Passive House Guide 2023

Page 1


The Passive House construction standard is the most rigorous, energy-efficient set of performance-based building technologies currently available, centered on creating ultra-low-energy buildings that have a minimal ecological footprint. A philosophy that took root in the wake of the energy crisis in the 1970s and early 1980s, Passive House has gained considerable traction in our climate-conscious times.

The Passive House concept—which can reduce heating and cooling energy consumption of buildings by up to 90 percent—represents today’s most compelling option for counteracting climate change in the built environment.

Since the first Passive House was built in the Hudson Valley over a decade ago, architects, builders, and home buyers have embraced the technology. New Passive House projects are being built across the state, from Hillsdale to Gardiner to Cooperstown, and beyond. Upstate House ’s third annual Passive House Guide highlights the innovations of Passive House technology on the regional level, showcasing leadingedge architecture and building techniques. For more Passive House resources, see page 63 or visit

A collaboration between PASSIVE HOUSE ALLIANCE and upstate HOUSE | SPRING 2023 • 51
A rendering of Groundworks, a Passive House retrofit in Gardiner designed by architect Ryan Enschede that is transforming a preexisting three-bay cinderblock garage into a general purpose studio space ready for gathering, dance, contemplation, and inspiration. Owners Kristen Leonard and Frank Leon Rose envision the space where people can come together to make positive ripple effects in the world.
52 • online at PASSIVE HOUSE GUIDE

Eternal Home Forever House in Hastings-on-Hudson

After completing Westchester County’s first LEED Platinum-rated building in 2009, a two-unit condominium, architect Christina Griffin tried to convince her residential clients to consider eco-friendly alternatives like Passive Houses, but interest was tepid. “We’re a desert, it’s a little sad,” she says. “People want big homes. And the higher the income level, the more carbon is emitted. A lot of people think they’re living green, but there’s a lot of hypocrisy.”

In response, she retrofitted a tiny 1905 cottage in Hastingson-Hudson to create a prototype for affordable, fossil fuel-free living. Then, to drive the point home, she moved in. Griffin calls her model Forever House because the principles are replicable and the systems are durable. Last year, the project won a Passive Project Design award from the Illinois-based Passive House Institute US (Phius), which establishes strict, measurable standards and certifications for passive buildings. She and husband, Peter Wolff, an environmental lawyer, used to live “in a big house nearby on the hill,” Griffin says, gazing subconsciously toward her former residence a half mile away. “It was energy inefficient, so I figured I had to walk the walk.”

An avid environmentalist with many projects sprinkled around Hastings-on-Hudson, she spreads the word about Passive House and

A collaboration between PASSIVE HOUSE ALLIANCE and upstate HOUSE | SPRING 2023 • 53
opens her home for tours. So far, a few dozen architects have visited. Opposite: Tasteful touches of wood trimming include the mottled cedar underneath the 30-inch eaves and an angled hemlock trellis that regulates heat inside the open first floor. Photo by Suzanne Levine Specialized software helped orient and delineate the size and placement of the southand southeast-facing windows. Photo by Suzanne Levine

The kitchen is accented with white oak and the open living area features large, southwestfacing windows that absorb the sun’s warmth.

Opposite: Despite being sited in the densely populated community of Hastings-onHudson, Forever House’s primary bedroom has large windows as well as a feeling of privacy.

54 • online at
Photos by John Maggiotto

To create Forever House, the couple retained two walls of the original 998-square-foot cottage and built a modern, 1,703-square-foot home with two new levels atop an unfinished basement. They also renovated a 187-square-foot former horse barn into a work studio for Wolff. It’s cozy, but not completely up to Passive House standards.

The first floor of the main house consists of an open, U-shaped great room punctuated by partitions (including the stairway) that create a mud room, a recycling closet, and a half bathroom. The main space is big and open enough to dance the tango with abandon—which the couple are known to do.

In the kitchen, faux concrete slabs that line the floor and part of the wall are really large-format porcelain tiles by Porcelanosa in Spain. Tasteful wood touches include white oak floors, sills, kitchen cabinets, and a serving/cooking island.

