What's bad?  What do you consider good design features?  
A writeup on your sunspace with lots of pictures would make my whole week!

Nick's multi-story solar space heating sun space
Or, if you have some thoughts, experiences, or questions on sunspaces, how about passing them on in a Comment below.


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