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Planning is Key to Net Zero Deep Energy Retrofit

You’d have to live under a rock (completely sustainable housing) if you didn’t realize that climate change, and rapidly increasing energy prices are a hot topic in today’s world. But why is the focus on the building industry?

Buildings consume nearly half of all the energy produced in the United States.

Globally, the percentages are even higher. Which explains why much of Europe is paving the way in both commercial and residential energy-efficient building.

It’s important to understand that energy-efficient building is about more than energy-efficient materials. A great deal of planning is needed to ensure the proper integration of materials and design, to achieve the best possible outcome.

Energy-Efficient Building

Passive Design, and Net Zero Energy Building (NZEB) are the two primary concepts for energy-efficient building. Passive Design uses a combination of climate-based passive and active design strategies to minimize the usage of energy, materials, and water.

Passive homes focus on the absolute minimal amount of energy use possible to heat and cool the building.

In 2015, the Passive House Institute of the US released the only passive building standard based upon climate-specific comfort and performance. The goal was to find the right balance between the up-front investment in a passive build, and the long-term payback, to achieve the most comfortable and cost effective building possible. Learn more at phius.org.

The basic premise of a Net Zero Energy Building is that they generate as much energy as they consume.

Designed to minimize the amount of energy they need to operate, and with renewable energy systems that meet their energy needs. Solar, wind, and geothermal are examples of renewable energy systems.  Design considerations to achieve net zero energy include passive solar design, triple pane or triple glazed windows, and high performance building envelopes. The US Department of Energy Zero Energy Ready Home program has been working to promote Net Zero building since 2008. Learn more at energy.gov.

Both Passive Home and Net Zero Energy Home certifications are generally based on the HERS Home Energy Rating Score, and certified by third parties, such as the Living Building Challenge.  To learn more about the certification process, click here.

The Deep Energy Retrofit

Most of the discussion about passive or net zero design centers around new construction.  It just makes good sense to plan ahead for the future. However, considering that the majority of the building inventory in the US was built prior to 1990, there is even more opportunity for energy savings in renovating and retrofitting existing buildings.

As the experts at Green Building Advisor explain, the process usually begins with a home energy audit and building analysis. Energy usage reductions are achieved through a whole-building approach, including insulation, heating and cooling systems, lighting, appliances, and water usage. A typical simple energy retrofit focuses only on individual upgrades, like heating and cooling.

Deep Energy Retrofits are a whole-building approach to maximizing energy efficiency.

The key to success in a deep energy retrofit, is utilizing skilled building science professionals who have the experience planning the integration of these systems into existing structures. Look to organizations such as the Building Performance Institute to direct you to certified professionals in the industry. That’s how we found Bill McKnight, CEO, Energy Conservation Specialists.

 

WATCH:  Net Zero Deep Energy Retrofit with ECS and ThermalBuck  

 

With over 20 years in the field of deep energy retrofits, Bill has achieved both BPI Accreditation and Energy Star Certification, teaches building science at Ulster University in NY, and has been featured in Home Energy Magazine. To learn more about the historic renovation project we worked on with Energy Conservation Specialists, and see how ThermalBuck was used to create a thermally efficient building envelope, read the full installation story here.

The Poplar Network features a clear-cut piece by Rob Freeman that explains the difference between Passive and Net Zero. For a more detailed reference, an excellent resource is Net Zero Energy Buildings, by Steven Winters Associates, Inc., a respected authority on building science and efficiency. It was featured in 2016 in the The Whole Building Design Guide, a program of the National Institute of Building Sciences which focuses on the latest technology and “whole building” design techniques. Data was also sourced from architecture2030, whose mission is to address climate change problems with design solutions of the built environment.      

Continuous Insulation – Making the Right Choice

If you’ve made the decision to include continuous insulation on your building, it’s time to pat yourself on the back.

The International Energy Conservation Code (IECC) has required continuous insulation since 2012. When the building envelope is insulated on the outside, it not only improves the energy efficiency, it also helps to reduce the possibility of moisture damage through thermal bridging.

WATCH:  ThermalBuck installation using polyiso CI  

Which type of continuous insulation should you choose? Good question.

Each type of insulation has different thermal properties, costs, features, and installation requirements, so you really need to consider what matters most in your application.

ThermalBuck is compatible with all types of continuous insulation, and will simplify the installation process.  It solves many of the common challenges builders find when installing windows with continuous insulation, and make the installation more energy-efficient by insulating the rough opening – typically a source of energy-loss in the building envelope. 

