Which material is the best frame for double-glazed windows – unplasticized polyvinyl chloride (uPVC), aluminum or wood?
Although all double glazing is better than singles, the type of frame can affect the overall performance of your window. You will find it in your interest to know how uPVC, aluminum and wood frames compare in terms of insulation efficiency, climate performance, carbon footprint and cost.
Chic and available in a variety of finishes and textures such as rosewood and golden oak, PVC window frames are very good insulators.
They can withstand normal weather conditions for a period of 10 to 20 years. Corrosion and decay are almost non-existent with PVC window frames, but are subject to cracking and fading over time. There is not much to do with uPVC frames, but to clean them up.
Although requiring little maintenance, uPVC window frames leave the most traces of carbon. They are non-biodegradable, irreparable and expensive to recycle. Environmentalists warn that toxic waste and potential health risks (during production and disposal) associated with uPVC will far outweigh your energy savings.
The elegant and modern aluminum is a bad insulator. Manufacturers have corrected the problem by adding a thermal layer, thus making aluminum more expensive than PVC units.
Aluminum frames can last up to 45 years. According to a 2005 report from the Aluminum Association, the metal is very resistant to weather and to many acids. The metal corrodes and stains well. Minimal maintenance is required to keep hinges, rivets and other moving parts well lubricated.
Aluminum double glazing may not be very energy efficient to manufacture, but it does not pose any disposal problems like PVC. Aluminum is abundant and highly recyclable.
The most traditional and expensive of the three is wood – an intrinsically good insulator. However, if it is not properly treated and sealed, the wood will deform, shrink and rot. The Hastoe report on sustainable homes estimates that wooden frames can exceed a 60-year life span and can easily survive up to 10 years to double-glazing of similar quality. The actual life cycle of wood double glazing can be much shorter and varies depending on the quality of the wood, the maintenance and the treatment.
Advocates of the environment prefer wood to any other material. The double glazing made of wood leaves no carbon footprint. The wood can be repaired, repainted, recycled and reused.