Recent technological advancements in HVAC manufacturing have made dedicated outdoor air systems (DOAS) easier to specify and install for contractors.
When rooftop units (RTU) from the 1980s and 1990s approached the end of their lifecycles, HVAC contractors are faced with retrofits that require upgraded outdoor air compliance with the American Society of Heating Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 62.1.