Massachusetts Data Shows Phius Projects Achieve Promised Energy Savings at Negligible Cost Premium

isaac picIsaac Elnecave, a member of the PHIUS certification team, has written this post examining data regarding the energy savings of Phius buildings.

From May 5-7, 2021, the Northeast Sustainable Energy Association (NESEA) ran the BuildingEnergy Boston Conference. Among the many can’t-miss sessions there were a number focusing on Phius including: The Proof is in the Project: Cost and Performance of Built Passive Multifamily. This panel focused on both the cost and energy use of multi-family projects built to the Phius standard.

Massachusetts agencies and utilities have established a robust set of incentives that have resulted in a sharp increase in the number of projects built to the Phius standard. Panelists for the NESEA session were: Beverly Craig of the Massachusetts Clean Energy Center (CEC), Brendan Place of the Massachusetts Department of Energy Resources (DOER) and Katie Bartolotta of Green Building United. The question addressed by the three presenters in this session was whether the projected energy savings from building to the Phius standard does, in fact, materialize, and whether it can be achieved cost-effectively.   

The CEC ran the “Passive House Design Challenge” that provided incentives for eight projects around the Commonwealth. A second incentive program is open for multi-family buildings of 4 stories or more. An incremental cost analysis of four of the eight projects that have moved far enough along (including one project that has been completed) to get cost data shows that these projects:  


  • Have an incremental cost range from 1.4% to 2.8%. (For completed projects and projects that have gone out to bid). 


According to an analysis by DOER, projects built to the Phius standard:  


  • Use 60% less energy than a comparable project built to the energy code. 


Cost Blog Chart 6.7.21This data, along with data from the Pennsylvania Housing Finance Authority and NYSERDA, dispels the myth that the energy savings, health benefits and resiliency that come with Phius projects come at an unacceptably high cost. Instead, the incremental costs are within the range of costs for these types of multi-family projects. Finally, as developers build more Phius projects, spurred by these incentives, they gain the experience and knowledge necessary to reduce construction costs reflected in the results shown above. 

Ultimately, once a sufficient number of developers, architects, and builders gain experience and comfort building to the Phius standard and the cost and energy savings information becomes more widespread, we expect to see the number of projects built to the Phius standard increase. 


How Onion Flats in Driving NZE Affordable Housing Nationwide

Within the following website, there is detailed information on the incremental cost of high performing buildings including Phius.

Early morning decarb musings…from the bottom up…join the conversation!

Note: After contributions from a number of fantastic guest bloggers, Katrin Klingenberg makes her return to the Klingenblog to give readers an inside look at her quest to achieve carbon neutrality both in her own life, as well as with her work at Phius.

It is June of 2021. Sipping my morning tea, reflecting. It has been a year of thought and reassessment and remembrance, letting go of the old ways…quiet before the storm…I feel grateful almost …the pandemic was harsh…training wheels for what is to come…are we ready?

In interviews with journalists, I often get asked: what was/is your core motivation? Why did you start Phius?

And my response is always along these lines: “I was looking for carbon neutrality in all aspects of my life; to take personal responsibility in light of a crisis, wanting to do my share, love and respect for the commons, a desire to distribute resources fairly so that all people can live in peace, balance and harmony.”

And then, as an architect, I recognized that buildings represent a big chunk of our global carbon emissions. Phius was my chance to be part of the solution. My professional commitment since 2002: I could no longer continue to add to the planetary carbon bill with my work. That effectively meant setting up every building to be capable of achieving zero and positive energy.

Climate change is an existential crisis that no one will be able to talk their way out of. There are no planet hospitals with a line out the door that impress on us how bad this is, no healthcare providers ringing the alarm. Well, actually…scientists and environmentalists have been sounding the alarm since the 60s. Society stuck its head in the sand and decided on doing fossil fuel biz as usual as if there was no tomorrow (pun intended). Consequently, we are really up against the wall now. We need courageous, superhuman really, political will and global consensus, turning every conventional notion of how things used to work upside down. We need a fast and effective campaign to inoculate our economies against the effects of shifting away from fossil fuels as fast as possible, just as fast and successful as the COVID-19 vaccination campaign.

The good news: Carbon neutrality is within reach. We are so close. That was our goal on our inaugural website in the mid 2000s. The Passive House Institute US declared its mission: making passive building standards code by 2020. 

For all intents and purposes, check! We effectively have achieved that goal in places that matter a lot, not as mandatory code but in the form of programs, incentives, local laws, alternative compliance paths: New York City, the State of Massachusetts, Washington State, Washington DC. And we initiated ASHRAE 227p. So, yes, on our way, check!!!!

