Not too long ago, there were not any structures in the US built to Passive House standards and certification. But the number of buildings now certified by the Passive House Institute US (PHIUS)is close to 100, with at least 40 more in cue in the pre-certification phase and at least another 100 under construction.
It’s a far cry from the tens of thousands of PHs found in Europe, in part due to how the original concept, “Passivehaus,” was developed more than a dozen years ago in Germany. But what America has that is less present on much of the European continent is a wildly varied climate. We have a soggy and cold Maine, a hot and humid Florida, four-seasons Midwestern states, and dry and hot conditions in the American Southwest. Where the bulk of energy waste and expenditures occur in winter for many areas, the real costs in Phoenix are almost entirely related to searing summer heat. For an American Passive House in different climates, certain features such as window overhangs, minimized windows on the south and west exposures, and the relative efficiency ratings of furnaces and chillers vary by region. There is no single, replicable PH type in the US.
But one factor is consistently demanded to achieve ultimate energy efficiencies in all North American climates. That is the tightness of the building envelope. If you want to keep the cool summertime conditioned air in, there cannot be leaky holes around door and window frames. If you want to keep out winter’s chill, thermal bridging at studs must be managed.
All of which is driving the development of new building products. This includes ZIP Systemsheathing and tape, manufactured by Huber Engineered Woods LLC of Charlotte, North Carolina. The maker of engineered wood products introduced the product for roof and wall applications in 2007. Designed to deliver a unique combination of ease-of-installation, moisture resistance, and air leakage protection, the system is made up of an engineered wood sheathing panel with a built-in weather-resistant barrier that eliminates the need for housewrap in wall applications; a roofing version of the product includes a felt underlayment. The all-in-one panel is taped at the seams with an advanced acrylic adhesive to create a rigid air barrier to help reduce air leakage and ultimately contributes to energy efficiency in the home. When compared to the installation of traditional oriented strand board (OSB) sheathing and housewrap, it can reduce installation steps and because the weather barrier is built-in, it eliminates risk of water getting trapped and causing rework delays. ZIP System sheathing and tape also carries a 30-year warranty.
ZIP System sheathing and tape can be used on any new wood frame construction where the building owners hope for high-energy performance. It’s not just for architects and builders hoping for a Passive House, LEED, or other green building certifications. But it can achieve both, and the experiences of a builder and an architect in Rhode Island show us why.
The project, a single-family residence in Wakefield, Rhode Island, is likely the first to achieve this designation in the state (it’s in the final certification stage as of press time). The 1,657-square-foot home was a first for builder Stephen DeMetrick, who planned for years to take his firm, DeMetrick Housewrights, into the environment-forward world of Passive Houses. “I had been interested in high performance homes, studying it for at least 15 years,” the Georgetown University graduate noted. So DeMetrick took an intensive, week-long class from PHIUS, given at the Rhode Island School of Design, which prepared him for the exam that led to his certification as a Passive House builder. But this certification didn’t automatically bring such projects to his Wakefield firm’s door.
“I tried to sell it to clients but few showed interest,” he says. There was little awareness of what Passive Houses were and what they could accomplish, even with the brutal Nor’easters and other winter weather conditions in New England.
But the opportunity arrived in 2014 when DeMetrick was one of the numerous builders interviewed by the eventual homeowner, who was determined to have the ultimate high performance dwelling. A PH can use 10% (or less) of the amount of energy a traditional home of the same size in the same climate zone might use. But the real goal is a net-zero and even net-positive energy home, the latter being when energy generated by the home, typically with photovoltaic solar collectors, is actually greater than what that home requires. The PH home must be tightly sealed and wrapped in insulation, in addition to having high-performance windows (think triple-paned) and doors, employs heat-recovery ventilation, and minimal space conditioning systems. PH structures exploit sun energy as needed and block it when it is unwanted.
DeMetrick was appropriately picked for the job, even though up until that point he had not actually built one. But then again, neither had the other builders considered for the job. The project architect, SteveBaczek of Steve Baczek Architect in Reading, Massachusetts, did have experience with Passive House construction and had just as much passion for the idea as builder DeMetrick. He’s also familiar with the unfamiliarity in certain regions that DeMetrick bemoans.
“Passive House is creating a conversation,” he offers hopefully, explaining that even if a client or builder isn’t familiar with the designation, they are learning to build tighter and to higher energy performance standards.
“Passive House is analogous to a bodybuilder for the person who just wants to get in shape,” he says. “We can show what is possible with a Passive House, so other builders and designers say, ‘why not get to 75% of that?’ We have the ability to do this, to make homes that are healthy and comfortable and durable, so why shouldn’t we do it? Passive House is the understandable line in the sand.”
We trust Baczek’s metaphorical bodybuilder doesn’t kick sand in the face of the 98-pound weakling houses, those built to leaky, 20th century codes. But it could. Traditionally built residences of all types consume 40% of the total fossil fuel energy in the US, and those historic homes in New England probably contribute a disproportionate share of that. Baczek’s oldest remodel project was a home first built in 1690. “If all the homes in America were retrofit to tighter energy standards, achieving even just half of what a Passive House can do, it would cut America’s fossil fuel consumption by a meaningful, game-changing amount.”