The second floor is more maze-like. The stairs ascend to a confined hallway, but cathedral ceilings add airiness. In addition to the master bedroom, two flex spaces can serve as an office, art studio, exercise room, or extra bedroom.

High Performance with Commonplace Materials

Once she found the cottage that would serve as the basis of her Passive House retrofit, located a short walk from the quaint village business district and the commuter rail station, Griffin assembled the components to achieve her goal of creating a zeroemission home that earned Phius+ Source Zero certification, the most stringent at the time. Nugent Construction Management in Highland Falls helped with the build out.

To achieve the goal, she replaced the oil burner and gas line with electric components, including a Bradley heat pump water heater system, a compact Mitsubishi split system air source heating and air conditioner and a centralized Zehner ComfoAir Q350 energy recovery ventilation (ERV) unit, which fits neatly into one of the two walk-in closets and circulates the inside air to keep it from becoming fetid.

An array of 28 Hanwha Q Cells solar panels on the roof helps generate more energy than the home uses. After powering the inhabitants’ needs,

the system feeds three Generac PWRCell battery modules in the unfinished basement, which store power and send the overage to the grid.

According to Lisa White, associate director at Phius, there are many ways to devise an effective and efficient low- or zero-emission house. “People instinctively think they need to use exotic materials, but it is possible to achieve high performance with everyday building supplies,” she said. “The main key is thoughtful design and execution.”

Using WUFI modeling software, Griffin developed Forever House’s exterior insulating sleeve, oriented the floor plan for maximum exposure to the sun, and optimized room and window placement.

Energy-efficient appliances include a Fisher & Paykel refrigerator and induction stove. Wythe high-performance triple-pane windows and glass doors seal off drafts. “We use so little energy, the heat is off in the winter unless it gets below 30 degrees,” she says. “This project could have been accomplished with a geothermal system, but that’s too elaborate for such a modest project.”

A collaboration between PASSIVE HOUSE ALLIANCE and upstate HOUSE | SPRING 2023 • 55

Pushing the Envelope

Located at the far end of a long row of homes arrayed right next to each other like dominoes, Forever House stands out due to its boxy configuration and sleek, space age finish, achieved with tongue-andgroove cedar cladding.

Inside the walls and underneath the first floor, the building’s thermal envelope ensures interior comfort and helps the home exceed its zeroemission goal.

The layers include gypsum board, horizontal furring, an Intello Plus vapor-control membrane, two double-stud walls sandwiching a layer of dense pack cellulose (18 inches in the roof, 15 inches in the walls), a sheet of CDX plywood, and Solitex Mento 1000 house wrap. A thick, heavy mineral wool blanket covers the ceiling of the unfinished basement and warms the ground floor.

High R-Values (one of a dizzying array of metrics and formulas that help determine a given space’s conformity to Passive House standards) far exceed typical building codes and attest to Forever House’s airtight seal.

Yet the insulation and weather-resistant barrier system act in concert to create a vapor-open set-

up that lets the home breathe as moisture escapes through air pockets and keeps things dry inside.

“For lack of a better term, it’s a smart technology,” says Griffin. “Back in the 1970s, some builders experimented with using plastic sheets to repel the elements, but then came the mold. There has to be some circulation, you can’t seal off the interior completely.”

Attractive and practical, wood accents adorn the home’s exterior. Expansive 30-inch eaves provide a passive cooling element, but the wide band of natural finish cedar wrapping the bottom along the edge also disguises a continuous ventilation shaft and contributes an earthy quality to the home’s exterior.

Strategically angled hemlock trellises above the first-floor picture windows and the south-facing roof deck add another aesthetic element that also shields the interior from the summer sun. Although their modest look suggests otherwise, the effect is palpable, according to Griffin.

