Living Green: Should I Build New, or Retrofit an Existing Home?

At some point in the decision to buy a home, there comes a critical calculation: Do I build a new house on my own land, or buy an existing one? And if that existing home is poorly constructed or simply outdated, how will that impact me over time?

Aside from the obvious fact that existing buildings are where they are, as opposed to where you’d like them to be, they also come with hidden costs that may not be immediately apparent to the average homebuyer. As one example, getting older existing houses up to current energy code, let alone the stringent standards of today’s high-performance buildings, can involve impossibly long payback periods.

Martin Holladay, in writing for Green Building Advisor, indirectly addressed this issue in his March 2014 article, The High Cost of Deep-Energy Retrofits. In the article, he asks the question, How much does it cost to perform a deep-energy retrofit on a 100-year-old single-family home?”

His findings? Around $100,000.

Mr. Holladay based his finding on a study that was sponsored by the New York State Energy Research and Development Authority (NYSERDA). The program, centered in the Utica, New York area, paid for deep-energy retrofits of four wood-framed buildings.

So, how were the “deep energy retrofits” defined? In a nutshell, the goal was to reduce energy use by 75% by insulating slab floors to R-10, below grade walls to R-20, above-grade walls to at least R-40, upgrading windows by adding either low-e storm windows or new windows to achieve a U-factor of 0.25, achieving an airtightness goal of 0.15 cfm @ 50 pascals per square foot of surface area, and updating to the latest HVAC systems.

Without going into the myriad steps required to achieve the above, the retrofits resulted in impressive levels of energy reduction. Though the goal of a 75% reduction was not met, overall energy usage was reduced by 60-65%.  But while the retrofits resulted in draft-free comfort with new siding, windows, and HVAC systems, the energy savings alone, in Mr. Holladay’s words, “…can’t possible justify the very high costs of this type of retrofit.”

In fact, when factoring in the retrofitting costs to the energy savings, at least on houses built in the early 20th century, the study found that the simple payback period was 139 years, longer than the houses were old!

So, getting back to the original question, how does the green home buyer evaluate building new vs. retrofitting an existing building? It’s a complex subject with many variables, but what becomes immediately apparent is that it can be easier, more efficient, and in some cases, less expensive to build your high-performance home from scratch than to retrofit an existing older home.

That’s not to say that existing homes shouldn’t be updated to improve their performance. There are many who feel that the greenest building is the one that is already built. Some buildings are indeed worth the investment because of the inherent quality and craftsmanship in their original construction. Moreover, with historical and rare buildings, even condition is relative and preservation may trump energy performance.

But some buildings are clearly not worth it for the opposite reason. The embodied energy in an existing building is only part of the energy equation. Operational requirements, especially involving fossil fuels, affect the true cost to the owner as well as the environment. Every energy retrofit should begin with that calculation. Better technology and systems for economically achieving deep energy retrofits need to be developed with an eye towards getting the cost down. There are some very interesting scanning technologies available today that just may be a way to get there.

It’s important to note, however, that most of the homes needed in the next 50 years (because of population growth and demise of existing stock) are yet to be built. The next generation home HAS to be much better in every respect, but especially in the elimination of fossil fuel dependence. Thankfully, the technology and systems for building sustainable, healthy, Net Zero-ready homes (with Passive House levels of air tightness) are available today.

Either way, to achieve the aggressive environmental goals the U.S. has set for the coming decades, all buildings (which account for over 40% of total US energy consumption) will need to do their part in forestalling climate change.

Unity Homes Celebrates 2nd Anniversary

“The typical American home is a performance dinosaur, and is too much of a long-term burden for homeowners and society. Unity Homes aims to help make this species extinct.”     

Tedd Benson

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New Hampshire Governor Maggie Hassan (standing, center) visiting the Unity Homes production facility in October 2013.

On October 9, 2012, Bensonwood launched Unity Homes with the goal of making ultra-efficient, off-site-built homes affordable for the average home buyer. To date, Unity Homes have been built along the East Coast as far south as Asheville, NC and as far north as Montpelier, VT, and have been praised as possibly the “greenest prefabs on the market” by TreeHugger’s Lloyd Alter.

Designed to consume 50 to 75 percent less energy than standard newly-built homes, Unity Homes currently has four distinct 2 to 4 bedroom styles ranging in size from 1,028 to 2,450 sq ft. The home models are the Tradd (a classic tall cape), Xyla (an American bungalow), Värm (a Swedish contemporary) and Zūm (a passive solar optimized modern). All four of the highly-customizable styles have been built.

