EEBA Newsletter

Solving the Appraisal Problem

Appraisers will be better able to value high-performance homes when more builders start documenting those homes' features
Solving the Appraisal Problem

by Sandra K. Adomatis

Fannie Mae and Freddie MAC are in the process of revising the Uniform Residential Appraisal Report (form 1004). Although the draft has yet to be made public, I believe that it will provide a path for more accurately describing and valuing energy efficiency and green features.

The recognition by the mortgage industry that buyers are seeking green features—especially features that lower their monthly energy bills— is a step in the right direction. It should improve the appraised values of these properties as well.

But while better appraisal forms will help, they're useless if the appraiser and real estate agent aren’t provided with the home's high performance details. The appraiser can't value green features unless those features are documented, and that's the builder's job.

The fact that few builders provide adequate documentation is costing everyone. I've seen many high performance homes that were valued the same as similar homes built to a lower standard. Each of these contributes to a wider problem by helping build a database that says high performance homes don't warrant a sales price premium.

A case in point illustrates this. Not long ago I appraised a house that earned ZERH, ENERGY STAR, Indoor airPLUS, WaterSense, Florida Green Building Platinum Certification, and Florida Landscape Certification. The home had a 45 HERS score. The builder did not complete the Appraisal Institute's Residential Green and Energy Efficient Addendum (AIRGEEA), so I completed it.

I made an MLS search of that neighborhood to identify comparable homes. My search turned up 16 sales in the previous 12 months of homes with living areas within 100 square feet of this home. Prices ranged from $170,650 to $226,000, with an average of $188,000.

Upon receiving my appraisal report, the builder confessed that this high-performance house with five labels had been valued by another appraiser at $5,000 less than the 16 sales in the immediate area that were only built to code. The obvious question: Why?

When I investigated further I discovered the following.

1. The builder had verbally given the certification details to the previous appraiser but had not provided written documentation, like the AIRGEEA and the green certificates.

2. There were no labels inside the home documenting the certifications.

3. The appraiser lacked the knowledge and training needed to accurately value high-performance features.

As of today, most publicly available records, like the property appraiser’s records, don't even identify solar photovoltaic systems, which are often visible from the street. Those records certainly don't include behind-the-wall details.

The Environmental Protection Agency doesn't collect or list addresses of ENERGY STAR certified homes on its website. The MLS, the database most appraisers use, needs improvement. Not all MLS's have searchable green fields and for those that do, the fields often aren't populated because the agents lack the documentation needed to verify the features.

Exceptions are RESNET and the Appraisal Institute (AI). RESNET's Appraiser Portal, which is available to Appraisal Institute Members, lists ENERGY STAR Certified homes by address. The organization also has a public database that anyone can search to find homes by address to find their HERS Ratings. AI has a database of confirmed HERS Ratings and ENERGY STAR Certifications.

Of course, you need an appraiser who knows how to use these resources.

Problems at Resale

Lack of documentation isn't just an issue with new construction—it also causes many high-performance homes to be under-valued at resale. Often, the owner no longer has the green certificates, the AIRGREEA, or other documentation.

If the home earned a low HERS score or green certificate when it was built, chances are the paperwork will have been lost by the time the home goes up for resale. If the features that went into earning those certifications are not highlighted when marketing the home for resale, there's little chance that it will sell for more than those code-minimum homes.

Why should a builder care about their homes' resale value? The answer is that homebuyers who enjoy the benefits of high-performance features and see a sales price premium when they sell are more likely to refer that builder to friends and acquaintances. After all, they likely paid a premium over the cost of a code-built home, so they will expect one when they sell.

Paths to Value

This all begs the question of how to document those features and how to make sure they're properly credited during an appraisal.

One step is to place stickers with the HERS rating and any certifications in a place where they won't be disturbed. I recommend placing them on the electrical box because it's something homeowners don't take with them when they move. If the local building code doesn't allow posting in the electrical box, post the information on a nearby wall or on the HVAC equipment.

This isn't a new idea: manufactured home companies have been doing it for years. I have inspected 30-year old manufactured homes’ model names, climate zone data, and insulation factors, all still visible inside the box.

You also need to search out a qualified appraiser. If the lender or the appraisal company assumes the builder used code-minimum construction, they won't go the extra mile to find an appraiser with the training and experience needed to value high performance homes, and you may need to get involved to make sure they do so. (The Appraisal Institute's Residential Green Registry is a good place to find someone with this training.) If you need leverage, remind them that Fannie Mae, Freddie Mac, and FHA all require that the appraiser have requisite knowledge of the property type.

Even with the right appraiser you will still need good documentation. The AIRGREEA lets you base inputs on preliminary or projected ratings. If the home isn't completed yet, the appraiser can make the appraised value subject to completion and confirmation that the final ratings match or exceed the projected ones.

Also make sure to give the appraiser the complete HERS Report based on a projected rating from plans and specifications.

If you want more detail, a good resource is the brochure, “Appraised Value and Energy Efficiency; Getting It Right.” It includes links to the secondary mortgage market guidelines, documentation needed by the lender and appraiser, and a sample lender letter for the borrower to take to the loan application.

Marketing Green

Documented green features make a great addition to your marketing toolbox. This is another area where a lot of builders could be doing better.

As soon as windows are installed on a new home, place the projected HERS Score in the front window. Buyers may not know what the number means but they will ask questions about HERS or look it up on their smartphones.

Encourage REALTORS to make a .jpg of the certification or energy scores to place in the home's online listing along with any photos, renderings, or plans. Potential buyers will review these before they read the listing information, and if they see a certification they will ask questions about its meaning or benefit.

Ask your agent to attach the full AI Residential Green & Energy Efficient Addendum to the home's MLS listing. This will help appraisers and potential buyers understand the behind-the-walls features that make the home high performing.

In the end, the work of documenting and promoting a home's green features benefits all parties. It will be easier for homeowners to borrow the money needed to pay for energy-saving features. Each high-performance home that sells at a premium over a similar home without the features serves as a potential comp for future sales, ultimately making the process easier for everyone.

And if you're a builder, imagine the boost to your reputation if you're known for quality homes that are high performing AND offer a good resale value.

Sandra K. Adomatis, SRA, LEED Green Associate, is the owner of Adomatis Appraisal Service in Punta Gorda, Fla. Her book, Residential Green Valuation Tools, was published by the Appraisal Institute in 2014.

Help Ensure Our Industry's Future

A new EEBA initiative will recruit and train the next generation of building science professionals. But we can't do it without you.
Help Ensure Our Industry

Builders are often complaining about the industry's lack of young talent – but complaining won't change anything. Improving the situation will demand focused action. It will require that builders, trades, manufacturers, and other industry partners band together in a systematic effort to attract that talent.

