Carrick Library Goes with the Flow While Notching a Passivhaus First

Posted by Diane Koch on June 1, 2017

Libraries have always been about the flow of information – from one generation to another, from different cultures, perspectives, and languages, and from the past to the future. So it is fitting that the new Carrick branch of the Carnegie Library system of Pittsburgh (CLP) will physically embody that notion of flow, and expand it to express the movement of energy, people, and water through the site.

Several years ago the CLP was close to shutting down several neighborhood branches due to a funding crisis. Thankfully, city residents voted to apportion taxes to save the libraries, and the CLP has been actively renovating neighborhood libraries ever since. Carrick library is one of the last to renovate.

Built into a steep hillside with windows only on the front of the building, the existing Carrick branch felt very much like a basement – dark, damp, and dingy. The initial plan was to redevelop the existing building, but the community wanted more, and petitioned the library for greater change. The CLP responded by buying the site next door – a corner lot on a prominent street in Carrick. The new building, designed by NK Architects and Thoughtful Balance, will double the library’s size to just under 8,000 sf.

To inform the design of the new space, our team interviewed everyone from maintenance staff, to librarians, library users, the library administration, and the community. The over-arching sentiment: “more connection to the outside and access to natural light, please!” Not surprising given the cave-like feel of the existing building.


To provide this natural light – as well as a quiet, healthy, and ultra-efficient building – the design team suggested that Carrick become the first Passivhaus library in North America. Passivhaus design manages the flow of energy to drive building energy use down by as much as 75%. The library’s generous windows and superinsulated walls will capture solar heat in the winter and retain cool in the summer. Heat recovery ventilation will provide a constant flow of filtered fresh air that captures and recycles the heat (or cool in the summer) from exhaust air before it exits the building.

CLP was already familiar with Passivhaus. In 2014, Thoughtful Balance had renovated the Hazelwood branch to Passivhaus standards, but not quite Passivhaus certification. The Carrick branch is on track to earn certification. Ron Graziano, Director of Facilities Development at CLP, liked the outcome of the Hazelwood branch: they doubled their space but use 16% LESS energy than previously, have more lighting, more open space, and improved acoustics. Convincing him to go with Passivhaus design for the Carrick project was an easy sell.


Laura Nettleton, principal at Thoughtful Balance and designer of the renovated Hazelwood branch, credits NK architect Steve Fischer for the “inspired design concept of using a ramp as the organizing feature” for the Carrick branch. The library didn’t want to take on the expense of an elevator and its service, but the design team worried a 1-story building would still be “a pancake dug into the hillside,” as Laura put it. “Steve’s idea of pulling the building away from both the front and side of the street, and going up one story with a ramp to transition the levels was brilliant,” says Laura.

Carrick Passivhaus Library ramp - Pittsburgh

The ramp design is an organizing feature of the design, putting the flow of people at the center of the concept. The ramp unites and promotes flow between important areas of the library: the children’s area, a space for teens, the main reading room, and a large community room. It also allows for an important reconfiguration of the book stacks. By lining the ramp with shelving, the design opens up significant floor space, providing for a variety of flexible meeting areas, and open flow throughout.


The City of Pittsburgh was put on notice by the Department of Environmental Protection to separate its storm water and sewer systems. Currently the antiquated system combines rainwater with raw sewage, sending sewage overflows into rivers and streets during heavy rains. In response to this local crisis, the library and its landscape captures storm water on its site, holding it to percolate into the soil or evaporate rather than sending it into the current system. A large cascading trough funnels water from the roof to a bioswale that surrounds the site. A fun graphic in the children’s area will illustrate the water cycle, engaging the public in active sustainability they can witness just feet away.

The library of today is more than a repository for books and a quiet place for study. It is a community center, an internet and tech hub, a space for after-school programs, and a place to access information in all its forms. The new Carrick library will beautifully embody the continuous flow of ideas, activities, energy, water, people, space and generations. As an institutional model of Passivhaus construction, it will also help build a future of climate security and resilience.

