Fitness Center Design Question

[Antifed]

Hello,

I searched through the forum to see if a previous post had the answer for which I am looking, but did not come across it. I searched for "fitness center", "gym", and "gymnasium" design and came across a few posts, but none with the answer. Our office has been tasked with providing mechanical design for a 1970s vintage fitness center. The fitness center has had its HVAC upgraded since the initial build (back in 2010), but the equipment is not keeping up with the loads in the facility (there is a fitness area, kickboxing room, spin room, aerobics, natatorium, etc.). Each space is served by its own packaged DX unit (the pool served with a Pool-Pak unit). The majority of the building is not insulated, to boot.

All of that being said, is there an appropriate diversity factor (Cooling Load Factor) that can be applied to the fitness area design in regards to the people load? The IBC occupant load is approximately 310 people (50-sf/person | 4.65-sm/person). The instantaneous load from 310 people is significant (over 710-btuh sensible and 1,090-btuh of latent load per person | 208-W sens/ 320-W latent). If the condition would ever occur such that that many people are in the space and working out, it would only be for a short duration. I just don't want to see us spend a lot of money on equipment for a hypothetical condition that MAY happen. The user has yet to respond with information regarding their current usage patterns which would help me use a "realistic" number of occupants. I was talking to my boss (also an experienced designer) and we figured that if the spaced conditions floated for an hour or two that we could use more conventional equipment instead of looking into dedicated dehumidification units or multiple units. We're also planning to install ceiling fans to improve air flow.

From previous discussions, it appears that the customer would like to stay with DX for the new equipment (direct replacements, but up-sized to account for loads).

Thank you very much. I appreciate your feedback. If you need more info, please let me know. In the fitness area, the driving load is the people (both heat generated and ventilation, the latter requiring close to 6,900-scfm | 3257-lps).

Respectfully,

Antifed

 

[BronYrAur]

Doesn't the facility have records of occupancy? They should be able to tell you how many people are in the building at various times of day.

 

[willard3]

If you don't design for maximum people load, your equipment will be undersized.

There are many ways to reduce the energy use when the loads are less than maximum.

 

[chicopee]

I suspect that the pool is increasing the humidity within the entire structure, so double check on the adequacy of ventilation within the pool area.

 

[dbill74]

The problem with a gym or fitness center is that fact that you have a massive difference between min and max occupancy. The only real way around it is to design a system that can adjust to the occupant loading. Dx systems are going to struggle without multiple units and staging. Chilled water system is going to be your best bet.

As for diversity, it will depend on the project's location and clientele. If the clientele is mostly military, then safe diversity factor is going to be 90-95%. Otherwise 70-75% is probably a safer bet. If the location is in an urban area and it is a popular gym, a higher diversity may be needed. Conversely, in a rural location, something less (50%) may be more appropriate. If your client doesn't have numbers or want give them to you, go pay the existing gym a site visit.

Also keep in mind when the peak loading will occur (morning and early evening). I don't know what load calc program you are using, Trane Trace and Carrier HAP allow you to adjust the occupancy schedules to account for more people in the morning or evening.

An "oversized" system can respond to rapid changes in the occupancy faster than an "adequately" sized system. Something that can potentially bring more users to the gym and generate more revenue for the owner.

 

[GT-EGR]

Look at the actual gym and count every single bench, machine, mat, etc all being used at once (then add some more for people working out together and spotting eachother etc) and figure out how many people that is.

The gyms I’ve gone to through my life are regularly 100% utilized for extended periods of time - and if the AC can’t keep up with this (which is the whole goal of owning a gym) then it isn’t doing its job

 

[Antifed]

Thank you all very much. As of last night, I am thinking that a chilled water system with decentralized units (e.g. fan coils/blower coils) to serve each space with DOASs to aid in dehumidification and to provide the ventilation air flow.

There are various restrictions on funding, funding streams, and programming documents that may impede providing the right solution vs. a "get it done" solution, unfortunately, so we'll see what the owner is willing to do.

Have any of you all ever used a liquid desiccant system? It's an option that I'm investigating as a means of combating the peak humidity levels. The building has an existing solar thermal roof that once was used to preheat domestic hot water, pool water, and provide space heating (it is highly suspect that the system does anything anymore) which could be repurposed to regenerate the desiccant.

 

[chicopee]

You are not telling us where the facility is located so it is difficult to judge your real problem from where we stand. I suspect that the number of people using your fitness center is not the real problem. You indicated humidity problem which could be due to the evaporation from your pool water. Before you do anything hire a competent ventilation engineer, then you can present the facts to the owner and perhaps options.

 

[Antifed]

The Natatorium is on a separate system within the simulation as is its evaporation rate; though I am waiting on the client to tell me what temperature they keep the water so that I can set a room temp setpoint and add in the convective cooling load from the pool.

The fitness center is on its own system. 309 people at 1090-btuh of latent per person is the challenge in that space--the people load greatly exceeds the skin loads.

The facility is located in the Baltimore, MD region. Hiring a competent engineer is not an option so they will unfortunately have to rely on me.

 

[chicopee]

In Baltimore it can get pretty hot and humid in the summer. Another thought is check the outside of the structure and determine if the sun reflection from other buildings on your structure may be a contributor to the heat load.

 

[willard3]

If they don't want to hire an Engineer, they don't want to solve the problem.

Looking here for a free Engineering answer is contrary to board policy and has the possibility of getting you a lot of problems.