Method: Cooling tower range is: Range = Hot Water Temperature − Cold Water Temperature Cooling tower approach is: Approach = Cold Water Temperature − Wet-Bulb Temperature Tower effectiveness is: Effectiveness = Range ÷ (Range + Approach) × 100 which is equivalent to: Effectiveness = (Hot Water Temperature − Cold Water Temperature) ÷ (Hot Water Temperature − Wet-Bulb Temperature) × 100 If circulating-water flow is entered, heat rejection is estimated from: Q = ṁ × c_p × ΔT using water density of approximately 1,000 kg/m³ and specific heat capacity of approximately 4.186 kJ/kg·K. The calculated percentage is commonly referred to as cooling tower efficiency, but technically it represents tower effectiveness based on the entered water temperatures and ambient wet-bulb temperature. Actual tower performance is also affected by air flow, water distribution, fill condition, recirculation, wind, fan performance, fouling, drift, tower design and measurement location.