AL-ThermalProperties

Aluminum Door Thermal Properties & ASHRAE 90.1

For non-residential entrance systems, aluminum flush doors and related stile and rail or monumental doors, are popular because of their distinct appearance.  Flush doors offer a variety of options for flexible configurations.   And monumental stile and rail doors always make a classy statement.
However, the appearance of these doors can disguise poor thermal characteristics which can lead to energy inefficiency as well as appearance and functional issues.
For instance, consider the effects of climate—hot summers and cold winters.
The temperature differential from interior to exterior can be dramatic and the door is the separator between these extremes, Summer, Winter, all year long.
Cold Meets Warm at the Door
As a result, some doors, designed only for appearance, suffer. This is especially true of plank-style aluminum doors. But other doors seem to weather the storms just fine. Why?
In addition to designing for appearance, Special-Lite doors are engineered for thermal efficiency.
One significant standard in this arena was developed by ASHRAE, the American Society of Heating, Refrigerating, and Air-conditioning Engineers.  ASHRAE standard 90.1 specifies the energy performance of non-residential buildings as well as a variety of building products and materials, including doors.  It is the definitive energy standard for buildings in the U.S. and beyond and the basis of countless local building codes.
For doors, ASHRAE 90.1 specifies performance as a desired U-factor.  U-factor expresses the rate of heat loss or gain.  Heat tends to move from warmer to cooler areas.  In our previous illustrations, the door experiences heat gain in Summer and heat loss in Winter.  A lower value for U-factor is better and indicates a low level of heat loss or heat gain.
Further, ASHRAE 90.1 demands thermal performance based on defined climate zones with the most stringent standards for colder climates. These are represented by Zones 5, 6, 7 and 8, covering the northern U.S. and much of Canada.
ASHRAE Climate Zone Map
In these zones, and for swinging, opaque doors, or aluminum flush doors, ASHRAE 90.1 calls for a U-factor no higher than 0.5.  And, for metal framed entrance doors or monumental stile and rail or doors, the Standard requires performance lower than U-factor 0.77.
The standard further requires that products be tested per NFRC 100.  NFRC is the National Fenestration Rating Council and 100 is their test procedure for U-factor evaluation.
Special-Lite products are tested by third party agencies to the NFRC specification in order to be considered compliant with the ASHRAE 90.1 standard.  Both ASHRAE 90.1 and NFRC 100 are accepted by ANSI, the American National Standards Institute.

So what are the results?

The Special-Lite SL-16, an aluminum flush door, has a measured U-factor of 0.33, well below the maximum allowed by the standard.
The measured U-factor for the SL-15, an aluminum monumental door is 0.62, once more well below the maximum specified by ASHRAE.
What does all this mean?  For aluminum flush doors and monumental stile and rail doors, you need thermal performance and energy standard compliance in order to achieve your goals:
  • Energy efficiency
  • Great appearance
  • Lasting and reliable functionality
Such products return value over the entire life-cycle cost model of your facility.
And that’s just one of the ways we build the special in Special-Lite.

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