I have an existing 90,000 SF, 3-story office building in Massachusetts consisting of VAV boxes with electric reheat and rooftop units that also have electric heat. The scope of this project consists of replacing these rooftop units with gas fired DX units. The VAV boxes will remain as is and are outside of the project scope. Since we now have gas as a heating source, ASHRAE 90.1 requires that the baseline system consists of DX cooling and a hot water fossil fuel boiler. I do not see any exemption that would allow me to model the VAV boxes as is.

So with the baseline model using a fossil fuel boiler for reheat and the proposed model using the existing electric for reheat I am not able to meet this pre-requisite. Is there an exemption somewhere that I am missing?