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Three interpretations of the Värm design shown here illustrate the highly-customizable nature of Unity Homes.

In the two years since its launch, Unity Homes has developed ways to raise the quality and performance of sustainably built homes while continuously trimming cost to make them ever more affordable. The company has already reached its original goal of trimming the typical build time to 30-35 working days for most projects and expects to get it down to around 20 working days in the future.

History

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Although Unity Homes first appeared in 2012, the seeds of the idea began much earlier. In 1991, Bensonwood began the long-term process of standardizing home production using computer-assisted design (CAD) software to optimize floor plans.

“I have long believed that the average American home should have a much higher standard of build quality, durability and energy performance,” Tedd Benson said in a 2012 Green Building Advisor article about the Unity Homes launch. After years of building a reputation for higher-end timber frame projects, Benson and the Bensonwood team wanted to bring his building innovations to the market-rate factory-built world.

There was also a philosophical element to Benson’s plan, describing the typical American home as a performance dinosaur, and too much of a long-term burden for homeowners and society. Then, as now, he wants to make that species extinct and transform the industry by offering an affordable home at a higher standard of efficiency.

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The LEED Platinum-certified, Net-Zero Energy president’s home at Unity College in Maine.

In 2008, Bensonwood received critical acclaim for its roles in fabricating the LEED Platinum-certified Unity House, a net-zero energy residence built on the campus of Unity College in Maine for the college president and his family.

The project was important, not only because the building was designed to maximize energy performance, but because it highlighted the Passive House standard for airtightness—the most cost-effective and easily achievable aspect of the Passive House standard.

Inspired by the project’s success and what the company learned from it, four years later Bensonwood launched a separate company producing high-performance prefab houses. The company was dubbed Unity Homes because it was thought the perfect name to express the democratic, egalitarian nature of these homes designed for the average American family.

Despite being in the throes of the worst housing crisis since the Great Depression, Benson realized that the company’s Bensonwood’s Open-Built® “operating system” capabilities and production capacity were being underutilized and warranted expansion. Tedd Benson also wanted to avoid reducing staff and a new division would allow the company to weather the housing downturn.

A 40-Year-Old Startup

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Building system team members assembling wall sections for an early Unity Home.

Unity Homes’ strategic vision began with a seemingly simple premise. “What if building only took 30 working days, all costs were known, the house quality was above anything the buyer had previously experienced, and the home could be net-zero-energy forever?”

For nearly a year, the entire Bensonwood team worked together to design and engineer the Unity Homes offerings and develop all the information, renderings and floor plans.

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An early Net-Zero Unity House planning session.

With no outside funding and many long hours, the company created a “40 year old start up,” Tedd Benson quipped at the time. In the end, Unity Homes was able to achieve both energy performance and price point goals with its high-precision panelized construction methods, keeping 60% of construction inside its production facility. Each home is organized into easily accessible “layers,” making for easier future upgrades and repairs.

By the time Benson announced the new company’s launch in an October 9 post on his blog site,The New House Rules,” Unity’s first two homes were already in production.

Montage: A Streamlined Process

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In Montage Building, pre-designed, high-performance elements can be easily reordered to fit homeowner budget, lifestyle or location.

The Unity Homes team sees these houses as more than another entry into the green prefab market, but rather as a complete rethinking of how houses are built. Many people in North America buy houses that might not last as long as they do; Unity houses, like the custom Bensonwood homes, are designed to last for generations.

Additionally, instead of prefab or modular, Tedd Benson prefers the term “montage” to describe the homes, which essentially means “assemble” or bring together disparate elements to form an integrated whole. That use of montage refers not only to the building process where panels are assembled at the home site, but also to a unique approach to vernacular design. The homeowner would not incur the cost of hiring an architect, nor would they be choosing from a limited product line as with most modular or prefab houses, but be allowed a range of customization to fit their lifestyle, budget and location.

Produced in Bensonwood’s Walpole, NH “studio,” the panelized wall, floor and roof assemblies are typically ready to ship to site in a few weeks. This work is concurrent with site prep and in parallel with other component fabrication such as the precision-cut beams and millwork.

The onsite assembly of the weathertight shell is usually accomplished in one to three days, depending on complexity and garage options. From there, Unity Homes can be finished quickly because of the open layout and packaging of systems, such as pre-assembled HVAC modules. While a standard new home takes 150 days to build, Unity Homes can now shave the building cycle down to as little as 30-35 days.

