Energy Savings calculators

[ACxpert]

I am looking for a calculator to estimate the energy savings that will result by changing out old commercial rooftop units to new high seer units. The units are all constant volume. Does not have to be exact, just an estimate. Any ideas?

[jayguy]

that is a big time loaded question! how oversized was the old unit compared to the new unit...have design conditions in the space changed...are you controlling humidity better than the old unit...this is just to start.

you are going to have to do a space load calulation first, then you can compare the old to the new.