We're working on a building that has a large natatorium.

The project is located in Utah so we can use outside air for
dehumidification. There is no mechanical cooling in the as-designed
system.

Per Appendix G, it appears that the baseline system should be a packaged
single zone unit with a fossil fuel furnace for heating, an air side
economizer (dry bulb high limit of 75 F), and DX cooling. We're
controlling the space temp at 88 F and the relative humidity between
40-60%. The baseline system would run as a constant volume unit with a
minimum ventilation air requirement of 0.5 cfm/sf (~15,000 cfm).

The Appendix G baseline system has a considerable dehumidification load
- which shows up as a cooling energy.

The as designed system is a heating only unit with an air side
economizer and heat recovery. The system uses outside air to dehumidify
instead of a DX coil (Utah has a very dry climate). Space conditions
remain the same. We've modeled this system by increasing the amount of
ventilation air delivered to the space until the relative humidity in
the space is between roughly 40 and 60%.

The results show a large electric fan penalty (due to the pressure drop
across the heat recovery), a large amount of heating savings (from the
heat recovery), and a large amount of cooling savings, since we're now
using OA, heat recovery and natural gas to dehumidify the space instead
of electricity.

Is this a reasonable approach per the Appendix G modeling methodology?
It seems unreasonable to us that we should be able to claim the
cooling/dehumidification savings, but per Appendix G this seems to be
the case. I would welcome any and all thoughts and feedback.

Thanks.

Greg Schlegel