‘Floating Boxes’ of new Multifamily Project to Bring Eyes onto Melrose Promenade

Posted by Zack Semke on May 16, 2017

Seattle multifamily building - Built Green 4-star Rendering of NK’s new multifamily project on Melrose Promenade, Bell View.

Seattle’s Melrose Promenade is one of those urban design diamonds in the rough, calling out “polish me!” to neighbors and urban planners alike.

While graced with panoramic views of Lake Union, Downtown Seattle, the Space Needle, and the Olympic Mountains, the Promenade’s Melrose Avenue and Melrose Connector Trail are rough around the edges. Fortunately, the thoroughfare is getting some well-deserved TLC from neighbors intent on creating a safe and pleasant amenity to walk and bike along. (See the Melrose Promenade Visioning Project.) Key to that effort is to get more “eyes on the street” from surrounding residences. The Connector Trail, especially,  can feel pretty isolated and hidden from view when traveled alone.

Melrose PromenadePhoto of current building (r), entrance to Connector Trail (c), and Connector Trail bike path (l)

NK’s new project, Bell View, is one step in this urban design renewal, enhancing the streetscape at the trail’s central entrance and bringing new residents to enliven the Promenade. The project’s two floating box forms will perch on the hill above, with generous west-facing windows providing a prospect for residents to survey the Promenade below and the sweeping views beyond.

Multifamily building on Seattle's Melrose PromenadeRendering of west-facing facade.

Our design team took advantage of the building’s high visibility, from both the Promenade and from Lake Union below, to engage passersby.

“The two floating boxes are split by this really dynamic moving architectural piece that has an iridescent quality to it,” Project Manager Rachel Hedlof explained. “As you move across the façade, it’s going to change colors from brilliant red to gold.”

The team also worked to incorporate the building into the circulatory needs of the neighborhood. The sidewalk in front melds into the bike path, and a notch in the building allows fire trucks and utility vehicles to turn around safely in otherwise tight quarters.

Multifamily building adds to streetscape experienceRendering of streetscape experience.

The building’s west-facing windows are of double laminated high performance glazing, designed to shield interior spaces from the noise of I-5 below. To ensure healthy interior air quality, two heat recovery ventilation (HRV) units provide a continuous stream of filtered, fresh air to all west-facing units and boost the building’s energy efficiency.

The team pulled the 58-unit building down toward the front edge of the property to preserve the site’s steep slope and revegetate it with native plants. Fully 7,000sf of hillside will remain unbuilt. Three tiers of green roofs will bring the garden onto the Built Green 4-Star building itself, both mitigating storm water runoff and creating new greenspace for critters and residents to enjoy alike.

“Melrose Promenade has been on and off the City’s radar for years,” said Principal Steve Fischer, “so it’s great to be part of its renaissance today.”

Project team included: Steve Fischer, Rachel Hedlof, Marie Caryl, and Cory Dion.

What to do in buildings when “fresh” air is actually polluted air?

Posted by Zack Semke on April 28, 2017

Polluted Pittsburgh in 1940s - courtesy University of Pittsburgh
Pittsburgh in the 1940s. (Image Courtesy of University of Pittsburgh)

Fresh air is great, right? Open up those windows, air out that stuffy room, take a deep breath of refreshing clean air. Ah, so healthy.

But “fresh” air isn’t always so fresh. In fact, in some locations it’s downright toxic. Yet the traditional approach to provide clean air inside buildings is to bring in outside air. For conventional buildings, this often means outside air seeping in through cracks in the building. For green buildings, this often means intentionally-designed “natural ventilation” strategies that passively flush interior air with exterior air. But for sites and cities where outdoor air is not fresh air, this strategy does not work.

I’ve got personal experience with this. For a couple years I worked in a building that met the most stringent green building requirements out there. To provide fresh air, the building monitored interior CO2 levels and automatically opened the windows when the air got too stuffy. This worked great for much of the building. But our office was at ground level facing a busy street with lots of diesel truck and bus traffic. The particulate matter borne by the “fresh” air coming in through those open windows was so high that it coated our desks in soot, not to mention our lungs. <Cough, cough!>

What otherwise would have been a fine “natural ventilation” approach to providing good indoor air failed because the “fresh” air was, in truth, toxic air.

