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

_DSC7399.1.72

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.

On the Boards: Cape Cod Pool House

cape cod pool house

In keeping with this month’s “Everyone into the Pool” theme, here is a charming little pool house we are helping fabricate on Cape Cod.

Designed by Rebecca Elsy Ribeiro of D. Michael Collins, Architects, the energy-efficient building features classic colonial carriage house styling with cupola and a sheltered overhang.

Bensonwood is crafting the timberframe, insulated wall and roof panels, and installing the Marvin Ultimate windows and a Marvin outswing bifold door. The timberframe consists of Douglas fir glulam timbers for the main structure and for the exterior timbers​.

Kenneth Vona Construction, a company that very much shares Bensonwood’s values, will be the builder. KVC is not only one of New England’s oldest and most respected custom builders, it is also one of the greenest.

pool house elevationsTheir ideal six-sided building envelope is one that breathes, insulates against losses, sheds water away for sustainability and remains energy efficient and reusable. Like Bensonwood, KVC believes a commitment to environmental responsibility results in immediate payback and comfort.

timber frame design for cape cod pool houseD. Michael Collins, Architects is a small, but high-quality design firm established in Natick, Massachusetts, in 1987. They specialize in new custom homes, additions and renovations, small scale commercial, institutional and historic restoration projects.

Most of the firm’s projects are located in Massachusetts, but they also have projects in Maine, New Hampshire, Vermont, New York, Colorado, Florida and the Caribbean.

We’ll profile more design-build collaborations with D. Michael Collins, Architects and Kenneth Vona Construction in the months ahead.

Customized Unity Xyla 212 Sits Softly on the Land

xyla 212

Artist’s rendering of our standard Unity Homes Xyla 212.

Dan Farrell and Melora Kennedy have long been interested in nature conservation. So when they wanted to build a healthy, comfortable, energy-efficient home — close enough to town that he could walk or bicycle to work—a friend, builder and energy consultant, Mark Snyder, suggested they call Unity Homes. Dan works for the Vermont Chapter of the Nature Conservancy as their Conservation Information Manager/GIS Analyst. Melora teaches preschool and kindergarten. The “GIS” in Dan’s title stands for Geographic Information Systems: a science which lets us visualize, question, analyze, interpret and understand data to reveal relationships, patterns, and trends. In the conservation context, GIS would come in handy in evaluating the impact his new home would have on his sloped, 8.9 acre parcel of land, with its old field species and natural plantings — some edible — as well as diverse wildlife crossings.Screenshot 2014-06-23 10.06.14 Unity’s low-waste off-site fabrication and rapid on-site assembly — coupled with its natural materials, extraordinary energy efficiency, and energy-sipping mechanical systems — will all help to reduce the carbon footprint on the sensitive landscape. Their Xyla 212, customized for a walkout, is heated and cooled with an air source heat pump and an optional ERV (Energy Recovery Ventilator) to condition air with minimal energy loss. Both HRV (Heat Recovery Ventilator) and ERV systems are vastly more energy efficient than plain ventilation systems or exhaust-only systems with no heat or energy recovery. Despite its higher up-front cost, Dan chose an ERV system for its edge in operating efficiencies, air filtration, degree of comfort (through greater humidification/dehumidification control) and environmental impact.

air pohoda ashp

The Air Pohoda ERV used in the Farrell home in a special housing devised by our Building Systems team.

