What is fuel source for heating? Forced air or boiler heat?

The design of your home? Two story? Finished basement?

A few details that need to be known.

IMO

+1

Gotta know more about the home and in this phase, spending the time on research and product selections (for all phases of the construction) will go light years to actually reducing the usage and ultimate size of the unit needed.

If you are factoring this into the loan on the home, now would be a good time to consider Geo-Thermal as the development costs will be much less with a new build depending on the application.

Have a heat gain/loss calc performed, so you will know how to size all the equipment.

Here is a link that might be useful: FREE Whole House Load-Calc