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Passive House for Beginners

adminZeta — Fri, 01 Jul 2011 17:10:30 +0000

Martin Holladay strikes again! He most concisely and eloquently gives us a the basics of Passive House in this superb article.

Passivhaus For Beginners

The History of a Superinsulation Standard

Posted on May 27 by Martin Holladay, GBA Advisor

An energy-efficient house without solar equipment. Designed by architect Christoph Schulte, this superinsulated home was the first Passivhaus building in Bremen, Germany.

More and more designers of high-performance homes are buzzing about a superinsulation standard developed in Germany, the Passivhaus standard. The standard has been promoted for over a decade by the Passivhaus Institut, a private research and consulting center in Darmstadt, Germany.

The institute was founded in 1996 by a German physicist, Dr. Wolfgang Feist. Feist drew his inspiration from groundbreaking superinsulated houses built in Canada and the U.S., including the Lo-Cal house developed by researchers at the University of Illinois in 1976, the Saskatchewan Conservation House completed in 1977, and the Gene Leger house built in 1977 in Pepperell, Massachusetts. Aiming to refine North American design principles for use in Europe, Feist built his first Passivhaus prototype in 1990-1991.

Feist later obtained funding for a major Passivhaus research project called CEPHEUS (Cost-Efficient Passive Houses as European Standards). Conducted from 1997 to 2002, the CEPHEUS project sent researchers to gather data on 221 superinsulated housing units at 14 locations in five countries (Austria, France, Germany, Sweden, and Switzerland).

The Standard Sets a Strict Bar
The Passivhaus standard is a residential construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. To meet the standard, a house needs an infiltration rate no greater than 0.60 AC/H @ 50 Pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 watts per square meter and windows with a maximum U-factor of 0.14.

The Passivhaus airtightness standard of 0.6 AC/H @ 50 Pa is particularly strict. It makes the Canadian R-2000 standard (1.5 AC/H @ 50 Pa) look lax by comparison.

Unlike most U.S. standards for energy-efficient homes, the Passivhaus standard governs not just heating and cooling energy, but overall building energy use, including baseload electricity use and energy used for domestic hot water.

Thick Walls, Thick Roofs, and Triple-Glazed Windows
Most European Passivhaus buildings have wall and roof R-values ranging from 38 to 60. Wood-framed buildings usually have 16-inch-thick double-stud walls or walls framed with deep vertical I-joists. Masonry buildings are usually insulated with at least 10 inches of exterior rigid foam. To meet the Passivhaus window standard, manufacturers in Germany, Austria, and Sweden produce windows with foam-insulated frames and argon-filled triple-glazing with two low-e coatings.

Although the Passivhaus Institut recommends that window area and orientation be optimized for passive solar gain, the institute’s engineers have concluded, based on computer modeling and field monitoring, that passive solar details are far less important than airtightness and insulation R-value.

In the U.S. and Canada, the phrase “passive solar house” was used in the 1970s to describe houses with extra thermal mass and extensive south-facing glazing. Because of the possibility of confusing Passivhaus buildings with passive solar houses, most English-language sources use the German spelling of “Passivhaus” to reduce misunderstandings.

Gotta Have An HRV
Feist recommends that every Passivhaus building be equipped with a heat-recovery ventilator (HRV). Since the space heating load of a Passivhaus building is quite low, it can usually be met by using an air-source heat pump to raise the temperature of the incoming ventilation air. In most European Passivhaus buildings, the heat pump’s evaporator coil is located in the ventilation exhaust duct, downstream from the HRV, to allow the heat pump to scavenge waste heat that might otherwise leave the building. In this way, the ventilation ductwork becomes part of a forced-air heating system with a very low airflow rate.

In Europe, most homes are heated with a boiler connected to a hydronic distribution system. Since residential forced-air heating systems are almost unknown in Europe, many Passivhaus advocates declare that their houses “have no need for a conventional heating system” — a statement that reflects the European view that forced-air heat distribution systems are “unconventional.”

Passivhaus Comes Back to the U.S.
The first building in the U.S. that aimed to meet Passivhaus standards was a private residence built by architect Katrin Klingenberg in Urbana, Illinois, in 2003. The home included an R-56 foundation with 14 inches of sub-slab EPS insulation, R-60 walls, and an R-60 roof. Klingenberg specified triple-glazed Thermotech windows with foam-filled fiberglass frames.

