Ventilation of Shower Rooms

I have a shower room with multiple heads. This is in a dorm setting and is used almost continuously due to class schedules. What should the air change rate be to remove moisture to prevent mold situations? ASHRAE 62.1 list locker rooms at .5cfm/sf but that will not cut it for this. I saw one gym with a shower room that had a ventilation rate of 19 air changes for the shower. Is there any reference or could someone point me in the direction of other research?

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Hi.

Check your local standards,... however here is Australia, as a guiding value we use 25L/s for WC fittings and 50L/s per shower head. Of course this varies depending on size of room, available infiltration & external ventilation etc,... however somewhere around these values shold point you in the right direction.

With showers in particular, its quite important to capture as near as possible to the source. So location of intakes is significant to solving the problem.

Good luck.

A few random thoughts, hope this helps.

1. Keep in mind that unless you have an air dryer, you won't be getting the humidity below the ambient relative humidity, and that may still be enough to support mold growth.

2. There are standards for laboratories that have positive pressure or negative pressure. Negative pressure keeps things (fumes, bacteria, etc.) from escaping, and makes the doors stick just a bit when opened. You could use the standard for that as a default.

3. If you aren't trying to convince anyone but yourself that extra ventilation is needed, just go for whatever level you think will be effective, and use that as the default standard.

Thanks for the comments. The 50L/s was the range I was thinking. The real key to this is how well the showers are cleaned. This is done by the occupants and this leaves something to be desired. There are other issues to consider, such as make-up air and such but that is what make projects interesting.

Remember that codes and standards should be considered as minimum requirements, and special conditions will require higher than specified ventilation rates.

Depending on outdoor conditions de-humidification might be required.

You may consider estimating how much water vapor is added to the air, then determine how much air needs to be replaced to take out the moisture to maintain an acceptable humidiy ratio. That way, if someone questions your design, you can show the rational for the high ventilation rate or dehumidification choosen. If they dispute your estimate, ask them for an estimate based on the conditions you described.

Whatever the code calls for in a single commercial shower could be multiplied by the number of shower heads. consider doubling the result to allow for "the duty cycle" and you should have a figure to work with. Compare the requirements to achieve that airflow with other similar facilities. Good luck.

From the field;

Whats the locker room temperature? If it is 85*f or higher drop it. What is your outside air like? If it is dry bring in more "make-up" air to a point that your A/C system can hold your locker room around 75*f. Keep the A/C fan running when the room is being used.Keep the room positive and let your new up sized exhaust fans relieve the room of humidity.

We do a lot of work at a very high end Spa in Las Vegas and this method works.

Mike

Dorms I have seen have also had toilets in shower area, in which case ventilation needs to keep the room negative.

Good point Ried. He will need a gentle balance.