Continuous Exterior Insulation: The Roadblock to Thermal Bridges

“If you want to stay warm, you wear your sweater on the outside. You don’t eat it.” - Dr. Joe Lstiburek   

Beginning January 1, 2020, the newest update to the California Building Code will take effect. For architects and builders, a significant change toward better performance of buildings and reduction of energy loads will be the inclusion of continuous exterior wall insulation on almost all new homes and buildings.

Though often seen as a nuisance, exterior wall insulation - EWI or EIFS, an exterior insulation finishing system - provides benefits surpassing cavity-insulation alone. In addition to sound attenuation and thermal comfort, the primary benefits of EWI are added thermal mass and mitigated thermal bridging - what occurs when a building material, often structural, passes continuously through the insulation layer from the exterior to the interior of a building.

In a typical home, an R6.5 stud within a wall of R19 insulation represents not merely a thermal bridge but a thermal super-highway. The differences in heat conductivity between these materials can lead not only to discomfort, but also condensation, mold, and mildew growth within walls. EWI, often in the form of rigid boards or high-compression batts, works as a roadblock against these thermal bridges and highways. 

In addition to improving energy performance, insulation materials give us great opportunities to reduce a building’s embodied-carbon footprint. Common EWI products include rigid woodfiber boards (such as Gutex), mineral-wool batts (such at Rockwool) and EPS (expanded polystyrene) or XPS (extruded polystyrene) foam boards.

Installing Gutex woodfiber boards.

Installing Gutex woodfiber boards.

Gutex boards offer a simple, carbon-neutral material. The 2’x4’ boards have thicknesses ranging from 1.5” – 4.75” with R-values ranging from R5.8 to R17. Some manufacturers offer product lines with inherent rainscreen capabilities, while others require membrane coverage and/or use a lime-plaster stucco finishing system.

Rockwool batt installation with furring strips for future vented cladding.

Rockwool batt installation with furring strips for future vented cladding.

Mineral-wool batts like Rockwool are often accompanied by furring strips and vented siding or cladding. The embodied carbon footprint is generally higher than woodfiber boards. It is inherently non-combustible and rot resistant.

An advantage of Gutex or Rockwool-type products as an EWI is their high vapor permeability and inherent drying capacity. After all, it’s not if your walls will get wet, but when. Rather than retaining vapor and moisture while offering food for mold and mildew, these materials will instead release moisture and dry out, thereby maintaining their thermal resistance capacities.

EPS (expanded polystyrene) and XPS (extruded polystyrene) foam boards are perhaps the most well-known EWI materials, however we encourage limited use of rigid foam products on buildings where not necessary. Foam insulation materials, being vapor-closed without drying capacity, require careful attention to the sequencing of wall construction to prevent moisture traps, growth of mold, and failure of assemblies. Why go down that highway when safer, easier options exist?

Finished exterior wall insulation with Gutex and lime-plaster stucco.

Finished exterior wall insulation with Gutex and lime-plaster stucco.

All rigid boards and mineral-wool batts are attached to wood sheathing and masonry with a screw-and-washer fastener. And while EWI has performance benefits, a challenge for architects and builders is to create new drainage measures. Work within a manufacturer’s waterproofing system. Locate your membranes to prevent air-leakage. And avoid moisture traps to ensure your assembly’s performance and longevity.. 

Wear your sweater on the outside. Don’t eat it!

Why Have an Onsite Battery System?

As most of us already know, home batteries are becoming a more common technology. Whether they are talked about at the residential or nonresidential level, batteries are an important technology that is only going to improve over time. There are many reasons to have a battery system for your house, this article will touch on four of them.

Time-of-Use: Local utility companies charge higher rates for customers during peak demand hours. A higher price per kilowatt makes sense from a business perspective, but it can significantly impact a user’s energy costs. This is where the battery comes into play. Energy stored in an onsite battery can be drawn upon during those peak rate hours (usually around the time period of 3-8pm), thereby reducing the customer’s demand on the grid, and charges on one’s bill.

