Life-cycle assessment (LCA) of air-handling units with and without air-to-air energy exchangers

The life-cycle assessment (LCA) methodology is used in this paper to assess the environmental effects of air-handling units (AHU) over a 20-year life cycle. This assessment is based on quantifying the consumption of resources (energy and materials), the harmful emissions into the environment (air, water, and soil), and the potential changes in the environment (climate change, acidification, and ozone production). A normal AHU, with a face velocity of 3 m/s (600 fpm), and a small AHU, with a face velocity of 4 m/s (800 fpm), are investigated with and without two types of air-to-air energy exchangers (plate and rotating wheel). The research demonstrates the following benefits of air-to-air energy exchangers: reduced energy consumption, reduced emissions to the environment, and reduced potential harmful changes in the environment. For both of the AHUs studied, these benefits are several times greater than the burdens arising from the production and operation of the AHU, where the function of the AHU is to provide 2000 L/s (4200 cfm) of outdoor air to the building space for 2500 h/year, but not to condition this air. A larger AHU with an air-to-air energy exchanger of higher efficiency has the smallest harmful effect on the environment.