EEBA took the first step to that outcome during our Path to Zero educational seminar in June. Eight scholarship students from the University of Denver attended free of charge, as their registrations were generously funded by EEBA partner companies. * These partners understand that recruiting and training the next generation of building science professionals will require a sustained effort and the money to support it.

The event was the beginning of the NextGen Scholarship Initiative. Its mission is to bring students, recent graduates, and young professionals from around the U.S to the annual EEBA High Performance Home Summit and our various regional trainings, where we will connect them with potential mentors and employers.


The seeds of NextGen were planted at last year's Summit, when the “Bring a Student to EEBA” scholarship underwrote the cost of attendance for 16 participants in the Department of Energy Solar Decathlon Design Challenge.

The feedback we received from those students was universally positive. They had their eyes opened to the fact that high-performance home building--and the industries that support those builders--have viable career opportunities where they can make a positive impact on the world.

"My experience at the Summit challenged some of my preconceptions on where the industry stands and what we need to do to make it thrive in the future," said Virginia Tech student Zachary Gould. "I was thrilled to have the opportunity to cultivate my ideas alongside experts in the field and look forward to continue doing so for many years to come."

Nathan's Story

Connecting students with experts is absolutely crucial. It's what really opens their minds to a career in high-performance homebuilding.

A perfect example of someone who made this shift and seized a new career opportunity is Nathan Kahre, the leader of the NextGen Development Committee, charged with designing and promoting the scholarship program.

Kahre, 27, earned a Master's degree in Sustainable Building Design and Construction from Appalachian State University in 2017. Although he was part of a team that designed a Net Zero home for the Solar Decathlon, he assumed that such homes were only offered by a tiny sample of custom builders. He assumed his future would be in commercial construction.

"I always looked down on residential," recalls Kahre. "In my mind there were two main groups of people building houses: big builders who cut corners to raise profits on the one hand and Jim Bob and his cousin working out of the back of a truck on the other."

That thinking began to change when he was approached at the Solar Decathlon by Gene Myers, an EEBA board member and CEO of Thrive Home Builders, a Zero Energy production builder in Denver. "We had a 20-minute conversation about indoor air quality and its impact on homeowners," he recalls. Then something clicked. "I began to realize that there were production builders who cared about these issues and that working for one could be a great opportunity."


Today, Kahre is Thrive's Performance and Healthy Home Manager—basically, the company's in-house building scientist. He is on the Quality Assurance team, with duties that include helping designers to create details that improve comfort and efficiency, advising the purchasing department on the best materials for those details, and training field crews on how to build them.

Kahre loves his new work, and after attending a couple of EEBA conferences, he is more enthusiastic than ever about the long-term career opportunities available to young people. "I've learned that the high performance residential world consists of many professional builders who understand building science and know how a home should be built," he says.

Kahre knows that the key to getting other students to share that enthusiasm is connecting them to those builders, as well as to other industry professionals.

At the Summit

That's exactly what the NextGen Scholarship program will accomplish. Our immediate goal is to provide funds for students from around the country to attend the 2019 EEBA High Performance Home Summit in Denver from October 1-3.

EEBA plans to offer scholarships to at least eight students: two from each of this year's four Solar Decathlon teams. Each scholarship of $1,500 will pay for full registration, transportation, meals and accommodations. If we raise enough money, we will provide scholarships to even more students.

Once there, students will be offered a structured program to help plug them into the industry. There will be conference sessions devoted to helping builders prepare and develop the next generation. There will be a mixer to connect students with builders, manufacturers, raters, and other industry partners. There will also be a private room where students can meet with industry representatives and learn more about working with these companies.

"Providing a space for students to connect with industry professionals will give them the opportunity to showcase what they know and what they're good at," says Kahre.

Ongoing Plans

As mentioned above, the Summit is just the next step in this effort. Follow-on scholarships will pay for students to attend local trainings such as Advanced Houses That Work and High Performance Mechanicals, making it possible for EEBA to reach students in different parts of the country.

Longer-term possibilities for NextGen include providing students and recent graduates with a job board and helping them find internships with industry companies.

"We're targeting Generation Z—digital natives who grew up with iPhones and tablets," says Steve Byers of EnergyLogic, a NextGen committee member and scholarship sponsor. "We're helping them see that our industry offers them the chance to do cutting-edge work and to provide environmentally friendly, affordable housing. It's a satisfying career with a real purpose."

Sponsors Will Reap the Reward

Of course, the ultimate beneficiaries of the NextGen Scholarship Program will be builders and other companies those students end up working for. EEBA's long-term goal is to develop a cadre of young professionals with deep knowledge of, and a real commitment to, high-performance home building.

"The availability of a pool of high quality young talent will provide builders with a huge benefit," says Adam Weinstein with Sonnen, another committee member and sponsor. "The NextGen program is a great springboard for developing that talent."

The fact is that a deep talent pool is critical to our industry's future health. EEBA members who build quality high-performance homes report growing demand from buyers, but without enough skilled young talent they won't be able to meet that demand.

That's why we need you.

How You Can Help

EEBA has already identified an excited core of industry professionals who have committed to working with our scholarship students. However, it's obvious that scholarships cost money. Our committee members are helping to fund the effort, but they can only supply a fraction of what's needed.

That's why we are asking every member of the EEBA community to consider this great opportunity and take action by helping to sponsor one of these students. If each of you gives just a small amount, it will guarantee the program's success. And of course, you will be helping ensure that our industry is able to achieve its mission of delivering affordable, healthy, energy efficient homes, while growing your own business and cultivating a talented workforce.

There are two convenient ways to support EEBA's effort to train the next generation of building science professionals.

By Credit Card

Please use our secure online form or call (952) 881-1098. We accept Visa, MasterCard, Discover and American Express.

You can do a one-time sponsorship of as little as $25 or, better yet, set up a monthly amount.

By Mail

You can mail a personal or business check or money order, payable to EEBA, to:

PO Box 47204

Plymouth, MN 55447


Sponsors will be recognized at the Summit.

As we said, talk alone won't change anything. But if we're all able to take this one small action, we will be ensuring the health of our companies and our industry.

*Eight companies sponsored the June event: Graf Engineering, Alpen HPP, EnergyLogic, Owens Corning, LP Building Solutions, Mitsubishi Electric Trane HVAC, SunStreet and CET & Associates.

Problem-Free Closed Crawls

The advantages of closed, conditioned crawl spaces have been well documented, but many builders need help with the details
Problem-Free Closed Crawls

by Alex Glenn and Tommy Blair

Roughly 15% to 20% of homes built in the U.S. each year have crawl space foundations. They're cheaper to build than full basements and more functional than a slab, offering a convenient place for plumbing, wiring, ductwork and heating or cooling equipment, as well as some bulk water resiliency.

