NESEA Passive House Tour, Part 2

Hi everyone, hope you got a chance to read part 1 of the virtual NESEA Passive House tour. (Remember, if you’re going to NESEA and you want to join the actual tour of Passive House products that I’ll be leading on the BE12 trade show floor, be sure to sign up for my workshop.)

We left off with the excellent options from Zehnder and Ultimate Air. To finish that discussion, The UltimateAir RecoupAerator  is the only American-made high-performance ventilator on the market that meets Passive House efficiency requirements. It is very affordable, but does have some more maintenance needs. This unit also has the best humidity recovery in ERVs, which is especially interesting for the humid North American climates (of course, it works just as well in the dry climates). One unique feature: the designer has a limited ability to dial in the humidity recovery level according to climate. Very cool!

Now, on with the tour. We touched on airtightness when talking about the excellent 475 product suite.

What about the rest of the envelope? Aren’t we talking super insulation? What about walls? NESEA has a range of Passive House walls on the floor. Here are the highlights: GreenFiber, National Fiber and International Cellulose Corp. are classics when it comes to super-insulated wall systems. Not only was cellulose used in the very first projects in Canada when Passive House principles were invented in the 70s (yes, we do have long-term experience with these wall systems, this is nothing new!) it also rates high in the context of the embodied energy discussion. Given the amount of material required, it’s a valid discussion.

I lean to using materials with very low embodied energy as sound good practice for Passive Houses. Cellulose has one of the lowest embodied energies and is only beaten by — you guessed it — straw bale. Cellulose is also a safer choice when it comes to the hygrothermal wall performance of a super insulated wall. Super insulation means very little heat loss from inside into the wall, therefore less drying potential for the wall and colder exterior sheathing surfaces, which is potentially a higher risk for condensation. Cellulose can mitigate some moisture that might occur, is more forgiving than other materials and if the wall was designed in a diffusion-open fashion (as it should be for a Passive Home) then potential moisture in the wall will dry out during the in-between seasons.

Another popular insulation choice is foam insulation systems. Icynene Spray Foam and Vantem Panels offer two environmentally sound solutions for those who like to use foam products. Foam is liked in this country for very good reasons: in North America we have many humid climates. If we super insulate, we increase potential for condensation in the wall. Add bad construction and failed air tightness measures and the building will have serious problems. To address these risks, many have come to rely on foam’s benefits of added air tightness, moisture retardation and relatively high R-value.

The 2 lb closed cell spray foam from Icynene has none of the high Global Warming Potential (GWP) blowing agent controversy attached to it. It is water blown, and eliminating the concern. Vantem Panels are another excellent alternative. They use Expanded Polystyrene for their Structural Insulated Panels. The blowing agent of this foam product is pentane, which has a GWP of only 7 (compared to approx. 1000 for the most commonly used high GWP blowing agents). In addition, Structural Insulated Panels (SIP) make it really easy to meet Passive House air tightness expectations. The monolithic panels themselves are airtight, if penetrations are avoided or detailed in a very conscientious manner, then the only connections left to air seal are the panel junctures and corners. An even better foam alternative is graphite-enhanced high density EPS used by some SIP manufacturers. This type of foam yield R-values in the range of 5 per inch.

Now, if you’re building a Passive House, you have all the materials in the shopping cart. Now, what else is missing?

You might want to find an architect who ideally also is a Certified Passive House Consultant, CPHC. To find a professional you have three options: Visit the Passive House North East (PHNE) table at NESEA BE12. It represents the forum of professionals in the Northeast. Also, if you are interested in getting hooked into local Passive House events, meetings and local conferences, get involved in the PHNE local meet up groups. It’s a great place to start for local expertise and advocacy work. These folks can tell you everything about available incentives for your Passive Dream Home, which will make it look even more attractive. (Massachusetts and the Northeast are ahead of all other regions in that regard — NESEA might be able to take credit for some of that too!).