And in its 2021 standards update, Phius made a very important decision – the flagship certification, while the zero energy passive baseline still exists – is now the Phius ZERO certification. I am so proud of our team, how far we have come as a community and how patiently we have built this shift together over the last 20 years. It is a marathon, not a sprint — sound familiar?

But we need to pick up the pace. Turning the entire building industry around is only step one. Even if we eventually build all new construction to our proven standards, decarbonize all buildings through deep retrofits, and decarbonize the energy supply, we still urgently need everybody’s help from the bottom up to take action.

That’s really what I’d like to discuss here. Start a discussion about meaningful personal action that can be taken by anyone who chooses to go in on this really important mission.

I’ll go first. Since all this has been a driving force in my entire life really, it has shaped my life path and my choices. Carbon neutrality requires rethinking and changing a few things.

In 2002, I decided that if I truly believed in the commons and fair share of resource distribution for everyone, I would have to walk the walk. 

I tried to determine the standard of living that could be attained by everyone in an equitable society while also meeting the carbon reduction goals required to adapt to and mitigate climate change. That meant reassessing everything in my life: where do my actions and life contribute to the problem and how can I fix it? Once you start thinking about it in this way it really ripples through everything. 

Let’s start with money. We all need to earn money to run our lives. Our economies run on oil. Every dollar in our pocket essentially represents wealth generated in some form by fossil fuels. The more dollars any one of us has, the more emissions you are essentially responsible for in your daily life transactions (carbon footprint by wealth category is another interesting topic, another blog). I decided to limit the money I was going to earn. And I decided to put the money I did earn back into the non-profit Phius to support market transformation toward zero energy buildings. 

I then, step by step, dialed in my living circumstances: how much space I was able to live in to stay within my fair-share space conditioning emissions budget, how much land around my house there should be and how I was going to use it (farming), my choice of car, vacation and travel miles, food choices…all had to be reassessed.

It was a process. But I’m happy to report that in 2021, reflecting over morning tea, I feel good. I feel really, really good about having achieved what I set out to do…at least in my personal life.

Smith House

Smith House

With little money to my name and no job at the time, I embarked in 2002 on building the Smith House like there was going to be no tomorrow if I did not do it. It was scary, but it turns out, where there is a will there is a way. 

The Smith House, 1000 sq ft, meant for three people, was built for being zero energy ready. In 2018, I finally added a 5 kW PV system, taking the house and about 10K electric car miles per year (a car which I don’t have yet) off the planetary carbon bill. 

What I overproduce in Urbana “pays” for my condo living in the city (since I am not using overproduction to drive). I never turn my heat or air conditioning on. It’s a small, but nice and comfy apartment, 30 minutes walking distance from everywhere I need to go. I have not been on planes, trains and automobiles in a long time and if I do get on I am conscious of each mile. 

I changed my diet, essentially vegan plus fish and an occasional egg. Looking at carbon emissions savings from those food choices…turns out they are very significant. I try to avoid the elevator, though, full disclosure, my apartment and office are both on the 14th floor, so that’s a challenge. Down is easier than up, let’s start there.

And…I’d like to deep energy retrofit my condo tower…already have a plan…but that for the time being will have to be done in the future.

What are your stories?

If you are interested in making similar changes, 2000-Watt Society is a great place to start.

Phius and Housing Equity: We Can Do This

What do we mean when we say equity in housing? Is it providing a place for all unhoused populations to live? Is it creating enough resources so that everyone has housing security, no matter their class, race, or age? What about high quality housing?

Finch Cambridge, an affordable housing project that won Best Overall Project in Phius' 2020 Design Competion.

Finch Cambridge, an affordable housing project that won Best Overall Project in Phius’ 2020 Design Competion.

Homes and apartments built to the Phius standard are airtight, energy efficient, super insulated, and low maintenance. They are comfortable, quiet, and provide a quality of life. These dwellings provide hard-to-find clean, high quality air, because the ventilation brings in fresh, filtered air and exhausts the stale air, something the coronavirus pandemic has shown is essential to mitigate spread of the virus. Better indoor air quality produces better health outcomes for people with chronic conditions like asthma.

Does your definition of housing equity include the quality of housing? It does for Phius.

Comfortable, well-built, and sustainable homes do not have to be for only the upper class. This is a policy issue. The cities and states of our country owe it to low-income citizens to provide them with a home that keeps them safe, does not strain their finances, and improves their quality of life. Affordable multifamily passive housing has proven time and again that it can be achieved at the same cost as a less sustainable or less reliable home. Single-family homes are being delivered at costs that range from 5 to 10 percent more than conventional buildings. Everyone should live in housing that is reliable and resilient.