Twenty years ago, nearly all crawl spaces were ventilated with outside air in an effort to control moisture. Most building codes required such venting.

The problem is that atmospheric venting is ineffective, to put it mildly. It can actually cause moisture problems, especially in humid climates when warm, moist air enters the crawl space and condenses on the framing.

Many builders and remodelers tried to address these problems by bringing in even more outside air, either passively by building more openings into the foundation, or actively by installing fans in the crawl space. This usually made the problems even worse.

Documented Benefits

Things began to improve in the early and mid-2000s after field research by Raleigh, N.C. Advanced Energy in mixed-humid climates found that properly detailed closed crawl spaces (with no atmospheric vents to the outside) not only avoided those moisture problems but also made homes generally healthier and more comfortable. Such homes had warmer floors, reduced drafts, less dust, fewer pests, and more stable indoor relative humidity.

Thanks in part to that research, most codes now allow properly detailed closed crawl spaces.

The key phrase is properly detailed, and in fact, builders are more willing to close their crawl spaces once they've been shown those details. Many have an initial fear that they will actually introduce problems, but this fear goes away once they know how to do the job right.

The System

Proper detailing is more than eliminating vents: it's a systematic approach to air-sealing, insulation, water management, and space conditioning. Remember that you're bringing the crawl space into the home's conditioned building envelope, so you need to treat it with appropriate care.

We've listed the details Advanced Energy recommends below. We've also listed common errors we see, along with their corresponding solutions.


Crawl space walls should be insulated with R-values appropriate to the local climate. The optimal choice over poured concrete or block is rigid foam designed specifically for humid applications. Batts are acceptable for wall sections framed with treated lumber (which we sometimes see on the upper portion of sloped foundations).

Encapsulate the batts. Batt insulation will only provide the advertised R-value if it’s encapsulated on all six sides. That means putting a rigid air barrier, such as OSB, on the interior face of any framed wall sections.

Don't insulate the floor. While installing batts between the floor joists can work if done right, we generally don't recommend this. Wall insulation combined with good air tempering (see below) will keep the floor just as warm, and because crawl spaces almost never have drywall on the ceiling, the batts inevitably pull away from the floor.

Remember the door. Any door to the outside needs the same insulation value as the walls as well as good weatherstripping and a secure latch.

Slope and Drain

Slope the ground to one wall with a perimeter drain or to a sump pump. There's no need to measure the slope; instead, just make sure that it's obvious to any observer that it is sloped.

Ground Cover

A 6-mil or thicker polyethylene vapor barrier over the ground serves two purposes: It keeps soil-borne moisture out of the crawl space and creates a draining surface for water that does get into the crawl, for instance from a plumbing leak. Extend the poly at least 6 inches up the foundation walls and behind the foam insulation. Securely fasten the top edge to the wall and seal it with crawl space liner tape or equivalent material caulk.

Lap it right. Hard as it is to believe, we've seen some builders reverse-lap the poly. It needs to be lapped shingle-style, with the upper sheet lapped over the lower so that water flows to the drain.

Air Seal

Most air infiltration will be through the band area so this needs to be carefully sealed.

Don't use caulk. It's nearly impossible to do a good job crawling around the space with a caulking gun, so we recommend open or closed cell spray foam.

Temper The Air

The mechanical system should provide moisture removal and should keep framing and other elements warm enough that moisture won't condense on them.

Make sure it's dry. Some builders install a dedicated heating and/or air conditioning supply register in the crawl. In humid climates, however, if the homeowners routinely turn off the air conditioner during spring and fall, the space can become humid enough for condensation and mold to appear. And, of course, if the AC system is oversized it won't have a chance to dehumidify the air.

A dedicated dehumidifier will solve the problem. It should be sized for the crawl space (you might need a couple of them) and should dump water into that perimeter drain or sump pump, rather than to a pan that has to be emptied.

Making It Affordable

Advanced Energy has worked with builders as part of its SystemVision program for nearly two decades now. Many of these have transitioned to closed crawls.

Most builders, once they understand the system and complete a few homes, find that closed crawl spaces don’t cost more to build than vented ones. For instance, the total cost of rigid foam on the walls installed before the floor is framed shouldn't be more than batts installed between the floor joists later on.

In fact, we have helped Habitat for Humanity transition to closed crawls in their crawl space homes, and they have generally found the comparative costs to be a wash.

Builders may need to complete a few homes to master the process, but the benefits more than outweigh that effort. As mentioned, closed crawl spaces are associated with better moisture control and air quality. They also lower the potential for surface mold growth, rotting wood, and termite and carpenter ant infestations. That means fewer callbacks and lower long-term costs for the builder.

For those wanting to know more, Advanced Energy offers additional resources, including articles, videos, and research reports; click here.

Alex Glenn is a building scientist, energy consultant and training specialist with Advanced Energy in Raleigh, NC

Tommy Blair is a residential subject matter expert with Advanced Energy in Raleigh, NC, providing education, quality assurance/control and technical guidance to a diverse set of clients and utilities

Properly closing a crawl space requires a systematic approach to air-sealing, insulation, water management, and space conditioning.

Can BIM Grease the Path to Zero?

This builder/developer is using the technology to do just that.
Can BIM Grease the Path to Zero?

While Building Information Modeling (BIM) is standard operating procedure on large commercial projects, relatively few residential builders have gotten on board. However, the technology has great potential for innovating homebuilding in general and green, high-performance building, in particular. The few homebuilders who are using it call it a game changer.

One of these is Jay Epstein, a Virginia builder/developer who started down the high-performance path more than 30 years ago. He was an early participant in the Building America program, and his company won three recent Housing Innovation Awards from the Department of Energy—in 2016, 2017, and 2018. Now he has teamed up with Skokie, Ill.-based DIGIBILT to use its BIM system for designing and managing construction of the state's first net zero ready community, Walnut Farm, which will consist of 75 single-family homes in Williamsburg, Virginia.

Epstein hopes the project will serve as an exemplar for the industry. "I want this community to show builders what's possible." While those possibilities include the performance features he puts into his homes, the community should also demonstrate the value of BIM.

Less Time, More Profit, Better Quality

The term BIM refers to a three-dimensional model of the home that links to one or more underlying databases with costs, schedules, product specifications, engineering data, and more.

The model offers several benefits. Because it shows the home's structural and mechanical systems, both in isolation and in relation to one another, conflicts (like a duct that runs into a water or drain line) can be identified and eliminated at the design stage instead of requiring field variances to correct. Also, the underlying data will immediately display the price and schedule implications of any changes and options. The model can even be used to generate 3D presentations and walkthroughs for use by the sales staff.

Used correctly, BIM yields lower design costs, more accurate estimates, fewer change orders, and easier sales.