If you want to go mod (modular) you’ll find the modular homebuilder who built the very first modular Passive House in the US! Check it out, stop at the Preferred Building Systems booth. The modular project is the Charlotte Habitat for Humanity Home in Vermont. Preferred Building Systems was the first one to put a fully certified Passive House together in the factory. That deserves great recognition for the vision and ability to make it happen!

If you want to build your Dream Home in some other part of the country, go to the PHIUS site to find a Certified Passive House Consultant (CPHC℠). You can sort by location to find CPHCs close to you. PHIUS is the leading technical research organization in terms of all things Passive in the United States and has trained more than 600 consultants over the past five years and certified more than 300 are nationwide. PHIUS also offers PHIUS+ project certification, a conscientious Passive House quality assurance protocol that assures that you get what you pay for. You can also take a look at the certified projects (more than 100 are in the review process).

Also visit the Passive House Alliance-US site. PHA-US is a PHIUS partner, a national membership organization providing education, networking and advocacy for the community. It has 11 chapters and affiliates active across the nation with more applications pending. Its members are architects, builders, manufacturers, other associates, advocates and Passive House enthusiasts. PHA-US has kicked the gear into overdrive in 2012. Member benefits are growing fast. National webinars on Passive House topics are being shared between the regional groups, and conferences are planned. To become involved in this exciting national effort to help make Passive House mainstream with US builders, homeowners and government policy makers, join the PH Alliance today.

Finally, some special recognition: Having been a long-time forward thinker and leader in education about the built environment, Yestermorrow Design/Build School is the first educational institution to license the PHIUS Certified Passive House Consultant training to integrate it into its training offerings. Kudos to this pioneer in so many realms of construction and environment.

This past January, Yestermorrow hosted the first inaugural Passive House Consultant class. It was a great success with great feedback; more classes are being planned for next year. Twenty-four students, instructed by myself and Marc Rosenbaum, huddled in for 9 days straight in what was easily the most intense studying setting ever. Fifteen of them took the final exam on day 9 and 13 passed! Watch out for the graduates from this class, they excelled in that learning environment like no others! And, Yestermorrow’s library is unprecedented in regards to items about Passive House history in the United States and Canada from the 70s until now. This organization is a leader in Passive House education.

Thanks to NESEA and all the friends out East that have given me the opportunity to do this review and I hope to see a few of you on the NESEA BE12 trade show floor! Be sure to sign up for my workshop — you need to sign up for the workshop to take the tour.


One-Stop Passive House Shopping: Join Me at NESEA’s BE12 Trade Show

I’ll continue with the climate-focused case studies from the last installment soon. Right now, though, it’s worth giving a headsup on an upcoming conference event.

In the early days of Passive House in the United States, finding Passive House components – windows, HRVs, etc. – was a project in itself. How far we’ve come! In fact, if you’re interested in building your Passive Dream House, you’ll be able to find everything you need on the floor of the NESEA Building Energy 12 trade show floor.

The national conference of the venerable Northeast Sustainable Energy Association, every year BE12 astonishes. This year in Boston will be no different.

Passive House has been at the forefront of recent NESEA conferences. This year, to meet the growing appetite for all things Passive House, NESEA asked me to lead a tour of Passive House products that will be displayed at the NESEA trade show. (You’ll need to sign up for my Tuesday workshop to join the tour.) And so it will be my pleasure to guide the tour, to introduce them to the forward-thinking folks who’ve made available awesomely performing materials and components to the designers, builders and homeowners of Passive Houses. And made the components cost effective.