Unity’s standard HRV system is designed to recover approx 80% of the heat in the air that is being exhausted from the house, while the ERV (Energy Recovery Ventilation system) is expected to recover over 90%. Given the ERV’s added efficiency, there would be a relatively short payback period on its premium cost over the standard HRV system. In comparing the ventilation systems, the ERV units are expected to save about 1315 kWh per year over the HRV system. At $0.15/ kWh, that comes to almost $200 per year at the current electric rate, with those savings continuing to rise as electricity rates increase. The Return On Investment calculator projects an 11-year payback on the $3,000 additional investment over the cost of a comparable HRV system.  (Source: EPA Greenhouse Gas Equivalencies Calculator.) IMGP7792But for Dan and Melora, it wasn’t just a matter of dollars and cents. Framing it more in conservation terms, the 1,315 kWh per year saved by their ERV over the HRV, is equivalent to 102 gallons of gas, 97 lbs. of coal or 21 barrels of oil. Saving that energy would be the carbon equivalent of 23 tree seedlings grown for 10 years or 0.75 Acres of forest grown in one year. The 2-bedroom, 1-bath Unity Xyla, with its super-efficient 1,028 SF first floor space plan and optional 939 SF walkout level, celebrates the lagom values at the heart of all Unity Homes. Roughly translated, lagom is a Swedish word meaning “not too much, not too little —  appropriately balanced.” The home is neither too big nor too small, but just right perched lightly on its steeply sloped site and in-balance with its surroundings. work in progress Xyla 212Entry is from the up-slope side (and future patio) directly into the living area, which is open to the eat-in kitchen and second bedroom. Down a short hallway and adjacent to bedroom two is the master bedroom and common bath. Dan and Melora plan to leave the ground floor, with its separate down-slope entry, unfinished for the time being, but it will eventually have a rec room and second bath. With the home fabricated off-site and assembled on-site over late spring/early summer, the Farrells expect to be in their home by mid August.

Texas Prefab Lake House

austin texas lake house 1 An admitted This Old House fanatic, Matt Risinger had grown up watching the PBS television series when, in 1989, a program aired that would change his life. The Wickwire Barn Series—the second time Bensonwood had appeared on the long running home improvement program— featured Tedd Benson and an old barn being converted to a new house: a project Matt had dreamed of building for himself someday. It became the seminal moment in his decision to become the best builder he could be.

Mette Aamodt AIA and Andrew Plumb AIA

Mette Aamodt, AIA & Andrew Plumb, AIA

Fast forward nearly two-and-a-half decades, and architect Andrew Plumb of award-winning Aamodt / Plumb Architects in Cambridge, Massachusetts, is looking for a builder to help assemble and finish out a highly custom modern timberframe ranch home he designed for a special client he has known for years. The lakeside projectTEXAS PREFAB, expected to approach near Passive House standards, would have an aggressive build schedule of one year, and it needed to come in at a fixed budget—so Andrew knew it had to be done right. His first thought was to call Bensonwood for its expertise in the sustainable fabrication of high performance homes, and his second thought was to call green builder, Matt Risinger, now of Risinger Homes, to say Tedd Benson’s company would be fabricating and installing the home’s shell. With the name “Benson” still fresh in his mind after a quarter century, Matt jumped at the opportunity. The home plan, viewable on the Aamodt / Plumb website, is a interpretation of the Texas Ranch vernacular, with two gabled buildings joined by a light-filled entry hall. Designed for a young family, this prefab home strives to create a relaxed, contemporary feel through the use of natural and reclaimed materials, ample daylighting and a thoughtful relationship to the site.

MATT RISINGER

Austin, Texas green builder Matt Risinger

“We sought to create a warm modern atmosphere through the interplay of simple forms, materials and natural light,” says Plumb. The play of the modern and rustic is achieved through material choices and elemental forms. Japanese (Shou Sugi Ban style) charred wood siding, mesquite and ash flooring, and an oversized FireRock masonry chimney and fireplace add a dramatic touch both inside and out. texas green prefab architects renderingThe light-filled open interior, with its elegant but simple timberframe, richly-finished flooring and high-end fixtures, perfectly complements the striking exterior while framing the surrounding views. Matt Risinger asserts that, “The most sustainable house is a pretty one. Architect-designed houses will be loved and cared for because they are beautiful. Ugly houses will fall into disrepair and be torn down eventually.” fireplaceBeyond the aesthetics, this house was designed to coast through the hot parts of the day with little need for air conditioning. This is achieved through rigorous attention to air sealing and our panelization process using super-insulated walls. All the exterior claddings are installed over a rain-screen air gap. The roof, wood siding and even stucco have an air gap behind them so that the potential for water intrusion over the life of the building is minimized. Risinger installed super-efficient mechanical equipment to make the best possible use of the resources consumed. 95%+ efficiency gas equipment, super high-efficiency AC, Ultra-Aire Split Dehumidifier prevents mold and allows the owners to keep thermostat settings high when the building is unoccupied.YOUTUBE TIMELAPSE IMAGE You can watch Matt Risinger’s YouTube video of the home being assembled here. Once the project is completed and finish photos become available, we will revisit this home to detail its space plan. Stay tuned.