You better believe that “natural ventilation” is not a popular strategy in polluted cities like Beijing.


Back in the 1940s, Pittsburgh’s air was at least as bad as Beijing’s is today. The infamous 1948 Donora smog incident was so intense that it killed 20 Pittsburghers and sickened 7,000 more over just a four-day period. This environmental disaster helped launch the modern clean air movement which led to great legislative and environmental progress. Happily, Pittsburgh’s air is much improved. Still, the city’s industrial legacy, soot from still-operating coal-fired power plants, and pollution from nearby fracking operations can still lead to pretty bad air in Pittsburgh, particularly by today’s standards.

Donora smog event of 1948 - image courtesy of CaliforniaUniversityofPennsylvania2The 1948 Donora smog incident. (Image Courtesy of California University of Pennsylvania)

So The Heinz Endowments has spearheaded the ROCIS Initiative in partnership with the University of Pittsburgh, Carnegie Mellon, the City, Allegheny County Public Health, and other agencies, including NK Architects and Thoughtful Balance. ROCIS (Reducing Outdoor Contaminants in Indoor Spaces) aims to “reduce the impact of exterior environmental pollution in southwestern Pennsylvania to improve healthy and energy efficient indoor environments where we live, work and learn.”

Tomorrow, at the International Passive House Conference in Vienna, NK’s Brandon Nicholson will present the initial findings of ROCIS and their implications for Passivhaus design and construction. According to ROCIS, one of the most effective ways to protect interior air from outdoor pollution is to combine an airtight building envelope with filtration of incoming air, two pillars of Passivhaus design.

Brandon will share data showing how the ROCIS mitigation measures that he employed in his historic Pittsburgh home, and the measures employed by our colleague Laura Nettleton in her home, dramatically improved interior air quality, even during spikes in outdoor air pollution.

The conclusions that Brandon draws from ROCIS are relevant far beyond Pittsburgh, of course. There’s a reason that Chinese designers and policymakers have grown so interested in Passivhaus design recently. It’s a building approach that promotes both human health and climate health.

Perhaps the air pollution and building design lessons from Pittsburgh will help Beijing clear its skies.

Read Brandon’s paper here

With Passivhaus growing exponentially around globe, NK visits Vienna

Posted by Zack Semke on April 27, 2017


Brandon Nicholson, NK Founding Partner, will speak at the International Passive House Conference 2017 in Vienna this Saturday.

NK’s Brandon Nicholson, Tim Weyand, and Jim Bischoff are in Vienna for the next few days to take part in the Passivhaus Institut’s gathering of international Passivhaus experts and leaders. Brandon will present his paper about the Pittsburgh-based ROCIS Initiative and how Passivhaus buildings protect occupants from outdoor air pollution.

The Vienna conference comes at a time of explosive growth in Passivhaus design and construction around the world.

Energy & Building Journal pegs the number of Passivhaus projects at well over 150,000 in Europe. What’s more, the entire European Union is set to require Nearly Zero Energy Building (essentially Passivhaus) for all new buildings by 2020.

China has taken notice of both the emissions reductions and indoor air quality benefits of Passivhaus and is poised to become a global leader. Passive House Institute US’ Katrin Klingenberg recently keynoted at the 3rd China Passive Building Summit in Shanghai, and observed:

“The Chinese have taken a surprising global lead in fighting climate change and have identified aggressive conservation goals for buildings as a valid strategy. At the rate China is going, I expect it will bring Passive building to the mainstream before the U.S. does because they have the political will, effective materials and components, knowledge of building science and energy modeling, and cost-effectiveness strategies to get there.”

As is true for all things climate-related, if China moves on Passivhaus that will a big deal for the global movement toward Zero Net Carbon Buildings.

Meanwhile, exponential growth continues apace in North America. According to Pembina Institute’s Dylan Hereema, the number of Passivhaus units in North America quadrupled last year. Read more Passivhaus findings from Pembina in their excellent report.

These are exciting times in Passivhaus design, and we NKers are eager to take in the insights that Brandon, Tim, and Jim bring back from their European Passivhaus sojourn.