Some suppliers have been there for decades: Pioneers such as Stephen Thwaites with Thermotech Fiberglass Fenestration. I used Thermotech windows for the first time in the Smith House in Urbana, Ill. In 2002, it was the only North American window I could find that approached the Passive House specifications for the Urbana climate. Little did I know how dialed-in the window design by Stephen Thwaites really was. After 10 years of experience with Passive House construction throughout all different climate zones I have come to appreciate the smart balance applied in this design. A comparison of the energy balance of a certified European window and the Thermotech windows for my house showed that they were performing virtually equally, Thermotech maybe even a little better. How could that be at somewhat higher overall U-values? It is all about the right balance of Solar Heat Gain coefficient and U-value dialed into the specific climate conditions. Thinner frames to maximize the glass area in a high solar radiation climate is where the money is at. Passive House two thumbs up for an excellent North American manufactured fiberglass window perfectly designed for cold and sunny climates.

And then there is Pinnacle Window Solutions, with another classic, SeriousWindows. Serious has been used in many Passive Houses across the nation. It is a North American manufactured fiberglass window featuring excellent U-values well suited for cold and very cold climates. The solution of the suspended plastic film technology instead of an additional glass pane to increase the R-value allows the creation of a window that features essentially quadruple window performance, while maintaining a manageable weight. This is an interesting choice for the cold and very cold and perhaps more cloudy climates in North America. The high R of SeriousWindows comes at a price: the Solar Heat Gain Coefficient goes down the better the R and the visible transmittance is lowered as well. In cold climates with very good solar opportunities, a high Solar Heat Gain window with less R might perform just as well or better. This only reinforces what we have been teaching in the PHIUS trainings: the right window for the right climate. And Serious definitely has a place at the table.

In the last couple of years many entrepreneurs have brought new options for high-performance European Style windows. For example, Intus Windows has been turning heads with amazing Euro-style windows at very competitive prices (typically the Euro style window comes at a price). European Architectural Supply and New England Fenestration, LLC offer more European window varieties from other manufacturers such as Schueco, Macrowin and Unilux, all superb performing windows, all of them featuring thermally broken frames certified for the cool moderate climate through the Passivhaus Institut.

Still another excellent choice: Bieber Windows, and ZolaZola’s booth will be staffed by Passive House veterans Florian Speier and David Gano.

Go and visit — you have to see and touch these windows to understand the quality.

Windows are critical to Passive House construction, and so are systems components for minimized micro-load mechanical and ventilation systems. They put Passive House within economic reach. On this front, too, NESEA will also include many exhibitors. In addition, I’ll give a workshop at NESEA on Tuesday on cost effective integrated mechanical systems for North American climates.

In the early days, I would begin designing Passive House projects by first sketching the continuous air tightness layer. Later that focus shifted slightly toward laying out the mechanical system and the duct system. I am in love with Passive House mechanical systems simply because I never dreamed of being able to design it myself, and being able to really integrate it into the design process. They are in their own right very elegant and if well done one the key quality indicator of a Passive House. Hence, Passive House homeowners are actually proud to show off their mechanical rooms.

My latest interest has shifted towards heat pump hot water heaters as viable Passive House solutions, even in cold climates. Stiebel Eltron, Inc. makes such an appliance. It is a true super-insulated tank a Passive House enthusiast dreams of. Our Passive House builder, who installed it in our last project, was blown away in terms of efficiency and quality. By far the most energy efficient solution on the market, the unit is slightly more expensive than other options, but a good value. Another Passive House two thumbs up. Heat pump hot water heaters are becoming a very interesting solution for integrated mechanical systems designs for Passive Houses. Located inside the thermal envelop in a super low load home (including cooling and latent loads) the contributions to cooling and dehumidification by a heat pump hot water heater can be significantly helpful and in some cases all it takes.

And then there are the mini-split heat pumps. NESEA attracted two significant Passive House players, Daikin AC Americas, Inc. and Mitsubishi Electric HVAC. The mini-split systems are quickly becoming the most popular heating/cooling and dehumidification systems for Passive Homes. Daikin and Mitsubishi are among the manufacturers offering a heat pump slim duct built-in option. The units can be obtained in small sizes for single-zone and multi-zone systems (just what we need for Passive Homes) starting at 6k BTU/h and up. They generally have very good SEER ratings, the slim ducted options have a little lower rating, but are still solid in cold and mixed humid climates with larger cooling and dehumidification loads where integrating the space conditioning in the ventilation system is preferred.

