Energetic, economic and environmental analysis of a health-care facility HVAC system equipped with a run-around membrane energy exchanger

• A novel membrane energy exchanger that uses a liquid desiccant (RAMEE) is simulated in the HVAC system of a hospital in 4 North American climates.
• Annual heating and cooling energy are reduced by up to nearly 70% and 20% respectively due to the RAMEE.
• The RAMEE allows the capacity of the heating and cooling systems to be reduced by nearly 50% and 25% respectively.
• The payback period for the RAMEE is 0–3 years.
• The RAMEE reduces greenhouse gas emission (CO2-equivalent) by up to 25%.

Run-Around Membrane Energy Exchanger (RAMEE) is a novel heat and moisture recovery system that consists of two separate supply and exhaust exchangers coupled with an aqueous salt solution flow. The salt solution transfers energy (heat and moisture) in a closed loop between outdoor ventilation air and the exhaust air from buildings. The system performance is a function of the flow rate of the salt solution and ventilation air and the outdoor air conditions. The dependency of system performance on the solution flow rate and the outdoor conditions requires adjustment of the appropriate flow rate which gives the optimal system performance at any specific outdoor condition. In this paper, the RAMEE is simulated for a hospital building in four different climates using TRNSYS and MATLAB computer programs. The steady-state RAMEE can reduce the annual heating energy by 60% in cold climates and annual cooling energy by 15–20% in hot climates. The RAMEE has an immediate payback in cold climates and a 1 to 3-year payback in hot climates depending on the pressure drop across the exchangers. Finally, the RAMEE reduces greenhouse gas emission (CO2-equivalent) by 25% and 10% in cold climates and hot climates, respectively.