The Unity Homeowner Experience: “Rewarding and Fun”

Tedd Benson has always stressed the importance of owner involvement in the homebuilding process, but J.C. and Nancy Woodward of Fitzwilliam, NH, took it to another level. J.C. and Nancy initially came to Bensonwood looking for a custom home, but after several discussions with associates, architect Chris Adams suggested they consider one of the new Unity Homes about to be launched. The Woodwards were intrigued and chose the Värm style—J.C. also chose to act as general contractor to cut cost.

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An early Värm in New Hampshire was finished by the owners to reduce cost.

The site was prepped in late 2012, production began in February 2013, and by April the crew arrived with the home’s shell, which Woodward would finish out himself with help from some local subcontractors. Having built another house 25 years prior, he expected the typical chaotic construction scene with a host of endless problems to address. Because of the obvious attention to detail and quality, Woodward says, any problems that arose were small ones and easily solved.

J.C. was there from 7 a.m. until evening every day and was stunned at how quickly and smoothly the home came together. He was also impressed by how, “every person on the Unity team deeply cared about my project’s success.” From architect Chris Adams “wringing function from every square inch” to make the house feel a lot bigger than its 1,700 SF footprint, to project manager Tony Poanessa repeatedly “going the extra mile” to make the project run smoothly, Woodward describes the experience as rewarding and fun. In fact, he was so inspired he is now taking a CAD drafting course at Keene State College and hopes to work as a project manager himself someday.

High-Performance

The airtight homes possess many of the standards of passive house: optional triple-pane windows, high levels of dense-pack cellulose insulation (R35  OBPlus Walls® and R44 roof), buttoned-up building shells with a Passive House level of airtightness to 0.6 ACH @ 50 Pascals or better, energy recovery ventilators, air-source heat pumps and more to reduce energy use by 50% to 75% compared to standard new houses. The homes’ operational efficiencies with low energy loads mean less power use and smaller HVAC systems. They’re also capable of achieving net-zero energy if the owner decides to add a modest solar electric system.

Health & Comfort

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Stressing health and comfort as much as energy efficiency, Unity Homes are well-lit, quiet, draft free and moisture controlled.

In addition to the energy-saving features, standard specifications of the two- to four-bedroom homes include low-VOC paints and finishes, all-electric water heaters, Moen fixtures, EPA WaterSense toilets from Kohler, and high-quality woodworking and cabinetry.

In addition, they’re comfortable, light-filled and spacious, have great air quality and are fitted with high-quality materials, finishes and fixtures. Another less-considered element is that they are quiet—something too often missing in our homes. Silence is a feature increasingly accepted as vital to health and emotional well-being; and with doors and windows closed there are no traffic sounds from the street, airplanes overhead, barking dogs or noisy neighbors. Tedd Benson often refers to these as providing vital “sanctuaries or “sacred spaces” for family.

Adaptability

Heavily influenced by the thinking of John Habraken and Stewart Brand, Benson and associates developed the Open-Built platform to allow simple modification of structures as occupant needs change. The central idea behind Open-Built is to “disentangle” the building’s interior and exterior systems into separate, functional layers, which improves the efficiency of the construction process. That disentanglement also allows for long-term access, meaning homeowners and professionals can accomplish changes, upgrades and renovations with less demolition and rework.

All systems within the Unity Homes will be continually scalable, with most mechanical and space upgrades able to be accomplished by the homeowners.

Cost

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The ultimate goal of all green prefab manufacturers is to get the quality control and efficiencies possible in a factory at an affordable price. A common complaint is that Unity Homes and its peers are not affordable when compared to conventional stick-built housing, despite the fact that these are not conventional houses.

In truth, cost for this “beyond code” design and performance is competitive with current on-site, building-code-based construction when all factors are considered. These include: resale value, energy bills, maintenance and repairs, health effects and remodeling cost.

Nevertheless, driving down cost is a top priority in the Unity Homes mission. Unity plans to broaden the market for their homes by continually reducing cost to match the cost of conventional building, which varies widely between geographical regions. The company has already achieved this in many areas of the Northeast.

Eventually, Benson says, as more builders use and demand high-performance products, competition will increase among manufacturers, creating a virtuous cycle of improved performance and lower costs. He is emphatic, “Americans deserve better homes, and the industry has the capacity to build them, we’re just not doing it on a consistent basis. If this type of building was industry wide, the costs would drop for everyone.”