Peak Offset: When grid energy is in high demand, infrastructure is more susceptible to failure. Peak offset is a strategic way to reduce the amount of grid electricity you consume during the time of high demand. It is important because it allows customers to rely on the energy from their battery instead of drawing off the grid. This has ramifications for the grid system overall and decreased use of “peaker plants”, which tend to be fired to meet peak demand and make generally more carbon intensive electricity. Like time-of-use, peak offset is significant to the time of day when energy is in high demand, however it is about demand, instead of cost.

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Self-utilization: Simply put, the battery can be used during non-peak times (or whenever you want) to power home appliances such as a washer and drier, a dish washer, A/C unit, or heater. The battery can be set to recharge directly from the photovoltaic (PV) system before sending excess to the grid. Nothing like running one’s home on the sun!

Backup Energy. The most common application of a battery is to supply energy to a house when the grid is down. When the battery kicks in, the necessary appliances will be able to operate. The amount of time that they will be able to operate is dependent on the size of the battery, how many appliances are tied into the backup panel, and usage patterns.

Batteries help customers lower their electric bill, help stabilize the grid, reduce overall carbon emissions from grid power, and provide energy during power outages. As nonresidential and residential builds incorporate PV panels, consider providing space in your drawings for batteries. In a future article, we will show dimensions for a sample full PV battery system, as well as the necessary components required to make sure the system is code compliant.

Interested in installing PV for your home or commercial project? Contact us! We can provide load calculations, system sizing and optimal ROI analysis for your PV Basis of Design.

Decarbonizing Our Future with Better Buildings

In support of the City of San Luis Obispo’s carbon neutrality goal and possible adoption of a de-carbonizing reach code, the San Luis Obispo Climate Coalition cordially invites city residents and the interested public to an evening of events focused on de-carbonization and electrification, Thursday, August 22, 2019.

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Mike Horgan, from the SLO Climate Coalition points out, “In California, homes and buildings are responsible for 25% of greenhouse gas emissions statewide, around two-thirds of which comes from burning fossil fuels such as natural gas and propane for space heating, hot water and cooking. In San Luis Obispo, building energy use accounted for approximately 40% of all emissions in 2016, and natural gas accounted for over half of those emissions. We felt we needed a way to inform our community about options for reducing the ongoing contribution of our buildings to climate change.”

The first program is a panel discussion on Building De-carbonization with nationally recognized leaders that will take place from 5:30 to 7:00pm in the San Luis Obispo Library Community Room and will be moderated by Denise Dudley.

Panelists will include:

  • Bronwyn Barry, Board Chair of the North American Passive House Network

  • Pierre Delforge, Senior Scientist at the Natural Resources Defense Council

  • John Neal, Director of Technical Services at The Association for Energy Affordability

  • Hannah Kaye, Expert Product Manager-Grid Edge, Pacific Gas and Electric Company

This discussion will provide attendees an opportunity to learn from experts about the benefits of electric appliances and equipment, and ask panelists questions of their own.

The second event is a Building Technology Expo which will take place from 6:00 to 9:00pm and will be held on Morro St. during the SLO Farmer’s Market. The Expo will feature distributors and manufacturers showcasing various technologies including:

  • electric heat pump hot water and space heaters

  • induction stoves

  • whole house batteries

  • sustainable building materials

This Expo is intended to provide Farmer’s Market attendees the opportunity to see real equipment and appliances in-use and in-person and ask questions directly of manufacturers. Design and building professionals are encouraged to attend.

For more information, see the event website: carbonfreeslo.org


Hone Your 2019 California Energy Code Knowledge

The Tri-County Regional Energy Network (3C-REN) will be hosting a public forum on Thursday, August 22, that will address significant changes in the upcoming 2019 Title 24, Part 6 Energy Code and the rationale behind them.

The forum includes guest speaker Brian Selby of Selby Energy, Inc. as well as a panel of professionals from our local government, design, and construction sectors.

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The discussion will highlight recent trends and pathways for building electrification and provide attendees an opportunity to learn how various industry groups and leaders are preparing for the changes ahead.   

When: Thursday, August 22, 12:30-4:30pm

Where: San Luis Obispo County/City Library, 995 Palm Street, San Luis Obispo

Lunch is provided.

