Replacing your windows can improve energy efficiency and give a new feel to an interior space. In Florida, the state building code provides regulations for all exterior glazed surfaces, including windows. If you're replacing old windows, your replacements must comply with current code, possibly necessitating some design changes. To ensure that your new window designs meet legal requirements, consult with local authorities for additional county or citywide ordinances or codes. If you wish to meet the EPA's recommended standards for energy-efficient windows, the Energy Star ratings provide further guidelines.

All window materials, including glass panes and frames, must identify their manufacturers to confirm that their construction complies with Florida Building Code. The identification label may be sand-blasted, ceramically fired, laser-etched, embossed or otherwise permanently indicated. All panes must fit within their frames securely enough that they cannot deflect more than 1/175 of the total glass edge length, or 3/4 inch, whichever is less. Any louvered windows, or windows that consist of individual glass slats, must have thicknesses of 3/16 inch or greater. Individual louvers cannot measure more than 48 inches across. All exposed glass edges must be smooth.

The Florida Building Code imposes additional requirements on windows placed in "hazardous" locations. Hazardous windows include glass set into swinging doors, fixed or sliding door panels, storm doors, unframed swinging doors or interior doors and enclosures for baths, showers, saunas and other bathing facilities. Any glass surfaces within 24 inches of a closed door's vertical edge are also considered hazardous. Any such windows must meet special requirements for "safety glazing." Manufacturers must identify them as such by the same permanent engraving methods as permissible for manufacturer identification. Safety-glazed windows must withstand set impact loads, determined by their type (whether swinging doors, panels or sliding doors) and their size (whether less than or greater than 9 square feet).

When replacing a window, you may qualify for tax credits and enjoy reduced heating and cooling costs by complying with the Energy Star rating system's requirements. For windows installed in southern climates, including all of Florida, the Energy Star qualification criteria demand that windows have a U-factor no greater than .60. The U-factor demonstrates a window's effectiveness at keeping heat from escaping, with smaller numbers indicating greater efficiency. It is measured in British thermal units divided by hours multiplied by square feet. Windows must also have a solar heat gain coefficient (SHGC) of 0.27 or less. The SHGC indicates the degree to which the window permits heat to enter; a lower value indicates greater resistance of heat energy transfer.