For simple unit-price estimates like roofing or insulation, the savings come from the extremely accurate Bill of Materials (BOM) generated by the model. In the past, Epstein's subs submitted turnkey bids that included material costs, but the model makes it easy to separate those costs and eliminate waste. For instance, he can send the framer a list of the exact amount of studs and sheathing panels the home needs and get a more accurate labor bid based on those numbers.

Estimating more complex trades like HVAC is less straightforward, but the BIM pays off there, too. "The model lets us create very efficient duct and plumbing layouts," he says. "This saves the contractor design time and reduces variances. Once they understand that, we see the savings reflected in the bid."

While some subs were skeptical at first, they embraced the new system after a trial run. "On the community's first home I told everyone that we would monitor the work to make sure our materials list was accurate," he says. "Then I reminded them that there would be another 74 homes to do." He says all his subs have gotten on board and that some trade costs have fallen by 30%.

He estimates the overall savings on a $440,000 home at around $14,000 after factoring in DIGIBILT's fee, which includes building a complete model of each home and working with the builder and subs to make sure the model reflects their construction processes. All of that savings goes to the bottom line.


Enabling High Performance

The above benefits are ones any builder should be interested in, but we began this article by saying that BIM is a particularly good fit for high-performance construction. The question is why.

As this newsletter pointed out in in a recent article, the path to a Zero Energy Ready home starts with good design, then moves through a series of decisions about construction detailing, equipment choice, plug loads and renewables, with each decision set building on the ones before it. The BIM model makes the decision-making process easier. It shows how every system in the home fits into the overall design and lets the builder quickly see how different choices at each of those levels will affect the budget. In addition, data from an energy modeling program like REM/RATE can be imported into the model.

Benefits like these will become more important as homes get more complex. For instance, Epstein is building to what he believes will be code in 2025. Each of his homes includes structural details like insulated Zip sheathing and a conditioned crawl space, as well as mechanical equipment like 20 SEER variable speed heat pumps that coordinate with the home's ERV. BIM technology helps him manage the design and installation of those systems.

The model also helps him show customers the benefits that differentiate his homes. "We can show them what's behind the walls and explain why those details will make a difference in their lives," he says. The homes at Walnut Farm will all have looped structural plumbing that incorporates an on-demand recirculating pump. Getting the hot water to fixtures more quickly will save each homeowner an average of 7500 gallons of water annually. Using the model to show this and other systems really helps customers understand what they're getting from him that they wouldn't from another builder.

Quality Assurance

In addition to BIM, the technology package Epstein is using includes other features. DIGIBILT worked with Underwriters' Lab to develop what it calls "BILTiD"—basically, a unique VIN number for each house. The model and all related information is stored permanently in the cloud (via Amazon Web Services) and authorized users can go online anytime in the future to call up that information. They can see everything that went into the house and how it all fits together.

They can also see the completed construction schedule, the results of blower door, duct leakage and other tests and certifications the builder might have had done, such as the HERS rating, the LEED score and ENERGY STAR compliance.

The BILTiD even includes quality documentation. For example, Epstein is using flash-and-batt insulation with open cell foam sprayed on the inside of the frame as an air seal. He built the critical path schedule to ensure that the siding goes on after the foam and that the job supervisor takes photos of the inside of the frame after the siding is complete. If the photos show siding nails penetrating the foam, then it's not thick enough and will have to be re-sprayed.

These pictures, as well as photos of other critical details like window flashing, three-stud-corner insulation, and duct mastic, become a permanent part of the home's record. Epstein says that his subs appreciate this. "It's a quality monitoring system they don't have to pay for."

One final benefit has to do with the future. At 68, Epstein is looking to transition his company to the next generation. He believes that the use of sophisticated digital technologies like BIM, along with the natural appeal of green building, puts him in a strong position to attract young talent.

The bottom line is that while most industries have embraced digital technology and run with it, a lot of builders are still moving at a crawl. Epstein says that's not acceptable for a high-performance builder. Zero Energy Ready homes and communities are the future, and anyone who wants to create them needs to have a business of the future. "The building industry is the second least digitized in the world," he points out. "It's time we grew up and started building smart."






Jay Epstein – President and Founder at Health E Community Enterprises of Virginia. Building Energy Efficient Homes in Newport News, Richmond, and Williamsburg, VA. Our homes ensure a healthy environment for there occupant's and promote better health for future generations. The homes have a high level of comfort and low total energy consumption during their lifetime.

Paths to Zero

There's more than one way to reach the goal of building Zero Energy homes. A new EEBA training helps builders chart their best course.
Paths to Zero

As more high-performance zero-energy ready homes get built, and as more customers learn the financial benefits of owning such a home, demand for them will continue to rise. But for builders who have never exceeded minimum code requirements, the prospect of building to zero can seem daunting. 

Those preparing to embark on the journey usually have a lot of questions. What features should they start with? How long will it take to master this way of building? How will my customers pay the extra upfront costs?

The answers to the first two questions, according to Bruce Sullivan, who teaches EEBA's new Path to Zero Energy Homes training seminar, are 1) you can start almost anywhere, and 2) once you get going you can move along at your own pace. He also says that the path can unfold in a nearly infinite number of ways. In fact, the seminar might better be called "Paths" to Zero, since the journey will be different for every builder. 

The path an individual builder takes will depend on an array of factors that include local market demand, climate zone, price range, architectural style, utility rates, and even company culture. "When it comes to Zero Energy there's no silver bullet," says Sullivan, who has been involved in high-performance and green building education for more than 37 years and has trained thousands of builders and other industry professionals. "It's more like silver buckshot because you're spreading your efforts over a lot of small actions."

Those who complete this journey with the fewest bumps, detours, and dead-ends are those who have a customized map to follow. EEBA's training teaches how to create such a map.

Charting the Course

In the Path to Zero seminar, EEBA presents a 12-step model for drawing such a map. If that sounds like a recovery program for addicts, it's an apt comparison.

Unhealthy behaviors often begin as responses to short-term anxieties, then end up creating more problems than they initially were intended to solve. What does that have to do with homebuilding? The answer is that conventional production building helps the builder satisfy the typical consumer's demand for trendy features and affordability--but this may lead to long-term destructive effects on both the environment and the builder's business, as the market changes. And the ongoing operation and maintenance costs are often more than the homeowner bargained for.


Sullivan presents his map as a more effective way to satisfy demand for affordable housing. "I'm bold enough to say that a zero energy home can be free," he says, and as an example, points to his own Bend, Oregon home. "The house my wife and I built a few years ago is all-electric, including charging for our electric car, and it still ends up paying us $8 per month."



He has taken the lessons learned from his home, as well as from other builders and designers, and applied them to the production environment. "In EEBA, we recognize that production builders have special situations," he says. "They need to create economies of scale, so the options include things that are reproducible and affordable."

