Heat recovery systems capture thermal energy from exhaust air, wastewater, or equipment operation and redirect it to heating or preconditioning incoming air or water. These systems reduce HVAC energy consumption by 15-40% by lowering the heating and cooling load that mechanical equipment must provide. Common applications include energy recovery ventilators (ERVs) in commercial buildings and heat recovery from chiller condenser water.
Technology Types
Air-to-air heat exchangers recover 50-80% of exhaust air sensible heat through plate-frame or rotary core designs. Enthalpy (moisture-exchanging) cores recover both sensible and latent heat, improving efficiency to 60-85% in humid climates. Water-side heat recovery systems capture 10-25% of condenser waste heat from chillers or rooftop units through plate-frame heat exchangers for domestic hot water preheating or process water heating.
System Integration
ERVs typically operate with 20-50% outdoor air fractions and reduce ventilation heating/cooling energy by 20-40% compared to systems without recovery. Condenser heat recovery adds 10-15% to chiller installation costs but reduces annual water heating energy by 30-60%. Maintenance requirements include quarterly filter changes and annual core cleaning to maintain 75% heat transfer effectiveness.