Exhaust Fan Sizing

The general rule is volume of room x required air changes/hour. The required air changes/hour varies upon the room application.

So it's for a locker room is it? Okay then, allow for 70m³/hr per person occupying the room to minimize the fragrance of BO and other bodily scents.

ASHRAE has published this information you are looking for you can refer the ASHRAE documents on Ventilation good luck

crm

Typically exhaust fans develop a negative pressure of about 5mm water gauge. This keeps the doors closed if they open outwards. Unless care is taken to provide adequate air inlet area the specified air changes are not achieved.

Usually 15 air changes/ hour are specified for normal activity in the room without any active heat or vapour generation.

Bioramani

Using ASHRAE 62.1s 'Indoor Air Quality Procedure' sort of says if there are bad farts and people 20 % of the people gag within 15 seconds the subjective analysis indicates the indoor air unacceptable.

However, the 'Ventilation Rate Procedure' requires 50/70 cfm per unit for a public toilet, but only 20 cfm in a residence if the windows are openable!. Locker rooms require .5 CFM/FT SQ and Locker/dressing rooms only .25 CFM/FT SQ.

Truthfully, this is a non-trivial subject that ASHRAE is trying to address with respect to building energy consumption and encourage creative and innovative solutions. I am sure your local building official will be inflexible and prefer you use the prescriptive VRP and not the subjective IAQ procedure.

Regarding Ashrea 62.1s Gentlemen the gas thus indicated in your conversation is generally and more specific H2S, although according to the regulation not limited to H2S, is also known as happy gas because kids laugh when it happens to generate an audible sound exiting from the source of generation.

Lots of humorous anecdotes are available regarding the production of noxious airborne contaminants, but what you are looking for is Table 401-3 of the IMC. This is a "prescriptive" chart, which means 'mandatory minimums' but is based on an older version of ASHRAE 62.1, the ventilation code.
The ensuing decades of research studies to determine 'real world' minimum ventilation rates for acceptable indoor air quality while minimizing energy use by mechanical systems has resulted in much-improved (though certainly not perfect) revisions.
See the latest ASHRAE 62.1 (2007) release for the newer Table 6-1.
If interested in getting into the Engineering of systems to achieve the best tweaks for lower operating costs you'll need to look into the ventilation-rate procedure, read all the supplemenary notes and exceptions, take advantage of displacement ventilation through the breathing zone, operate the exhaust based on occupancy sensors, vary the fan speeds and HVAC response based on the changing loads, institute Active Filtration with a combination of electronic agglomerator/ozone generation with carbon-impregnated media, and install Energy Recovery Ventilators in place of those obsolete 'exhaust fans' everyone's been using to dump their treated air outside.
Have fun!
Oh - a quick Google revealed an accessible reference copy of the current table

Cheap way out. FeBreeze.

What I might like to see in a new building is the following:

1. Increased reliance on stack effect to ventilate spaces - no fans in buildings of greater than some certain height. Stack effect would have to be controlled through adjustable dampers.

2.. Very reduced exhaust fan size - way undersize the motor to reduce energy consumption.

3. Motion sensor energized exhaust fans timed to turn off after the user leaves, except in the case of locker rooms where moisture control may be an issue. In fact, perhaps the air conditioning to such a room could be shut off and the room cooled evaporatively by causing the space to under negative pressure.

I am looking for ways to decrease the net energy use of buildings, which accounts for a significant share of the worlds use of energy.

The exhaust fans for toilet shall be designed for 15 too 20 air changes per hour. The door of the Toilet shall be with door transfer grill and toilet door shall be open able outside the door transfer grill shall take the air required for exhausting the toilet air and keep free of odor /smell.