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,













Metal with Thermal Break





Nonmetal or Metal Clad





Glazed Block























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

2012 IRC & Multi-Family: Don’t Forget the Blower Door Testing

posted Mar 30, 2015, 2:19 PM by Stephen Mogowski   [ updated Mar 30, 2015, 2:19 PM ]

The 2012 IRC was a quantum leap with respect to energy efficiency.  For the first time in residential construction, all homes built under the 2012 IECC have to be tested by a 3rd party for whole house air leakage (blower door testing) as well as duct tightness if any portion of the duct system (unit included) is outside the building thermal envelope.

The multi-family arena qualifies under the IRC in almost all circumstances and is subject to these changes.  Most multifamily units will incorporate closet air handlers or pancake units and ducts within the floor system or drop soffits allowing for the exemption of duct leakage testing.  However, there is no exception for the envelope leakage testing.

Most municipalities will allow you to “sample” in order to keep the scope of work and costs reasonable.  There is little to be gained by testing each individual unit if the construction practices are uniform throughout construction.  The only way to know your municipality’s requirements is to ask—and even then you may get conflicting responses.  A good “default” is RESNET Chapter 6 Sampling Protocol.  If your city or town doesn't have a method in place, go ahead and suggest they follow that standard.

A major problem with testing small homes in general is that they have a disproportionate ratio of common leakage areas.  For example, a 2700sf 4BR 3BA home is likely to have a range vent, dryer exhaust, 5 or so exhaust ducts and a fresh air ventilation system.  A 1350sf 3BR 2BA apartment may have the exact same amount of exhausting appliances sans a few exhaust fans.  The result is that as the square footage (or more accurately, volume) increases, it does so in a way that favors larger homes.

Multi-family homes face another dilemma.  They are designed with adiabatic (shared) walls that are typically not air sealed due to the fact that the adjacent units will be conditioned as well.  Energy raters should take note that the sealing of receptacle boxes in the same stud bay for different units must be sealed per the 2012 IFC (fire code).  Proper execution of the fire code will help reduce infiltration between units.  Regardless, special consideration should be taken to these walls as well as exterior wall systems since the leakage at final will not be isolated to the exterior wall systems.

Lastly, even with ICAT rated can lighting and other quality building practices, there will be some amount of connection between the ceiling/floor system and the livable space.  Common areas of connection include failure to seal supply and return cans/boxes to drywall, gasket failure on ICAT lighting, duct leakage, top plate to drywall intersection and other ceiling penetrations.  If the systems are connected, you can pull air from adjacent units to either side if the units are not properly compartmentalized.  Again, a continuous firewall should help this area but in real world scenarios—we do see unsealed pipes and wires go unnoticed.

In summary, there are a lot of ways that multi-family units can fail the blower door test at final.  Proper planning should be taken to ensure there isn’t a major problem at final that will delay the project being turned over and incur unexpected repair costs.

In the conceptual phase, ensure the building thermal envelope is defined and there are no major points of breakdown.  Ensure your mechanical designer or contractor use install dampers where needed.  Go ahead and put it in someone’s scope of work to seal the exhaust fans, supply boots and return can(s) to the ceiling drywall with generic acrylic-latex caulk.  This is a small detail that is a good building practice that can reduce headaches later on.

While framing, have your energy rater perform a site walk to ensure there are no major problem areas.  Look at a few different unit types in a few different layouts (i.e. Unit A –Ground, End, Unit A- Top Mid, Unit B, Mid Mid, etc).

If you’ve done everything thus far, you shouldn’t have to hold your breath while the blower door fan kicks on at final.  The biggest obstacle we see in the multi-family arena is that our builders are unfamiliar with the process.  Hopefully this article sheds some light on the situation.

And, as always, the biggest piece of the puzzle?  Communication!

Thanks for reading,
Stephen Mogowski

Duct Sealing & Indoor Air Quality

posted Dec 30, 2014, 11:35 AM by Stephen Mogowski   [ updated Dec 30, 2014, 11:37 AM ]

Quality duct design can create a comfortable environment for occupants.  Software programs Wrightsoft and Elite Software that utilize ACCA Manual D help create designs that will provide the recommended air flow for a given room or area based on variables like insulation, glazing specs and areas, room size, orientation, etc.