Affordable housing, how do we define that? Usually it means housing built for lower-income individuals and families, those on a tight budget. It should also mean housing that is affordable to maintain and to heat or cool. It is not affordable if the occupants have to make a choice between paying for food and paying their utility bills. Multifamily buildings built to the Phius standard use 40-60% less energy than a comparable building built to code, resulting in similar reductions to utility bills.

Homes built to the Phius standard are resilient and reliable. In 2021, the state of Texas froze when its power grid failed. The information from the passive houses we have from Texas show that the temperatures in the building never came close to freezing. Families would have been able to stay in their home and no pipes would have burst, saving hundreds if not thousands of dollars in repairs and replacement.

Imagine living in a home that maintains its temperature no matter the season outside; that weathers severe temperature swings, and costs you less money to live in. Did you feel your stress levels lower just a bit? Don’t your children deserve to live like that? Doesn’t everyone’s child deserve that? How about your parents too?

The infrastructure can be created. This country can do it for its people.

How do we do this? Reach out to your city council, to the people who represent you on the most local level, to educate them about the benefits of passive building to the community.

Many states, like Massachusetts and New York, already have incentives for energy efficient homes. In Pennsylvania, 7 Phius certified projects, representing over 350 units of affordable housing, have been built and shown to be cost-effective. Incentives in Massachusetts have led to the construction of 8 Phius low-income projects with almost 550 units. These projects have come in at between 1.5% and 2.8% above building code. Massachusetts, building on this success, just passed a progressive energy bill that will push it’s already progressive buildings sector forward.

The change is possible and we all deserve it, including those who never even seem to get a piece of the pie.

Help Wanted: Identifying conditions that can complicate retrofits

32tev__gPhius Senior Scientist Graham Wright weighs in here with a guest post about some on-the-ground research he did regarding retrofits. Graham conducted a brief street-view survey of residential housing in Portland, Oregon (Glenfair, Glendoveer, Rockwood neighborhoods), and documented conditions that would complicate panelized retrofit solutions. He invites you to do the same in your neighborhood, and to submit what you find to advance research on panelized retrofit solutions.

It looks like I will be pivoting to concentrate my work on retrofit for a while. This is in connection with the Advanced Building Construction Initiative (ABC) of the U.S. Department of Energy. Under the program, RMI was funded to set up a collaborative and phius is a member. The vision shared at the recent summit is to figure out how to decarbonize ALL BUILDINGS by 2050. A study of the building typologies is underway, led by NREL.

It is already clear that single-family detached houses are the vast majority of buildings by number, they probably also dominate the aggregated “thermal loads” of heating, cooling, and hot water that comprise most of the energy/emissions savings opportunity.

The NREL data set does not have all the building properties that one would need to identify the technical barriers to deep energy retrofits. There is general awareness on the ABC team that the U.S. housing stock is very diverse and that this is a challenge to the concept of industrialized retrofit. So to get a better sense of this I spent a couple of hours looking at houses within walking distance of where I live in east Portland, Oregon. I looked for conditions that would complicate an exterior panelized envelope insulation retrofit, or that would complicate air-sealing. I looked at 33 houses and noted 30 separate conditions. These are assigned four-letter codes as shown in the table below. Some were much more common than others, such as attached garages, and some were so universal I did not even list them, such as gutters/downspouts.

My takeaway from this excursion was that the number of conditions that one would need to have a plan for is large but not endless. There are obviously some missing, such as balconies and widow’s walks. It’s not a large sample and I could only see one or two sides of the houses from the sidewalk. Many of the houses pictured are on crawl space foundations as indicated by vents, and that could also be considered an air-sealing complication, though I did not call it out here.

Here’s a slide show with problem conditions annotated:


Please send photos of houses near you! If possible, annotate conditions as I have in the gallery, using  the codes in the table below, or adding other conditions not listed, that also seem troublesome from the point of view of exterior retrofit and air-sealing.

Here are the problem conditions I classified, along with the number of cases I identified on my walking tour:

ACOD – air conditioner outdoor unit (3)
AGAR – attached garage (10)
CATV – cable tv line (1)
DISH – satellite dish (5)
DRYV – dryer vent (2)
E@RF – electrical mast through the roof (8)
EMTR – electrical meter (3)
EOUT – electrical outlet (1)
FENC – adjacent fence (13)
FCHM – fireplace chimney (17)
GCHM – gas appliance chimney (5)
GMTR – gas meter (3)
HOSE – hose bib / reel (3)
MLCA – mature landscaping close aboard (9)
MSXT – masonry extension from wall (5)
OV@R – overhang attached at roof (5)
OV@W – overhang attached at wall (5)
PBVT – roof plumbing vent (3)
PBCO – plumbing clean out (1)
RFVT – roof vent (4)
SKLT – skylight / sun tunnel (3)
SOFF – overhang with soffit (3)
STOV – wood/pellet stove chimney (1)
TCOM – telecom or mystery wall box (7)
THIC – change in cladding thickness (5)
TITE – can’t add wall thickness (20)
WART – wall art (1)
WBOX – window box (2)
WING – wing or fin wall (1)
XTLT – exterior light fixture (12)