Klingenberg later founded a nonprofit organization, the Ecological Construction Laboratory (E-co Lab), to promote the construction of energy-efficient homes for low-income and middle-income families. In October 2006, the E-co Lab completed Urbana’s second Passivhaus building: a 1,300-square-foot home that resembled Klingenberg’s home in many ways.

As Klingenberg devoted more and more time to promoting Passivhaus buildings in North America, she decided to found the Passive House Institute US — basically, a North American outpost of the Darmstadt institute — in Urbana.

Although Klingenberg’s first and second Urbana homes were built to the Passivhaus standard, she didn’t bother to have the homes certified and registered. The first U.S. building to achieve that goal was the Waldsee BioHaus, a language institute completed in Minnesota in 2006. That building includes an R-55 foundation with 16 inches of EPS foam under the concrete slab, R-70 walls, and an R-100 roof. The building’s triple-glazed windows were imported (at a high cost) from Germany.

How Do I Learn More?
An easy way to learn more about the Passivhaus standard is to visit the bulletin board and Web forum hosted by the Passive House Institute US.

In the United Kingdom, the Building Research Establishment has produced an excellent English-language primer on the Passivhaus standard.

A GBA blogger, Rob Moody, is sharing details of his ongoing Passivhaus project in a series of blog postings.

Builders and designers interested in learning more about the Passivhaus standard may want to invest $225 in a Passivhaus software program, the Passive House Planning Package. Available from the Passive House Institute US, the software is a spreadsheet-based tool that models a building’s energy performance to help designers fine-tune the specifications of a building aiming to achieve the Passivhaus standard.

Finally, a 2007 interview that I conducted with Dr. Wolfgang Feist has been posted on the Web by the Passive House Institute US.

Tags: Feist, Klingenberg, passive house, Passivhaus, superinsulation, Waldsee Biohaus

Kudos From an Energy Nerd

adminZeta — Thu, 19 May 2011 22:27:09 +0000

Great blog write up by building science aficionado Martin Halloday, senior editor of Green Building Advisor, from a recent trip to Olympia to tour one of our current Passive House projects, The Jewel Box.

Read full article here.

Excerpt:

This blog, a report on my three-day visit to Passivhaus construction sites and the Passive House Northwest conference in Washington state, picks up where last week’s blog left off.

After leaving the North residence job site, we drove to the Freas house, another construction site in Olympia. The steep site has a dramatic view of Budd Inlet, an arm of Puget Sound, to the west.

Energy Code Sticker for Your Home

adminZeta — Sun, 20 Feb 2011 08:54:27 +0000

Imagine a day out new car shopping… There’s no information provided about the performance of any of the cars for sale. But, every lot has a salesman who assures you that their model is the most fuel efficient model on the road.

Hard to believe, but that is how we’ve been buying houses. Good news, this has changed in the state of Washington.

If you are a home owner or home buyer? Read on…

As of January 2011, the Washington State Energy Code has been updated with a juicy new requirements that will help level the playing field in terms of understanding the energy performance of one house versus another. It simply requires stating basic performance information.

Here’s what it says:

A permanent certificate must be placed within 3′ of the electrical panel that lists your R-Values, widow U-Values, heat type and duct leakage results as well as your envelope testing results.

What does this mean to me?

This is pretty exciting news for the home buyer and the home seller. The real estate industry confirms that a home with a higher energy performance will sell more quickly and at a higher price than a more conventionally built home. The sellers of an energy efficient home can quickly see the value in this. Buyers looking for a high performance home will now have a way to comparison shop. There are many homes stating green features or energy efficiency, but this will actually allow a person to compare apples to apples removing the guesswork.

In the past it would be nearly impossible to know what the performance value of the windows are, or walls, or “how leaky is the house” (which can be measured with a blower door test) much of that information ceases to exist once the installer drives away from the building site or the stickers are peeled off the windows just before move in day. These are basic pieces of information that are easily determined yet pack a huge punch on energy accountability. This is powerful information which will create more informed decisions by homeowners and home buyers in the immediate future.

Fortunately, this type of code language potentially not only addresses comfort and cost issues for individual owners and buyers, but, ultimately, it can have a net positive impact on the bigger regional conservation picture when we consider communities of higher performing houses.