But once the plans are stamped and ground is broken, the focus shifts from planning to reality.  And the reality is the importance of excellent installation practices has never been more important.

In Phoenix, the majority of custom residential builders have shifted to conditioned attic systems (insulation applied to the roof deck).  This installation strategy reduces the heat gain on the duct system but does not diminish the importance of duct sealing with respect to indoor air quality.

Indoor air quality, the oft forgotten benefit of a tight duct system, can suffer drastically if the system isn't air tight.  Proper practices include sealing all transitions (i.e. Y's, S-Drives, etc) with mastic (duct sealant) or metal tape/sealant combination.  Flex to collar connections should be secured with a zip tie and sealant.  Collars to plenums should be secured with sheet metal screws and followed with sealant to prevent any leaks.

Remember, leaks on the return side will result in filter bypass and can expedite coil clogging-- which is a direct performance issue that will result in higher energy bills for the occupants, reduced air quality and potentially comfort complaints and service calls from a system freezing up.

Leaks on the supply side directly reduce the amount of air flow to that was engineered at conception.  It can also pressurize the attic system which (depending on the design) could create problems.  Furthermore, kinked/smashed/poorly routed ducts can reduce the recommended amount of supply air too.

Once the HVAC contractor finishes their installation, the drywall contractors will cut out a hole for each supply and return can.  Unfortunately, no one is perfect and the gaps around each supply boot and return can contribute to duct leakage if left unsealed.  Caulk is the easiest and most durable choice of sealant for this application.

For our firm, if we are performing a duct leakage test at final-- we require the contractor to seal these junctions before we test.  We typically see about 2-3% of CFA (conditioned floor area) leakage from this item.  When you consider the 2012 IECC only allows for 4% total for the entire system, you recognize this is a major contributor of duct leakage.

Creating a tight duct system combined with routine filter change-outs and a well-maintained home can lead to better health for our tenants. 

Caulk and duct sealant is cheap.  Quality is tough to come by.  If you're a HVAC contractor, it is time for you to take the next steps... because code is starting to require it.

  • Design with Manual D
  • Seal all seams and transitions
  • Contact HERS Rater for testing (if required or desired)
  • Follow up with caulk around all supply and return cans
  • At start up, seal all non-gasketed air handler cabinet doors with caulk or metal tape
  • Give homeowners a 3-pack of the filters you want them to use with your system and tell them where to buy replacements

RESNET Chapter 6: Sampling... it just isn't getting the job done

posted Oct 31, 2014, 3:09 PM by Stephen Mogowski

Imagine taking a poll at the latest mega-subdivision in your hometown:
You interview everyone who just bought a home.  Maybe its their first home or their energy efficient dream home!

Now imagine the look on their faces when you tell them that only 1 out of 7 of the homes constructed in their subdivision were actually inspected!  For the mathematicians out there, that comes in at just under 15%.  I suspect your new subdivision is less than pleased.

For those that don't know, sampling is an acceptable strategy for RESNET Sampling Providers to implement in order to certify a large amount of homes instead of testing each one individually.  There are many benefits to the builder (less cost) as well as the rater (charge per certification not per inspection) but there are huge drawbacks to this strategy as well.

Before we get started, there are rules to sampling... for instance you need a "first seven" or "first three" lots to pass consecutively before the sampling process can begin.  And if a home fails, you test two more... if one of those fails, you test the remaining "batch" of 7 homes.  I get all that, I once helped certify thousands of homes per year for ENERGY STAR.  And yes, it was all due to the sampling process.

The theory behind sampling is sound.  If you see a problem, you fail it and reinspect on the next houses that normally wouldn't have been inspected had the item passed initially.  It is built off the premise that if the same contractors are doing the work at all the houses, their craftsmanship should be the same.  This is problem #1.  

All framing/insulation/air sealing/etc crews are not created equal.  The construction industry in general is made up of a lot of temporary employees in large part to due to the volatility of our market with respect to the economy.  So assuming that one skeleton crew is going to outperform another is no guarantee.