1st evoDOMUS – Bensonwood Project Underway

evodomus rendering

Architect’s Rendering by Alexander Kolbe

When husband and wife architects Alexander and Michelle Kolbe, co-founders of evoDOMUS, a Cleveland-based firm, wanted to design and build high-quality, sustainable homes in the U.S., they went looking for a manufacturing partner who could match the quality of homes they built in Alexander’s native country of Germany.

They sought a montage homebuilding company of the caliber of the venerable Huf Haus and Baufritz, Germany’s leading off-site building companies, which helped establish off-site panelized building as the primary construction methodology throughout Europe. Both companies are more than a century old and, like Bensonwood Unity Homes, combine timber framing influences with advanced design and high-performance building.

However, the Kolbes wanted a more personal connection to the client through the entire process—the level of attention a smaller company could provide—to reduce the stress homeowners often associate with a custom house project, such as designers not tuned-in to their clients’ needs, unreliable contractors, as well as schedule and budget overruns. After thoroughly researching high-quality panelized builders, fabricators and timberframers, the names Tedd Benson and Bensonwood kept popping up. So Alexander got on the phone and, much to his astonishment, Tedd picked up.

Upon hearing of the Kolbes’ high standards and montage building interest, Tedd replied, “That’s exactly what we’re doing!” A meeting with Tedd and project manager Hans Porschitz followed and it was soon apparent that the synergies and shared values of the two companies were aligned. A relationship was established: Bensonwood would fabricate the evoDOMUS home shells.

Now, the first joint project between evoDOMUS and Bensonwood is underway in Fairfield County Connecticut: a 5,000+ SF 4-bedroom Bauhaus-inspired modernist home in the “Cloud” Series of evoDOMUS homes. Strikingly original and family-friendly, Cloud is also inspired by current Mexican and Spanish interpretations of modern residential architecture. Customized to their clients’ needs, the home’s clean lines, contemporary materials and use of advanced building science are all characteristic of evoDOMUS home designs.

evodomus elevation

East & West Elevations

Designing the home for its two-acre site had its challenges; its wooded setting with wetlands, an awkward slope and rock ledges all needed careful  consideration. In addition, the home had to incorporate passive as well as active solar design, requiring precise siting along with design elements such as a south-facing second floor loggia to shade the first floor in summer months.

The Kolbes’ strong focus on sustainability prompted the use of triple-glazed Loewen windows and a Zender Energy Recovery Ventilator, which recovers up to 90% of the energy of the extract air to warm the incoming fresh air, saving on heating costs. The air distribution system then channels the optimally tempered fresh air to individual rooms as needed. The exterior is clad in Resysta siding made of rice husks, common salt and mineral oil, which makes it both environmentally friendly as well as extremely weather resistant against sun, rain, snow or salt water. Resysta siding also requires minimal care and offers the look and feel of wood and can be painted.
evodomus logo

The home has 4,100 SF of living space with 2 stories above grade and a 900 SF finished basement and 924 SF garage. Off the garage are a mud room, a half bath and a yoga fitness room. The first floor has an open great room with living and dining areas adjoining another open space with a kitchen and family room. Rounding out the first floor is a bedroom/study with adjacent bath. The second floor plan includes the master bedroom, three additional bedrooms (each open to a long balcony), a family bath, a study and a laundry room.

evodomus floor plan

First Floor Plan

EvoDOMUS uses low or no VOC paints and finishes in their homes and only formaldehyde-free materials. Material selections consist primarily of products with high-recycle content, as well as FSC certified woods and bamboo.

Alexander and Michelle Kolbe wanted to offer their customers not only the highest quality, sustainable homes available, but an excellent experience as well. By partnering with Bensonwood, evoDOMUS could put its resources into delivering superior design, customer service and care, rather than making investment in fabrication facilities, with financial partners and the loss of control and client interaction that would imply.

By maintaining that control, evoDOMUS is able to fulfill its mission of making homes as beautifully designed and high quality as German cars—with a customer experience to match.