Types of Continuous Insulation

There are three main types of continuous insulation: rigid foam, mineral wool, and cork. The most widely used is rigid foam, which is split into three main categories: EPS, XPS, and Polyiso.

Expanded Polystyrene (EPS):  R-4 per inch

EPS is the most commonly used rigid foam. While it has the lowest R-value, it’s also the least expensive around .31 cents per sq. ft., which makes it a favorite for code compliance within budget. EPS does absorb water, and has the lowest compressive strength of the rigid foams.

Structured Insulated Panels (SIPS) and Insulated Concrete Forms (ICFS) are comprised of EPS. Insulfoam, a division of Carlisle Construction Materials, is largest manufacturer of block-molded expanded polystyrene (EPS) in North America.

It is important to note that EPS should be used over housewrap, and supported by OSB or plywood when used as sheathing.  

 

Extruded Polystyrene (XPS):  R-5 per inch

Many green builders discount XPS right off the bat, because it is the least environmentally friendly option. It contains the flame retardant HBCD, and its blowing agents have high global-warming potential.

However, with it’s higher R-value and moderate pricing at .47 cents per sq. ft. it is widely used. It’s stronger than EPS, and more water resistant, making it a preferred choice for under-slab and below grade applications.

XPS is available faced or unfaced, which affects the vapor permeability. Owens Corning Foamular “pink board” is some of the most widely recognized XPS on the market.

 

Polyisocyanurate (Polyiso or ISO):  R-6.5 per inch

Polyiso is the most expensive of the three types of rigid foam, as much as .70 cents per sq. ft. for a 1″ thick panel. However, the higher R-values often make the added expense worthwhile in the long run.  All polyiso is faced on both sides, most often with foil.

Polysio is considered the most-environmentally friendly of the three foams. It does absorb water, and generally cannot be used below grade. Johns Manville is a leading manufacturer of polyiso foams.  

One of the primary benefits of polyiso, is that it can often be used as a WRB behind your cladding. While it may cost more upfront than EPS or XPS, not installing a separate WRB component can save a considerable amount. It really depends on your climate, if this feature will be a long-term benefit, or present a building science challenge. 

 

Mineral Wool:  R-4 per inch

When you think mineral wool, you think of Roxul, easily the best known brand on the market. Mineral wool is also known as stone wool because it is made of basalt rock and steel slag, making it a favorite choice of green builders.  Easy to work with, fire-resistant, sound resistant, and water resistant. It’s the only insulation recognized by code as a firestop.

ComfortBoard is Roxul’s exterior insulation.  With an R-value of 4, it is lower than most rigid foams, however, there is no reduction in R-value over time, which will happen with foam insulation materials that rely on lower-conductivity blowing agents that slowly leak out or allow air to leak in.

Mineral wool is highly vapor-permeable and easy to install. Roxul is approximately .64 cents per board foot. 

 

Cork:  R-3.6 per inch

Thermacork, is the most widely recognized an all-natural rigid insulation material made from expanded cork. It offers excellent acoustic control, is highly durable, has high vapor permeability, and meets fire-safety requirements without flame retardants. It is labeled Red List Free for use in Living Building Challenge projects.

Cork is by far the greenest of the green in the insulation category, but it’s significantly higher cost and limited availability make it more of a niche product.

It’s important to take your specific climate into consideration when evaluating building materials.

EPS and XPS increase in R-value as the temperature drops.  A great thing if you’re in Wisconsin. However with Polyiso, the R-value actually decreases when the temperature drops. Not such a great thing when you’re in Wisconsin.

To choose the best continuous insulation for your project, analyze all of the variables: performance needs, climate, building codes, and budget.

No matter which continuous insulation you choose, proper installation is critical to achieving the desired performance.

Our energy-efficient homebuilders in Utah, Thomas & Melissa Griffiths, did extensive research on the features and benefits of the different types of exterior insulation, and decided on Atlas EnergyShield Polyiso for their dream home.

Thomas wanted the highest R-value his budget would permit, and appreciated the fact that he could use the continuous insulation as his WRB. To eliminate the thermal bridge around their Alpen 525 Series windows, they chose ThermalBuck. Take a look at their recent ThermalBuck installation below.

ThermalBuck simplifies the installation of windows with all types of continuous insulation, making a truly high-performance building envelope.  To see additional installation steps, strength and installation challenges, view the ThermalBuck Installation page.

For an in-depth conversation about rigid foam types, we recommend the experts at Green Building Advisor. For additional videos of polyiso installation, we recommend this one by Synergy Construction.  Of course we would recommend the use of ThermalBuck over the plywood bucks, to limit thermal bridging and improve the performance of the window installation.

