Architectural Testing Home

Solar Calorimeter Testing
Frequently Asked Questions



Q:

What is Solar Heat Gain Coefficient (SHGC)?

A:

The portion of directly transmitted and absorbed solar energy that enters through a fenestration product. The higher the SHGC, the higher the heat gain.

Back to Top

Q:

What is Shading Coefficient (SC)?

A:

The ratio of solar heat gain through a product relative to the solar heat gain through 1/8” (3mm) clear glass under identical conditions. As the Shading Coefficient number decreases, heat gain is reduced.

Back to Top

Q:

What specifications are used for testing Solar Heat Gain Coefficient (SHGC)?

A:

At the present time the only outside specification for testing SHGC is the National Fenestration Ratings Council (NFRC) 201 test method. ASTM is presently working on a procedure but it is not expected to be approved for several years. ATI has an internal test procedure that can be used.

Back to Top

Q:

Can center of glazing be tested and combined with simulation to determine the SHGC?

A:

YES; for some types of products in which a glazing is tested it is possible to test the glazing only. The result of the glazing test can then be combined with frames for a total SHGC.

Back to Top

Q:

Can three dimensional products be tested?

A:

YES; common three dimensional products tested are tubular daylighting devices, skylights, and garden windows. Some products cannot be simulated so testing is required. Owners and designers may prefer actual tests to confirm the real performance of a product.

Back to Top

Q:

What SHGC is required for Energy Star?

A:

At this time, it is necessary to have an NFRC rated products to obtain an Energy Star rating. The actual rating depends upon the type of fenestration and area of the country, with the warmer climates requiring lower SHGC to qualify. Visit http://www.efficientwindows.org/energystar.cfm for exact requirements.

Back to Top

Q:

Is it possible to scale SHGC?

A:

If the center of glass can be tested independently then the total product can be scaled by simulation. However, for total product testing the full size must be tested and the results are applicable only to that size.

Back to Top

Q:

What is the minimum and maximum size specimen that can be tested?

A:

The minimum size is somewhat dependent upon the type of product but testing one square foot samples is common, and smaller samples have been tested. The largest sample size that can be tested is 84 inches by 84 inches.

Back to Top

Q:

Why is it necessary to test outside?

A:

There is presently no solar simulator that accurately reflects the total solar spectrum of the sun. Because of this, SHGC testing done with a solar simulator may have significant errors so the best source to simulate the sun is….. the sun!

Back to Top

Q:

What types of products can be tested for SHGC?

A:

Essentially any building envelope construction can be tested for SHGC. The only limitation is if the SHGC is so low it cannot be accurately measured.

Back to Top

Q:

At what angle of incidence is SHGC measured?

A:

The most common angle of incidence is with the sun normal to the test specimen. However, it is possible to test at any angle of incidence or with fixed specimen.

Back to Top

Contact Us with your questions.

The Power in Performance Testing
Copyright 2019 Architectural Testing, Inc.