Vinyl, aluminium, wood or fiberglass frames in windows and skylights

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Aluminium, wood, vinyl and fiberglass
windows, doors and skylights

The efficiency of an entire window, skylight or patio door can be very different from that of the glass alone.

Frames and sashes (the glass element fits into the sash, and the frame holds the sash) are also important elements of energy efficiency, durability and cost.

Window, doors and skylights frames and sashes can be manufactured from a variety of materials – aluminum, fiberglass, vinyl (PVC), wood, or combinations of these materials – with different thermal performances, durability, environmental impact and costs…

Low-priced, poor quality fenestration are a bad investment. Good performing windows, skylights and doors – with quality frame, sashes and glass - provide savings, last long, and cost less in the long term.

Aluminum frames

Common aluminum windows, skylights and patio doors are durable and offer low maintenance…

But … they have a big drawback: aluminum is a highly conductive material, causing high energy losses. It has bad thermal performance. Which doesn’t mean that all aluminum windows, skylights and patio doors have bad thermal performance: aluminum frames with thermal breaks (that is, with an external and an internal frame unit, separated by a good insulating material) can rate high in moderate climates.

You may use the Energy Star UR-value and other equivalent rating (the ER number, in the case of Canada) to assess the effectiveness of thermal break.

Fiberglass frames and sashes in windows, skylights and patio doors

In terms of energy performance, fiberglass frames and sashes are excellent. And they also offer good structural strength, high durability and minimal or no maintenance costs.

Note:
Fiberglass hollow sections of the frame and sash can be filled with foam insulation, which increases the energy efficiency of the window, skylight or patio door.

Vinyl frames and sashes

Extruded vinyl frames are good or even excellent in terms of energy efficiency, and demand low or no maintenance costs; vinyl frames can be filled with foam insulation, which increases the energy efficiency of the windows skylights and patio doors, while thermally welded corners also improve its performance (preventing air and water leakage).

But there is a huge drawback concerning vinyl (PVC): vinyl is the worst plastic from an environmental and health perspective. Vinyl it's often called the 'poison plastic' and is a cause of very harmful impacts during its product life and its manufacturing, and you should avoid it.

Besides, large vinyl windows (skylights and patio doors) need to be reinforced to allow a better strength, and some reinforcing materials aren’t good in terms of energy efficiency.

Wood frames and sashes

Solid wood frames have a good insulating value. And also a good structural strength…

The drawback? The impact of the weather on them… and their possible short durability and high maintenance costs.

High performing wood frames and sashes demand factory-applied cladding and finishes, and well-sealed corners and gaskets.

Composite windows (skylights and patio doors)

Some window (skylights and patio doors) frames/sashes combine two or more materials (aluminum, fiberglass, wood…) making possible to combine the best features of each material to get good thermal efficiency, high durability, high strength and minimal maintenance.

Anyway, the composite nature of a frame or sash doesn’t mean that a high performance. The performance of a window, skylight or patio door depends on multiple details.

Which are the best frames and sashes?

Each material has some benefits and some drawbacks in terms of durability and costs, or insulating value, strength and aesthetics…

Good energy efficient windows, skylights and sashes can be made using aluminum, fiberglass, wood... Or combinations of these materials...

The best indicator of energy performance is Energy Star, NFRC or equivalent ratings (ER, in the case of Canada).

Selecting frames and sashes

When choosing window (or skylights or patio doors...) frames and sashes, you may check or inquire about:

- - Tight-fitting sealed joints (they prevent air and water leakage).

- - In the case of aluminum (and other materials requiring thermal breaks), ensure that the exterior and interior surfaces of the frame are separated by an adequate insulating material.

- In the case of large windows (skylights and patio doors) requiring additional reinforcement, you should inquire about the impact of the reinforcement material on the thermal performance.

- the sealing methods used in the interface between the glass unit and the sash (to prevent water from entering).

These technical analyses are crucial, unless the windows, skylights and patio doors have an Energy Star or NFRC label, informing their energy efficiency.