Future

OPTI_MEIR-AUER-5June-2013-001Tedd Benson is pretty clear about his future plans for Unity Homes: expanded production facilities across the country to lower shipping costs, continual improvement in the production process, and lower cost.

Eventually, Unity Homes wants to merge its current panelization process with modules that would allow Unity to complete mechanical rooms, bathrooms and kitchens at its facility, and leave only 20% of the building process for on-site construction.

Last, but not least, he wants Unity Homes to stand as a sustainable model for the industry, and with that to change how Americans view homebuilding from something to be dreaded and endured to something that is rewarding and even fun. In the end that will be a source of healing not only for future homeowners but for the planet.

Unity Home Pioneers: Part of a Greater Movement

Unity Homes TraddFor those wondering if the green movement in homebuilding is on track to address personal and environmental needs, that train has already left the station. New-home buyers wanting to be part of the larger movement towards low-impact, healthy living while at the same time moving towards F3 (fossil-fuel-free) energy independence, have taken a hard look at Unity Homes’ family of high-performance, customizable homes—and decided to invest in the future.

In the two years since launching in 2012, Net-Zero-ready Unity homes have sprouted up in three regions of the country (the northeast, southeast, and mid-Atlantic). Moreover, their owners, green home pioneers and early adopters of the new homebuilding technologies, have selected homes from all four of Unity’s design platforms—Tradd, Xyla, Värm and Zūm: an architecturally diverse collection of homes—customizing them to their personal lifestyle preferences.

So, who’s buying these highly versatile, architecturally diverse homes, and what’s motivating them to invest in a low impact, high-performance lifestyle? To answer that question, let’s visit a few recent Unity homebuyers, all of whom coincidentally (or possibly not) are related to the health and wellness industry.

Downsizing in Southern Vermont: A Nurse/ Midwife Customizes a Xyla 212

Unity Homes Xyla elevationsHow did Laurie Coursin, a Certified Nurse/Midwife and mother of an Antioch University student and pottery maker, come to discover Unity Homes? In her words, “The stars just all lined up.”

Elaborating, Laurie continued: “ For the past 14 years, I’ve been living in a timber frame home Tedd Benson built 30 years ago in Gilsum, New Hampshire. I am actually the second owner, so I had had no direct experience building my own home, or working with Bensonwood. I’ve loved the quality of the home and wish I could keep it, but I needed to downsize and wanted to be mindful of the latest advances in sustainable, energy efficient living. So, I wanted to build a mini-version of my home, but the whole process seemed overwhelming to me.”

Then, a bit of serendipity happened, according to Laurie: “It was at this time, that a pediatrician in the Keene, NH area told me about Unity Homes, so I gave them a call, and from that time on, it seemed like it was meant to be. From the start, I met with Unity sales person, John Dunbar. As it turned out, I had helped deliver one of his babies! So, from the outset, the Unity folks felt like a family to me—so supportive—and they’ve made the process so hassle-free. Beyond that, John showed me how high-performance homes like Unity were the wave of the future.”

And in order to live as lightly on the land as possible, Laurie also wanted the perfect location for her new high-performance home. Again, in her words: “I had become interested in an intentional community, Putney Commons, just across the Connecticut River in Putney, VT, and found an 11-acre parcel of land, with 6 existing homes (mine would be the 7th of 9 planned) that would be perfect for me. In addition to investing in sound land stewardship, I would be able to walk to the Quaker meeting house I frequent, as well as to the co-op and the library. And I’d be part of a like-minded community!”

UNITY HOMES XYLA FLOOR PLANAs for green energy, Laurie plans to buy into a solar farm (Soveren Solar’s Vermont Community Solar program), to power her home’s high tech HVAC system, with Air Source Heat Pump and HRV (Heat Recovery Ventilation). And since the intentional community doesn’t permit wood burning, she plans to use a small, gas-fired Yodul stove to replace her old fireplace, for the warmth and ambiance it provides.

Regarding the ability to customize her Xyla 212 plan, Laurie was able to extend the garage to add a special pottery-making room.  “I wanted to build a pottery studio for my son while he’s away at college;” Laurie said, adding, tongue-in-cheek, “It may be the only way I’ll get to see him.” Her design also includes a custom connector between the house and garage that incorporates a bath, laundry and entry. To further illustrate the flexibility of the Unity Homes platforms, when it was determined that the original site would have some site preparation challenges—leading to higher than anticipated costs—an alternate lot was selected and the original floor plan was modified to fit the new site without significant changes to the shell components.