To register, please visit:   https://energycodeforum.eventbrite.com

This event is part of an innovative day of programming organized in collaboration with the City of San Luis Obispo and the SLO Climate Coalition. It will be followed directly by a separate panel discussion on de-carbonizing buildings and construction, to be held in the same room. There will also be an electrification “Tech Expo” at the SLO Farmer’s Market that evening.

To learn more about building decarbonization and building technologies or for more information, visit https://carbonfreeslo.org.

Don't Wait Until Construction: Commissioning Includes Design Review

If you’ve been working on new projects over 10,000 SF, or LEED projects of any size, you’ve come across commissioning of energy-related systems. Commissioning (Cx) is a great process to verify that all the building systems work as intended, but if you’re used to waiting until construction to get started, you’ll need to adjust your process – all the way back to schematic design.

The requirements for commissioning are spelled out in the Title 24 Energy Standards, with supplemental requirements in CAL Green. The current 2016 code, and soon to be the 2019 code, includes a requirement for a Design Review by an architect or engineer, either in-house or 3rd party, depending on the size and complexity of the project. The design reviewer’s process is related to, but distinct from, the Commissioning Agent’s (CxA) work.

Although the requirement has been in place for a couple of years, recently we have seen more consistent plan check comments requiring the “NRCC-CXR” forms, especially for projects over 10,000 SF.

To help you plan ahead, here’s a chart to determine if 1) commissioning is required and 2) what kind of review is needed.

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Getting Started at Schematic Design

All new non-residential projects require a Design Review Kick-off with the owner, architect, design engineer and design reviewer, ideally during schematic design but it could be during DD. For efficiency, you may want to fold it into a regular team coordination meeting. If you like filling out the forms yourself, look up NRCC-CXR-01-E, available for free at the CEC website. This first form is pretty painless and simply records that the requirement to hold a design review kickoff meeting has been met and what was generally discussed. For projects over 10,000 SF, the kick-off should include review of the Owner Project Requirements (OPR) and the Basis of Design (BOD).  

Next Steps: 90% Construction Documents:

The rest of the forms come into play during the actual design review at 90% CD. At this stage, the reviewer goes through two lengthy checklists to make sure everything is addressed including applicable envelope, lighting/daylighting, water heating and general HVAC code elements. The original designer has the opportunity to respond to any comments. A fourth form is signed by everyone on the team to document that the review has been completed. Then the rest of commissioning proceeds as usual, with the OPR, BOD, Commissioning Plan, Functional Performance Testing, and so on.

Really, more forms?

No one likes to add a bunch of paper work to a project, but as part of commissioning, a design review helps catch missing items or oversights. The requirement for a design review may or may not come up as a plan check comment, but if you incorporate it into your design process, starting at schematic design, you’ll see the benefits during construction and operation.

Have questions about commissioning? Contact us, we’d be happy to help!



Residential ZNE is Almost Here: Code Changes and Practical Applications

With code updates on the horizon (Title 24 2019 takes effect January 1, 2020), many of our clients are beginning to focus on how to design to the new “Zero Net Energy” (ZNE) requirements for residential construction. 

We recently presented a summary of residential energy code changes for Santa Barbara’s AIA, and we’ll be presenting for AIA Central Coast (SLO) on June 19. As with past code cycles, there are prescriptive and performance paths for compliance, with the former serving as baseline for the latter.

Jennifer Rennick, Certified Energy Analyst and our in-house energy modeling specialist, noted that, “Envelope improvements and photo-voltaic (PV) energy systems will be required, as expected. Less obvious is that the new code takes into account that our peak demand is now 2 PM – 8 PM, so high energy demand during those hours will take a bigger hit than in the current code.”

Within the prescriptive path, the code offers options for new HVAC and water heating systems that help projects comply with more demanding energy use rules. Notable is that Quality Insulation Installation (QII) will be required for the prescriptive path, but remain a credit under the performance method.

For projects that use the performance approach, an Energy Design Rating (EDR) will need to be calculated. One part of the rating is energy efficiency, the other incorporates the addition of a renewable energy system. 

