What is the downside of using fiberglass instead of aluminum?
Top. Brandon Tinianov: The only real downsides are the maximum allowable structural loads and cost. The embodied energy is much lower for fiberglass and the maintenance is the same. 14. What about wood frames? Top. See information on different frame materials on the Efficient Windows Collaborative site at http://efficientwindows.org/ftypes.cfm. 15. What is the long term migration of argon gas in insulated units? Top. Studies have shown less than 0.5% leakage per year in a well-designed and well-fabricated unit. In Europe, the norm EN1279 prescribes below 1% gas loss per year. So these gas loss rates are achievable. But this depends on the quality of the seals, the glazing design, and on quality control during the manufacturing process. If seals break, all gas is lost. As Tim McGlinchy mentioned, from 2010 on, the National Fenestration Rating Council and Energy Star will require that the units used in certified windows are also certified under recognized IG certification programs. This