Each of the map's steps includes an overall goal, a set of design principles and construction details, as well as a menu of equipment and material options to chose from. For instance, nearly all builders understand the benefits of a thermal envelope with high R-value insulation, minimal thermal bridging, and advanced air sealing--but many lack a good system for evaluating the options that will get them there. Will it make more sense to use 2x6 studs and foam sheathing or to frame double 2x4 walls? What are the advantages, disadvantages, and economic consequences of each?

Or take the example of heating. The vast majority of U.S. production builders install gas furnaces with an average efficiency of about 90 percent, but a zero energy home might be better served by a smaller, more efficient unit. If the builder is also the developer, switching to heat pumps might let them eliminate the cost of installing a gas infrastructure in the community. 

In each step, you can choose the most cost-effective option or the one that makes the most sense for your homes. The end result will be a home tailored to your climate, your market, your architecture, and your business.

Pyramid Scheme

Having a set of steps is more than most builders have, but the steps will have even more impact if they're weighted. The Path to Zero training groups these 12 steps into what Sullivan calls the Zero Energy Pyramid. Although you can get on the path anywhere, the Pyramid shows you how to prioritize your actions to get the best returns.

It looks like this:

Design (the base)

1. Start with Smart Design

2. Orient for Sun Tempering

3. Optimize with Energy Modeling


4.Super-seal the Envelope

5. Super-insulate the Envelope

6. Select Optimum Window Efficiency


7. Ensure Clean, Fresh Air

8. Specify High-Performance Heating and Cooling

9. Heat Water Wisely

Plug Loads

10.Select High-Efficiency Lighting

11. Choose Efficient Appliances

Renewables (the capstone)

12. Use Renewable Energy

The path to zero energy building is a pyramid with each successive level building on the one below it.

The Pyramid structure makes an important point. A good thermal envelope will offer the most benefit if it's part of a well-designed home with solar features optimized for the climate. Likewise, efficient HVAC equipment will only deliver its full value if placed in a well-designed and detailed shell. For instance, Sullivan's own zero energy home includes a 4.3-kilowatt solar array, but the reason he enjoys a new monthly profit from the electricity it generates is that he started with good design principles then moved up the pyramid.

Learning to Sell

While the path to building a zero energy home is one of design and technology, selling it is a matter of knowing how to present the benefits in a compelling way. The EEBA Path to Zero Energy Homes seminar covers that, as well, and teaches builders how to use various calculators to show homeowners the economic consequences of each choice. "If someone is more concerned about initial cost than ultimate benefit, you need to know how to turn that around," he says. "You need to show them they will benefit economically the minute they walk in the door."

The seminar includes detailed information about returns on the investment in zero energy features, the costs of ownership in different parts of the country, and other metrics that can be used to educate homebuyers. 

As you would expect, this article barely scratches the surface. Those who want to learn more should check out the new EEBA Path to Zero Energy Homes seminar in-person as more trainings are scheduled around the country. It will also be offered at this year's EEBA High Performance Home Summit, October 1 - 3 in Denver, along with dozens of other technical sessions and networking opportunities for builders and manufacturers. If you're in the high-performance building industry, you don't want to miss it!

Q&A with Geoff Ferrell

The new board president shares his thoughts about the future of EEBA.
Q&A with Geoff Ferrell

In January of this year, Geoff Ferrell stepped up as President of the EEBA board, succeeding Gene Myers of Thrive Homebuilders.

Mr. Ferrell's deep immersion in high-performance home building makes him well qualified for the position. He currently serves as Chief Technology Officer for Mandalay Homes in the Prescott, Arizona area, a company that has been recognized by the U.S. Department of Energy as one of the most innovative home builders in America and was recently named ENERGY STAR Partner of the Year for the 3rd consecutive year. His duties include ensuring that the company's specifications and construction practices consistently meet its performance goals, and as part of that he leads the company's quality assurance efforts.

We asked Mr. Ferrell for his thoughts on the EEBA board's priorities for the next few years, as well as his personal goals for the organization.

EEBA: How did you get introduced to EEBA and why have you stayed active?

GF: I attended my first EEBA Summit in 2013. Mandalay had just competed in the DOE Challenge Home competition, the predecessor to the Housing Innovation Awards.

I was very impressed with the people I met. In addition to well-known industry names like Sam Rashkin, there were many top-notch builders, raters, and others. It was a great learning opportunity.

What really surprised me at my first Summit was the attendees' willingness to talk about what would be considered trade secrets in other industries. Everyone seemed willing to freely share their expertise and their hard-won lessons. As someone who began his career in the computer technology world, where so much information is considered proprietary, this openness was new and refreshing to me.

My first impression was of a community of professionals who genuinely wanted to raise the quality bar for the industry. That impression hasn't changed.

EEBA: Why do you think EEBA builders are so willing to help one another?

GF: As a group, and as individual builders, we agree that the buying public deserves better homes. In this day and age, it's ridiculous that a more affluent homebuyer gets higher quality construction, while a couple busting their butts to support a family of three has to be satisfied with lower quality because they can't afford anything better.

These days, an inexpensive car will run trouble-free for well over 200,000 miles, even though it doesn't have the same amenities or cache that a more expensive model does. We need to do the same. A $150,000 starter home should be as durable, efficient, healthy, and safe as a multi-million dollar mansion.

Everyone I've met in EEBA has this same concern and agrees that we need each other to learn how to consistently deliver that level of quality. We're trying to change the industry, and we need each other to make that happen.

EEBA: What do you see as your role as board president?

GF: My perspective is to re-evaluate what EEBA does publicly, to strengthen the things we do best and to look for ways we can offer more value to the industry.

We want to continue to be a training and a networking resource for industry professionals. We want to be the place builders, manufacturers, raters, specifiers, and others go to help one another.

Going forward, I want to get the board involved in expanding our reach. We need to find ways to connect with more builders locally and to get them to attend a training seminar like Houses That Work.

EEBA: How would you like to see EEBA evolve over the next few years? What would you like to see it accomplish?

GF: I think it's important that we continue to grow our training programs. For instance, we will launch a program at this year's Summit called “The EEBA Path to Zero Energy Homes” that will give builders a roadmap for reaching the goal of building Net Zero Energy homes. Training is the top obstacle to a builder when it comes to consistency and performance in my mind.

A priority for all builders is to attract more young people to the industry. I believe that high-performance builders are in a unique position to do that because of our embrace of new technologies and our environmental commitments. EEBA is the process of launching a NextGen initiative that will include scholarships for students to attend our Summit and our regional trainings. I want to see more of that.

would also love to see EEBA partner with other organizations. For instance, the Passive House Institute (PHIUS) and the Structural Insulated Panel Association (SIPA) do great work but they don't have our industry reach today. A partnership would help get them in front of a larger audience and would help the EEBA tribe benefit from their amazing resources too.