Summing it all up, Laurie took a longer view: “At the end of the day, I want to be a responsible home buyer and citizen, so I can have some impact on the world my son, and his children, will inherit.”

 A Unity Tradd Rises in Central Vermont for a Young Doctor’s Family

Unity Homes TraddWhen Kimberly White, a homemaker and mother of two children, now aged 4 and 6, and her husband, Joshua, a medical doctor moved east from Minneapolis, Minnesota, they bought a plot of land in picturesque Barnard, Vermont and rented a basement apartment in a commercial building while researching high-performance home builders.

In Kimberly’s words: “We really wanted to be self-sufficient, and build a beautiful, healthy, solid house—and one that’s also good for the environment.”

They had learned from experience, Kimberly indicated: “I was pregnant with our second child at the time we came east. We had moved from an 80+ year-old stucco house in Minneapolis, with drafty windows and doors and gas heating, to a dank apartment with few windows—a space that was hard to keep warm enough for two small children—so building a tight, energy-efficient home was at the top of our list as we began looking for high-quality, green home builders.”

Regarding their insistence on quality, Kimberly offered: “My husband is very forward thinking. After we had done a lot of soul searching, at one point he said, ‘This is going to be our home—our life!  Where our kids will grow up. It needs to be a healthy, comfortable environment. And with the way the economy is going, the price of energy is going to be a major factor when considering a home’s design.’”

vermont xyla unity homesOn how they found Unity Homes, Kimberly said: “My husband is an avid researcher. He began looking into quality builders in the area and Bensonwood and Unity kept coming up. So we visited their New Hampshire facilities, and then took a tour of a nearby Unity home. What really struck us besides the overall quality,” Kimberly said, “was the tightness and even temperature of the home. The homeowners said that they often had to crack a window when they used the fireplace. That really spoke volumes about the quality and tightness of the house,” Kimberly noted.

The White’s bucolic wooded property, up a steep, winding road, has a couple of ponds and nice views, the perfect setting for their new Tradd 123, a 3,084 SF classic tall cape with 3 bedrooms, and 2.5 baths, plus a walkout basement that will be living space in the near future. The home will be rapidly raised and finished this fall, in time for the holidays.

The home’s standard open living plan has exposed timbers and the first floor includes the living, dining and kitchen areas, a powder room and a laundry room. Upstairs are the master with bath, and two additional bedrooms with shared bath. An unfinished walkout level rounds out the space plan. Because Unity floor plans are highly customizable, the second floor was flipped so that the master bedroom could take advantage of the views. Lastly, for outdoor living enjoyment, the home has a 287 SF porch and deck. An elongated, freestanding, 581 SF 2-car garage will accommodate their tractor.

Besides the reconfigured floor plan, the Whites opted for several upgrades, including an ERV (Energy Recovery Ventilator) air handling system to complement the standard air source heat pump.

In concluding, Kimberly re-emphasized: “It was really important to us that the home not only be healthy for our family, but healthy for the environment as well.”

A Retired Doctor & Teacher Retire to a Unity Xyla in Southern Connecticut

Unity Homes Xyla RenderingWhen Nikki and Joanna were contacted for the purpose of this interview, they were flush with excitement and anticipation after having just viewed their completed weather-tight Xyla 212 shell rise as if by magic, within a week’s time, in the coastal Connecticut town of Guilford.  Nikki, a retired family doctor, and her partner, Joanna, a retired teacher and practicing artist, were drawn to Unity Homes for a variety of health, environmental, and aesthetic reasons, but seeing the home materialize so quickly was a real thrill.

Not long before, the two weren’t sure a high-performance home was even achievable within their means. As Nikki explained, “Though we were familiar with the passive solar standards out there, and wanted to live lightly on the land, we didn’t think we could afford an environmentally-advanced home.”

Unity Homes XylaThen, describing how they discovered Unity, Nikki continued, “We were originally involved with a co-housing group in Bethany, Connecticut, but we were concerned that things were moving slowly and that, at our age—in our early sixties—getting a truly sustainable home was going to take too long. Sensing our frustration, a builder who had previously recommended Unity Homes to the co-housing group, directed us to the company website.”