A Retrofitting Mission Forever House showcases one way to bring a drafty 20th-century home into the energy-saving era. No

matter the cost to convert, many Passive Houses offset the expense over the long run by eliminating or dramatically reducing utility and heating oil bills. “The initial hurdle is not that significant a jump and investments in quality insulation absolutely pay for themselves,” says White at Phius.

The carrot of financial incentives from the state and municipalities, coupled with the stick of stringent building codes for new construction— known as stretch codes, which surpass standard codes and sometimes edge into passive territory— will lead to a greater awareness and creation of low-energy use buildings, including private homes according to White.

Hastings-on-Hudson adopted a stretch code in 2020 and there are other signs that builders and homeowners in Westchester County are coming around: Griffin is working on a Passive House home in Yorktown and a mixed-use Passive House project in Yonkers.

But her main mission centers on upgrading or replacing older housing stock. “I can only do so much in my little home,” Griffin says. “My hope is that one small house can multiply and then make a big difference.”

56 • online at
The backyard and rear view of Forever House. A former horse barn was turned into a work studio. Photo by Suzanne Levine


After months or even years of researching the benefits of high-performance homes, you’re finally ready to embark on the journey of building your own. You’ve found an architect who is ready to lead the design process, and you know that hiring a builder is another necessary step toward breaking ground. But what else should come between?

According to Bryan Bleier, an engineer at New York-based New Energy Works, collaborating with a specialist in building enclosures early in the design process can facilitate a faster, more sustainable way to achieve the high-performance home of your dreams.

Long known for its beautiful custom timber frame homes, employee-owned New Energy Works has been at the forefront of high-performance building enclosures for 30 years. “In the early 90s, we had a strong desire to enclose our timber structures with wall, roof, and floor assemblies as quickly as possible, so we began pre-panelizing enclosures by way of carpenters under roof,” Bleier says.

Now, New Energy Works is bringing the latest iteration of its pre-panelization technology, “High Performance Made Easier™” (or HPEz), direct to

homeowners, architects, and builders looking for an accessible path to complete a high-performance structure with less on-site labor, time, and materials. “We have a passion for sustainability, and we want to make high-performance buildings more accessible to more people,” says Bleier.

How it works: During the conception phase or after your home’s initial drawings are complete, New Energy Works’ team evaluates the designs and provides guidance on how they can best be optimized for panel fabrication. They sit down with you and your architect to go over everything from basic drawings of floor plans to 3D models that offer a sense of all the spaces of the future home.

After plans are finalized, craftspeople fabricate your panels using semi-automated equipment, following a scrupulous quality control process. The panels are made with renewable carbonsequestering materials such as wood fiber, cellulose, and hemp insulation that reduce impact on the environment. The result is a healthier and betterperforming structure built without the use of chemical foam-based products.

Once the panels are complete, the enclosure is

shipped out to your new home’s job site, ready to set, fit, and finish in significantly less time than building the assemblies in place on-site. “We can install the enclosure as soon as the site is ready as a partner service to the builder, architect, and homeowner,” Bleier says.

In a high-performance home, the building envelope is the key to unlocking its major benefits, such as a smaller carbon footprint, lower energy bills, interior comfort in every season, and impeccable air quality. “Execution of that assembly is paramount to performance,” Bleier says. “Panelization is faster, easier, and more accurate, and in the long term your energy savings are going to be better.”

Anyone who still thinks of prefab as lower-quality can think again. “There can be a perception that panelized is lower-end, but there are a handful of us in the industry that definitely don’t fall into that spectrum,” says Bleier. “We push the limits on the materials and the approach because we’re passionate about what we do.”

A collaboration between PASSIVE HOUSE ALLIANCE and upstate HOUSE | SPRING 2023 • 57

Family Flex

Passive Houses Designed for Change

Passive House construction defines a cost-effective, sustainable path to a net-zero way of living. The team at North River Architecture & Planning demonstrates their dedication to that path in their most recent build in Stone Ridge: Basten Farm, two homes that have earned Passive House (PH) and other energy-efficiency certifications. And, embodying the “no person is an island” ethos, the North River team trained local contractors onsite in PH methods and invited local officials, realtors, and community members to visit during construction and learn more about the process.