In short, we want to be the place that builders and designers who are new to high performance building come to get solid grounding in high-performance building and to learn from others who have gone before them. Then we want to serve as a forum where more experienced people can continue learning from one another.

EEBA: If you had to give a big message to the building industry, what would it be?

GF: We all need to care about what we are doing. Building a home is about more than profit or units sold. When you go to an EEBA event you will connect with people who really care about the impact they have on their customers and their communities.

If you have never experienced a gathering like that before, it will feel like another world at first. If you want to connect with some really amazing, innovative, passionate professionals, EEBA is the place to be. Join us and help make the industry a better place through collaboration and learning.

A Revolution In Water Recycling?

New septic technology could help reduce pollution, save water and qualify homes for LEED points. It could also let you build on otherwise unbuildable lots.
A Revolution In Water Recycling?

Dave Hopper has been in the septic installation business since the late 1980's and rarely sees anything new that qualifies as a game-changer.  That was until last year when his company, H&M Construction in Walton, Kentucky was asked to install a new type of system from Cincinnati-based NextGen Septic.  He has since installed about a dozen of these systems and now offers them to builder customers where the project warrants.

Although his customers end up paying an installed cost about twice that of a conventional septic, none of them complain because it lets them build on lots they could not build on otherwise.  "The system basically sells itself," he says.

Problem Solver

The NextGen system consists of a stainless-steel treatment unit placed on top of a two-chamber septic tank.  The unit is small enough to fit between the tank's two risers.

Rather than flowing to a leach field, effluent from the septic tank is pumped through the NextGen unit, where biomedia remove nitrogen, phosphorus, viruses, bacteria and other organic contaminants.  Hopper says the unit's output is clean enough to be discharged into the environment or for use in landscape watering.  "It's cleaner than any system we have ever seen," he says.

In fact, NextGen claims that the unit's output exceeds the standards used for wastewater treatment plants.  It removes up to 99% of nitrogen and phosphorous from the effluent, the main causes of algae blooms and other water pollution issues.

It also eliminates the need for a leach field.  "That makes it a great solution for a lot with poor soil conditions, as well as one that's too small for a leach field or whose topography won't accommodate one," says Hopper.

Hopper isn't the only contractor who sees these advantages.  NextGen president and inventor Rakesh Govind, who is also a professor of chemical engineering at the University of Cincinnati, says that it has been installed in 37 homes since earning state certification from Kentucky and Ohio.

Water Saver

Govind believes that decentralized treatment technologies like his make a lot more sense from an environmental standpoint than even the most effective municipal treatment plants.  That's because the output from most municipal plants ends up in the ocean, which does nothing to replenish local groundwater.  "This has led to declining ground water levels worldwide," he points out.

But despite the case this makes for local water recycling, current on-site technologies often do more harm than good.  For instance, conventional leach fields clog over time, sending pollutants into aquifers, lakes and estuaries.  "There are more than two million failed leach fields in the U.S.," says Govind.  "I've seen ponds in subdivisions with algae blooms created by this discharge."

The technology also has water conservation potential.  The discharge is clean enough to be pumped to a graywater plumbing loop for use in flushing toilets and watering lawns, two of the biggest water loads in a typical home.  (Toilets alone account for 40% of most homes' water use.)  That would make it less environmentally damaging to build in places where water is scarce, like the desert Southwest.  The reduction in water use can also help earn the home LEED points.

The system has two pumps that obviously use electricity, but combining it with a solar panel will ensure that treatment continues even during power outages.

At this point, the NextGen system requires state-by-state approval as an alternative septic.  However, it's undergoing tests at a National Sanitation Foundation lab, a process that takes about six months.  Govind expects to earn certification by September, which would make it a recognized system in most of the country.

The NextGen Septic treatment system consists of a water treatment unit placed on top of a conventional septic tank.  Internal biomedia remove nitrogen, phosphorus, viruses, bacteria and other organic contaminants.  The system totally eliminates the need for a leach field.

How To Dominate A Competitive Market

A Seattle rater and consultant shares lessons he has learned working with the top green builders

Green building is like any other endeavor.  Look at a local market and you will see most green builders going about their business the usual way—doing good work but competing with one another for the best jobs.  You will also likely see a few companies that have managed to rise above the herd.

The latter companies are the ones who create a recognized brand based on their green building expertise.  They're less affected by price pressures and stay busy even when the real estate market cools.

The obvious question is: how did they get there?

You can get a good perspective on that question from industry professionals who work with those market leaders as well as with the rest of the pack. That's why we decided to spend some time with Tadashi Shiga.

Shiga is Principal of Evergreen Certified in Seattle.  He has worked with 250 builders in what may be the greenest building market in the U.S.  His company provides verifier and rater services for programs that include PHIUS+, HERS, ENERGY STAR, and the Seattle-area's BuiltGreen program.

Here are what he sees as the answers to that question.

1.  Partnerships are powerful

More builders will rise to that top tier when there's healthy consumer demand for green building. The best way to create that demand is to get industry and government working together, which is the case for Seattle's BuiltGreen certification program.

Shiga says that BuiltGreen is similar to LEED Gold.  To get certified, a home must perform 20% better than the Seattle energy code and has to meet additional requirements that include indoor air quality and recycling.  It has become a real benchmark for local build quality, with more than half of local new construction now meeting its standards and some types of housing doing even better. "I estimate that 90% of townhomes and row houses here have certification," says Shiga.

He credits much of that success to a partnership between government and industry.  The program is offered by the Master Builders Association of King and Snohomish Counties—the Seattle metro area—but has been embraced by local permitting authorities.

Certification from BuiltGreen qualifies the builder to build a bigger home in certain areas and for faster permitting from the City of Seattle.  "I've seen them take six weeks off the permit time," says Shiga.  This has increased demand for green among consumers and builders.

2.  Standards are a starting point

Some builders seem to view program standards as performance ceilings.  The market leaders understand that they're minimums.

All of the 250 builders Shiga works with are pursuing BuiltGreen certification but just five have committed to exceeding the minimum standards.  Only three of those builders consistently succeed at it.  "We have five Passive House projects underway and will probably complete about 10 NetZero projects this year," he says.

In other words, in a market where consumers already embrace the benefits of a green home, just being green isn't enough.

3.  Architecture is Job One

While home performance is crucial, it's not enough.  "The top green builders offer sexy, cool designs," says Shiga.  "Their homes aren't just green—they're beautiful."

Builders that epitomize great green design include Dwell Development and Green Canopy.  They're two of the three consistent high performers Shiga mentioned (the other one is Cascade Built).

For instance, Dwell (which this newsletter profiled in December 2018) has won awards for architecture as well as for home performance.  Its projects sell faster, and for more dollars per square foot than any other local spec builder.  "People would buy from them even if they weren't green," says Shiga.

