Energy Logic – All Homes Will Be Energy Efficient

all-homes-will-be-energy-efficient-robbyschwarz

EnergyLogic is in the news! Check out this interview with Robby Schwarz, one of the founders and continuing principals here at EnergyLogic. You’ll find the article supporting how EnergyLogic continues to help builders, salespeople, and consumers in our industry better understand the long-term benefits that energy efficiency will bring to their lives.

To access the article, please click on the link below:

Northern Colorado ENERGY STAR® Article

 

Robby Schwarz

 

Who to Contact:
Robby Schwarz
Principal, Director of Builder Relations

Email Robby
720-838-0677

Field Fusion Recap: The Disconnect Between Fire & Energy Codes

The Q3 Field Fusion event delved into air-sealing and sound transmission challenges in multi-family units through a guided discussion that included perspectives from Code Officials, Insulators, and Raters. Read more here.

There are many complexities that accompany building townhomes and duplexes.  For example, townhomes and duplexes built with common fire separation walls (party walls) are twice as leaky as single family houses that are twice their size.

Why?

The shaft wall, which we see most often in Colorado, is open directly to the outside through the designed gap between the shaft liner and the framing, thus creating a leaky assembly.  An additional complexity arises when the reduction of unit-to-unit sound transmission is taken into account, which requires correctly installed insulation.

EnergyLogic’s August 31st Field Fusion delved into the details of these assemblies through a guided discussion that included perspectives from Code Officials, Insulators, and Raters.

Clarification: What Part of the Shaft Wall Assembly is Fire-rated?  recap-of-ff-image_1

We must first define what part of the shaft wall assembly is fire-rated, as the entire assembly is not.  This is an important distinction that allows for more air sealing options once understood.

In chapter 3 of the IRC, Section R302 “Fire Resistant Construction” and Section R302.2 “Townhouses” states, “The common wall shared by two townhouses shall be constructed without plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend to and be tight against exterior walls and the underside of the roof sheathing.”

This statement in the IRC is our first indication that the two layers of sheetrock in the shaft liner wall are the fire-rated two-hour wall, designed to slow the spread of fire from unit to unit.  Thus, the two layers of 1” drywall cannot be penetrated with ducts.

The framing (which is held off the fire-rated assembly by a clip) often has ducts or plumbing in it and is specifically designed to burn and separate from the two-hour assembly when the clip melts.  This allows one unit to burn and fall before fire is able to pass through to the adjacent unit.  The UL (Underwriters Laboratory) listing for many of these assemblies’ references section 705 of the International Building Code (IBC) which states in Section 705.2 “Structural Stability”, “Fire walls shall have sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall for the duration of time indicated by the required fire-resistance rating.”  This is another indication that UL listings and the code are in agreement that the fire assembly is the two layers of 1” drywall and not the framing adjacent to the drywall.

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It is important to point this out because throughout Colorado there is not a common understanding of what constitutes a shaft liner fire-rated party wall assembly.  Some jurisdictions still hold that the assembly is the drywall, air gap, clip, framing and interior drywall while others hold that it is as explained above.   What is consistent is the understanding that the assembly must be built continuously from the foundation to the roof deck.

EnergyLogic suggests having a discussion with jurisdictions, in an effort to:

  • Ensure a common understanding of this assembly
  • Determine how the assembly will be air sealed to control airflow to meet the air leakage requirements of the energy code.

One thing to note: jurisdictions throughout the state require that the two layers of sheetrock run continuously from the foundation to the roof deck, but not the entirety of the rest of the assembly.  The most conspicuous example is the interior drywall, which is always missing on the ventilated attic side of the party wall.

Challenge: How to Achieve 3 ACH50?

Now that a common understanding of the assembly has been achieved, it is time to determine how the assembly can be air sealed in order to meet the air leakage target of 3 ACH50 for the 2012 and 2015 IECC.  Most jurisdictions have not amended the requirement to meet this airtightness level, so pre-planning is crucial in order to be successful.

The clip that holds the framing off the two-hour party wall assembly creates a 1” gap that is connected directly to the outside at the front and back of the unit, as well as to the attic.  This is where the UL listing of the assembly comes into play. UL is an American safety consulting and certification company that provides the one or two-hour rating for fire-rated assemblies by testing them in a laboratory environment. The UL listing for these assemblies is often mixed up with code’s definition of the assembly, which creates confusion regarding what materials are allowed to be used to seal them.