Meet Suzi Davison, youngest Certified Passive House Consultant in the US

Posted by Zack Semke on April 20, 2017

Map of NK Architects' Certified Passive House Consultants and Designers

We just learned that our cadre of newly minted Passivhaus consultants at NK includes USA’s youngest CPHC: our own Suzi Davison, age 23.

Suzi graduated from the University of Washington last year with her BA Arch Design degree and joined NK Architects that summer. Our affordable housing portfolio initially attracted Suzi to NK, though as she learned more about our Passivhaus studio she got interested in the potential for Passivhaus affordable housing.

Suzi Davison, youngest CPHC in USA“Housing is a human right that sometimes we neglect,” said Suzi, who also serves on the board of the nonprofit, Imagine Housing. “The challenge is remembering that it’s not just another building. How do you create a beautiful and healthy place for residents, on a small budget? That’s why I’m so excited about Passivhaus.”

While Passivhaus buildings are known for slashing utility and maintenance bills, they also deliver superior thermal comfort and interior air quality to occupants.

“For so many affordable housing clients who are dealing with health issues, living somewhere with stable temperatures and clean air is a great place to start,” Suzi said. “When people think of affordable housing, they might think of slum lords and dilapidated buildings, not ‘clean’ or ‘healthy’ buildings. I want to change that stigma by creating beautiful, hopeful places.”

The Passive House exam was tough. Like many CPHCs, Suzi took it twice.

“The first one was horrible,” Suzi laughed. “But the second time was much better. It’s very challenging, and kind of humbling to know that you’re not going to finish the exam. I was initially in the college mode of memorizing and regurgitating. I wasn’t getting to the deeper level. It’s really fascinating, but you have to nerd out to understand. You have to enjoy it to really get it. Otherwise your body says, ‘no!’”

Suzi and others held study sessions to prep the office for the second exam. Knowing what to expect, they focused on deeper exploration of the many equations that underpin Passivhaus design.

“We had a group that was really dedicated, and NK provided the study snacks, so that was helpful, too,” she winked.

She’ll have the chance to apply her Passivhaus knowledge soon.

“It’s exciting that I can take the lead and have that confidence,” she said. “Regardless of how young I am, I know what I’m doing and have shown the dedication to earn this designation. I hope I can make lots of buildings better through Passivhaus!”

Passivhaus Senior Housing to Revitalize Heart of Pittsburgh Neighborhood

Posted by Zack Semke on April 17, 2017

Morningside Crossing Passive House retrofit of elementary school

Conventional wisdom says that high performance buildings are expensive. The reality is that in 2017 that needn’t be the case. The Passivhaus senior living project we’re designing with Thoughtful Balance in Pittsburgh’s Morningside neighborhood is the latest proof.

It’s not as if the Morningside Crossing project is short on ambition. The team is taking an abandoned 1897 elementary school recently acquired by developer AM Rodriguez, retrofitting it and its 1929 addition to the rigorous Passivhaus standard, and adding a new Passivhaus wing. The revitalized building will provide 46 units of affordable senior housing, a Neighborhood Center (a joint project with Pittsburgh Citiparks Department), a public plaza, and landscape features that will capture all storm water onsite.

How much will all this cost? The projected construction budget is $146/sf, actually lower than the average construction budget of $168/sf for other housing projects funded by the Pennsylvania Housing Finance Agency.

The reason for this low cost has parallels in the world of clean energy, where wind energy and solar power keep getting cheaper. We as an industry are getting better at designing and building these projects. Because Passivhaus design sees the building itself – its skeleton and skin – as technology, innovation drives performance up and cost down. So Passivhaus buildings, with healthier interior air, superior thermal comfort, and 50-75% less energy use can be built at little or no added cost compared to conventional buildings.

All of this is exciting, and imbues Morningside with local and national importance. But the Passivhaus revitalization of a building is just part of the story. It’s also about revitalization of community.

