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Posted by Keith D on August 15, 2006, 6:55 pm
 
I'm looking for ideas on how do conduct a full energy audit of my house. The
purpose of this audit is to examine areas where I can reduce consumption,
look at things I do that require a lot of energy (and ways of reducing that
energy demand) with the ultimate aim of then introducing renewable energy
into the mix.

Any ideas on how to do this in a structured, formal, yet scientific way?



Posted by Astro on August 16, 2006, 11:47 am
 

Keith D wrote:

I'd start by reviewing information on the web regarding the worst
offenders in most households as this will give you leverage points to
start your investigation.

For example, in cold climates, typical home energy consumption is as
follows:
space heating: 58%
water heating: 19%
fridge: 12%
appliances and lights: 11%

(taken from "Residential Energy" a book by Krigger and Dorsi.) Get this
book. It's an excellent overview and will give you detail in many
areas.

Next, I would compare these areas to my actual usage. make a
spreadsheet where you can put all the data you collect. Take a year or
two worth of electric, oil/gas bills and note monthly cost and usage
values.

With a few hours of work, you'll paint yourself a picture of where your
energy use is throughout the year.

To get more detailed, look at months tht you neither heat nor cool.
These months will largely remove space heating/cooling from the
electric bills and give you your baseline energy consumption. Subtract
that value from the other months to find out how much you're actually
using to heat/cool your house.

Next, you can start looking at house metrics like BTUs per square foot
per heating degree day. This will give you a number that you can
compare to see how efficient your house/usage is currently. Again, this
will give you some good information to let you know whether you can
gain a lot or a little.

At the next level, I'd perform a heating and cooling load analysis on
my home's structure. You do this by calculating all the sources of heat
gain and loss through the house and summing them up. For example, you
might have 1000 sq. ft. of roof, insulated to R-20. That will gain/lose
1000/20 = 50 BTUs per hour per degree temperature difference between
indoors/outdoors (forget about solar insolation for now, this is just
an example). Do the same for windows. Say 100 sq. ft. of R-2 windows =
100/2 = 50 BTUs/hour/degree. And exterior walls. Say 2000 sq. ft. at
R10 effective = 2000/10 = 200 BTUs/hour/degree.
So in this example, you are losing 50+50+200 = 300 BTU's/hour/degree.
If you have a temperature difference of 40 degrees, the loss will be
40*300 = 12000 BTUs/hour.
you can go crazy calculating the heat gains/losses in your home. Sanity
check your numbers against your utility usage.
Get a book on Manual J calculations and it will go through all the
details.

Or, hire a home energy auditor and have them run a Manual J on your
home using their software. This will be much faster but you won't learn
all the details. Depends what you want.

Hire someone to run a blower door test on your home. This should be one
of the first things you do as it will give you some hard metrics as to
the leakiness of your home.

You might want them to do some infra-red scanning of the home as well.
That can give you a clear perspective on where your walls are cold.

that should be enough to keep you busy for a while  ;-)


Posted by Gary on August 16, 2006, 1:09 pm
 Keith D wrote:

Hi Keith,

Here is how I did mine:
http://www.builditsolar.com/References/Half/Half.htm

Your list of projects will end up being different, but the ideas the same.
There is a making a "plan" page here:
http://www.builditsolar.com/References/Half/Planning.htm

We did 22 energy saving projects that ended up cutting our total energy use and
GHG by about half -- the first year rate of return was 44% -- with us supplying
most of the labor.

Gary



--


Gary

www.BuildItSolar.com
gary@BuildItSolar.com
"Build It Yourself" Solar Projects









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