The 2nd problem with sampling is that not all homes have the same design features.  So if the inspected home was a one story without a band joist but houses 3 and 4 of the batch are a two story home with a band joist-- there could be issues that go unnoticed.  This could be repeated several times before the problem is caught in a test home.  But once it's caught, there is no going back in time to fix the problems of the previously certified two story homes.  Those homes are flawed but receive the same certification and marketing label that the inspected homes receive.

Moving forward.  "Builder Sign Offs" are a method of allowing problems with a lot to be fixed and repaired without triggering sampling protocol.  The following passage from ENERGY STAR v3 Checklist Rev07 shows that you can have up to eight (!) problems and have them corrected and move forward... but what about the other six houses in the batch?  Do we honestly believe that all builders are going to go through and verify that each of these issues is being resolved at their other active lots?  And the problem with this oversight is the Builder Sign Off could be repeated again and again!

"The only exceptions to this rule are in the Thermal Enclosure System Rater Checklist, where the builder may assume responsibility for verifying a maximum of eight items. This option shall only be used at the discretion of the Rater. When exercised, the builder’s responsibility will be formally acknowledged by the builder signing off on the checklist for the item(s) that they verified."

The last issue I have with sampling relates to simple economics.  At the heart of every company there is a financial side.  And it is also important to keep your clients happy.  Builders do not like to "fail" inspections for a multitude of reasons but I've found that the main one is that construction delays are costly and reflect negatively on the manager's performance.  Failed inspections also trigger sampling protocol which requires more site visits for the energy rater.  More site visits equal less profit for the energy rater. is in the best interest of all parties (financially speaking), to pass or "Builder Sign Off" most lots.  This is compounded by the fact that subcontractors are often paid piecework so their workmanship can be substandard if they are trying to maximize the number of jobs they complete.

At the end of the day, RESNET's Sampling Protocol wasn't written to be exploited.  It called upon the good nature of raters and builders alike to build MORE homes efficiently.  And the Protocol has worked-- there are many, many builders who build ENERGY STAR that wouldn't be able to if there wasn't a Sampling Protocol.

But I challenge whether it is time, as our industry gains momentum, to revoke RESNET Ch. 6 and start giving quality inspections to all new energy efficient homes.

Thanks for reading!

Major Performance Issues with Fiberglass Batts at the Roof Deck

posted Oct 14, 2014, 4:28 PM by Stephen Mogowski   [ updated Nov 3, 2014, 7:25 AM ]

Fiberglass batts remain in existence (and prominence) today not because of their superior performance but rather their cost and ease of installation.  After all, time is money.  With fiberglass batts you save on material costs but also don't have to wait for off-gassing of foam or drying of wet-spray cellulose.

But what we often forget is that after we drywall, our clients live with our choices.  And fiberglass batts strapped to the roof deck are a bad idea, 100% of the time.

We've seen it multiple ways.  Batts 'secured' to the deck with insulation hangers between top chords or more commonly, tension cables secured at the ridge and eaves with eye hooks to prevent fall out.

Here is a fact: If you use air permeable insulation and it is not in direct contact with the air barrier (in this case, the plywood roof deck), you will experience convective loops within your assembly as well as unwanted radiant heat transfer.

Out here in Arizona, when you have 120F ambient temperatures the roof deck reaches outrageous temperatures... even with clay tile roofs outperforming asphalt single roofs.  So the importance of a thermal assembly making contact with your air barrier is even more important!

Unfortunately, not every home is built right the first time.  The IR picture is taken on a typical summer day in Phoenix.  Notice the ridge is illuminated at approximately 118F.  After analysis using BPI methodology for deducing R-Value of misaligned batts, it was determined that the attic insulation for this example was performing at R-7... despite the fact that it was 10" R-38 unfaced batts that were installed.

Building on the previous example, the expected attic temperature was 80F (remember, sealed/conditioned attic space) but in the afternoon it was recorded at 93F (+13F).  The result was that the mechanical equipment and duct work were exposed to unexpectedly higher temperatures.  Because the duct work was initially designed to be in conditioned space, the R4.2 flex was now susceptible to heat gain and the homeowner was unable to cool their home effectively.  Even after upsizing the unit a half ton, there were still comfort complaints.  Especially on supplies that were at the end of the run.