The same goes for the other top builders.  In each case, when visiting their websites you're greeted with two things: the company's commitment to making a difference for the environment—its green message—and photos of beautifully designed homes.

In this regard, Shiga thinks builders can learn something from the electric car industry, which was the first to demonstrate the power of combining aesthetics with environmental commitment.  "Electric cars didn't take off until Tesla came out with one that offered high performance and a real cool factor."

4. Passion and purpose are superpowers

How well a home performs and how well it's designed are reflections of the builder's priorities.  Those priorities grow out of what the builder sees as its defining purpose.

Of course, it's a cliché to talk about the purpose-driven company, but the fact that so few companies in any industry give this concept anything more than lip service makes it a powerful differentiator.

"The top builders are all driven by a purpose," says Shiga. "They each have a very clear vision about how they want to lead their field."  That invariably includes positioning their environmental commitment as something that helps make the local community a better place to live.

That commitment starts at the top of the organization.  "Company leaders have to really drive it," he says.  "Leadership is required to get employees and subs on board, and if you don't get them on board it will be an uphill battle."

In fact, he says that the best builders truly invest in their teams.  This creates a reputation that attracts the best workers.

5.  Leaders aren't afraid to share

Shiga regularly teams up with Anthony Maschmedt of Dwell Development to give presentations about green building to groups of consumers and builders.  He says that type of information sharing is typical for the top green builders.  "A great thing about truly sustainable builders is that they want to help each other out," he says.  "Their mission includes helping save the world, and they know they can't do it alone."

They also know that information sharing is a great business strategy.  Besides the obvious benefit of raising name recognition, it also helps the builder get better.  "The presentations that Anthony and I do are great networking events," he says.  "They're an opportunity to learn from other builders, contractors, and designers who are building green homes."

Public information sharing can also uncover business opportunities.  For instance, once Shiga became known, technology providers and product manufacturers began asking him if he knew any builders that would be interested in trying their products.  That led him to start EkoVate, a company that serves as a matchmaker of sorts between the two groups. He also saw a demand and became the area's first AeroBarrier installation company.

6.  There's no fast track

The final lesson is that patience pays.  Builders who want to rise in the green building game shouldn't expect to get there overnight.  "We advise them to start by taking baby steps," says Shiga.

"Get some training on building science.  A good start is one of EEBA's seminars or its annual Summit," he says.  "Then sign up for a program such as BuiltGreen or LEED that can give your homes some type of certification.  Then find a good consultant or HERS rater to help you along the path."

If you understand and follow the above lessons, and if you seek to join that top tier of green builders, then you will gain a real marketing edge.  A lot of builders have no idea how to attract a following on social media but a company with a real purpose, great architecture and a commitment to sharing information will find it easy.  They will earn more than likes: they will build a reputation that commands higher prices and helps carry them through the inevitable market shifts.

"Following these lessons is an insurance policy," says Shiga.  "The building industry is coming into a downturn.  What I learned from the last downturn was that the companies that did well were the ones that built a brand and gave real value to homeowners."

Tadashi Shiga is Principal of Evergreen Certified in Seattle. His company provides verifier and rater services for programs that include PHIUS+, HERS, ENERGY STAR, and the Seattle-area's BuiltGreen program.

HERS Raters: An Untapped Resource

These professionals can help with a lot more than inspections, but few builders understand that fact.
HERS Raters: An Untapped Resource

by Steve Byers

According to RESNET, just 20% of new single-family homes have a HERS rater involved.  When you consider that a rating is the most accurate way to gauge home performance, it's obvious that the industry has a long way to go.

Even those builders who regularly contract with HERS raters seldom take advantage of the full value these industry pros can provide.  That's unfortunate.  The best raters offer more than code or program compliance: they're extremely cost-effective quality assurance partners.  They can even help reduce a builder's liability for health and comfort issues, something today's overworked site supervisors seldom have time for.

As CEO of a building consulting and training company with more than 25 years in the home performance business, I find that builders are more willing to take advantage of a performance-focused rater's services if they better understand how we work.  The relationship is more like that with the architect or engineer than with the plumber.

What Raters Do

The most obvious job of a rater is to produce the HERS index score.  A good enough score will demonstrate energy code compliance and can qualify the home for certification from programs like ENERGY STAR, Zero Energy Ready and LEED.

However, the HERS Index is the cherry on top of our work, not the work itself.  When done properly, the rating process serves an important quality control (QC) function.  For instance, if the home doesn't pass the blower door test, the rater can tell the builder where the air leaks are.

But QC is just the minimum we offer.  Builders who want to leverage their rater's skills will make them part of the quality assurance (QA) program.  The difference here is one of depth: while QC is a simple and straightforward pass/fail test, a rater who offers QA will find the underlying reasons behind that air leakage (or any other performance-related issue), suggest approaches for doing better next time, and train the builder's team on those approaches.

The most effective QA starts at the design stage.  A performance-focused rater can look at a set of plans and see what's going to be difficult to get right in the field.  For instance, the rater might spot areas in a complicated roof design that will be a challenge to insulate and air seal.  The rater might work with the architect to determine the best locations for duct chases.

A good HERS rating organization will also likely have additional value-added services they can offer to builder clients.  For instance, my company does HVAC Design and performance services like airflow balancing.  We can train the builder's sub-contractors in high-performance building.  We have even offered builder clients post-closing walkthroughs to train homeowners on performance issues like how to use the smart thermostat as well as how and when to change the furnace filter.

These quality control steps are above and beyond what most project superintendents have time to provide.  When made part of the schedule for every home, they play an important role in lowering the builder's risk exposure.

Finding a Rater

Of course, builders who want to tap into the full potential of a performance-focused HERS Rater will have to find one first.  As with any trade or profession, quality and competence vary widely from company to company.

A good start is the RESNET Rater Registry (, which lets anyone find HERS Raters in their area.  However, it doesn't tell you how good each rater is.

Fortunately, every HERS Rater operates under the oversight of a HERS Provider, which performs periodic QA on the rater's work.  The builder should ask the Provider about any issues, past or present, with a particular HERS Rater they are considering.

Things to ask the rater directly include their pricing, what valued added services they offer, what trainings they have attended, how long they have been in business and how many homes they have rated.  And of course, get—and actually call— a few builder references.  Production builders should also ask the rater about their capacity and determine if they can keep up with the builder's volume.

It's a good idea to go to the ENERGY STAR website to see if the rater is qualified to deliver certification (  Even if you don't need this, it's a useful filter—ENERGY STAR sets a relatively low bar for raters, so I would be suspect of a rater who hasn't at least made that effort.