While written in 2010, this piece from Green Building advisor about Using Rigid Foam as a WRB, still has merit.  Updated in January of 2016, ICC document AC71 Foam Plastic Sheathing Panels Used as Weather-resistive Barriers establishes guidelines for evaluation of foam plastic sheathing panels used as water-resistive barriers in combustible construction. See your rigid foam manufacturer specifications for more information.  

BRINC BP Announces ICC-ES Approval for ThermalBuck

BRINC Building Products, Inc. is proud to announce the publication of the International Code Council Evaluation Services, LLC (ICC-ES) Evaluation Report ESR-3753 for ThermalBuck, Division: 07 00 00 – THERMAL and MOISTURE PROTECTION, Section: 07 21 00 – Thermal Insulation. The properties evaluated by the ICC-ES are as follows:

  • Thermal Resistance (R-value)
  • Surface-Burning Characteristics
  • Physical Properties

The completed evaluation report for BRINC BP confirms that ThermalBuck complies with the thermal insulation requirements of the following codes:

  • 2015, 2012 and 2009 International Building Code® (IBC)
  • 2015, 2012 and 2009 International Residential Code® (IRC)
  • 2015, 2012, and 2009 International Energy Conservation Code® (IECC)

This confirmation, as evidenced in ICC-ES Evaluation Report ESR-3753, provides guidance and assurance to code officials, architects, builders, and energy consultants that ThermalBuck will perform effectively as thermal insulation under the applicable codes.

“ThermalBuck’s innovative design provides a simple, energy-efficient solution for the challenge of installing windows with continuous insulation, and limits thermal bridging in the building envelope.”

-John Brooks, President of BRINC BP

The ICC-ESR provides third-party verification that individual products meet the rigorous requirements of the International Codes.  The ICC-ESR Evaluation Report is confirmed evidence of a product’s code compliance, as well as a summary of relevant installation requirements and testing references. ICC-ES is an independent subsidiary of the ICC, which was developed in 2003 when four national building product evaluation services combined forces to provide consistent, professional evaluation of building components, products, methods, and materials.

ThermalBuck Outperforms Wood Bucks 2:1 – Thermal Transfer Testing

Improving the energy-efficiency of new and existing construction has long been a focus of the building industry. When it comes to insulation, exterior is the choice of many architects and builders, because it eliminates the thermal bridging through the studs.

However, continuous insulation presents its own unique challenges with installing windows and flashing the rough openings. The mounting point is no longer flush with the sheathing, it must be extended out to meet the exterior insulation depth. Rough openings are always a weak spot for potential water infiltration – and extending the mounting point for windows compounds the problem.

Until ThermalBuck hit the market, there really wasn’t a good way to insulate and create a thermal break around the mounting points of windows & doors. The traditional method to bump out windows was to build a wood window buck. Wood does extend the mounting point, but it doesn’t hold up well to moisture, and it has a low insulating value. With an r-value range of 4.4 per inch, ThermalBuck is a better insulator than wood. But how much? We performed some third-party testing to find out.

 

ThermalBuck installation vs. wood buck installation - thermal break           

Thermal Transfer Performance: ThermalBuck  vs. Wood Buck


Using thermal imaging, we recorded the performance of ThermalBuck against a traditional wood buck in a controlled environment. In the two mock-ups below, three temperature sensors were placed on both the ThermalBuck installation (l) and the wood buck installation (r). The temperature condition on the exterior of the structure was -6.67 ºF, and the indoor of the structure 72.76 ºF.  

 

Performance -Thermal Image wood buck vs. ThermalBuck           thermalbuck vs. wood window buck

These photos show two window installations side by side. (l) ThermalBuck (r) traditional wood buck. 

 

54% More Heat Transfer with Wood vs. ThermalBuck

On the exterior of the structure (point A) the wood buck looses 7.88 ºF, or 14.55 ºF total degrees from the outside temperature. ThermalBuck only loses .11 ºF , or 6.78 total degrees from the outside temperature. The wood window buck allows twice as much energy to escape, while the window installation with ThermalBuck is effectively limiting thermal bridging.

thermalbuck vs wood buck thermal transfer testing drawings
thermalbuck insulating value data charts with Rockwool photo vertical

 

ThermalBuck High-Performance window buck creates a significant thermal break at the mounting points of windows & doors. Using ThermalBuck as part of your continuous insulation solution is an effective way to limit the amount of thermal bridging that occurs through your building envelope.

To learn more about thermal bridging, see what the experts have to say at greenbuildingadvisor.com

Editor’s Note: This article was updated in July 2018. The testing results and thermal images were not changed.