Sometimes described as “undiscovered,” other times as “left behind,” the Morningside neighborhood has not experienced the renaissance that other parts of Pittsburgh have enjoyed recently. The reason may be geographical, as Morningside is isolated from the rest of town by a ravine. But the isolation has become generational as well. Much of the population is elderly now, living in the same big houses they’ve been in for years. Given the choice, many of these lifelong Morningsiders would downsize to more practical senior living in the neighborhood. This shift would free up houses for young families to move into. Morningside is an attractive community, with great housing stock, tree-lined streets, and still-affordable real estate. The problem is that no senior housing is available in the neighborhood.

Enter Morningside Crossing and its 46 units.


Morningside Elementary School has been at the center of the community for generations, standing at the spot where the Morningside’s residential and commercial centers meet. Thousands of local kids have learned their “three Rs” at the school over the decades, and lots of those kids stayed in the neighborhood, became adults, and now are elderly. Many of the seniors who will move to Morningside Crossing will be returning to their childhood school.

The rebirth underway at the site will reach beyond the building’s walls as well. The school closed in 2006 and became a drag on the neighborhood. That’s about to turn around. The Neighborhood Center and public plaza will provide a focal point for community life, including meals programs, fitness classes, arts events, neighborhood meetings, holiday tree sales in the winter, and outdoor movie screenings in the summer. AM Rodriguez’ aim is to give this old school building another hundred years at the center of civic life in Morningside.

Deep sustainability, intergenerational affordability, and urban vitality – when a creative community-based developer looks beyond “conventional wisdom” surprising results are possible today, in a way that makes economic sense.

Morningside Crossing Passive House Senior Living

How ‘negawatts’ help the building industry fight climate change

Posted by Zack Semke on March 24, 2017

Pax Futura passive house apartmentsPax Futura multifamily Passive House project in Seattle’s Columbia City neighborhood (developed by Cascade Built).

It’s clear to me that if we hope to avert catastrophic climate change we need to start viewing our buildings as clean energy power plants. As I’ll show below, it’ll be easier than you think.

Earlier this month I attended a three-day Climate Reality Leadership Corps training in Colorado led by former Vice President Al Gore. Gore and the global experts he convened for the training emphasized three things:

  1. We face a climate crisis emergency.
  2. We have the means to solve the crisis.
  3. Cities and states need to lead climate action in the U.S. Our future depends on determined collective action now.

With reversals in U.S. climate policy underway and the Paris climate agreement in question, it’s easy to lose sight of the fact that the clean energy transition is already underway.

Falling renewable-energy costs are now challenging fossil fuels on price, without subsidy, in more regions of the world. Because clean energy is technology, not fuel, innovation drives costs down. More demand for clean energy means more deployment of clean energy, which leads to more experience and learning — further driving costs down.

This is fundamentally different from fossil fuels, which are extracted commodities. Each ton of coal is harder to reach than the last, and drives costs up.

The clean energy sector has stunned energy analysts over the past few years with faster-than-predicted uptake and cost declines. For example, the overall (levelized) cost of solar energy decreased by a staggering 85 percent over the last seven years, according to investment firm Lazard. Wind energy costs went down by 66 percent over the same period.

Likewise, the lithium ion batteries used in electric vehicles, home power storage and utility scale storage dropped by 80 percent over the past six years, according to McKinsey & Co.

This nascent clean energy transition is translating into jobs. One out of every 50 new jobs created last year in the U.S. was in the solar sector. Solar jobs in the U.S. now outnumber coal mining jobs as well as oil and gas jobs.

Generating “negawatts”

The global boom in renewable energy is reaching an important inflection point.

Renewable energy (plus some nuclear energy) made up 51 percent of the new supply of energy in 2015 globally. Many analysts, including from AllianceBernstein and U.K. research firm Trusted Sources, expect 100 percent of net new energy supply to be non-fossil fuel by 2020.

“Peak fossil fuels” may be right around the corner. That’s good news for the planet. But without a revolution in the energy consumption of our buildings, it is not enough.

The building sector is the biggest single contributor to greenhouse gas emissions in the U.S. today. We know buildings are a problem. They also can become part of the solution as a source of energy, and I’m not just talking about rooftop solar panels.