There’s no question, energy efficient homes are here to stay and are only getting better as people are empowered to easily discern the difference between a high performing home and something less.

Energy Performance Monitoring

adminZeta — Thu, 21 Oct 2010 08:25:20 +0000

Some of you are curious to know how our Passive Houses (PH) will perform over time and how accurate the PHPP modeling software really is for predicting continued performance. Well, we’re curious too… but, being so intrinsically aware of how the whole Passive House approach works, we are very confident in its performance. That said, it’ll still be interesting to do some comparisons in a years time, just for fun and nerdy curiosity.

In addition to the testing required by the Passive House Institute US (PHIUS) which verifies compliance with the Passive House performance characteristics, there will be additional testing on our houses by the Washington State University Energy Program. We are now partnered with them under the Building America Program, which is an industry-driven research program sponsored by the US Department of Energy. The program was “designed to accelerate the development and adoption of advanced building energy technologies”. They will be collecting performance data from our Passive Houses over time which will add to their knowledge of cost-effective energy innovations in the building industry. This, of course, leads to a broader base of knowledge that informs how we will all build in the future.

The benefits of the Building America Program to the homeowner is:

Reduced costs—Building America homes use less energy which translates into large reductions in utility bills
Improved comfort—Building America homes are constructed to reduce temperature fluctuations and room-to-room variations
Higher quality—Building America homes utilize strategies and materials that improve the overall structure and operation
Durability—Building America homes are designed to resist long term degradation caused by weather and age
Environmental sustainability—Building America homes save energy and reduce pollution.

There’s quite a lot of great information on their site.

We’ll keep you posted as results come in!

Humidity Control in a Passive House

Randy — Thu, 21 Oct 2010 01:37:36 +0000

We’ve recently received some great questions about humidity control in our Passive Houses, read on to see how we address this hot topic:

What controls the humidity level inside a passive house?

There are two types of ventilation systems available that are being used in Passive Houses. One is a heat recovery ventilation system (HRV), the other is an energy recovery ventilation system (ERV). The difference between the two is that an ERV manages moisture as well as heat while delivering fresh air into the home. With both systems, incoming fresh air receives heat from the stale air that is being exhausted. With an ERV, moisture in the air is exchanged as well. The Artisans Group is specifying ERV’s in all of the Passive Houses that we build.

Does/Can the fresh air system filter the air?

Yes. The HRV/ERV industry is quite mature, and the industry did not develop exclusively for Passive House. The basic provision behind the success of the industry is that of excellent indoor air quality. Moving relatively low volumes of air through highly effective filters is a great way to improve air quality.

In my case, I have a spouse that can be quite sensitive to pollen in the spring. Can the fresh air system be configured to remove dust and pollen from the air?

Filters that are designed to meet the specific needs of all Passive House occupants can be integrated into these systems. HEPA, electronic, and other high-efficiency filtration systems work well with the ERV’s that we install.

Thanks readers for engaging with us, we enjoy hearing from you!

Is Passive House Overkill?

adminZeta — Mon, 18 Oct 2010 08:57:47 +0000

This excellent post is reprinted from a June 16th, Building Capacity blog posting. See original here.

Passive House: Isn’t it a bit of overkill? James Jenkins, Certified PH Consultant responds

Jenny Nakao Hones of Three Frogs Design asks the question: Passive House seems like it could be a great idea for places that have extreme weather conditions, with significant temperature swings. I’m wondering about more temperate climates though, such as the West Coast. Isn’t it a bit of costly overkill?

Great questions, Jenny. For those unfamiliar with Passive House (PH) it’s a green building standard originating in Germany, gaining popularity worldwide. It’s based on predicted performance and results in very low-energy buildings that maintain comfortable temperatures with minimal input. The name is a bit of a misnomer; the German word “haus” translates directly to shelter or building – not house. So it applies to non-residential projects as well as homes. PH’s technical focus is on Energy and IAQ.

The principles found in the PH Standard actually have deep roots in the super-insulation movement of the US mid-west decades ago. Many of these projects failed because moisture and ventilation were not well considered and the same R-values were used universally, independent of climate. PH has taken the idea and infused it with building science to ensure that the problems of the past are not those of the future.