Another interesting product from Daikin is the point source “Quaternity” Heat Pump wall mount unit. The SEER rating is 26.1 and it has an additional feature for warm humid climates where dehumidification might be needed when there is no cooling need: a dehumidification mode only. This unit is available in three capacities, 9k, 12k and 15k BTU/h. The Mitsubishi’s wall units have one of the best SEER ratings (26) and operate down to very low temperatures, making it appropriate for cold and very cold climates.

Mitsubishi has also truly excelled in terms of control of its heat pumps. Recently Mitsubishi introduced wireless technology eliminating the need to run wires and offering a centrally located thermostat just the way we like it.

Wagner Solar Inc and Tarm Biomass offer extremely low source energy heating options for multi-family Passive House projects (we are seeing more and more coming into the certification process). One major challenge of the multi-family typology is meeting the source energy criteria. Both companies sell wood and pellet boilers that offer excellent low carbon heating systems options. One boiler can be used for an entire medium-sized apartment complex if combined with Passive Solar. The Tarm Biomass boilers range from 75-80% efficiency for wood, 85-87% for pellets. Wagner Solar Inc offers a Pellet boiler with the efficiency of up to 93%. Smaller units for single family are available in Europe in combination with a hot water heat exchanger. It’s worth checking on availability of these systems. They are fine low source energy solutions for cold climates with predominantly heating requirements and lots of wood.

475 High Performance Building Supply is bridging the gap with many products not only in regards to air tightness but also over into the ventilation system realm. This Brooklyn, NY-based outfit has an interesting suite of specialty products mainly imported from Europe. They offer airtightness solutions from INTELLO plus and Pro Clima, a wood fiber sheathing/insulation product from Gutex, triple pane skylights from Fakro, and Foamglass from Pittsburgh Corning.  They offer a through-wall decentralized apartment venting solution with a ceramic heat recovery core from Lunos and a compact heat pump by a Swedish company Nilan (not available yet but in testing – coming by year-end according to 475). The configuration is cost effective for cities, as it saves a lot of space by comprising all the mechanical functions of a Passive House into one compact box the size of a refrigerator.

Another high performance ventilator on the NESEA floor is Zehnder America, Inc.; it’s still the only game in town on this show floor in terms of high efficiency heat recovery ventilation. As important as high efficiency heat recovery ventilation is to Passive Houses, we still hope for a little more competition and for the North American ventilation system manufacturers to come up to speed. In the  ventilation systems by Zehnder — integrated solutions for pre-warming the incoming air through ground source heat exchange and fast flex ducting systems – continue to impress. New this year: it received the Home Ventilation Institute Testing stamp of approval. The results show the heat recovery efficiency of this HRV under this testing protocol coming in second with 93% Apparent Sensible Effectiveness (ASE) which is topped by only one other ventilator made and sold in America, the UltimateAir RecoupeAerator with 95%. Zehnder products are a little pricy, but with the ease and time savings of installation and an impeccable maintenance record, it seems a well worth investment.

That’s it for part one of the tour…here’s part two, where we get into some more airtightness and wall system products.



Reality Show: Monitored Passive House results from Salem, Oregon

All — thanks for all of your contributions and comments about fine-tuning the standard. It’s going to be an exciting process. Continuing that discussion, let’s look at a few really good examples of certified Passive Houses that were modeled for various North American climate zones, and for which we have good monitoring data. The graphic below makes clear that generally, the climates of North America and Central Europe are not directly comparable. One small region–running from the northwest U.S. Coast into Canada–matches the Central European conditions.


Therefore, we’ll look first at a certified project in Salem, Ore., and evaluate how accurately the PHPP modeled the actual monitored experience.