But what about cost? Does the Passive Home require the owner to shell out so much it is only accessible by the well-to-do?
“The cost of Passive House building has been a touchy subject,” notes Baczek. “But while the first ones we built five years ago cost around 12 to 14% more, today I’m telling clients it’s more like 10%, and usually it comes in less than that. The more we do of it, the more we learn and get better at it. Sixteen-inch walls are no longer necessary because we see that 12 inches will do.”
Materials developers like Huber Engineered Woods LLC help bring that along. In 2012, ZIP System R-sheathing was launched to deliver all the moisture and air-tight sealing benefits of ZIP System sheathing and tape, but with an added attached layer of continuous foam insulation. The multi-functional ZIP System R-Sheathing system helps eliminate thermal bridging, the loss of energy when heat conducts through places such as stud walls, nails and fasteners, while providing structural durability, moisture resistance, and air leakage protection. Further, the water-resistant barrier built onto the engineered wood panel, protects the insulation layer from water migration into and through the R-3 and R-6 rated panels. This protects the R-value of the wall assembly.
Labor costs, very importantly, can be reduced as well. One study conducted by the company, showed that simply installing ZIP System sheathing—and taping the panels instead of installing housewrap and tape onsite—on a 6,000-square-foot house required 17 fewer hours of labor and was completed in 46% less time.
DeMetrick says that instructing his subcontractors on using ZIP System sheathing and tape also went quickly. “There’s a mental investment required,” he says. “But while some PH materials can be complex, the only real difference was the tape application, using a J-roller instead of their hands. Our first Passive House was remarkably easy.”
There are critics but most are mistaken, says Baczek. They suggest these tight envelopes might be too tight, preventing a healthy exchange of fresh air into the house. Those fears are unfounded. “The only problem is when houses are under-ventilated,” Baczek notes. “The design of the ventilation system must coordinate with the duty of the size and shape of the house.”
Which brings up Baczek’s favorite topic, that of the total-systems approach to this kind of design and construction. “Passive House has created a holistic sense that we can’t look at things like windows and building mechanicals alone. We have to consider the ventilation strategy, and work collaboratively with PH consultants and contractors and subcontractors. It aligns us as a team. Subcontractors can be a wealth of knowledge,” he adds. “They come up with solutions.” That whole-team, whole-house approach probably has something to do with how Baczek was formerly an electrician, then a builder, before becoming an architect.
Baczek has another custom home project that was built in Redding, Massachusetts, where the owners’ 4,000-square-foot house had only $200/month gas bills in the brutal winter of 2014 about a third of what the family had previously been paying in their previous, smaller home.
“This house was only 2% more expensive, with about $4,000 in incremental costs, because of the enhanced features,” which included ZIP System R-sheathing and tape, says the architect. “The return on investment was achieved in 20 months.” Which is pretty good, considering the several hundred years that Yankee home might exist.
BUILDERS KNOW BEST – BE SURE TO ASK WHAT THEY ARE THINKING
The experiences of architect Steve Baczek and builder Stephen DeMetrick in building the first Passive Houses of Rhode Island and elsewhere in New England were about innovation, leadership, and investment. Both see the future, but the vast majority of their client base isn’t there yet.
Part of the problem is regional in nature, which has perplexed the Passive House Institute US organization. Europe had it relatively easy with a fairly consistent set of climatic conditions across the continent, particularly in Germany where the standard has flourished. But your PH in Texas won’t be your father’s PH in Vermont. Standard adaptation is what PHIUS needed across the board.
To be clear, air-tightness is one of the three pillars of an American (as well as European) Passive House, the other two are source energy and space conditioning. Which to national manufacturers such as Huber Engineered Woods, is critically important—creating region-specific products can be costly in manufacturing and distribution.
But you can’t argue with weather. This is something that Kurt Koch, vice president of product engineering and innovation, confronts daily. One of the areas under his tutelage is codes and regulation, which are by their nature very local for good reason. Koch’s responsibilities also include responding to market demand. Which he emphatically says requires a listening, “curious” culture.
“We hire people in sales and other functions who have an inherent curiosity about how buildings are constructed and how the building process might be improved,” he says. “Many companies hire sales people whose job is to sell the current portfolio. We want people who seek to understand the builder’s needs. They need to take a solutions approach, not just push products. They can’t be afraid to ask questions. They should think holistically about assembling related products of a complete solution.” Such assemblages could include recommending a high performance window that can complement ZIP System sheathing and tape in forming a tighter envelope.
Several product innovations came from that builder-architect dialog. Known as the ZIP System portfolio of products, they include ZIP System sheathing with built-in weather-resistant barrier, ZIP System R-sheathing with attached insulation, and a radiant barrier roof panel. “Their feedback told us that installing housewrap over sheathing was a real hassle,” Koch says. “Often it would rip off on windy days. It was very hard to flash around irregular-shaped penetrations and sharp corners.” These two insights were catalysts behind the built-in weather-resistant barrier on ZIP System sheathing and the taped seams.
