Specific heat capacity (Cp) is the amount of energy required to raise one kilogram of fluid by one degree Kelvin. It is measured in J / (kg · K) [SI] or BTU / (lb · °F) [Imperial]. The heat transfer equation is:

Q = ṁ × Cp × ΔT

where Q is heat flow (W or BTU/hr), ṁ is mass flow rate, and ΔT is the temperature difference across the heat exchanger.

Ethylene glycol solutions have a lower Cp than water. At 40% V/V and 68 °F (20 °C), Cp is roughly 10–15% lower than pure water, which means a larger flow rate or temperature differential is required to transfer the same amount of heat. This directly affects heat exchanger sizing, chiller capacity, and pump selection in HVAC and process cooling systems.