Technical Details for Our Windows:

1. We Use Super Spacer

What causes window condensation to always start near the edge of the glass?

What is responsible for the window’s actual insulation performance (measured by the R-value) to be normally 15 – 20 % worse than advertised?

The answer to both questions is the metal spacer that holds the glass panes together.

At the edge of an insulating glass unit, the glass is physically connected by a metal spacer which gives the unit its structural stability. But the metal connection also permits heat loss by conduction, so much that current glass edges can lose energy at a rate 120% greater than the center of the glass.

To improve a window’s insulation capability, “cold edges” can be replaced with less conductive “warm edge” spacers.

2. But why would we worry about edge of the glass insulation anyway?

Because warming the edge will:

  • Virtually eliminate condensation
  • Increase overall insulation value of already good windows
  • Save more energy through increased insulation

The number one reason for demanding Super Spacer Structural Foam is to virtually eliminate condensation.  Condensation often causes expensive water damage to window sills and frames, curtains and carpets, and even paint and walls.  At the very least, it degrades the view through the window.

Condensation will form on glass edges even in homes with as little as 15% relative humidity if standard “cold edges” exist and outside temperatures drop to 20 degrees Celsius. Substitute a superior “warm edge”, and the inside humidity can go as high as 50% before condensation forms on the glass.

Simply put, condensation is a function of the thermal efficient of windows, particularly the edge of the glass.  The solution to condensation formation on glass is to increase the thermal efficiency of the edge of the glass, the window’s weak link.

3. Thermal Breaks

One of the most important characteristics of a good window is thermal efficiency – its ability to minimize heat loss from the inside to the outside or heat gain from the outside to the inside of a structure.  A window must not only admit maximum light, it must be energy efficient. It must function to maintain internal room temperature with a minimum expenditure of energy.  It must ensure that air-leakage (a major cause of heat loss) is reduced to a minimum; that heat – loss through glass by conduction or radiation is minimized; and that framing members function as efficient insulators.

Consumers are sometimes misled about the thermal efficiency of aluminum as a framing material by the fact that at room temperature, aluminum tends to feel cooler than both wood and vinyl.  The reason is that your hand, at body temperature of 37′ C or 98.6 F, is much warmer than the usual room temperature of 22′ C or 72′ F.  An excellent conductor, aluminum allows heat to flow from your hand to the metal – thereby “cooling” your hand, though all three materials are exposed to room temperature.

In absolute terms, all materials used to make modern windows – wood, vinyl, aluminum – conduct some heat.  To minimize thermal conductivity, the windows are manufactured by “thermally breaking” both the window sash (the part that contains the glass), and the main frame (the part that surrounds the sash).

In modern aluminum windows, framing members are composed of three pieces: an outer extruder frames; a central core of insulating material; and an inner extruder frame.  The central core must not only be structurally strong and resistant to deterioration over the service life of the window – it must also be a good insulator.  The structural core of these composite frame members acts as a barrier to heat flow from a warm interior to a cold exterior in winter, and vice-versa in summer.

4. Strength and Rigidity

50 years of proven durability, aluminum is 3.4 times stronger than vinyl, and 43 times stronger than wood – see tables below:

Just how strong is aluminum?  Two sets of forces are at work on any material. One force can cause stretching; the other force can cause twisting or bending.  Table 1 compares the tensile strengths of aluminum, wood and vinyl (PVC) and Table 2 compares the rigidity and resistance to bending to aluminum, wood and vinyl (PVC).

Table 1 – Tensile Strength*

Material Mpa Psi
Aluminum 150 21,750
Wood (across grain) 3.47 504
Vinyl (PVC) 44 6400

Table 2 – Modules of Elasticity (E-value)**

Material Mpa Psi
Aluminum 68,965 10,000,000
Wood (across grain) 9,517 1,380,000
Vinyl (PVC) 2,965 430,000

*Values are in Mpa (megapascals) and in psi (pounds per square inch).  Materials compared are aluminum alloy 6063 T5 temper (the alloy used for aluminum windows), Ponderosa pine in air-dry condition, and vinyl profile compound Geon 87416.
**These values show that aluminum is 3.4 times stronger than vinyl, and 43 times stronger than wood.  Coefficient of expansion and contraction (inch / inch /°F)

Material Actual Relative Actual*
Aluminum 0.0000132 1 21,750
Wood (across grain) N/A* N/A* N/A*
Vinyl (PVC) 0.0000132 2.6 *

*Comparison based in a 1524 mm (60″) long frame or sash member over a 66.7°C (120°F) temperature range – note that wood shrinkage and swelling is dependent on species and moisture content.

For a 1524 mm (60″) long frame member over a 66.7°C (120°F) temperature range – the difference between a cold winter and a hot summer day, the aluminum frame will stretch 2.41 mm or 0.0950″ (approximately 1/10″).  The vinyl (PVC) frame will stretch 6.2 mm or 0.2448″.  The higher value for vinyl (PVC) results in greater relative movement between components – specifically between the frame and the glass, and the frame and the building.  Such expansion and contraction over time can lead to frame distortion, window seal failure, air and water leakage, as well as binding or sticking of sliding or swinging window elements.  As the temperature rises and falls, vinyl’s (PVC) physical properties change.  With rising temperature its strength decreases; with falling temperature, it becomes more brittle and therefore less resistant to impacts.  Both these changes occur within the normal operating temperature ranges of windows.

5. No Maintenance

6. Natural Resource – Environmentally Friendly

7. 100% Recyclable