UL often refers to fire-blocking materials.  Fire blocking materials are usually defined within the UL assembly and can be any one of the following:

  • 2” nominal lumber
  • Two thicknesses of 1” nominal lumber with broken lap joints
  • One thickness of 0.719” wood structural panel with joints backed by 0.719” wood structural panel
  • One thickness of 0.75” particleboard with joints backed by 0.75” particleboard
  • Gypsum board, including 1” DensGlass Ultra® Shaftliner and 5/8” DensArmor Plus drywall
  • Batts or blankets of mineral wool or fiberglass
  • Other approved materials installed in such a manner as to be securely retained in place shall be permitted as an acceptable fire block (Section 717.2.1, 2006 IBC). recap-of-ff-image_3

As some fire blocking materials are air barriers and some are not it important to choose a material that can stop the flow of air.  EnergyLogic has seen the most success when builders tackle fire blocking on each individual floor.

Application: The Picture Frame Method

When looking at the party wall assembly, envision a picture frame around the perimeter of the wall. All four sides need to be fire blocked.  The material of choice right now is the same 1” gypsum board used in the 2-hour rated assembly.  Install the 1” gypsum board in the 1”  gap between the interior of the unit and the outside at the front and back of the units, between floors, and to the attic.  Again, picture framing the party wall.

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Depending on your foundation type, if you are standing on the first floor you will need to air-seal the two layers of gypsum and the bottom plate to the slab in the shaft wall, or address the rim joist connection in the basement or crawl space to the shaft wall. At the rim joist be sure sill seal has been installed between foundation and sill plate as it is your primary capillary break, then seal the sill plate to foundation, seal rim board to the sill plate, and seal the rim board to sub floor.  Pay special attention to any knockouts for foundation bolts.

Once the large 1” gap has been fire blocked with an air-impermeable material such as gypsum, seal the smaller gaps between the fire block and the shaft wall and the fire block and the framing.  A fire-rated caulk or expanding foam works for this. Following these steps, with careful attention to detail, should enable you to successfully achieve 3 ACH50.recap-of-ff-image_5

A few words of caution:

  • Ensure that the drywall lid is air-tight: duct boots and other penetrations need to be sealed. In addition, as required by ENERGY STAR, the drywall to top-plate should be sealed. (This is a requirement of code that is generally not enforced.)
  • Mechanicals can derail all good air-sealing intentions. Undampered ducts run to the exterior for combustion or ventilation air as well as atmospherically vented appliances. These combustion air ducts can ruin one’s ability to build a tight home that gains control and predictability of the airflow in the building.

Don’t Forget: Sound Reduction

Lastly, these assemblies should reduce sound transmission from dwelling unit to dwelling unit.  The party wall is assumed to be an adiabatic wall, i.e. there is no heat loss or gain through the wall between two conditioned spaces as the temperature is the same on each side. Therefore, the insulation is primarily installed to lower sound transmission.  The principles of sound reduction and heat flow are the same, so proper installation of the insulation in the framed cavity of the party wall is imperative.

NAIMA, the North American Insulation Manufacture Association, states that the installation of insulation in a party wall application should “comply with the manufacturers’ instructions including filling the entire stud cavity and cut to fit around outlets, junction boxes, and other irregularities in the cavity.”  In other words, the insulation in a common party wall should be installed to a RESNET, Grade 1.

To learn more please see EnergyLogic’s Tech Bulletin on “Fire-rated Party Walls”  which includes an article by Building Science Corporation.

Have a technical question? Contact Robby Schwarz.

Our next event will take place on November 16th. It is focused on Selling High-Performance Homes.  Our guest speaker, Todd Gamboa, President of Building Trust LLC., has a wealth of experience and perspectives to share.  Please see details here.

If you have suggestions for topic you would like to see discussed in depth, please let us know. We will be releasing our Q1 2017 event topic and date soon.

Robby Schwarz (faked)

 

Robby Schwarz

Principal / Director of Builder Relations

EnergyLogic, Inc.

