| Environmental Assessment as prepared by |
| Enermodal Engineering Limited |
| 368 Phillip Street |
| Waterloo, Ontario N2L 5J1 |
| Tel: 519-884-6421 |
| Fax: 519-884-0103 |
Introduction
The environmental impacts of windows were studied as a part of the design process for the Waterloo Region Green Home. There were eight environmental factors that were considered when the decision was made to install windows with pultruded fiberglass frames and high-efficiency glazing system as outlined below. A comparison to aluminum-clad and vinyl high-performance windows was made.
Materials Used
Fiberglass for window frames is made of from 65 to 85% glass fibres and 15 to 35% resin. Silica sand is melted and spun into glass fibres. The resin is a thermoset polyester which is a petroleum-based alkide containing styrene, glycols, and acids. The insulation in the frames is expanded polystyrene. The pultruded lineals were produced by Omniglass of Winnipeg using fiberglass and resins from Owens Corning. The windows were manufactured and assembled by Accurate Dorwin of Winnipeg. The high-performance glazing units consisted of three panes of glass with LOF Energy Advantage low-E coatings on surfaces 2 and 5, low-conductivity silicone Super Spacer from Edgetech, and two argon gas fills.
Resource Depletion
The raw material reserves for silica sand are very large at present and are not expected to be exhausted. Quality control concerns in the production of glass fibre presently preclude the use of recycled fibre and waste is not recycled into the process though these options are being investigated.
In-plant waste resins for fibre glass are reused and re blended. The raw material reserves are based on the limits of petroleum products. The amount of petroleum is relatively small and contributes to a durable product that has a long life and energy efficiency not available from other products.
The polystyrene insulation is a petroleum product and, as mentioned above, has reserves based on the limits of petroleum. Again, a durable insulation is produced that has advantages in energy use reduction during the life of the window compared to other products.
Vinyl windows require a large quantity of poly vinyl chloride resins, which use petroleum as feed stock. Wood windows require clear heartwood for visible components placing a strain on old growth forests.
Emissions During Manufacture
Glass fibre production is said to be a closed process, with few emissions escaping to the environment. Resin manufacture is also said to be a closed process, with very few emissions to the environment. There is a chemical risk from the resins but it is less than that of PVC production. Expanded polystyrene is not produced in a closed process and some of the pentane blowing agent and other volatile compounds are able to escape.
The production of PVC releases petroleum byproduct to the atmosphere. the production of aluminum releases two fluorine gasses with potent greenhouse warning potential.
Ozone Depletion
There are no ozone-depleting chemicals used in the manufacture of fiberglass windows. The expanded polystyrene, however, uses pentane (approximately 7% by volume) as a blowing agent (a greenhouse gas).
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