From the "calculator" the default "heat to" temp is 68. That seems kind of absurd to call a default indoor air temperature during winter months. Is used for all day or just night time temps?
The Manual J (industry standard approach to load sizing) uses 70 dF for heating and 75 dF for cooling as its defaults, so we could definitely update the defaults to those, too.
I guess I can try their model and find out.