Fiberglass provides low levels of conductivity without the need for thermal breaks.
Fiberglass frames are more energy efficient than aluminum or vinyl windows, allowing less heat or cold to travel through the frame material itself. Fiberglass significantly outperforms even the best thermally broken aluminum windows (as shown below):
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Since it does not usually require reinforcement, fiberglass is also less conductive than typical vinyl window configurations. The steel added to reinforce vinyl frames reduces their energy performance – losing up to 20% of their R-value – and makes the frames feel colder, in winter conditions. Fiberglass frames are more energy efficient and feel warmer in winter conditions (as shown below):
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Office building in Nunavut, featuring 300 Series windows.
Thermal modeling demonstrates the superior efficiency of fiberglass frames, compared to reinforced vinyl or aluminum. The window sections at left use identical glazing units, but the fiberglass frames are shown to be warmer in cold winter conditions – with reduced heat loss and improved condensation resistance.
