Architectural Library
Our mission at Bristolite is to provide our customers with the highest quality products and supreme service at an exceptional value. We also aim to provide the industry with an abundance of accurate and useful information relative to daylighting and energy conservation. We take our corporate responsibility to our employees, associates, industry colleagues and customers very seriously and we see ourselves as stewards for the efficient use of sustainable carbon free energy.

NFRC Certification

How useful is NFRC Certification of plastic unit skylights?

In our review of all NFRC certified plastic unit skylights (which the NFRC identifies as domed skylights) on the NFRC web site, www.nfrc.org on September 7, 2011, we once again noted that none of the skylights showed a value for light transmission (VT) or had a detailed description of the units tested and certified.

Following is the total information presented when checking a manufacturer’s certified skylight under the Certified Products Database. No other information is available on the NFRC web site or by request.

GENERAL INFORMATION
Manufacturer: Company Name
Series Name: A Trade or Brand Name
Operator Type: XXXX

CPD # Manufacturer Product Code Frame / Sash Type U-factor SHGC VT Condensation Resistance Glazing Layers Low-E Gap Widths Spacer GapFill Grid Divider
A 15 character alpha numeric string A product trade or brand name / Double Dome AI/NA 0.74 0.42 0 41 1     N   N NA

Let’s take an inventory of what the above information provides a prospective skylight specifier or buyer.

  1. Manufacturer’s company name
  2. Trade or brand name for a series of products that the tested skylight is part of.
  3. Frame material
  4. U Factor
  5. Solar Heat Gain Coefficient (SHGC)
  6. Condensation Resistance (CR)
  7. Glazing layers (although in most cases this was different than the information provided under “Manufacturer Product Code”)
  8. And lastly, the last 6 items in the table apply to glass only and do not apply to plastic. 

Now, let’s take an inventory of what the above information DOES NOT provide.

  1. The specific model or part number of the skylight tested and certified.
  2. Glazing details such as: material, thickness, color and shape.
  3. Frame and frame cap details other than material such as: frame and frame cap dimensions, thicknesses, thermal break or not and if so what design, and frame coatings.
  4. Sealant details such as: material and form.
  5. Identity of the actual NFRC test reports (by the testing laboratory’s name and test report number) that were used for certification of the performance numbers.

The fact is a specifier or buyer really doesn’t know anything about the skylight that was tested other than three performance numbers presented as certified. Consequently, there is no way to verify that the skylight specified or purchased is the same model, same design and same materials of construction as the skylight that purportedly produced the NFRC certified numbers.

  1. And, MOST SIGNIFICANTLY of all.
    A certified Solar Heat Gain Coefficient (SHGC) without a corresponding LIGHT TRANSMISSION (VT) performance number isn’t very useful.

Light transmission and solar heat (SHGC) have a direct and opposing relationship. It is not possible to reduce solar heat without reducing light transmission. A specifier or buyer selecting an NFRC certified skylight based on a low SHGC needs a corresponding light transmission (VT)

The reason the NFRC does not have VT in their plastic unit skylight certification program is they do not have a standard or testing procedure for VT testing of plastic unit skylights. We would hope that at sometime in the future they would adopt an ASTM VT standard and include this in their certification program. We do not know why specific information on the tested and certified skylight is not provided.

Of the three most important performance measures of a skylight: light transmission, U Factor and SHGC, light transmission has by far the greatest impact on a skylight’s ability to reduce energy costs by turning off electric lights. On a lumens or foot candles versus wattage comparison sun light is much more efficient than electric lights. Approximately 80% of an electric lighting system’s energy is emitted as heat rather than light. This is in contrast to approximately 50% for sun light.

Reducing light transmission to reduce solar heat in skylights and daylighting systems is very often a poor economic trade off in terms of building energy savings. To prove this point, let’s run a few SkyCalcs on two skylights, one with a low SHGC and a correspondingly low VT, and the other with a terribly high SHGC and a good VT. To isolate our comparison on VT and SHGC, both skylights have the same U Factor and are employed on the same building. We will also run the SkyCalcs in the two very different ASHRAES of Los Angeles and Minneapolis.

Building: A 100,000 square foot retail operation with a 30 foot ceiling and an electric rate of $0.12kWh.

Daylighting System: Five percent of the roof area skylighted with a quantity of 166, 5 foot by 6 foot skylights.

Skylight A - 47% VT, .42 SHGC, U Factor .74

Skylight B – 70% VT, .65 SHGC, U Factor .74

Results: In review of the following SkyCalc Tabular Results it’s clear where the “money” is. For daylighting it’s all about turning of the electric lights and turning off electric lights is all about VT. Daylighting’s affect on heating and cooling energy cost combined is generally only about 10% of the effect it has on lighting energy costs.

In the Los Angeles ASHRAE skylight B (terrible SHGC and good VT) produced 24% more annual energy savings than skylight A (very low SHGC and correspondingly lower VT).

In the Minneapolis ASHRAE skylight B (terrible SHGC and good VT) produced 112% more annual energy savings than skylight A. (very low SHGC and correspondingly lower VT).

We started this document with the question how useful is NFRC Certification of plastic unit skylights? In our opinion, until light transmission and detailed descriptive information of the skylight tested and certified is added to the program the answer is, it’s just not useful.