The Salem, Ore., home that's been monitored for a year.

Again — as stated in the inaugural blog post, the core principles behind the Passive House concept, some of which date back to the early 1970s — are not in question. Minimizing the peak loads to a point when balancing the ins and outs (losses and gains) produces  a building that nearly reaches equilibrium. Such a building needs very little active energy input — and this only a few months of the year — to maintain comfort.

If the space conditioning meets our 1 W/sqft peak heating load and 0.8 W/sq peak cooling load requirements, then we get the icing on the cake: For mechanicals, we can either use point sources throughout the space or integrate the space conditioning in the ventilation air. In the Northwest, with next to no cooling requirement and lots of passive cooling potential, integrating conditioning and ventilation could prove to be the most cost effective solution.

Let’s look at how one Passive House project played out in Salem, Ore. The 16th & Nebraska project (also known as the Rue-Evans House, named for its owners) was built by Blake Bilyeu and his father. Blake Bilyeu is a pioneer — he took one of the first PHIUS Certified Passive House Consultant training courses offered. And by 2010, he had completed the 16th & Nebraska project. It became one of the first projects certified by PHIUS.

By U.S. Department of Energy climate zone definitions, Salem is considered a marine climate, characterized by:

  • mean temperature of coldest month between 27-65 F
  • warmest month mean of less than 72 F
  • at least four months with mean temperatures over 50 F
  • dry season in summer (month with heaviest precipitation at least 3x of driest month)

Here’s the Salem climate data at a glance:

And data for Bonn, Germany.

The climates are very similar: Average temperatures in Salem are a little higher by 4.6 F in winter in Salem, summer highs are the same, and precipitation is generally higher in the Pacific Northwest. Both locations have limited solar availability.

The project’s PHPP data at a glance confirms that both Passive House criteria are met: the annual heating demand criterion with 4.02 kBTU/sqft yr as well as the peak heat load with 2.9 BTU/hr.sqft. There is no need for cooling.

The general specifications of the exterior envelope components are:

  • R-45 in the wall, the roof has R-96, the floor over crawl space has R-51.
  • The average window installed U-value is 0.226 BTU/hr.sqft.F with orientation specific SHGC of 0.23 for E-N-W orientations and 0.46 SHGC for the South

Note: The window figures are unadjusted NFRC values. Passive House window calculations will result in slightly adjusted values. The PHIUS Technical Committee is developing a method for converting values and/or a protocol to more accurately calculate the window values needed for PHPP. The Tech Committee will make it available for comment in an upcoming PHIUS e-Newsletter.  Many thanks to Graham Irwin, John Semmelhack and Graham Wright, who already have devoted a lot of hours to this project!

Energy consumption at the project was monitored for a full year. Over that period, the home was occupied by its new owners (a young couple and a dog, and eventually the couple’s newborn baby. The owners blogged about their early experience — check it out.)

A detailed monitoring report on the first year was prepared by the company Ecotope. (Many thanks to the Ecotope team that graciously gave PHIUS permission to make the information available to the Passive House community. PHIUS plans to share more monitored data from other projects soon—stay tuned.)

Download the full report here. From the executive summary:

The 16th and Nebraska Passive House project located in Salem, Oregon is an impressive example of an energy efficient home. The home is built to the stringent requirements of the Passive House (PH) program. The home’s energy use for the first year post-construction place it in the top tier of the most energy efficient single family homes in the Pacific Northwest. The first-year stats for the project are listed below:

  • First Year Total Annual Energy Use: 5,413 kWh/yr
  • Electric Utility Cost per Year: $700
  • Energy Savings estimate over Oregon Code: 9,064 kWh/yr
  • EUI (using gross sq ft of 1,885 sf): 9.8 kBtu/sf/yr2

The Salem Passive House home blows away today’s code homes, and nearly meets — right now — Ed Mazria’s Architecture 2030  Challenge for 80% reduction:

Back to the original questions: how do actual results compare to what was modeled in the PHPP, and what conclusions can be drawn from potential deviations of the measured results to the modeled results?