According to Joanna, “One of the primary reasons we came to Unity was how well the homes were constructed, with large sections finished in the factory, unexposed to the damaging effects of weather. Our present home is a 50-year old house, with drafty windows and doors and a gas furnace. We thought of retrofitting it for energy efficiency, but it was totally impractical, if not impossible. With our new home, we want to reach Net -Zero energy, so we plan to add PV (photovoltaic) panels to our Xyla.”

The couple wanted a large master bedroom, a yoga studio, and a home office/studio. To achieve this within the Xyla 212 platform, a master bump-out was added to the plan and interior partitions were reconfigured—all while retaining the core volume and window configuration.

On the ease of achieving their wish list, Nikki had this to say: “The Unity model was a great combo, where the design is already set, but the space plan had the flexibility to meet our needs. For example, we wanted a larger master bedroom, so they put the whole team on it—you know, in-house designers, engineers. They ended up taking a master bedroom from a larger Xyla and added it to the Xyla 212 plan. We also really liked having many of the design decisions pre-set, while at the same time, having the flexibility to change the floor plan.”

unity xyla barnard vermontIn addition to the master bump-out, they did specify a number of finish choices to make the home uniquely theirs, like a special Japanese Shoji screen pocket door, a screen porch and cedar siding on the exterior to better weather the shore climate.

On the style of their Xyla 212, Joanna had this to say: “We really love the design. We find it organic and aesthetically pleasing, and we love the post and beam, the exposed timbers. We also really like the low profile—it being built low to the ground, which will make for easy, single-floor living as we get older.”

Summing up, Nikki spoke of the growing movement towards green living: ”It seems like everyone we’ve talked with in this area, even people overhearing our conversations and joining in—a waitress, a real estate agent, a cop—they were all interested in environmental building…in what we’re building. They all wanted to know what we were doing.”

Nikki then added, “We get the sense there’s a real movement building towards green living, and for Joanna and me, it feels really good to be out ahead in that movement.”

 

 

A Passive House Design (with a Few Curves Thrown In)

passive house designUnlike many panelized home builders who enclose their home shells using standard XPS and EPS foam core SIPs exclusively, Bensonwood builds many of its own structural, insulated wall and roof panels to realize the visions of its in-house design team and outside architects alike, while reducing waste by eliminating cutouts for doors and windows, which are not recyclable and end up in landfills.

Our walls feature dense-pack cellulose for insulation (a renewable, recycled product), and can be easily upgraded to extreme R-Value and air tightness for Passive House levels of performance. They also incorporate our Open-Built® chases for easy access to wiring and plumbing.

passive house curvesPerhaps best of all, our custom panels can accommodate curved walls and join complex, compound roof pitches to realize the contemporary designs of even the most innovative architects. One such Passive House design, by Jonathan Knowles and Laura Briggs of Briggs Knowles Architecture + Design, is a strategically sited home on a wooded lot in the Hudson River Valley of New York. Passive House is a rapidly emerging standard requiring that buildings use extremely small amounts of energy for heating and cooling.

The striking 3-bedroom, 2.5-bath house re-imagines the often utilitarian designs of the Passive House vernacular with its own unique curvilinear aesthetic, open space plan and multi-level views.

passive house walls panelThe first-floor plan includes a living area with a wood stove and screened porch, a separate kitchen and dining area, 2 bedrooms, 1.5 baths, a mechanical room, and a polished concrete floor. The dining area and one of the bedrooms are built into the curvature of the outer wall design, creating interesting interior spaces and angled wall partitions.

The second-floor plan has a generous, curved master suite complete with a large walk-in closet, sauna, bamboo wood floor, balcony, and dramatic, cantilevered porch. Rounding out the second floor is a large playroom open on one end to the living area below.

Bensonwood delivered and rapidly raised the home shell in the middle of winter, with R-49 roof panels and R-35 wall panels pre-installed with Zola triple-glazed windows. From there, the on-site builder, John Hommel of Ashley Homes, added additional layers of insulation to easily bring the house up to Passive House levels of performance.

Unity Homes’ Air Source Heat Pumps: Pulling Energy Out of Thin Air

By Rheannon DeMond

Bensonwood/ Unity Homes Energy and Sustainability Specialist

ASHP DIAGRAMHeat pump technology has been around for over a century, and even though the technology has advanced, the principles are still the same. There are some who are still critical about Air Source Heat Pump (ASHP) technology, but we at Bensonwood and Unity Homes prefer to use them whenever possible as they’re especially well suited for highly- insulated, airtight homes with very low heating and cooling loads. In fact, our building envelopes are so energy efficient that our smaller, open floor plan homes can often be comfortably heated and cooled with one central unit. Regardless of home size, however, Air Source Heat Pumps are an extraordinarily efficient and feasible option for our homes, and this article will cover why we think this technology is the best all-around choice.