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Trituff Copolyester Passes 267 lb/
36" ASTM Drop Test

A new, pending ASTM skylight fall protection drop test requires dropping a 267 lb sand filled canvas bag with a 5.5" bull nose from a height of 36" on the skylight glazing. As evidenced by this video Trituff Coployester passes the test. The total impact force and pressure developed in this test is 2,278.6 foot pounds and 95.9 lb per square inch.

Tufflite Heavy Weather / High Security Polycarbonate Takes a Tromping

Rick Beets, Bristolite President, demonstrates the resilience of Tufflite for customers. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Tufflite Heavy Weather / High Security Polycarbonate Takes a Beating

Rick Beets, Bristolite President, demonstrates the impact resistance of Tufflite for customers. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA# 10-0216.02 and Florida Building Code Approved # FL14006.

Energy Star Fiberlite CC1 Fire Resistance

Energy Star Fiberlite, Trituff Copolyester and Tufflite Polycarbonate are all CC1 Fire Rated.

Custom Glass Skylight Positive Load Cycling after Large Missile Impact Test

Positive load cycling from 10.30 psf to 51.38 psf after large missile impact test. This model 1000 custom glass skylight series is Miami Dade County Hurricane Zone Approved NOA # 07-0524.05.

Custom Glass Skylight Positive and Negative Load Cycling

Positive load cycling from 10.30 psf to 51.38 psf and negative load cycling from 20.6 psf to 34.3 psf. This model 1000 custom glass skylight series is Miami Dade County Hurricane Zone Approved NOA # 07-0524.05.

Custom Glass Skylight Negative Load Cycling

Negative load cycling from 20.6 psf to 34.3 psf after multiple large missile impact tests. This model 1000 custom glass skylight series is Miami Dade County Hurricane Zone Approved NOA # 07-0524.05.

Custom Glass Skylight Large Missile Impact Test

Large missile impact test requires firing a 9 lb missile at a velocity of 49 fps to 50 fps at a distance of 17 ft from the skylight. This model 1000 custom glass skylight series is Miami Dade County Hurricane Zone Approved NOA # 07-0524.05.

Custom Glass Skylight Large Missile Impact Test

Large missile impact test requires firing a 9 lb missile at a velocity of 49 fps to 50 fps at a distance of 17 ft from the skylight. This model 1000 custom glass skylight series is Miami Dade County Hurricane Zone Approved NOA # 07-0524.05.

20 Year Old Energy Star Fiberlite
Supports 5,000 lb

20 year old Energy Star Fiberlite supports 5,000 lb in a concentrated (1 sq ft) load test by an independent 3rd party testing laboratory.

Trituff Copolyester Supports 1,950 lb

Trituff Copolyester supports 1,950 lb in a concentrated (1 sq ft) load test by an independent 3rd party testing laboratory.

Tufflite Heavy Weather / High Security Polycarbonate Negative Load Cycling

Negative 19.5 psf to 32.5 psf load cycling. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Tufflite Heavy Weather / High Security Polycarbonate Positive Load Cycling

Positive 11.0 psf to 55.0 psf load cycling. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Tufflite Heavy Weather / High Security Polycarbonate Negative Load Cycling

Negative 19.5 psf to 32.5 psf load cycling. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Tufflite Heavy Weather / High Security
Positive and Negative Load Cycling

Positive 11.0 psf to 55.0 psf and negative 19.5 psf to 32.5 psf load cycling. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Tufflite Heavy Weather / High Security Polycarbonate Negative Load Cycling

Negative 19.5 psf to 32.5 psf load cycling. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Tufflite Heavy Weather / High Security Polycarbonate
Positive and Negative Load Cycling

Positive 11.0 psf to 55.0 psf and negative 19.5 psf to 32.5 psf load cycling. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Gladiator Safety Screen
Supports 600 lb Static Load

Gladiator Safety Screen installed on a wood curb supports two 300 lb loads in opposing corners.

Gladiator Safety Screen
Supports 867 lb Static Load

Gladiator Safety Screen installed on a wood curb supports two 300 lb loads in opposing corners and a 267 lb load in the center for a total static load of 867 lb

Gladiator Safety Screen
Passes 267 lb / 36" ASTM Drop Test

A new, pending ASTM skylight fall protection drop test requires dropping a 267 lb sand filled canvas bag with a 5.5" bull nose from a height of 36" on the skylight glazing. As evidenced by this video our Gladiator Safety Screen passes the test. The total impact force and pressure developed in this test is 2,278.6 foot pounds and 95.9 lb per square inch.

Gladiator Safety Screen
Passes 267 lb / 36" ASTM Drop Test

A new, pending ASTM skylight fall protection drop test requires dropping a 267 lb sand filled canvas bag with a 5.5" bull nose from a height of 36" on the skylight glazing. As evidenced by this video our Gladiator Safety Screen passes the test. The total impact force and pressure developed in this test is 2,278.6 foot pounds and 95.9 lb per square inch.

Tufflite Heavy Weather / High Security Polycarbonate Large Missile Impact Test

Large missile impact test requires firing a 9 lb missile at a velocity of 49 fps to 50 fps at a distance of 17 ft from the skylight. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.

Tufflite Heavy Weather / High Security Polycarbonate Large Missile Impact Test

Large missile impact test requires firing a 9 lb missile at a velocity of 49 fps to 50 fps at a distance of 17 ft from the skylight. This Tufflite model HWHS (Heavy Weather High Security) skylight is Miami Dade County Hurricane Zone Approved NOA # 10-0216.02 and Florida Building Code Approved # FL14006.