720-838-0677

Contact Robby Schwarz

Introducing our new HVAC Designer, Scott Olson

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Introducing our new HVAC Designer, Scott Olson

Q&A: Learn more about Scott, his design philosophy, background, and credentials!

What was your first job in residential construction industry?

Construction Superintendent for a National Home Builder in Denver. The Job consisted of front and back‐end scheduling, and warranty work.

How and when did you first become interested in high performance homes and energy efficiency?

While working for a local home builder, I helped create their High Performance testing on all homes. I received my Residential Energy Services Network (RESNET) Certification and tested homes for energy code compliance and made sure homes were ENERGY STAR compliant. I balanced the needs of a production builder with ENERGY STAR best practices.

How did you get into HVAC Design?

I was challenged by my boss, while working for a large production builder, to take on a whole new role as an HVAC Designer. My construction experience as a superintendent was a huge advantage and I strived to make my designs be trade friendly and cost-effective.

What insights did you gain on HVAC designs when you worked directly for a large production builder?

Designed cost effective, construction friendly and functional HVAC systems

What elements of EnergyLogic’s HVAC design philosophy resonated with you and attracted you to the job?

EnergyLogic’s HVAC design services, with a goal of ensuring comfort and efficiency with properly built envelopes integrated with properly-sized and designed HVAC systems.

What are some of the common design mistakes or misconceptions builders should watch out for?

Sizing HVAC with a rule-of-thumb calculation. With today’s tighter building envelopes, rule of thumb often results in oversized systems that cost more upfront and cost more to operate over time. Oversized systems also don’t dehumidify as well as properly sized systems because the run time is shorter, so occupants are actually paying more for discomfort. 

What do you like to do in your free time?

In my free time, I enjoy grilling, working on projects around the house, and camping.

IECC and Multi-Family Buildings

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Up and down the front range of Colorado we are seeing more and more code jurisdictions adopt either the 2012 or 2015 IECC.  From a building science perspective, this is a step forward toward better performing buildings because these two codes require mandatory air leakage targets be met by all segments of residential construction three stories or less.  What I mean by this is that the code understands the importance of gaining control and predictability of the air flowing through our buildings.  I like to say that air is a freight train and like a train it carries cargo from point A to point B. The cargo it carries is heat/energy, moisture, and pollutants. The issue is that air does not always carry its cargo in a straight line on tracks from inside a house directly outside the house and deposit its load into the ambient air. A properly ducted fan may take air and its cargo to the outdoors, but often air takes its cargo into building assemblies and deposits it there, causing long-term building durability and efficiency issues for our homes. The code now recognizes that tight homes increase durability and efficiency and now understand that visual inspection itself cannot ensure house tightness.  The fundamental change in the code from the 2009 IECC to the 2012 or 2015 IECC is this recognition and the move from a choice to administer a blower door test or visually inspect to a mandate that you visually inspect and test to ensure tightness of the homes we build.

EnergyLogic tests homes and has been helping builders use the Simulated Performance pathway through code since the 2006 IECC.  Unlike other pathways in the energy code, the flexibility gained in the performance path allows for the most cost-effective means to develop the energy specifications for a house because we can trade off house tightness for R-values and U-values in the thermal envelope. This means that we understand that there is absolutely no problem achieving the code required 3 air changes per house at 50 Pascals (3 ACH50) in a single-family home.  In fact, the 2012 and 2015 IECC offer a checklist for how to be successful in the mandatory air barrier and insulation table R402.1.1.  We also know with certainty that it is not easy for multi-family buildings to achieve this same air leakage target. Currently, code does not recognize the difficulty of achieving 3 ACH50 in multi-family homes and buildings.  The City of Denver has accepted EnergyLogic’s code amendment to allow multi-family homes and buildings to have a leakage rate of 4ACH50. The city of Fort Collins allows a CFM/sqft of shell area measurement to be used to express air leakage in multi-family project.  So far they are the only jurisdictions in the state that I am aware of that have amended this section of the code to better reflect the realities of creating airtight multi-family buildings. On a national level, EnergyLogic has submitted a code change proposal for the 2018 IECC that makes a clear distinction between single-family detached homes and multi-family attached homes with achievable air leakage targets for both. We will have to wait until October to see if the proposal is accepted.