The “negawatts” we can “generate” through ultra-energy efficiency in buildings is an under-tapped energy resource. Those negawatts are especially valuable to the grid because their “production” naturally peaks during times of high demand.

So negawatts offset the energy that would otherwise be produced by carbon-intensive coal or gas “peaker” plants designed to meet that peak demand. In this way, buildings can become a form of climate action.

When we make our built environment more energy efficient, we are destroying demand for fossil fuels, and its price goes down. When fossil fuel prices go down, the more difficult-to-extract fossil fuels get stranded in the ground because they become too expensive to dig up for a low market price.

The more energy-efficient our buildings, the more fossil fuels are left stranded in the ground. Combine this with a transition to renewable energy, storage and demand response, and you’ve got the recipe for meaningful climate action.

The no-brainer choice

Architects, designers and builders have a starring role to play in climate solution-making. Architecture 2030 recognizes this, and Zero Net Carbon building design is the vehicle.

Start by creating a highly energy-efficient building to generate negawatts. Add on-site renewable energy as feasible. Finally, add locally sourced off-site renewables to reach Zero Net Carbon.

Innovation in high-performance building design is the key. If our purpose in sustainable design is to help save the planet, then we need to focus on meaningful carbon-reducing building solutions that are scalable. We do that by making our buildings so high-performing and cost-effective that the approach becomes the no-brainer choice for building owners, developers and project teams. Passive House makes this possible.

The genius of Passive House design (and other energy-efficient building approaches based on rigorous building science) is that it recognizes the building itself — its skeleton and skin — as a technology. Passive House innovation therefore improves both performance and cost, a la other clean energy technologies.

Powered by modern building science, energy modeling and an advanced analysis of the thermal properties of building structures, Passive House architecture sits squarely in the realm of information technology and science-based innovation. That is a potential game changer for the role of buildings in the clean energy transition.

Many Passive House projects today are approaching cost parity with conventional construction. When a significantly better product becomes available for little or no extra expense, then mass adoption becomes possible.

When Passive House buildings become commonplace — as they are in Europe and beginning to in Vancouver, B.C. — then the negawatts generated by this stock of ultra-efficient buildings can truly help power the grid. Future electric vehicles can be powered by these negawatts, enabling Passive House architecture to reduce emissions from both the building and the transportation sector.

Recent research by the Grantham Institute at Imperial College of London suggests that the market impact of the low and continually declining price of solar energy and electric vehicles could significantly curtail demand for fossil fuels and limit warming to between 2.4 and 2.7 degrees Celsius, when combined with strong but politically feasible climate policies. The research team concludes that decarbonization of buildings is vital to reaching the 2 degrees Celsius target.

The need to act boldly on climate solutions is urgent, given federal intransigence. Our peers in Vancouver are leading the way with their Zero Emissions Building Plan.

The city of Seattle should match that ambition and adopt Zero Net Carbon building policies aimed at making highly energy-efficient buildings scale in our city. Innovative finance structures like MEETS (metered energy efficiency transaction structure) that value building efficiency negawatts exactly like power from a power plant should be accelerated.

Now is the time to reclaim our city’s position as a beacon of sustainability. It is not hyperbole to say that our future may well depend on it.


(Editor’s Note: This article originally published by Seattle DJC.)

NK Architects now has the most Certified Passive House Consultants and Designers of any firm in North America

Posted by Zack Semke on February 15, 2017

Uptown Passive House Apartments, Seattle
Uptown Passive House Apartments in Seattle, one of our multifamily Passive House projects currently underway.

As reported recently by Vancouver, BC-based Pembina Institute, North America is experiencing exponential growth in the design and construction of Passive House projects: buildings that meet the world’s most stringent energy efficiency standard.

With this growth in Passive House design and construction has come an acceleration in Passive House training among architecture firms focused on sustainable design, sparking a friendly rivalry between companies. I’m proud to report that NK Architects just claimed pole position in this high performance design training race. On Monday, we received results from Germany’s Passive House Institute for the recent Certified Passive House Consultant and Designer examination.

NK now has 21 CPHCs and CPHDs, the highest number of any firm in North America.