The homes, each roughly 2,500 square feet, are modeled after North River’s “Flexhouse,” a design that features flexible living spaces and the ability to adapt the home to future needs. The key is a simple shape, according to partner and design director Peter Reynolds. “We’re trying to get people to build energy-efficient envelopes, with flexible interiors,” he says. “People really don’t need to have 25 gables and 16 corners.” Inspired by the simple, low-cost, easily modified home design championed in Stewart Brand’s book How Buildings Learn, Reynolds and his team aim to create buildings that will last for 10 to 20 generations.

“Our homes are adaptable to changes in one family’s needs over a lifetime: A couple, children, multigenerational, and aging in place,” says North River partner and technical director Stephanie Bassler. “This came into focus in the COVID era, when more people began to work from home, in a dedicated space—not just in a corner of their home. We paid attention to that flexibility, and it turned out to become a feature of daily life: a 24-hour living space, instead of a place to leave to go to an office.”

58 • online at
North River Architecture designed and built Basten Farm, two Passive Housecertified homes in Stone Ridge that embrace the future of net-zero energy efficiency.

Net-Zero Living

The Flexhouse’s features mirror the core concepts of Passive House construction. Thermal control is managed by its airtight building envelope: four-inch-thick polyisocyanurate insulation under the exterior siding and on top of taped Zip sheathing over plywood, with a 15-inch-thick, “floating” concrete slab. The wall cavities are filled with dense-pack cellulose, and the engineered roof trusses are insulated with blown-in cellulose. Zehnder energy recovery ventilators (ERVs) control the movement of air throughout the home, circulating fresh air and evacuating kitchen and bathroom exhaust. “The ERV recovers 90 percent of the heat from the air,” Bassler says. Both Flexhouses use Mitsubishi ducted heat pumps, which function better at low wintertime temperatures than ductless units, she adds. The final considerations in PH construction are radiation and moisture concerns; both are mitigated through tripleglazed windows comprising two layers of vacuum gas between three panes of glass. “These are not the 1970s south-facing glass panes that sweat and feel like a greenhouse,” Bassler points out.

“The attention we pay to the building envelope and triple-pane glazing is an investment in low-energy costs for the life of the building,” Bassler emphasizes. The base price for a Flexhouse is about $400 per square foot, but that includes site utilities: the septic system, well, and electric. The initial investment offers a payoff when the home’s annual energy costs are zero, Bassler says: “Once you invest in the envelope of the building, you can install smaller mechanical systems and reduce the costs of heating and cooling.”

“Solar-ready” roofing is a PH requirement, too, and the Flexhouses don’t disappoint: Their standing-seam metal roofs by Sheeley Roofing can support enough solar panels to fully power the homes on an annual basis. “We can offer net-zero living to clients, which is meaningful in the Wild West of electrical costs in the Hudson Valley,” says Bassler.

The Prescriptive Path

Guiding North River’s steps through the process was Phius, a nonprofit whose goal is to decarbonize the environment by mainstreaming passive building standards. The Basten Farm flexhouses were the first project to be “design certified” through Phius’s Prescriptive Path, a checklist detailing requirements for Passive House certification. The Prescriptive Path aims to simplify the certification process and encourage more Passive House builds in single-family residential construction. “All of those design standards made sense to us, with very clear goalposts, so we can clearly talk about net-zero buildings connected to renewables that offset the energy consumed,” says Bassler.

Now in their 14th year of designing and building Passive Houses, North River embraces a commitment to their larger community by providing an opportunity to make those building techniques transparent and available to everyone. “We’ve used every one of our houses as test cases for affordable passive house construction, so as many local officials and designers as possible can visit and learn more about it,” Reynolds says.

The firm sources local subcontractors for their builds, and trains them on the job. “The subcontractors have been trained by us, and now they know how to build Passive Houses and can bring that training to other projects,” Bassler says. “The outcome could be significant. The mechanical subcontractor, for instance, gained credentials as a qualified installer of heat pumps standard to Passive Houses.” North River also holds workshops in their buildings to train other builders, architects, and realtors.