Mechanical Summit Re-cap: A Good Time Was Had by All

Al Mitchell

Al Mitchell

Phius technical staff member Al Mitchell is our guest blogger, providing a thorough re-cap ofthe Phius Mechanical Summit. Remember that the entire proceedings were recorded, and you can still register to view all four or any of the days a la carte. You can earn up to 16.5 CPHC CEUs.

In the week leading up to Earth Day, Phius hosted the  Mechanical Summit online, a virtual gathering to advance the conversation around mechanical systems in passive buildings. Some came for direct solutions to their problems, some came for involved discussion between designers and manufacturers, some came for CEUs, but everyone had a rousing good time.

The summit was organized into four days, each with a defining theme. Pre-recorded presentations from expert panelists were available on-demand and led up to a two-hour live webinar; each featured a lead panelist presentation and short distillations of the pre-recorded presentations, after which the panelists fielded questions from the live audience.

Attendees asked their questions via the Zoom webinar format, but the chat remained open for the audience to debate and respond to different ideas.mech summit sig

The first of four days detailed building mechanical design principles and best practices. Lead panelists Dan Whitmore and Sloan Ritchie discussed their past experiences and used previous projects as case studies to demonstrate how they developed mechanical solutions for their Pacific Northwest climate. Other presentations included topics such as properly-sized domestic hot water distribution systems, ventilation integrated space conditioning, proper duct sizing, and rater-focused commissioning and testing of systems for passive house certification.

On the second day, presentations focused on solutions for closing the gap and tools and strategies to respond to the design principles. Lead panelist Tim McDonald detailed mechanical designs from multifamily projects located in the Philadelphia, Pennsylvania area. He explained his incremental development of mixing an ERV and ducted heat pump system by dumping the fresh air supply from the ERV into the return of the heat pump, and eventually trying a ventilation and space conditioning integrated unit. Other presentations explained proper space conditioning load sizing for single family homes, building monitoring and comparing results to predicted outputs, design of space conditioning integrated ventilation units, and mechanical systems controls.

Day three dealt with products and systems designs. Lead panelist Chris Benedict presented on a retrofit project in Brooklyn, New York, where the mechanical systems and building enclosure were rebuilt with minimal tenant disturbance. This raised questions on system choices and detailing the complicated world of building retrofits. Other presentations included manufacturers explaining improvements to their products and how they are responding to the needs of passive building designers, and some design methodologies and installations that are aimed at efficient, low carbon mechanical systems.

The closing dayffeatured Doug Farr, determined architect and new urbanist from Chicago. He celebrated Earth Day and discussed how to build a ground-up movement to build more efficient and sustainable communities, a more optimistic and engaging approach to the problem compared to many top-down approaches. To carry off at the neighborhood level, the additional presentations detailed building electrification, smart DC low voltage power systems, and passive buildings’ interaction with the grid. PHIUS Executive Director Kat Klingenberg made another nod to Earth Day and unveiled the new Phius branding and re-alignment to the institute’s mission.

There were a few themes that seemed to interweave through the days. One is the ever-popular question of kitchen range hoods and managing make-up air for direct exhaust devices. Without fail, it was discussed on all three mechanically focused days of the summit. While the panelists and attendees presented multiple solutions, no “silver bullet” solution emerged. This represents the reality of many passive buildings, that a one-size-fits-all solution is not available, and each project requires a thoughtful and inquisitive design professional to determine the correct path.

Many panelists mentioned that they felt that the building enclosure is the easy step for them, and the mechanical systems require more thought. A lot of these issues have been known from the beginning: the need for balanced ventilation, tight enclosures, and the massive reduction in sensible and increased need for dehumidification. Some designers called on manufacturers to address the need for microload equipment, and the manufacturers’ representatives showed some products in the works, and made the case for increased demand to bring the types of mechanical products to the North American Market. Seeing the large uptick in Phius Certified buildings, there is good reason to be optimistic.

While mechanical systems are frequently seen as the weak link in passive building design, the Phius 2021 Mechanical Summit left many feeling sanguine. Phius will continue to work and keep the conversation going on mechanical systems moving forward. Help Phius continue the conversation and submit an abstract for PhiusCon 2021 in New York.