The newest product launched this year at the International Builders’ Show (IBS) in January also addressed achieving air-tight seals around windows and penetrations.. The new game changer? ZIP System stretch tape—a unique acrylic tape designed to stretch in all directions and seal out moisture and air from hard-to flash areas like curved windows, penetrations, and sills with a single, easy-to-apply piece.
They also found in product comparison trials that ZIP System sheathing and tape saves time over conventional OSB sheathing and housewrap, in no small measure due to the fact the weather-resistant barrier overlay is fused to the engineered wood substrate during the manufacturing process. Only the taping at joints needs to be done on site.
These taped seams help achieve increasingly stringent air leakage code requirements, as established by the International Energy Conservation Code (IECC). Measuring air exchanges through blower door testing has become mandatory for all states that have adopted the 2012 IECC. The ZIP system products are so effective at meeting these that architect Steve Baczek and builder Stephen DeMetrick tested the Rhode Island house before exterior cladding was installed—and were able to confirm the air-tight ZIP System sheathing and tape had a significant effect on reducing air exchanges.
DURABILITY IN SYSTEMS, AT ALL PRICE POINTS
Sustainability is a term that is sometimes overused or misapplied, vaguely alluding to climate change and environmental responsibility. But what probably moves the needle, and is more likely to accomplish those more global goals, is when green-oriented materials and methodologies work on a very practical level for building owners and occupants.
One could further argue the philosophy of sustainability, for some, was and is defined solely by achieving green points in building construction to achieve certifications such as the USGBC’s LEED ratings. In other words, the goal was focused on the first few years following construction or renovation. Often, sustainability largely skewed to upper price-point programs.
But according to Huber Engineered Woods’ Kurt Koch, it might serve longer-term purposes to take a “systems-solutions” approach, which includes consideration for how multiple building components contribute to building envelope and structural performance over time. If energy savings can extend to 30, 40, or 50 years into the future, why shouldn’t that be a benefit to all kinds of homes—including those made of wood?
Koch cites the multiple challenges in building wood-framed structures that go beyond responsibly sourced wood. “There are many influences and demands on how buildings are assembled,” he says. “Energy codes are certainly part of that as they become more stringent. Also, green initiatives and ratings systems such as Passive House, Home Energy Ratings (HERS) and LEED have point systems that our products can help achieve. We also have to think about mitigating risks related to disaster events like earthquakes, tornadoes, hurricanes, and wildfires.”
This has led to some region-specific solutions. “In Gulf Coast areas, measures like sealed roof decks are easily achieved with ZIP System sheathing and tape,” he says. “These are helping homes meetFORTIFIED Home guidelines to increase homes’ resiliency—or ability to be quickly re-occupied—following hurricanes or tornadoes.” FORTIFIED Home is an evaluation standard established by theInsurance Institute for Business & Home Safety, designed to guide new build and existing homes projects through techniques that create resilience against natural hazards. Qualifying structures typically receive reduced insurance premiums.
There is no lack of interest in reducing such costs and preventing storm damage in the first place. On the East Coast, there continues to be extensive rebuilding in the wake of 2012’s Hurricane Sandy. In Southampton, New York, on a site overlooking the Shinnecock Bay on the Atlantic side of Long Island, a homeowner rebuilt her cottage to LEED certification standards due to the town’s tax credits being offered for green construction. This is a homeowner who is, understandably, wary of water.
Her builder convinced her to use two Huber Engineered Woods products: AdvanTech subfloors, which remain stable (no warping or curling) even when exposed to extreme weather, and ZIP System sheathing and tape for walls and the roof.
It would seem that this homeowner might instead go the route of the smartest of the three little pigs, choosing bricks instead of sticks to resist the huff and puff of a big bad storm. And it may seem that masonry construction would withstand heavy winds better than wood frame. But reality trumps the intuitive (so much for fairy tales). For example, in storm-prone Florida, building codes require both masonry and frame homes to be able to tolerate up to 120 mph winds (i.e., a category 3 hurricane).
Wood construction can also lead to substantial cost savings. On the West Coast, where sustainable forests are plentiful, a fair degree of interest is evolving in building larger frame structures. The embodied energy of lumber is far less than that of concrete and steel, helping achieve that environmental goal. What makes it even more attractive is how an architect in Newport Beach, California (Newman Garrison + Partners) has a patent-pending method of building called New Block, which is a design that substitutes wood-frame construction for concrete podium or wrap designs that depend on concrete and steel. The architect and builder managed in 2013 to fit a 70-unit apartment building onto a 2.2-acre plot in Buena Park, California at a cost of $135 per square foot. This is significant relative to the $165 to $250 per-square-foot cost of a comparable concrete and steel structure.
It’s a strong business case for sustainable construction. And wood is at the heart of it.
That house on Long Island is in the pricey Hamptons. By contrast, the Buena Park, California structure is subsidized housing. It appears as if sustainable buildings made with 21st century engineered wood materials, which could include ZIP System sheathing and tape and AdvanTech subfloors, might work financially in both types of applications, as well as everything else in between.
It seems that sustainability—by way of a systems approach, focused on long-term durability—can be achievable on a broad scale. That’s what curiosity can do.