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Non-NFRC Rated Fenestration: Hidden Costs Abound

posted May 28, 2015, 9:30 AM by Stephen Mogowski   [ updated May 28, 2015, 9:35 AM ]

All things being equal, if you have a choice between a product that is tested and one that isn’t, you would probably choose the tested product.  Tested or certified products reduce risk and increase the likelihood of customer satisfaction.  However, in the real world, tested products will likely have a larger upfront price tag than untested products swaying potential buyers to opt for the cheaper, untested product.

In the fenestration industry, this scenario is apparent with respect to NFRC ratings.  Quality manufacturers will design their product lines to perform with respect to energy efficiency and they will have their products tested so their consumers understand how the products perform.

In addition, new energy codes have stringent requirements for U-Value and SHGC.  The International Energy Conservation Code (IECC) requires that fenestration be rated in accordance with NFRC 100 and 200, respectively.  However, it is possible to utilize non-NFRC rated fenestration but one must to utilize default values[1] set by the IECC.

Because non-rated products are unproven, the IECC penalizes them significantly.  In fact, under the 2012 IECC, if you opt to utilize non-rated vertical fenestration there is no climate zone where you can qualify for the Prescriptive Path.

The result is that the project must follow the Performance Pathway—which allows trade-offs between components so long as the overall design is as efficient as baseline reference home built to the Prescriptive Path specifications.  On the surface, this isn’t a huge problem, however there are some key factors that everyone know.

1.       Depending on your design, energy code and climate zone, non-NFRC rated fenestration simply may not be an option.

a.       Advice:  Run the energy calculations immediately.  Never assume that a package will comply.

2.       Any or all of the following components may need to be improved in order to offset the non-NFRC rated product.

a.       Ceiling insulation

b.      Wall insulation

c.       Foundation insulation (slab/crawl wall)

d.      Basement wall insulation

e.      Floor insulation

f.        Water heating systems (if utilizing Performance Path)

Clearly, there will be additional costs involved for improving other components.  Those costs will vary based on the project.  The best course of action would be to develop two energy models: one with utilizing an NFRC rated system and the other with the non-NFRC rated products.  Determine what needs to be improved for the latter and obtain bids for improving the necessary components.

Lastly, compare the total costs.  In most cases, the difference between the two bids will shrink significantly… which very well may make the client reconsider their decision.

Thanks for reading,
Stephen


TABLE R303.1.3(1) DEFAULT GLAZED FENESTRATION U-FACTOR 

FRAME TYPE

SINGLEPANE

DOUBLEPANE

SKYLIGHT

Single

Double

Metal

1.20

0.80

2.00

1.30

Metal with Thermal Break

1.10

0.65

1.90

1.10

Nonmetal or Metal Clad

0.95

0.55

1.75

1.05

Glazed Block

0.60

 

TABLE R303.1.3(3) DEFAULT GLAZED FENESTRATION SHGC AND VT 

SINGLE GLAZED

DOUBLE GLAZED

GLAZED BLOCK

Clear

Tinted

Clear

Tinted

SHGC

0.8

0.7

0.7

0.6

0.6

VT

0.6

0.3

0.6

0.3

0.6



[1] ICC Council: 2012 IECC Code & Commentary: Table R303.1.3(1) , Table R303.1.3(3)