“Subcontractor by subcontractor, and trainee by trainee, we’re building a cohort that recognizes the importance of energy efficiency,” she adds. “There’s some skepticism at first, but that sparks conversation.”

Efficiency, Not Trends

Pushing the Envelope

March 23, 5:30–6:30pm, Virtual


discuss the

House construction standard (the

rigorous, energy-

set of performance-based building technologies currently available); highlight recent Passive House projects in the Hudson Valley; and examine the technology’s role in the roll-out of New York State’s ambitious climate goals.

The event will feature presentations by builders and architects and a panel discussion moderated by Chronogram Media editorial director Brian K. Mahoney.

The homes themselves are as stunning as they are functional. Basten Farm was named after the family who first owned the property. The Flexhouses on the site are named Basten Farm North and Basten Farm South.

A collaboration between PASSIVE HOUSE ALLIANCE and upstate HOUSE | SPRING 2023 • 59
the conversation
Forever House, a Passive House in Hastings-on-Hudson designed by architect Christina Griffin.
with Presented by

North River Architecture’s goal in design is eliminating visual clutter. That aim is exemplified in this Flexhouse stairwell/closet combo.

60 • online at
A collaboration between PASSIVE HOUSE ALLIANCE and upstate HOUSE | SPRING 2023 • 61
The design theme throughout both homes is minimalistic, with a nod toward Scandinavian light-wood construction, exemplified in the South home’s built-in office.

The North home measures 2,544 square feet on 7.75 acres, with three bedrooms and three baths. The exterior is LunaWood, a thermally modified spruce. It has a naturally golden color that will mature to a silvery grey. Lighting in the home is from Kingston-based RBW. The kitchen has SpaceTheory cabinetry.

The South home measures 2,400 square feet on 13.3 acres, with three bedrooms and 2.5 baths, plus a main-floor home office. Its exterior is a dramatic, black-painted pine. The kitchen and bathroom cabinets are from local cabinetmaker DCN Woodworking. Like many modern builds, this home has a Scandinavian minimalist feel with light wood accents throughout. Pops of amazing color show up in Popham Design’s Moroccan concrete tile that forms a kitchen backsplash and fills the walls of a walk-in shower in one of the bathrooms.

Both houses are sited to take advantage of outdoor views, recognizing again that beauty is as important as function. “For me, the design goal is always to make beautiful things that have Passive House principles baked in, rather than designing homes that make the technology apparent,” says Chris Ruel, North River’s operating director. “Balancing expansive views with tight-framed vignettes, modern detailing with warm finishes, and an honest palette—for example, concrete floors because it’s the most efficient floor within our system, not because it is a trend.”

The kitchens are designed with step-saving and adaptability in mind. The kitchens have movable islands, for instance, to accommodate larger dining events when needed. “What we offer is a highly flexible kitchen,” Reynolds says. “It’s a ‘onetouch’ kitchen, where dishes dry in place and space is used effectively.”

Other low-maintenance elements include waterproof plaster in the bathrooms, peastone gravel around the perimeter of the houses, and North River’s own wildflower mix—a proprietary blend that means no lawnmowing and fewer habitat for nuisance critters. “Our thing is zero energy, zero maintenance, and zero ticks,” says Reynolds.

North River Architecture’s techniques and passion are innovative, and they hope to lead the charge toward making net-zero living more mainstream.

“I think that our work as designers and builders gives us a unique seat at the table with families as we create their most intimate spaces,” Ruel concludes. “While this is a joy, it is also a responsibility. We must give them spaces that root them to a place, bring them comfort and enjoyment, but to also build in a way which shows the generation that will grow into these homes how seriously we take the charge to make sustainable stewardship the norm in our lives.”

62 • online at
Popham Design’s Moroccan concrete tile adds color to Basten Farm South’s bathroom shower and kitchen backsplash.


