cellulose has more weight so it settles
faster than fiberglass. but it also has a very
fine 'dust' that will find its way into
the house via small cracks & gaps.

in the attic look for dirty areas of insulation.
move the insulation aside and you will find
an air leak.
some common air leakage places are recessed lights,
oversized cuts for bath fans, stove vents.
recessed lights are a big leakage. if you have
IC insulation contact lights you'll be able
to see light comming in from living space
when in the attic. you can buy inserts to make
them air tight. get brand name & model number
to shop for these inserts & trims.

in 73 they put some type of insulation in the walls.
it is difficult to add insulation in walls that have
insulation in them already.
I'd look instead into sealing the walls so that
they are air tight.

look into a blower door test for your home
to find leakage areas. this testing will measure
amount of leakage..and pinpoint leakage areas for
you to seal.

utility companies have gotten into free or cheap
audits. if you want independent testing Resnet.us
lists energy raters nationwide. BPI also trains
people for the audit business.

caulk is a great air sealer. it expands and contracts
to keep a tight seal. foams like great stuff dry and
shrink over time and do not provide a lasting seal.

best of luck.

I didn't check for air-leaks...I just decided to get wall insulation to help keep out both summer heat and winter cold. It also helps dampen some noise from neighbors garage band.

In the summer, I felt that my house didn't get a hot as usual. It used to get hot inside my house by 1 pm, but after adding the wall insulation the house gets hot by 5 pm. This means that I don't have to turn the a/c as early as before, thus saving some cooling $$$.

In the winter (now), my house is more comfortable than it used to be. My walls in my bedroom used to feel cold at night (considering that I'm a mild winter zone) just by putting my hand close to them. Now, it's not as cold even if I touch the wall.

Okay, this is all subjective data. If I had to do it over again, I would have chosen the fiberglass insulation over the cellulose.

I already had R-25 batt insulation in the attic, but I had the insulation guys use loose fiberglass insulation in all the areas that I missed when I installed the batts myself. I had missed about 10% of my attic primarily above the kitchen.

Overall, I paid $1630 to do all the walls (1200 sqft of walls) and about 150 sqft in the attic. I also got a $170 rebate from my gas company.

I already have double pane windows and a new aluminum back door. I have a glass door on my wood fireplace (it's a decoration piece) that I never use.