This developments builds on the firm’s commitment to Passive House design, including the design of Seattle’s first certified Passive House, Park Passive, a custom home that won the national 2014 Housing Award from American Institute of Architects and the 2016 Passive Projects Design Award from Passive House Institute US (PHIUS). We now have several major multifamily Passive House projects–and one Passive House library–underway between our two offices:


  • Morningside Crossing: a Passive House retrofit and addition to an elementary school, to become 46 units of senior housing.
  • Glassport: another Passive House retrofit and addition to an elementary school, to become 55 units senior housing.
  • Carrick Library: a two-story Passive House replacement of the outdated Carrick Branch of the Carnegie Library of Pittsburgh.


  • Pax Futura: a multifamily Passive House building in the Columbia City neighborhood, with 32 studio and one-bedroom apartments and 3 live/work units.
  • Uptown Passive House Apartments: a multifamily Passive House building in Lower Queen Anne with 56 studio, 1, and 2-bedroom units, as well as 3 live/work units.
  • 11th and Republican: a 20-unit Passive House retrofit and new multifamily building with a rooftop solar array that connects an historic Capitol Hill home with a modern new building.
  • Arbors Passive: a luxury Passive House home in Maltby, WA.

Congratulations to our Certified Passive House Designers and Consultants who make these projects possible!:

  • In Pittsburgh: Jim Bischoff, Loren Brandford, Marc Ford, Rebecca Griffith, Shanna Kovalchick, Lauren McCunney, Brandon Nicholson, and Alyssa Swisher.
  • In Seattle: Marie Caryl, Suzi Davison, Emily Evenson, Steve Fischer, Alec Gardner, Joe Giampietro, Christine Goodwin, Rachel Hedlof, Peggy Heim, Katie Luedeman, Briana Peretti, Brittany Porter, and Alyse Zimmer.



We Remain Optimistic About Our Climate Future. Here’s Why.

Posted by Zack Semke on December 14, 2016


Earth's atmosphere, from International Space Station

With federal policy on climate set to reverse in January and the Paris Climate Agreement hanging on a thread, the struggle to secure a livable future for humanity has taken a hit.

But one significant cause for hope is the nascent clean energy disruption, driven by technology, innovation, and falling prices for renewable energy, battery storage, and electric vehicles.

Because Passivhaus understands that the building itself–its skeleton and skin­–is technology, it too is part of this disruption and can help accelerate our transition to a post-carbon world. Just as innovation in PV technology improves performance, innovation in Passivhaus design and construction drives down energy consumption and building cost, opening the real potential for market transformation in the building sector.

Read our report, “On Buildings, Swans, and the Power of Arithmetic,” (drawing on research by Carbon Tracker Initiative, CitiGPS, AllianceBernstein, and others) to learn more and to understand why we remain optimistic about a future of prosperity and climate security, and the role that buildings will play in achieving that future.


Is Passive House the solution to our climate crisis?

Posted by Tim Weyand on November 7, 2016

Key design breakthroughs center on the skeleton, skin and respiratory systems of buildings.

The message from scientists is clear: The planet is on a finite greenhouse gas budget and the longer we wait to reduce emissions, the faster we’ll have to reduce later to avoid catastrophic climate change. Time is of the essence.

While we have made remarkable progress over the past decade in delivering more energy-efficient buildings, we are moving too slowly given the urgency of the climate crisis. According to the U.S. Energy Information Agency’s 2014 projection for building energy use, efficiency gains will be offset by the 60 billion square feet that will be added to U.S. building stock between 2005 and 2030.

That’s not good enough. If we’re serious about our climate goals, we need to bend the building energy use curve downward.

The good news is that we — architects, engineers and builders — can transform building energy performance today. Passive House (aka Passivhaus) design and construction, for example, can reduce overall energy consumption by up to 75 percent and launch the built environment toward the Zero Net Carbon goal recently announced by the World Green Building Council, Architecture 2030 and others. And we can do this cost-effectively and predictably.

