Energy-Saving Window Film in Philadelphia

Where Philadelphia Homes Lose Energy Through Glass

A lot of Philadelphia houses still have original wood sash, often single-pane, sometimes with aluminum triple-track storm windows added on the outside in later decades. Others have early vinyl or aluminum replacement windows with basic double-pane glass and no low-E coating. All of these let a lot of heat through.

In summer, that heat comes from the sun, mainly through south and west glass. In winter, the flow reverses: heat from the furnace or boiler escapes through the cold glass, and rooms near big windows feel drafty even when the sash is tight. Energy-saving films address both directions, though different films lean one way or the other.

How Energy-Saving Window Film Works in Both Seasons

Solar control films reduce summer heat gain by rejecting a share of incoming solar energy. That lowers the work your air conditioning does on the hottest afternoons, which is when electric demand on PECO's system is highest.

Low-emissivity films add a coating that reflects long-wave heat, the kind radiated by warm room surfaces and people. In winter, more of that heat is reflected back into the room instead of passing out through the glass. The effect is modest compared with a new insulated window, but on single-pane glass it is a noticeable step up for a fraction of the cost.

For most Philly houses we recommend a low-E or selective film that balances both seasons, rather than a dark summer-only film that also blocks useful winter sun.

Energy Film, Utility Bills and Philadelphia Gas Heat

In the city, most homes buy electricity from PECO and heat with natural gas from Philadelphia Gas Works, though some use oil or electric heat pumps. On the Main Line and in other suburban areas, PECO supplies both electricity and gas. Whatever the fuel, the windows are one of the weakest parts of an older home's envelope.

Film will not replace air sealing, attic or roof insulation, or a well-tuned heating system, and those often pay back faster. But once the cheaper fixes are done, the glass is usually what is left. We are glad to work alongside an energy audit and can provide film specifications for an auditor's report.

Energy Film on Historic and Storm-Windowed Philly Houses

Window replacement on designated buildings in Society Hill, Old City and other historic districts often requires Historical Commission review, and owners are commonly encouraged to repair original sash rather than replace it. Interior film leaves the original window in place and can be removed later. Owners of designated properties should still confirm with the Commission before installing, particularly on street-facing windows.

If you already have exterior storm windows, film normally goes on the inside of the primary sash. We check the gap between the storm and the main window, since some films are not suited to glass that sits in a closed, hot air space, and choose a product rated for that setup.