Super-Insulated Building Envelope

Continuous insulation around the entire building reduces energy demands and increases comfort. Because of the increased ability to retain heat through the building envelope (or block it in warm weather), the size of the heating/cooling system is significantly simplified and reduced.

High-Performance Windows

For single-family residential homes in the Hudson Valley (climate zones 4a, 5a, and 6a), triple-pane windows are usually necessary. In addition to better insulated glass, Passive House-approved windows reduce drafts through improved airtightness when they are pulled closed.

Airtight Building Envelope

The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air. A small change in the air-tightness of a building makes a big difference and it’s accounted for from the beginning of a project. While the current building code already requires air-tightness verification, the Passive House standard is far more stringent.

Balanced Ventilation

Most homes do not have a system for delivering fresh air for healthy living. We have relied on air leaks at gaps that allow outdoor air to move in or out, such as leaky windows and doors, recessed lights and other openings, and where the house meets the foundation. These unintentional gaps also allow moisture movement, are a pathway for bugs and rodents, and introduce dust. Passive buildings use heat recovery ventilation systems (HRV), or, more commonly, energy recovery ventilation (ERV). In an ERV, exhaust air is replaced with outside air, but the heat and moisture of the air leaving the building pre-conditions the incoming air. The result is fresh indoor air with only minimal energy penalty. Incoming air is filtered, so if the windows stay closed the home will be surprisingly dust-free.


Long-Term Cost Savings

Even as building energy codes require higher insulation levels and greater air-tightness, the Passive House standard provides a 40 percent to 90 percent reduction in energy consumption when compared to a code-built home.

Reduced Carbon Emissions

Less energy use translates directly to less carbon emitted into the earth’s atmosphere. According to the AIA Architecture 2030 plan, the building sector accounts for roughly 40 percent of our total global carbon emissions.

Increased Durability

In the old way of building, we created a leaky building envelope and then oversized our heating equipment. When the building envelope is sealed and super-insulated, the movement of water vapor can no longer have a direct avenue to dry out and can no longer cause serious durability issues.

Improved Thermal Comfort

Thermal comfort is determined by the surface temperature of a surface. If it is within seven degrees of the living area, most people will find that to be very comfortable. Every interior surface in a Passive House is verified to fall within this comfort criteria.

Superior Indoor Air Quality

A requirement for Passive House certification is a balanced ventilation system. These systems, known as HRVs or ERVs (heat/energy recovery ventilators) bring fresh air in from the outside, move it throughout the house, and then expel the stale air to the outside. In the process, the air is filtered with a MERV 13 filter (minimum requirement) which has proven to drastically reduce allergens and other particulates from the air we breathe.


The Path to Net Zero

A prerequisite for Passive House certification is the Department of Energy’s Zero Energy Ready Home program. Whether renewable energy is immediately installed on the project or not, it is engineered for the smallest energy demand possible so that net-zero energy consumption can easily be achieved.

Phius Alliance-New York

Given the momentum of certified passive building in the Northeast and with the support from NYSERDA and the national Phius organization, the Phius Alliance-Hudson Valley Chapter is rebranding in 2023 to expand its reach into all of New York State. Since January of 2023, the chapter has expanded its board of directors to include representation from Long Island (Metro NY) and Buffalo, and Rochester (Western NY) and has organized into regional committees to support ongoing Passive House specific programming in several regions. This new organization, now called the Phius Alliance-New York, continues to provide a robust membership-based network with members throughout the region and provides training, resources, marketing and advocacy support to its members. Its mission is to contribute to a low-carbon future through education, training and advocacy for the Phius standard and make it mainstream in New York and beyond. For a complete directory of chapter members, consultants, builders and verifiers, visit

A collaboration between PASSIVE HOUSE ALLIANCE and upstate HOUSE | SPRING 2023 • 63
A rendering of a Passive House multifamily development in Cooperstown designed by River Architects and completed in January. The 17,000-square-foot building has 13 apartment units but appears to be a single-family house when viewed from the street.
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.