Of course, energy efficiency goes hand in hand with high performance assemblies, a specialty of In Balance’s Mike Horgan, a licensed contractor and Certified Passive House Consultant. He recommends EDPM gaskets and air-tight adhesives for sealing sill plates, a common and pervasive location for air leakage. He emphasized, “From sealing, to insulation, to waterproofing, details that effectively convey to contractors how to construct air-tight and vapor permeable assemblies will be essential.”

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Mike finds that constructing models of details that will live onsite, such as this one demonstrating an applied eave detail for a continuous “red line” exterior envelope, facilitate communication and lead to better building outcomes.

Two online resources that can be helpful for visualizing examples of high performance assemblies include:

·      Foundation Design Handbook by Oak Ridge National Laboratory 

·      Illustrated Guide: R22+ Effective Walls in Wood-Frame Construction in British Columbia

Interested in ZNE detail consulting or constructability?  We offer personalized sessions at your office, online, or on the job site (with props!) to discuss your project specifics. 

For Santa Barbara projects, reach out to Michelle Zimney.  In San Luis Obispo and surrounding areas, please contact Jennifer Rennick or Mike Horgan.

Shedding Some (LED) Light on Operating Costs

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We’re a fairly handy crew here at In Balance, so when Mike Horgan – licensed contractor and Passive House consultant – recently joined our ranks, we put him right to work … on our own office.  While our work spaces enjoy plenty of daylight, on cloudy winter days and toward the back of the office, we can use a little boost. Recently, some of the lamps finally died, so we decided to replace them (and the rest of our fixtures) with LEDs.

Here’s a breakdown of the costs and considerable benefits.

Our office has six fluorescent lights – each consisting of three 32 Watt lamps inside a 2’x4’ ceiling troffer - with a total wattage of 109w including the ballasts. Assuming electricity @ $0.20/kWh:

·      When operating 8 hours each day, 5 days a week, at $0.20/kWh, the total annual operating cost for each fluorescent fixture is $45.41.

·      The new 40 Watt, recessed LED panel operating 8 hours each day, 5 days a week, at the same $0.20kWh, will cost just $16.64 annually to operate.

*LED bulbs rated for 50,000 hrs/2000 per year = 25 years. Fluorescents need to be changed every 20,000 hours.

*LED bulbs rated for 50,000 hrs/2000 per year = 25 years. Fluorescents need to be changed every 20,000 hours.

Net Savings

The material cost for the 2’x4’ LED fixtures is $80. Mike did the install, but let’s assume hiring a licensed contractor for a total cost of $200/fixture. 

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At a net savings of over $3,000 over the life of the bulbs for our fairly cozy space (and even more when considering labor costs for installation on CFL replacements), the economic benefits of the retrofit are evident.  Equally dramatic, though less quantifiable, are the improved color rendering and absence of humming or flickering with our new lighting, which make being in our space more comfortable. And of course, we are saving energy and carbon emissions, which we love most of all.

Want to take on energy retrofits? We can help identify cost-effective strategies. Contact us.

Tri-County Regional Energy Network (3C-REN) Rolling Out on the Central Coast

New funding for energy efficiency improvements, workforce education, and carbon emission reduction projects is on its way to residents and businesses in the tri-county region.

In December, San Luis Obispo county joined its counterparts in Santa Barbara and Ventura in an agreement to allow utility ratepayer fees earmarked for efficiency programs to stay within our region, instead of being pooled and redistributed statewide.

This new program, known as 3C-REN, allows tri-county governments to collaborate and effectively operate programs that reflect our regional needs and allow for local innovation and autonomy. Outreach and opportunities are being identified now, with implementation beginning mid-2019.

Specifically, 3C-REN programs and funding will reduce energy consumption, reduce carbon emissions, directly benefit the residential and commercial construction industries and increase regional economic activity in three major categories:

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The first two program areas serve the building industry directly, including architects, engineers, builders, trades, and inspectors.  The third program area serves residents through a direct install program, expanding to serve renters as well as home owners.

We congratulate our county partners in establishing 3C-REN and look forward to engaging with the new programs and opportunities for energy efficiency on the Central Coast.

Have good ideas for training or programs? Let us know and we’ll pass it along!