You should also look for signs that they stay current with industry trends and practices.  Do they belong to the local HBA?  Do they participate in ongoing training events like the annual EEBA Summit?  For instance, my company and others have formed a collaborative, Energy Professional Exchange ( to advance the level of professionalism and performance in the rating industry.

Time invested in finding a good, performance-focused rater pays real dividends.  This pro can help you solve problems, put more effective construction details in place and, ultimately, build better homes for your customers.  It could be the best business relationship you never thought about.

Steve Byers is CEO of EnergyLogic, Inc., a building performance consulting company in Berthoud, Colorado.

The Problem with HRVs

When integrated with the HVAC system, most E/HRV's don't deliver the desired ventilation air. A new design seeks to solve this problem, but we need your input.
The Problem with HRVs
by Srikanth Puttagunta, PE

Builders believe that if they install an Energy Recovery or Heat Recovery Ventilator (E/HRV) they have ensured good indoor air quality. In reality, that's seldom the case.

To deliver the needed fresh air, an E/HRV must be installed in a way that guarantees balanced airflows—where the intake and exhaust airstreams move equal volumes. But the design of these units makes proper installation difficult and, when integrated with the HVAC system (as most are), almost ensures that they fail to work as advertised.

Of course, an E/HRV costs more than other ventilation strategies, so if it doesn't do what it's intended to, the builder has wasted that extra money.

Steven Winter Associates is collaborating with a major manufacturer to develop an ERV that solves the shortcomings of conventional units. We have completed the second prototype. We hope to have a final design by Fall of 2019 with commercial availability sometime in 2020.

Before moving to the final design, however, we would like input from the EEBA audience to make sure the product will meet your needs. We have included a link to a short survey at the end of this article.

The three major issues that lead to unbalanced airflow with today's E/HRV's are:

1. Typical duct configurations

2. The frost prevention controls they use

3. Installs that make them difficult to properly maintain

Duct Issues

Let’s start with typical duct configurations.

If the E/HRV's intake and exhaust ducts aren't similar lengths with the same number of bends, their resistance to airflow will vary, throwing the unit out of balance. To compensate, some manufacturers provide static pressure taps that let the installer adjust the unit's fans during installation. That compensation might be sufficient for an E/HRV that has its own ductwork, but it won't be for the majority that are integrated with the HVAC system's air handler unit (AHU). The following two scenarios explain why.

Scenario 1. Here, the E/HRV pulls stale air from the return duct, then delivers tempered outdoor air further downstream in the same duct, closer to the AHU. For this to work, the E/HRV needs to run in sync with the AHU fan. However, this also results in unbalanced air flow, as the larger AHU fan will impact the smaller E/HRV fans. In this case, result will be more supply than exhaust air.

The unit could be adjusted at startup to compensate for this imbalance (though we don’t commonly see this in the field). The problem is that most of today's AHUs have two-stage or variable-speed fans, so the E/HRV can only be balanced under one of those fan speed conditions.

Scenario 2. Here, the E/HRV pulls stale air from the return ductwork and delivers tempered outdoor air to the AHU's supply ductwork. While manufacturers recommend the AHU fan run in unison with the E/HRV, most don't require it and with the AHU off, the unit may end up ventilating the AHU but not the rest of the home.

Frost Prevention

Next, let’s look at cold climate frost prevention controls.

When the outdoor air falls below a certain temperature (which varies with the E/HRV model), the core will be at risk of freezing. Manufacturers prevent this in a variety of ways, none of which are ideal.

  • On/off cycling. When temperatures fall below the frost threshold, the unit switches off for a set period of time (in really cold conditions, this could be 20 minutes or so each hour) to give the core a chance to warm up.
  • Air recirculation. Here, the outdoor intake and exhaust ports are closed, and indoor air redirected through the core's outdoor air pathway to warm it up. During this period, no whole-house ventilation is provided.
  • Exhaust only. Some units run in exhaust-only for a period of time allowing the core to warm back up. During this period make-up air will be supplied through leaks in the building envelope.

In each case, the home has poor or no ventilation during frost prevention. Alternatively, an electric resistance pre-heater can be installed in the outdoor air duct to prevent frost from forming in the core. This maintains continuous airflow but is energy intensive.

Install Errors

A proper E/HRV installation leaves enough space around the unit for regular maintenance, which includes periodically changing the air filters and removing the core for cleaning. Based on what we see in the field, I wonder how many builders and installers understand this. Many installations make it difficult to access the filter and core, while in other cases access is blocked by ductwork and plumbing that was installed later.

You would also assume installers know how to connect the ducts, but I've seen a lot of problems here as well, including supply and exhaust ducts hooked up to the wrong sides of the E/HRV. I also see a lot of flex duct that's not pulled tight, creating static pressures that can severely restrict airflow through either side of the unit or both.

Our Solution

With support from the DOE's Building America program and industry partners, Steven Winter Associates is developing an integrated ERV that will make balanced ventilation easier in homes. Our design includes the following improvements.

1. Simplified installation through a better form factor.

The unit will connect directly to the return side of an air handler and will pull stale air from the air handler's return ductwork. Not only does this avoid the drawbacks of each configuration type, but the fact that the ERV unit only needs two duct connections rather than four makes proper installation easier.

The unit is sized for mechanical rooms with standard ceiling heights. For an up-flow configuration, the total combined height of the ventilation unit, the air handler, and a standard supply plenum will be less than 8 feet. Maintenance access for the core and filters is also from the front, so it matches the service area required for the AHU.

2. Fans that ensure balanced ventilation under constantly varying conditions (varying AHU fan speeds, outdoor winds and indoor pressure changes, for example).

We are incorporating ECM fans. Nothing new here, right? A lot of E/HRVs have ECM fans. But rather than the typical constant torque ECM fan we are using constant flow fans, which will maintain roughly a ± 5cfm airflow range. This also allows the unit to be configured with MERV 13+ filtration.

3. Better frost prevention

The system is designed to maintain balanced whole-house ventilation during the frost prevention cycle without using electric resistance pre-heat. It does this by using a modulating damper to mix a small amount of air from the AHU supply duct with the outdoor air to pre-temper it above the core's frost point. Overall airflow through the outdoor air pathway of the core is increased, but the portion of outdoor air to exhaust air remains balanced.

Have I piqued your interest? Then take a look at the drawing.

As we continue to make refinements to the components and controls, we hope you will assist us with some feedback. This will help us ensure that the final product truly meets the industry's needs. We have posted a short questionnaire online that will help us better understand your approach to whole-house ventilation as well as what features we need to prioritize.

The survey takes five minutes or less and can be completed anonymously. We thank you for your interest and look forward to hearing from you.

Srikanth Puttagunta, PE, is a Principal Mechanical Engineer with Steven Winter Associates, Inc.

Page 2 of 4 << < 1 2 3 4 > >>