Certified models meet all ENERGY STAR requirements as listed in the Version 4.0 ENERGY STAR Program Requirements for Ventilating Fans that were effective as of October 1, 2015 or the Version 4.1 requirements that are effective as of July 24, 2018. A detailed listing of key efficiency criteria are available at https://www.energystar.gov/products/heating_cooling/fans_ventilating/key_product_criteria .