Technology

Unlike combustion-based systems that produce heat at around 80-95% efficiency, ASHPs move heat from one location to another using the energy drive from the refrigeration cycle. This process is very similar to how a household refrigerator works.  The increased energy drive allows a heat pump to produce 100 kWh of heating and cooling energy using only 20-40 kWh of electricity, resulting in efficiencies of 200-350%.

ASHP IMAGEHow much electricity is consumed is dependent on the temperature differential between the outdoor and indoor air. In fact, a common reason people have shied away from using ASHPs in the past is because the efficiencies drop in cold temperatures, making these units not as ideal for cooler climates. However, recent advances in the inverter technology of these systems now allow ASHPs to operate down to -17°F, and produce heat at 100% of its capacity and efficiency down to 0°F.

Energy Usage

ASHP technology is efficient and here is a real life example to put it a little more in perspective:

For a 1,780 SF northern Vermont home that requires around 57.1 million Btus per year to heat:

Heating with #2 fuel oil would cost around $1,600 a year at current rates.

  • Heating with a propane-fired system would cost around $2,000 a year.
  • Heating with wood would be the least expensive option at around $850 per year (but the effectiveness is highly dependent on the user, stove design and kind of wood being burned.)

It should be noted that all of the aforementioned options use combustion, which we know is bad for the environment.

  • Electric resistance heat would cost around $2,500 per year and the impact that would have on the environment would be dependent on the source of electricity.
  • Air Source Heat Pumps can generate the same amount of heat for only $1,090 per year, and they can provide efficient cooling in the summer!

Environmental Impact

If the electricity used to operate an Air Source Heat Pump is generated by a renewable energy source, then the system has little to no impact on the environment. Oil, gas and wood-fired systems create heat using combustion. Combustion creates carbon dioxide, which is harmful to the environment and is a leading cause of unsafe emissions released into the atmosphere every day.

Using the same northern Vermont home as an example, the difference in electrical usage between electric resistance heat and the heat produced from an ASHP is around 9,500 kWh per year. A great way to look at those savings is how it will reduce the impact on the environment, as well as your wallet.

This EPA website allows one to input estimated energy offsets and see how those savings will reduce the impact on the environment. A savings of 9,500 kWhrs is the equivalent to eliminating the CO2 Emissions from 737 gallons of consumed gasoline, or 7,037 pounds of coal burned or 15.5 barrels of oil consumed. And that is just one year. Imagine what the environmental savings would be over 30 years.

Feasibility

Air Source Heat Pumps can be ducted, centrally located or zoned with multiple head units.  The system uses small copper refrigeration lines for connections, which minimizes required mechanical space and makes zoning much simpler. They offer a variety of head units that fit easily in both new and existing construction projects, and with their low operating loads these systems can be easily powered by a small renewable energy source.

Installation Costs and Return on Investment

We’ve already discussed how Air Source Heat Pump systems can save money on annual utility bills, but for something so efficient one would think it has to cost more money than conventional systems, right?  Wrong. These systems are very cost competitive with most other systems, and remember, they provide whole house cooling and heating, so they may even end up being less expensive.

So what is the return on investment on a system that will not cost the consumer any additional money? It is immediate, but on average this system will pay for itself in energy savings in less than six years!

 Cold Climate Operation

The one downfall to these systems is that at around -17°F there is a chance these systems will shut down and stop producing heat, which is what scares some people away. What these people do not understand though is how infrequently the temperature drops below minus 17°F in most of the United States. Even in the coldest climates this is not a common occurrence, so not using a system that is as efficient as this one because of that one fact is not the right approach.

A simple back up source of heat can be installed for use in these rare occurrences. In our homes we use electric resistance for back up heat, because it is inexpensive and can also serve as zone heating. There are also systems available with electric resistance back up heaters that will continue to operate into these low temperatures.

Other Types of Heat Pumps

After heating and cooling, domestic hot water consumes the most household energy, but luckily they also make a heat pump for that. Heat pump water heaters operate at high efficiencies, and have settings to ensure a steady rate of hot water.  When compared to electric resistance, oil and propane powered systems, these units will see a return on investment in less than three years. The only catch is that how efficiently they operate is dependent on the ambient air around the system, so installing a unit in a cold basement would not be ideal, but if you have a continuous source of heat to pull from, these units are a great and affordable solution.

