Did you know windows of different designs and implementations can significantly impact your energy bill and indoor comfort? Let's crunch the numbers: For example, let's take a 240ft² total wall area, of which 40ft² is installed with a window with U-0.4 (R-2.5) rating. Assuming the wall assembly itself without a window has an effective R-20 rating, this relatively poor performing window contributes to 62% of heat loss of the total wall, while it only taking up 17% of the total wall space. And the effective R value for this one-window wall is R-9.2.

Let’s say we try to improve the wall’s overall performance by effectively increasing insulation from R-20 to R-32 (or 60% better). Leaving the window alone, the effective wall R-value will improve by 17% to R-10.8.
On the other hand, if we leave the wall at R-20 and install a higher performance window at a U-0.25 (R-4) rating (or 60% better), the effective wall R-value improves by 30% to R-12, a R-2.8 improvement from the original wall. This ONE new window reduces an annual heating energy consumption by 111 kWh in Los Angeles, CA, or 305 kWh in Halifax, NS. With this level of window performance, we will also expect comfort improvements including the reduction of indoor drafts and temperature variance as well as the risks of condensation and mold growth.

Investing in higher performance windows is often the smartest investment you can make in a building, in both dollars and comfort. We build structures to keep the people and things we love safe and healthy- high performing windows help protect them.

Window frames are typically made of materials like wood, PVC (or vinyl plastics), fiberglass and aluminum. Here, we have an obvious preferred material for window frames – WOOD! Besides its great low thermal conductivity, wood is increasingly recognized as the more responsible choice for the environment, with a lifetime energy cost far lower than vinyl or metal. Innovative windows are also being designed and produced with materials of higher insulation values, such as cork and Accoya®. There are even studies conducted on how wood furniture and indoor plants have a positive effect on students’ behaviors and their learning abilities- being surrounded by wood just feels right. A recent report, Wood as Restorative Material in Healthcare Environments, by FPInnovations, provided evidence we're all “healthier, happier, and more productive when connected with nature” through material choices like wood.

While windows made of wood frames naturally benefit from its thermal and structural properties, they also able to be engineered and manufactured with a modern looking, functional aluminum clad exterior. Wood windows with aluminum cladding, called wood-ALU windows, are becoming increasingly popular. Fortunately for architects and homeowners, while aluminum has a high thermal conductivity property, there are already proven cladding application systems that break the heat transfer between wood and ALU, while introducing water drainage and drying opportunities. This gives the building the sleek look of aluminum with the performance power of wood underneath.

Windows make up some of the toughest performance and durability challenges of a building. We can evaluate window performance by it components including the window frame, glass and spacer. For example, compared to a wall assembly, window materials are often much less insulated, and higher in thermal conductivity, resulting in an undesirable amount of heat transfer. The thermal conductivity of a piece of aluminum is over 1000 times higher than of a piece of lumber of the same thickness. Poorly insulated windows will often result in an indoor draft, as air circulates between hot and cold spots, and condensation problems that lead to unhealthy air quality with mold growth. This happens even on the surface of inorganic materials like PVC (vinyl plastic); nature wins. Compounded with an improper water drainage design or installation, a window can be damaged beyond repair. Water and mold can also get into the wall structure to further damage the building. In the Testing & Certification section, we share the programs that are readily available providing fenestration education and measurement transparencies. Higher performance window designers and manufacturers mix the art and science together for our greater visual and comfort enjoyment every day. Some even consider wood window a piece of furniture and a beauty to admire.

Please feel free to explore each section on window styles, components, their functions, manufacturing processes, performance evaluations, and more building science facts and studies. We want to further the awareness and the importance of window design, quality, performance and roles in building comfort and energy conservation – a path to grow the availability and affordability, supply and demand, of higher performance windows in more comfortable and less energy consuming buildings. If you are thinking of becoming, or already are a window manufacturer, check out the Quick Start section to get some kick-starting and business development ideas.

We also welcome YOUR knowledge. Get connected. Please share any thoughts with us, or showcase your projects here with us.