To qualify as environmentally friendly, building components like windows and doors need to fulfill a couple of requirements. First, they need to have as little impact on the environment as possible in both their manufacture and life cycle. This can include things like being made of recyclable or renewable materials and not generating much in the way of pollutants during their existence or when they’re being retired. Second, they need to contribute to reducing energy consumption when in use. As you might suspect, these qualifications also make them great cost cutters as well.
Fortunately, the common door materials of wood, steel, and fiberglass are pretty kind to the environment. Wood stands out as the most eco-friendly available but only from the right sources. Timber from dedicated tree plantations offers an alternative to wood from old-growth forests. Manufactured wood products like medium density fiber board allow normally unsuitable rapid-growth tree species to be used. Along with being strong and durable, steel is easily recycled and in fact, most of the steel produced in the world comes from scrap. While not nearly as recyclable as steel, fiberglass takes a bit less energy for initial production. It also lasts a lifetime without denting or warping like wood and steel. Regardless of the exterior material used in doors, an insulated core, especially polyurethane, is a must because even solid wood does little to block heat and cold from outside.
Glass And Gas
While it’s simple to add an insulating core to an exterior door, windows need special technologies to make them energy-efficient. One method to reduce heat loss is by adding a low-emissions or low-e coating to them. These invisible metallic films prevent warmth from escaping by reflecting back indoors. At the same time, they reflect UV light and summer heat away from the interior. Using multiple layers of glass with dead air space in between helps provide a measure of insulation. More recently, the spaces are being filled with argon or krypton gas by some manufacturers to boost the insulation value to R-9 in some cases.
Breaking It Down
All windows and doors eventually wear out and need replacing. This can place an additional burden on the environment and it’s not easy to say which materials are friendlier here. Steel can be indefinitely remelted but requires considerable energy each time. Wood can be reused while consuming less energy by being ground down and added to manufactured materials, but only once or twice. Then again, it can reduce energy consumption by being burned as a bio-fuel.
While harmless gases like argon conduct less heat than air does, they can still leak out over time. At the same time, a vacuum space transfers even less heat than the best insulating gas. A possible future green technology being researched involves creating clear films that contain microscopic vacuum pockets throughout them that, in tests, produce up to an R-20 value. Best of all, as films, they can be applied to existing glass panes.