All air conditioners that are sold or installed in the state must meet the minimum efficiency ratings of the Florida Building Code-Energy Conservation. These efficiency ratings must be minimums and may be updated in the Florida Building Code-Energy Conservation by the department in accordance with s. 553.901, following its determination that more cost-effective energy-saving equipment and techniques are available. It is the intent of the Legislature that all replacement air-conditioning systems in residential applications be installed using energy-saving, quality installation procedures, including, but not limited to, equipment sizing analysis and duct inspection. Notwithstanding this section, existing heating and cooling equipment in residential applications need not meet the minimum equipment efficiencies, including system sizing and duct sealing.