Geothermal or Ground and Water Source Heat Pumps (GSHPs) operate using the same heat pump technology as air source, except they move heat using the consistently warmer temperatures of the earth and ground water.  Because of this they can operate at efficiencies of 300-600%. These systems are very popular in European countries with very strict guidelines for energy usage.

GSHPs are growing more popular in the cold climates of the United States, but they have high upfront installation costs and a small pool of qualified installers. Like most emerging and efficient technologies, it may take some time before these systems are offered at prices that offer an attractive return on investment.

Conclusion

Buildings are responsible for around 40% of the carbon emissions released into the atmosphere every day, and with the fluctuating cost and availability of fossil fuels, and threat of irreversible climate change, another solution is very necessary. With the advancements in heat pump technology and decreasing costs of renewable solar energy, achieving net zero energy consumption is not just feasible, but a great investment as well.

Aquatic Dreamhouse Required Fluid Construction Strategies

Pool-Centric Vision Posed Technical Challenges

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Faced with a significant technical challenge, Alfandre Architecture, PC and its construction company, EcoBuilders Inc., teamed up with Bensonwood to fabricate and install the large-span glulam timbers and insulated shell of this spectacular 6,000 SF timbered dream house — all built around a large 2,000 SF indoor pool — for their client, a retired couple in Putnam County, NY.

pool house living areaThe challenges included engineering the long timber spans of the pool room, humidity control and the sensitivity of the rocky build site, to name a few. Here, Bensonwood’s expertise in timber engineering, off-site fabrication of panelized assemblies and rapid on-site installation was instrumental in realizing the ambitious project with minimal disruption to the ecology of the home site.

The house, recessed into the bedrock of its 15-acre site, was designed by architect Rick Alfandre to complement its natural setting, with the pool room both anchoring the design and providing the homeowners with the physical, social and emotional benefits of their daily one-hour swim. To add to the ambiance, the light-drenched, four-bedroom, five-bath home has over 70 triple-glazed windows to draw the surrounding landscape into its interior.

pool in upstate ny dream houseGC and local construction company, EcoBuilders Inc. (owned and operated by Rick Alfandre) completed the foundation and walkout walls, first floor system, infill, window installation, mechanical systems, and finishes.

From this project, Bensonwood went on to contribute the timberframe and roof panels for Alfandre Architecture’s offices across the Hudson River in New Paltz, NY, for which Alfandre is seeking LEED Gold certification.

For more photos, visit our Houzz Page.

Bensonwood Featured in “The New Net Zero” by William Maclay

the new net zeroThe New Net Zero: Leading-Edge Design and Construction of Homes and Buildings for a Renewable Energy Future

Bensonwood is featured prominently in a new book on Net Zero building by renowned architect William Maclay. We collaborated with Maclay Architects as a member of the team which designed and built the award-winning net-zero Bosarge Family Education Center at the Coastal Maine Botanical Gardens. The LEED Platinum-certified center was Maine’s first net-zero institutional building.

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WILLIAM T. MACLAY, AIA, NCARB, LEED AP

The new threshold for green building is not just low energy, it is net-zero energy, and in The New Net Zero, sustainable architect William Maclay charts the path for designers and builders interested in exploring green design’s new frontier—net-zero energy structures generating as much energy as they use while remaining carbon neutral.

Since traditional American buildings account for roughly 40 percent of our total fossil energy use, the significance of net-zero building is growing increasingly important—among designers interested in addressing climate change as well as homeowners concerned about energy efficiency and long-term savings.

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The Bosarge Family Education Center at the Coastal Maine Botanical Gardens. Photo by Robert Benson

Maclay, an award-winning net-zero designer whose buildings have achieved high-performance goals at affordable costs, makes the case for a net-zero future; explains net-zero building metrics, integrated design practices, and renewable energy options; and shares his lessons learned on net-zero teambuilding with like-minded companies such as Bensonwood.

The comprehensive overview is accompanied by several case studies, which include institutional buildings such as the Bosarge Family Education Center, commercial projects, and residences.  Both new-building and renovation projects are covered in detail. Unity Homes is profiled in the book, as is our multi-layered Open-Built® system.

The New Net Zero is geared toward professionals studying net-zero design, but is also suitable for laypersons seeking inspiration and strategies for beautiful and renewably powered net-zero options.