Greetings-
I am preplxed by a dramtic increase in heating load for my building- 35000 sq ft two story office.

Base case equipment is Packaged Single Zone DX, fixed outside air (15%). Base board perimeter radiators to heat.

The Propsed Case is Packaged Multizone with HW heat. I added economizers, and kept the same baseboard.

The base case condtion used 183 MMBTU/year.
The revised model consumes 3338 MMBTU/year.

Space temperatures looked slightly different, but with in 2F-5F

Any thoughts? All things are identical expect the RTUs. I have checked everything I could think off.

Regards,
W. Peter Anderson, P.E