The beauty of this new and improved approach to passive technology is that it addresses what many believe is the biggest threat we face today – climate change and maintaining a habitable planet – in a way that leverages lessons learned about how buildings actually perform, and provides multiple “side” benefits to the building owner (more on that later).

Achieving PH’s strict energy requirements is typically done through a super-insulated envelope, nearly air-tight construction, and a heat recovery ventilator (HRV) to provide continuous fresh air. There is no prescribed approach beyond meeting the maximum energy consumption targets, however. Katrin Klingenberg, Director of Passive House Institute (US) recently completed a post occupancy evaluation of her personal residence in Illinois. Passive House Planning Package (PHPP), the rating system’s energy modeling software, proved to be accurate within 10% of her actual energy consumption and 70% lower than the typical American home.

In another study of a low income housing project, Katrin concluded that the cost per kWh saved was 7 cents when building to PH standards. By way of comparison, this is slightly less than the cost of purchasing a kWh from the Seattle City Light (around 8 cents per kWh). Thus it is cheaper to save the energy than to purchase it. Bearing in mind that in Seattle energy is relatively cheap today, but isn’t expected to stay that way, the long term cost justification for PH will only get stronger. There are several PH projects under construction in the Seattle area, and like other green certified buildings, reported first costs are all over the map – ranging from 0% to 18%. Given this wide range, it does not seem that PH is the driving force where first cost premiums exist.

Let’s discuss your first concern, whether super-insulation is cost-effective in mild climates. It’s important to keep in mind that the PH system includes little reliance on conventional technologies. This is the key to it being cost effective. We need to insulate passive buildings only to the extent that we can minimize or eliminate the traditional heating and cooling equipment found in typical buildings. Precisely calculated insulation values allow the internal and solar gains in a building to be roughly the same as the heat loss through the walls and windows in any climate. Super-insulation may not be necessary, or appropriate, in all climates. In general, higher indoor to outdoor temperature differentials will require higher insulation values in heating dominated climates, moderate climates such as Seattle might require R-40 walls in a single family residence. (This is roughly twice the Washington State Energy code minimum; in colder climates, you’ll see wall values of R-50, 60, or even higher.)

And let’s not forget windows! Even at their best, windows are the single largest source of heat loss in all buildings. PH requires the indoor surface temperature of a window be 64 degrees F, based on the low design temperature for the climate zone. In the Puget Sound area that’s roughly U-.19. The bottom line is that PH projects in milder climates can use less expensive windows and less insulation when compared to more extreme conditions.

An even more important aspect to PH is air tightness. PH details achieve .6 air changes per hour at 50 Pascals (ACH50). This significantly improves energy savings in two ways, by reducing air infiltration, and by redirecting heated air flow through the HRV where it can be of use.

With proven operational savings and a cost-effective design approach, PH is a financial boon to green designers, builders, and building owners looking for answers in this lean and mean economy. But that’s not all the system offers. There are several additional owner benefits, including:

Predictable long term ownership cost;
Comfort;
Passive survivability in cases of lengthy power outages or energy disruptions;
Protection against likely carbon taxation;
Lower replacement cost of mechanical equipment due to less complex systems requirements; and
Future readiness for net zero energy capability.

Designers thinking about employing PH should know that the modeling protocols for PH are not accepted by other rating systems (such as LEED) at this time. Its proven accuracy suggests, however, that it’s a great tool to optimize designs. Designers will be able to identify the least cost strategies required to meet an energy savings target. PHPP software can be used to find just the right window u-values, insulation R-value, and window placement for your project.

For builders wondering how they can make the case to owners, understand that when we design the envelope precisely and with the goal of eliminating the traditional mechanical system, added insulation and better windows are not added first costs but costs that can be offset. The key challenge to the contractor will be meeting the aggressive air tightness requirements. Even at its best, current practice rarely generates anything below 2.0 ACH50. However, this challenge also serves as a tremendous opportunity for the business-savvy contractor to add value to their building projects. Quality assurance on a PH project is critical. Better buildings will be the result. That means fewer callbacks, and better referrals – as well as experience you can transfer to other projects.

James Jenkins, CPHC, CSBA, LEED AP BD+C, and Homes, is a Project Manager at O’Brien & Company, consulting on residential and non-residential green building projects. He is a Certified Passive House Consultant and currently serves as Vice-President of Passive House Northwest. Linda Whaley provided the construction photo. You can see more in-progess shots at her blog Existing Resources.

