I manage a facility that houses 2 above ground 90 degree pools in a Louisiana warehouse & have multiple temperature control & humidity issues.
Facility: 2,000 square foot warehouse space with an average 20' ceiling. The walls & slab is steel supported concrete (probably about 1-2' wide). The building is rectangular. North end: the pools occupy about half of this space, with 4' high deck seating (for clients). The North wall has an exhaust fan at 20. The South half has ground level seating, a ground level installation that houses bathrooms, showers, changing rooms. (Above the Bathroom & Shower rooms is an open air office, at 12' high.) On the South wall there is the business entrance and a garage door. (The business door has 20 clients entering & exiting every 30 minutes. The garage door can be opened if the weather is agreeable).

Problems: Humidity- Unsolved. Currently, we cover the pools & have a high power exhaust fan maintain airflow.
Temperature Control- Winter: Currently, we have a gas heater dropped from ceiling. Comfort: Wet students (coming out of 90 water) are comfortable, clients on 4' mid deck are too hot, ground level clients & bathing suited students are too cold (w door use- 20 clients enter/leave/ half-hour) & office staff at 12' cant work in the heat. Summer: Currently, we are using exhaust fans & directional fans. See comfort above, but add heat, heat & more heat.

With the understanding I can't reconstruct the design and may be limited by budgeting to do this project in 2 stages: How would you suggest breaking this project down? & What would be the most important first step (with winter on the horizon)?
Suggested Sizes & Combo Units: Dehumidifiers, One unit AC/Heat? Would a few ductless systems be an option w directed climate control at each level- ie. ground & mid-deck, office?
Additional Suggestions: Regulating temp control at multiple levels (0, 4 & 12)? Regulating the comfort of clothed clients & wet suited students? Keeping humidity down & client comfort with 90 degree pool water? Handling the air escape with clients entering & exiting the business? And one last HAIL MARY: at 12' in a warehouse, we would prefer the office to be cooler for staff and office equipment.
Thank you in advance for all of your advice, suggestions and expertise!!