Swimming pools
Evaporation in the swimming pools in normal activity in kg/h m2
The rate of evaporation in kg/h m2 can be estimated for the swimming pool in normal activity,
integrating splashing due to the bathes on the accesses of a limited zone (Smith, et al., 1993)
(ASHRAE, 1995), according to the following formula:
• W = Rate of evaporation at the surface of the water level (kg/h m2)
• Pw = Vapor pressure at saturation taken at the temperature of surface of water, in kPa
• Pa = Vapor pressure at the dew point according to the temperature of the ambient air of
the room, in kPa
• V = Air velocity above at the surface of water, in m/s
• Y = Latent heat necessary according to the change of state of the water vapor at the
temperature of surface of water, in kJ/kg
Function = Pool_evap1(ts1, ts, Hr, Saw, Z)
- ts = Dry temperature in °C of the ambient air of the swimming pool
- ts1 = Temperature in °C at the water level
- Hr = relative Humidity in %
- Vit = Air velocity in m/s at the level of water
- Z = Altitude in m
Evaporation in swimming polls in kg/h m2 according to the type of activity in the covered
swimming pools
For a latent heat (Y) of a value of 2330 kJ/kg and with a speed of air (V) at 0,10 m/s and while
multiplying by a factor of activity (Fa) to reduce the rate of evaporation estimated according to
the corresponding level of activity, the equation is reduced to the following expression:
• W = Rate of evaporation at the surface of the water level (kg/h m2)
• Pw = Vapor pressure at saturation taken at the temperature of surface of water, in kPa
• Pa = Vapor pressure at the dew point according to the temperature of the ambient air of
the room, in kPa
Type of swimming pools Factor of activity (Fa)
Residential swimming pools 0.5
Condominium 0.65
Thermal baths 0.65
Hotel 0.8
Public swimming pools or Schools 1
Whirlpools, spas 1.5
Wave pools, water slides 1.5 (minimum)
Evaporation at the level of water in kg/h m2
- ts = Dry temperature in °C of the ambient air of the swimming pool
- ts1 = Temperature in °C at the level of water
- Hr = Relative humidity in %
Function = Pool_evap2(ts1, ts, Hr)
Evaporation at the level of water in kg/h m2 (another formula)
Evaporation at the water level in kg/h m2
• W = Rate of evaporation at the surface of the water level (kg/h m2)
• We = water content of the air at the temperature of the water level (kg/kg of dry air)
• Wa = water content of the air of the room (kg/kg of dry air)
• V = Specific volume of the air in the room (m3/kg of dry air)
• Vµ = Specific volume of the air at the level of water (m3/kg of dry air)
Function = Pool_evap(ts1, ts, Hr, Z)
- ts = Dry temperature in °C of the ambient air of the swimming pool
- ts1 = Temperature in °C of the water level
- Hr = Relative humidity in %
- Z = Altitude in m
For this type of formula, it is necessary in theory to add projections of water and the latent gains
caused by the bathers
Sensible contributions by radiation
• T water = temperature of the water of the basin
• Ts = Ambient temperature of the swimming pool
Function = Pool_rayon(ts1, ts)
- ts = Dry temperature in °C of the ambient air of the swimming pool
- ts1 = Temperature in °C of the water level
Sensible contributions by convection
T water = temperature of the water of the pool
Ts = Ambient temperature of the swimming pool.
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