Fitness centre HVAC

Fitness centres are often built in spaces designed for something else: former retail units, office floors or warehouse bays. The HVAC that served a clothing store or an office is rarely adequate for a room full of people on treadmills and in spin classes. Exercising people release several times more heat and moisture than people sitting at desks, and they notice immediately when a room is stuffy or too warm.

This guide covers the main design drivers for gyms, studios and locker rooms, whether in a standalone club, a community recreation centre or a corporate fitness room.

Why exercising people are a large load

Metabolic heat output rises sharply with activity. The ASHRAE Handbook of Fundamentals tabulates heat gain from occupants by activity level. Approximate values:

A busy spin class of 30 people can therefore produce as much heat as a much larger office floor, with a high proportion of it as moisture from sweat and breathing. Cardio equipment with motors and displays adds further load. See internal heat gains from people, lighting and equipment.

Ventilation requirements

Ventilation is designed to ASHRAE 62.1 through Part 6 of the NBC or the provincial code. The standard assigns high people-based rates to exercise areas.

Values should be confirmed against the edition referenced by the governing code. Locker rooms and showers are typically handled through exhaust requirements rather than outdoor air rates. See the ASHRAE 62.1 ventilation rate procedure for how these combine into system airflow.

A 150 m2 (1,600 ft2) group fitness studio at the default density of 60 people would need roughly 650 L/s (1,370 cfm) of outdoor air. Heating that much outdoor air at -30 C (-22 F) is a large load, so heat recovery is highly valuable in Canadian fitness facilities.

Demand-controlled ventilation

Occupancy in fitness centres swings widely: packed at 6 a.m. and 6 p.m., nearly empty mid-afternoon. Studios are full for 45 minutes and empty for 15. Demand-controlled ventilation using CO2 sensors in studios and large workout areas reduces outdoor air during quiet periods while ensuring rooms are well ventilated when full.

Design temperatures and humidity

Exercising people prefer cooler conditions than office workers. Typical design targets:

Relative humidity should generally be kept below about 60 percent in workout areas. High humidity makes rooms feel oppressive and can lead to condensation and mould on cold surfaces. Equipment sized only for sensible cooling may not remove enough moisture, especially when oversized units short cycle. See dehumidification strategies.

Studios and specialty rooms

Each type of studio has its own needs:

• Spin and HIIT studios: high cooling and ventilation per square metre, fast recovery between classes, and fans for air movement. Instructors often want local control.
• Hot yoga studios: heated to high temperatures with added humidity. They need humidity-tolerant construction with a robust vapour barrier, corrosion-resistant equipment, a strong exhaust purge between classes, and controls that prevent the space from becoming dangerously hot.
• Boxing and martial arts rooms: high activity and heavy perspiration, often with mats that hold moisture.
• Climbing walls: tall spaces where chalk dust requires good filtration.

Locker rooms and showers

Locker rooms are a common source of complaints about odour, humidity and mould. Good design includes:

1. Continuous exhaust from showers, toilets and locker areas, sized to keep them negative relative to the workout floor and reception.
2. Exhaust grilles located near showers and toilets so moist air is captured before it spreads.
3. Make-up air drawn from adjacent areas or supplied directly, with heat recovery where practical.
4. Corrosion-resistant ductwork and grilles near showers.
5. Moisture-tolerant finishes and adequate heating to dry surfaces.

Saunas and steam rooms need dedicated exhaust and careful vapour control in adjacent walls. Pools in fitness facilities have their own requirements, covered in our indoor pool guide.

Odour

Odour in workout areas comes from people, rubber flooring and mats. Adequate outdoor air, good air distribution and continuous locker room exhaust address most problems. Running ventilation for a period before opening and after closing, plus routine cleaning of mats and equipment, helps further.

Noise

Music, amplified instructors and dropped weights mean fitness centres can be loud, but HVAC still needs attention. Equipment located above studios should be well isolated, and in mixed-use buildings, the gym's noise and vibration need separating from neighbouring tenants. Rooftop units over yoga and meditation studios should be selected and located carefully.

Converting existing spaces

When a fitness centre moves into a former retail or office unit, the existing rooftop units are often undersized for cooling and ventilation. A load calculation using exercise metabolic rates, a check of outdoor air capacity and economizer function, and a review of exhaust paths for new locker rooms should come before signing a lease. Air balancing after fit-out confirms each studio and locker room receives its design airflow.

Key takeaways

• Exercising people produce several times the heat and moisture of office workers.
• ASHRAE 62.1 assigns high outdoor air rates to exercise areas, so heat recovery pays off in Canadian climates.
• Demand-controlled ventilation suits the highly variable occupancy of studios and gyms.
• Workout areas need cooler setpoints and humidity below about 60 percent.
• Locker rooms need continuous exhaust and negative pressure to control odour and moisture.
• Spaces converted from retail or office use usually need significant HVAC upgrades.