So ultimately, the builder opted to replace the insulation with a pillowed cellulose 
application.  The cellulose made contact with the roof deck and effectively reduced the convective loops and radiant heat transfer to a point where the homeowner was able to be comfortable and have vastly reduced energy bills.

In the above example, the mechanical engineer designed a system utilizing ACCA Manual J, S and D.  The energy rater contracted to inspect the insulation was unable to verify whether the batts were in complete contact with the deck.  It looked okay-- so it was approved.  Had the application been found to be unacceptable, all of the headaches would have been avoided.

The moral of the story?  Pay attention to your material choices and their applications in the design phase.  Spend a little more to prevent big problems down the road.  And if in doubt, consult with an energy rater before making a costly mistake.

Thanks for reading.
Stephen Mogowski
Desert Skies Code Compliance


This article wasn't meant to discredit fiberglass batts in all applications.  But it is meant to clearly state that they have no business in a sealed attic.  Some governing bodies will no longer allow the application due to issues with condensation control.  See below for 2012 IRC language.

R806.5 Unvented attic and unvented enclosed rafter assemblies. 
Unvented attic assemblies (spaces between the ceiling joists of the top story and the roof rafters) and unvented enclosed rafter assemblies (spaces between ceilings that are applied directly to the underside of roof framing members/rafters and the structural roof sheathing at the top of the roof framing members/rafters) shall be permitted if all the following conditions are met: 

1. The unvented attic space is completely contained within the building thermal envelope.
2. No interior Class I vapor retarders are installed on the ceiling side (attic floor) of the unvented attic assembly or on the ceiling side of the unvented enclosed rafter assembly.
3. Where wood shingles or shakes are used, a minimum 1/4-inch (6 mm) vented air space separates the shingles or shakes and the roofing underlayment above the structural sheathing.
4. In Climate Zones 5, 6, 7 and 8, any air-impermeable insulation shall be a Class II vapor retarder, or shall have a Class III vapor retarder coating or covering in direct contact with the underside of the insulation.
5. Either Items 5.1, 5.2 or 5.3 shall be met, depending on the air permeability of the insulation directly under the structural roof sheathing.
5.1. Air-impermeable insulation only. Insulation shall be applied in direct contact with the underside of the structural roof sheathing.
5.2. Air-permeable insulation only. In addition to the air-permeable insulation installed directly below the structural sheathing, rigid board or sheet insulation shall be installed directly above the structural roof sheathing as specified in Table R806.5 for condensation control.
5.3. Air-impermeable and air-permeable insulation. The air-impermeable insulation shall be applied in direct contact with the underside of the structural roof sheathing as specified in Table R806.5 for condensation control. The air-permeable insulation shall be installed directly under the air-impermeable insulation.
5.4. Where preformed insulation board is used as the air-impermeable insulation layer, it shall be sealed at the perimeter of each individual sheet interior surface to form a continuous layer. 


2B and 3B tile roof only0 (none required)
1, 2A, 2B, 3A, 3B, 3CR-5
4A, 4BR-15

a. Contributes to but does not supersede the requirements in Section N1103.2.1.

DSCC: New in 2014

posted Jan 12, 2014, 3:11 PM by Stephen Mogowski   [ updated Jan 12, 2014, 3:12 PM ]

As 2014 begins, we'd like to announce a few immediate changes for DSCC.

Rates unchanged for 2014: We maintain a $0.10 per heated/conditioned square foot fee with $250 minimum.

Turnaround Time: We've reduced our turnaround time from 5 business days to 2 business days, standard.

We are excited about the reduced turnaround time for our clients moving forward; some of our best feedback has been our speedy turnaround.  We hope to build on that in the new year.

Stephen Mogowski
Owner, Director of Operations

Phoenix, AZ Adopts HERS Index Score as Alternative to 2012 IECC Prescriptive/Performance

posted Dec 14, 2013, 3:05 PM by Stephen Mogowski   [ updated Dec 14, 2013, 3:07 PM ]


Phoenix, Arizona Adopts HERS Index Score as Building Energy Code Compliance Option

Across the nation state and local governments are adding a HERS Index Score target as a performance compliance option to their building energy code.

The City of Phoenix, Arizona has joined the list of jurisdictions that have added a HERS Index Score as an option to meet their building energy code.

