Radiant Barrier Savings Calcs

[OOC]

I know there is a monster radiant barrier thread here http://hvac-talk.com/vbb/showthread.php?t=112101 , I thought it best to start a new one for my specific question.

Anyone use the radiant barrier and increasing insulation savings wotksheet at the DOE ORNL site, here http://www.ornl.gov/sci/roofs+walls/radiant/rb_05.html ?

I'm not getting the calcs to predict great savings for my home that I expected. Anyone else look at those calcs? Did it persuade your decision on an RB or not?

[paul42]

Their calculations are hard to follow.

But, the more insulation you have in your attic, the less savings you will get from RB.

If your duct work is not in your attic, you will have less savings from RB.

The more efficient your AC is, the less savings you will see from RB.

The payback on the RB sheathing I put in my house appears to be more than 20 years.

[OOC]

Is that 20 years based on their calcs, on your actual utility bill savings?

[paul42]

Is that 20 years based on their calcs, on your actual utility bill savings?

Their calcs.

The house was built with RB sheathing, so I don't have any before numbers.

[OOC]

OK, thanks.

[jax1]

Paul,
Did you pay more for the radiant barrier in your new house? RB attached to roof decking at the factory should be minimal or no more than plain plywood decking.
My payback was 0 yrs (no extra charge) for RB.