So where does that leave our multi-family builders?

Whether you are building duplexes, townhouses, or stacked multi-family buildings, house tightness is solely dependent on attention to detail with regard to air sealing adiabatic common fire rated walls, floors, and ceilings.  We recommend beginning by removing all draft-stopping materials (rock wool and fiberglass that are air permeable) in these fire rated assemblies and replacing them with solid fireblocking materials that actually stop the movement of air. By doing this you now have reasonable-sized holes that, depending on the jurisdiction, the assembly, and the skill level of the air sealing contractor, can be sealed. Next, you must treat common walls, floors, and ceilings as you would treat assemblies that separate conditioned space from the outdoors. The codes air barrier and insulation mandatory table/checklist must be applied to these common fire rated assemblies. For example, if there is a tub or shower pan, drop ceiling, or knee wall adjacent to an adiabatic common fire rated wall, floor, or ceiling, an air barrier needs to be installed.  Lastly, these details cannot be an afterthought!  They need to be addressed from the first design charrette, through a trade partner kickoff meeting, to mid-phase air barrier and insulation rough quality assurance inspection, if there is to be any hope of achieving 3 ACH50 when the home is blower door tested at a final inspection.  Blower door testing occurs when the home is complete and when it is impossible to achieve significant air sealing objectives at this point of construction.  Small changes in the tightness of the home may be able to be achieved, but air takes the path of least resistance; so if you have not blocked and sealed it out behind the drywall it is unlikely that you will be able to do more that achieve a small increase in the tightness of home at a final stage of construction.  In other words, the work has been done at the time of the rough inspection and the evaluation of the work is done at the final inspection.

In conclusion, get involved and take full advantage of EnergyLogic’s third-party inspection and testing services.  Get us involved as early as possible in the design of your multi-family project, and let us train all your trade partners at a kickoff meeting, how to successfully work toward meeting the requirements of code.  It is not easy, but attention to detail, quality assurance inspection, and greater understanding by the trade base will make 3 ACH50 achievable.

 

Robby Schwarz

 

Who to Contact:
Robby Schwarz
Principal, Director of Builder Relations

Email Robby
720-838-0677

Whole House Ventilation Strategy

Duct fan modificationAs houses continue to be built tighter and tighter, the importance of ventilation and providing adequate fresh air to occupants grows.  Ventilation requirements of ENERGY STAR® and the 2012 IECC reflect this growing importance.  Recognizing that many builders are installing exhaust fans to meet whole-house ventilation requirements, manufacturers are offering some new-innovative fans and controllers to meet this growing demand.

Panasonic Whisper Green® series and Broan Ultra® series are two products we see often.  Both fans are designed to operate at a continuous ventilation speed for background ventilation. They can also be ramped up to an exhaust (maximum) speed for spot ventilation.  When properly wired to a wall switch, the fan ventilates when the switch is off and exhausts when the wall switch is on.  Ventilation speed is set by a knob on the fan itself so that it can be adjusted to meet the ASHRAE 62.2 ventilation rate.

At EnergyLogic, our biggest frustration has been finding these fans incorrectly wired to operate as designed.  The wiring process is different than a standard bath fan and to complicate matters, different from one brand to another.  Quite often we test fans that cannot be adjusted to meet the ASHRAE requirements and either over ventilate or under ventilate the home.  Each time, the fans are not wired per the manufacturer instructions.  (We have even seen oversized fans that are modified with an inline damper to try to adjust the flow to meet ASHRAE. This limits the effectiveness of the fan and drastically increases the noise.  A loud fan is a fan the homeowner will turn off.)

By understanding how these fans are supposed to work and properly wiring them, builders can be assured that their investment in a high quality, multi-use fan will perform as designed, providing fresh air to the homeowners and running quietly in the background.  As Raters we strive to be knowledgeable in the ventilation systems our clients are installing and to help their trade partners understand the technical aspects of the systems.  We encourage our builders to contact EnergyLogic directly for access to our tech bulletins on exhaust ventilation wiring and installation or to get help navigating the maze of various products and configurations available to meet the new ventilation requirements.

Rusty Buick

 

By Rusty Buick
Field Services Manager
EnergyLogic, Inc.