To start, some of the results are rather unexpected:

The actual first year’s energy use came in between what was predicted and what is allowed in the Passive House program, 5,413 kWh/yr. This results in a 63% energy use reduction over an electrically heated home built to the Oregon 2008 Code. This represents a savings of $750/yr in utility costs.

The DOE Building America Program aims for 70% in overall energy reduction. With 63%, this is below what one might have expected. If the modeled results had actually been met the building would have been saving 73% over the code home. Reading on:

This home represents the upper limits of conservation that can be controlled by the designers and builders; or what can be achieved by applying most of the energy efficiency measures currently available. Space heating and DHW represent 13% of the home’s total energy use. The remaining loads are plugs, appliances, lights, cooling, and energy recovery ventilator (ERV) fans. Since PH is a modeled certification program, there is no guarantee that a home modeled to meet the PH standard will actually perform to the PH standard once built. It is clear that maintaining the PH energy use levels is a function of occupant behavior and lifestyle choices. More research and development of tools for modeling plugs and appliances in the PHPP program should be made available to the PH community.

The report points out higher plug loads and attributes this to the American lifestyle. As we have compared electrical loads modeled in PHPP and actual consumption, we find a large discrepancy between what’s modeled and actual results throughout many North American projects which seems to confirm the author’s explanation.  

Conclusion: We need more accurate protocols for the American household. We need to identify realistic stringent savings recommendations and adjust the initial assumptions in the household electricity sheet accordingly. This measured result also points to the potentially higher importance of the source energy criterion rather than the focus on annual heating demand.

The measured space heating demand constitutes only 1/4 of what was actually predicted. Once the additional household consumption is taken into account, though, in the internal heat gains the results once again are pretty close to what PHPP predicted. The modeled kWh amount for space heat in the diagram is reflecting the assumed 3.2 COP of the heat pump; if provided through direct resistance  that would amount to 3.2 times 694 kWh,  equaling a little over 1800 kWh/yr. The discrepancy is roughly the additional kWh use for the DVR and server, which is direct electric internal heat gain (no bonus through COP). That explains the total higher energy consumption.

In short, the predicted space heat demand result is indeed very close to the modeled prediction. On the flip side though, there is talk about energy used for cooling in the report and the PHPP modeled 0 energy use for cooling. Additional household consumption can be used to replace heating needs in winter, in summer it adds to the energy used for cooling needs.

The report concludes:

This 16th & Nebraska Passive House home represents the leading edge of current energy conservation. Insulation has been maxed out, the envelope is extremely air tight, and the glazing percentage has been reduced to 15%. The solar water heating system is providing 69% of the hot water energy, the home uses highly efficient appliances, low lighting levels, and a very efficient ERV. The remaining loads are a product of the American lifestyle and are the hardest loads to control without major impacts to lifestyle.

For the Northwest, the Salem example indicates that the PHPP is, as expected, reasonably accurate in predicting the annual space conditioning. Assumptions for household and plug loads need to be revisited and entered as correctly as possible, but this is not a climate but rather a market issue.

Just as in Germany, the Salem project proves Passive House is a good basis for net zero. From the report:

This project is a great example of what is possible with the PH program and represents one path to achieving net zero energy use. A 6-7 kW PV array on the roof with the current 3 people living in the home would take this project to a net zero energy status.

That’s a sizable PV installation, but, just like in Germany, forgoing active energy in favor of conservation is more cost-effective.

So we’ve seen what happens when we apply Passive House in a climate very close to the European climate. To predict space conditioning it works very well. American life style and market, we have some work to do.

Applicability in regards to humidity, hygrothermal concerns and the impacts on airtightness recommendations for this climate will be addressed separately at a later time.

Next, we’ll venture into more extreme North American climates to evaluate that experience. Stay tuned for more!