Nevermind the gap

Ever since the New Buildings Institute published its 2008 paper documenting the performance gap between modeled and actual energy use of LEED buildings, the predictability of performance in LEED and other high-performance buildings has been the topic of much study and debate.

passivehousegraph by Passivhaus Institute, redrawn by NK Architects
There is no such debate with Passive House performance. The consistent finding is that Passive House modeling (via the Passive House Planning Package or PHPP) is highly correlated with actual building performance.

Research from Germany bears this out. Data from independent researchers, shared by Passivhaus Institut, compares the heat consumption of four developments: three Passive House settlements and one non-Passive House settlement (though still fairly energy efficient.) Their findings:

  1. Passive House radically outperforms conventional energy-efficient buildings, by up to 80 percent in heat consumption.
  2. Occupant behavior varies widely. It is normal to see a swing in energy use of around 50 percent for identical units within a settlement. The S-curves that emerge for each development illustrate the variance between energy “misers” and energy “hogs” across functionally identical units within a community.
  3. Passive House modeling has strong predictive power. The PHPP model’s predicted heating consumption for the three Passive House settlements is nearly identical to the actual average heating consumption of each.

Predictable performance

Passive House models are highly correlated with actual building energy performance for two reasons.

First, the data inputs for the PHPP performance model exactly correspond to the actual building materials and assemblies used in a Passive House project. And these assemblies control convection, conduction, radiation, and the movement of heat, air and moisture.

Second, Passive House quiets the volatility (measured in temperature deltas, moisture gradients and air leakage rates) that we see in non-Passive House buildings. Energy models of stable systems are more accurate than energy models of volatile ones. So, the quiet and comfortable interior environment in a Passive House is a boon for both the occupant and the modeler.

The key design breakthroughs of Passive House center on the skeleton, skin and respiratory system of buildings.


For centuries we have ignored the thermal (and condensation) implications of the structural elements of our buildings, blithely allowing beams to jut through walls without a care for the energy transferred through these thermal bridges. In fact, steel beams thrusting through otherwise decent exterior walls can still be seen as a signature architectural gesture today.

But even far less egregious examples of thermal bridging, like wood studs in a wall, dramatically reduce the overall performance of the building envelope.

If not detailed properly with thermal breaks between inside and outside, the skeleton of a building can undermine energy performance, yet thermal bridging is either ignored or incompletely accounted for by many modeling protocols and by many designers.

Passive House is the gold standard of thermal bridge-free design, dramatically improving energy performance, predictably.


In a Passive House, building envelope and ventilation function together as a system. Airtight construction is central to this system because it limits the movement of air, and the heat and moisture that air carries, through the building envelope. This dramatically reduces the loss of thermal energy from buildings, especially when combined with a thick sweater of insulation. It also protects the integrity of building assemblies, limiting the movement of moisture into wall cavities where it can cause mold and rot.

Equally important are the health implications of this approach. Airtight construction stops random, uncontrolled air leaks through cracks in building materials and enables designers to bring filtered fresh air in through balanced ventilation with heat recovery. This approach delivers superior indoor air quality to building interiors. (This is why the 2017 Washington Code will require DOAS, or Dedicated Outdoor Air Systems, in commercial buildings.)

The heat recovery of ventilation air brings major energy performance benefits as well. And because the airtight envelope eliminates random air and heat leaks, the system becomes easier to model: predictable energy performance.

At what cost?

I’m often asked, what does Passive House cost? What’s the premium?

It really depends on the building typology and program, of course. And if Passive House is tacked on late in project development as an afterthought it can be expensive. But when part of an integrated design approach, Passive House’s “premium” can be negligible.

Recently released data from the Pennsylvania Housing Finance Agency illustrates the point. In 2015 and 2016, the agency received 179 project proposals for Low Income Housing Tax Credits: 59 of those proposals were for Passive House projects and 120 were for conventional buildings. The average projected construction cost for the Passive House buildings was $171/square foot, compared to $168/square foot for the conventional projects. That’s a difference of just 1.8 percent.

Revolutionary efficiency, predictable performance and negligible cost premium? That sounds like a pathway to move our industry from being part of the climate problem to being part of the climate solution. And not a moment too soon.

(Editor’s Note: This article originally published by Seattle DJC.)