Why Triple Glazing?

• Why buy Thermotech?
• Why Fiberglass Windows/Doors?
• Why bother with energy efficient Windows/Doors?
• What Windows/Doors do Professional architects use?
• Why Triple Glazing? 

Why Triple Glazing? Given the condensation resistance, energy savings and enhanced comfort of triple glazing, all at modest incremental costs – the question is not; “Why triple glazing?” The questions is; “Why not triple glazing?” Weight

• fiberglass’ superior strength can take the weight

Condensation Protection

• dramatically better than double glazing

Energy Savings

• insulates up to 60% better than a low e argon gas filled double

Thermal Comfort

• 80% less radiation heat transfer between glass and room

Cost

• starts at 5% more than double glazing

Weight

• Traditional argument against triple glazing is the extra weight.
• The extra rigidity and strength of fiberglass is eminently suited to for the heavier weight of triple glazing.
• Weaker sash materials like wood and vinyl can have problems with the extra weight of triple glazing.
• There are, however, some hardware limitations.
  • These are defined in the size limit section for product type.
  • Example:
    • triple glazed casements are restricted to a 30” width.
    • wider triple casements can be accommodated with:
      • Heat Mirror™ products. (Low e coating is on film between two pieces of glass.)
      • Restrictor that limits the amount a casement window can be opened.

Condensation Protection

• Over time people’s tolerance of wintertime desert like interior humidities has decreased.
  • While it may have been normal for your parents to wake-up with dry throats, today people expect their homes to be more humid.
• Higher humidities lead, not surprisingly, to greater and more persistent condensation on windows.
  • Persistent condensation leads to both visible and hidden toxic mold.
• Double glazing was improved with low e glass and argon gas filling.
  • Center of glass R-values increase from R-2.0 to R-3.7 .
  • But, condensation starts at an edge – improving the center of the glass R-value is of limited advantage.
• Increased condensation protection requires an improved edge.
  • However, even the addition of the warmest of the warm edge spacers – SuperSpacer™ has only a modest effect on edge of glass temperatures.
  • For proof look at the thermographic images below.
    • Triple glazing with aluminum spacers is warmer than the double glazing with a foam spacer.
    • Warmest edge of all is the triple glazing with SuperSpacer™.

Double Glazed Aluminum Spacer	Double Glazed SuperSpacer ™ (Silicone Foam)
Triple Glazed Aluminum Spacer	Triple Glazed SuperSpacer ™ (Silicone Foam)

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Energy Savings

• Not surprisingly, a triple glazed window is warmer not just at its edge, but over its entire glazed surface.
• The table below shows the percentage improvement of Thermotech’s two main triple glazing options, when compared to double glazing with low-e and argon.

• Added R-value of triple glazing makes a BIG difference in the overall heat loss. Just look at the following examples, one for an existing home and one for a new superinsulated home.

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Existing House

• Consider an existing house with the following characteristics:
  • 30’x40′ two storey house
  • R-20 average wall and ceiling insulating value
  • 360 ft 2 of windows (15% of its floor area)
  • R-2 average window insulating value (clear double glazing)
• Upgrading the windows from R-2.0 to R-4.3 decreases the home’s envelope heat loss by about 30% –
  • Same impact as upgrading the walls and ceiling from R-20 to R-40!
  • Put another way; upgrading the existing windows to 321 triple glazing (one low-e and one argon) has about the same effect as adding 6” of insulation to the outside of this home.

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New Super-Insulated House

• Consider a new super-insulated home with the following characteristics:
  • 30’x40′ two storey house
  • R-50 average wall and ceiling insulating value
  • 360 ft 2 of windows (15% of its floor area)
  • R-3.3 average window insulating value (double glazing w/ low e and argon)
• Upgrading the windows from R-3.3 to R-5.3 decreases the home’s overall envelope heat loss by about 20%
  • Same impact as upgrading the walls and ceiling from R-50 to R-100!
  • Put another way; upgrading from a typical Energy Star window to the best triple (two low-e’s and two argons) has about the same effect as adding another 15” of insulation to the outside of this home.

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 Thermal Comfort

• New homes and new commercial buildings are featuring larger and larger glass areas.
  • While spectacular, they can be uncomfortable when temperatures plummet.
  • They are uncomfortable for two reasons
    • natural convection
    • radiation.

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Radiation

• Radiation is the reason you don’t need to be beside a wall of windows to be cold, even when the room air temperature is 22C (72F).
  • Although you may be out of the direct path of natural convection, you’ll still be losing heat by radiation to the large colder surfaces.
• Think of the windows as a negative campfire.
  • A campfire makes you feel warm – even when you are surrounded by cool air
  • Large wall of windows is the opposite of a fire
    • Makes you feel cool – even when you are surrounded by warm air.
• Radiation heat transfer varies with temperature difference to the fourth power.
  • Double the temperature difference and the radiation heat transfer increases by 16 or 1600%.
  • Small increases in glass surface temperatures pay big dividends in comfort.

• The table above shows how small increases in the center of glass temperatures make big differences in radiation heat transfer.
  • Large relative radiation loss with clear double glazing
    • heat source is required beneath window.
  • Triple glazing dramatically reduces relative radiation heat loss

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Natural Convection

• During the heating season, windows are cooler than room temperature.
  • The air immediately next to them is cooled and falls.
    • Called natural convection.
    • Driven by temperature difference between the inside face of the glass and the room temperature.
    • As inside glass temperature drops, the speed and volume of air being convected increases.
• Natural convection explains draft at the bottom of a fixed window on a cold day.
  • Heating systems are placed below windows – so that they can counteract the cold draft off the glass – at least while the furnace is on.
• Warmer window diminishes natural convection, and results in greater thermal comfort.

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Cost

• Once you’ve decided to buy a quality window, the cost of triple glazing is modest.
• Thermotech’s window system designed to accommodate full depth (two 1/2” spaces) triple glazing.
  • No setup charges for special sashes, glass stops, glass orders or other head scratching exercises.

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