The Phoenix code provides:

R401.2.1 Alternative approach for compliance.   A Home Energy Rating System (“HERS”) Index of 73 or less, confirmed in writing by a Residential Energy Services Network certified energy rater may be used in place of the approach described in section 401.2 above. Compliance may be demonstrated by sampling in accordance with Chapter 6 of the Mortgage Industry National Home Energy Rating Systems Standard as adopted by the Residential Energy Services Network.

The HERS Index Score option was added in conjunction with the adoption of the 2012 version of the International Energy Conservation Code.

The City of Chandler and Maricopa County has joined Phoenix in adopting the HERS Index Score option to their codes.

In addition the Maricopa Association of Governments (MAG) adopted a model code for the municipalities in metropolitan Phoenix to define the verification procedures for the inspection and testing required in the 2012 IECC.  The model standard states:

RESNET Testing & Inspection Protocol. The Residential Energy Services Network (RESNET) Mortgage Industry National Home Energy Rating System Standards Protocol for third party testing and inspections, shall be deemed to meet the requirements of sections R402.4.1.1, R402.4.1.2 and R403.2.2. and shall meet the following conditions:

1) Third Party Testing and Inspections shall be completed by RESNET certified Raters or Rating Field Inspectors and shall be subject to RESNET Quality Assurance Field Review procedures.

2) Sampling in accordance with Chapter 6 of the RESNET Standards shall be performed by Raters or Rating Field Inspectors working under a RESNET Accredited Sampling Provider.

3) Third Party Testing is required for the following items:

  • R402.4.1.1 – Building Envelope – Thermal and Air Barrier Checklist
  • R402.4.1.2 – Testing – Air Leakage Rate
  • R403.2.2 – Sealing – Duct Tightness
4) The other requirements identified as “mandatory” in Chapter 4 shall be met.

MAG is the regional planning agency for metropolitan Phoenix local governments.

Phoenix has joined jurisdictions in Arkansas, Idaho, Colorado, Kanasa, Massachusetts, New Mexico and New York have adopted a HERS Index Score as a compliance option,  For a listing of communities that have adopted the HERS Index Score go to HERS Index Score as Code Compliance Option

The reasons why a HERS Index Score is being tied into energy codes include:

  • The inspection and testing protocols are established in RESNET’s national home energy rating standards. RESNET is a national not-for-profit membership standard setting organization. It is accredited by the American National Energy Standards Institute (ANSI) as a Standard Development Organization.
  • The professionals that undertake the inspection and performance testing are certified following RESNET’s standards stringent training and testing procedures.
  • All certified RESNET home energy raters are subject to RESNET’s quality assurance oversight procedures.
  • The RESNET national home energy rating standards are recognized by the federal government (U.S. Department of Energy, Environmental Protection Agency, Internal Revenue Service) and the mortgage industry.
  • The HERS Index is a trusted measurement of the energy performance of a home. Over 1.3 million homes have been issued a HERS Index Score in the US.
© 2013 RESNET 
Residential Energy Services Network

Why use DSCC?

posted Aug 19, 2012, 6:09 PM by Stephen Mogowski

You may find yourself asking, why pay for a service that I can perform in house?

Well, first off, at DSCC we offer guarantee on our work.  That means if your plan is rejected by the city and it turns out to be our fault-- we redo the model and we will refund the money you paid us in the first place.  We made this somewhat extreme guarantee to show our clients that we're crazy about perfection and that nothing else is acceptable.

Secondly, you could train an architect to run the energy models, but that takes time and money.  Plus, once he or she learns to accurately model the homes-- how long will it take them?  Our pricing is low because our experts are incredibly efficient.

At the end of the day, it's your call whether to request our services or not.  But if you do, we'll be here-- ready to honor our guarantee.


Welcome to DSCC. The first one's on us.

posted Jul 25, 2012, 9:46 PM by Stephen Mogowski   [ updated Sep 22, 2012, 12:49 PM ]

Thanks for checking us out.  We're online and ready to work for you tomorrow.  In attempt to earn your business and trust, we'll be offering you a complimentary code compliance report.  It'll be valid through September of 2012 so if your turning out a new batch of plans, this is a great opportunity to save even more money off our already low rates.

We look forward to working with you!

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