Comfortable Vaulted Rooms

adminZeta — Thu, 14 Oct 2010 22:08:51 +0000

We’ve had several inquiries during the recent Tour of Homes about the 17’ vaulted ceiling in our featured home. Mainly the question was about heat being captured in the vault leaving the lower areas cooler and less comfortable.

Read on to learn about why vaulted ceilings can be miserable in older homes yet work so nicely in a Passive House:

Comfort in a home is determined by many subjective variables, however what makes a home ‘thermally comfortable’ is well known. Below are the four comfort measures, that, when in balance make for a very enjoyable living space:

•   Air Temperature
•   Temperature of surrounding surfaces (ie walls, windows)
•   Speed of air (draft)
•   Humidity

Let’s say in our typical home, we set the thermostat to 72°F to keep the chill off, anything much lower than that often feels chilly. Then we look at the temperature of surrounding surfaces, inefficient windows, doors and walls will be cooler or cold to the touch. When the heated 72°F air hits those colder surfaces interesting things happen. One thing is that cold air is heavier than warm air, as the heated air cools off on the cold surfaces, it sinks. So, imagine the heated air coming from the furnace is lighter than cold air, it stays ‘high’ up in a room until it starts to cool off on those cold surfaces, it starts to sink, while being replaced by more light, heated furnace air, and so it goes. In older homes this movement of air would be called a… draft. In many older homes, when combined with air leakage this looping of air can actually feel breezy. It’s very uncomfortable.

Then there is humidity. This makes things even more interesting in our quest for comfort. High humidity levels play a big part in why 72°F doesn’t always feel warm enough in our older homes. For example, imagine a winter day in Colorado, at 28°F with low humidity levels, you might actually ski in a long sleeve t-shirt and be very comfortable. While, the same day in Olympia, WA at 50°F with humidity levels above 45% will have you drinking tea in your hot tub.

The other juicy thing about unbalanced humidity in your home is that it can cause loads of condensation on cold windows and walls resulting in serious deterioration and mold issues. Not good.

In a Certified Passive House, we don’t have inefficient, cold windows, doors and walls and we have no air leakage. With super insulation and critically efficient windows and doors, we avoid all that looping of sinking cold air and rising warm air… no draft! The temperature at the vault peak will be within a couple degrees of what it is at floor level. Given that, there is no need to crank up the heat to 72°F to overcome all that air movement found in an older home, in a Passive House 65°F feels exactly like 65°F no matter where you are in the room!

In our Passive Houses, those comfortable, ambient temperatures combine with a fresh air delivery system for a delightful synergy of human comfort, efficiency and durable structure. Passive Houses are so simple and work so well. Pretty cool.

Passive House and SIP's

Tessa — Wed, 06 Oct 2010 01:29:18 +0000

Framing trusses- Passive House

Close up – Larsen Truss wall section prior to tilting into place. Note thermal break between studs.

Thanks to a recent reader comment, we’ve taken the time to address the question (one we often get) about structural insulated panels (SIP) and why we don’t use them. Read on if you are curious.

Comment from reader:
From the photo it appears that you’re not using structural insulated panels (SIP) on this project. Can you tell me what design you’re using? Thanks.

Reply from Tessa Smith, Certified Passive House Consultant | The Artisans Group

Great question! We chose not to use SIPs on our Certified Passive House for several poignant reasons. We found on the North project that we could achieve better energy performance for less cost with a Larsen Truss wall assembly. A Larsen Truss is essentially a double 2×4 wall with plywood gussets at three locations that make the outer wall cantilever off of the interior core, which is load bearing and lateral. This also simplified our floating slab assembly, because we can’t have any thermal bridging in a Certified Passive House, we needed to wrap our foundation in insulation at least 6 inches deep for performance reasons. A SIP could not be used in this instance, they are not strong enough to cantilever one of their skins off of bearing, and a continuous bottom plate would be an unacceptable thermal bridge. The Larsen truss bears on our edge of concrete and then cantilevers over the continuous foam beautifully. SIPs are very costly, and tend to get cut up at every lateral strap location and plumbing or electrical junction.

Another reason we have yet to use SIPs on one of our 12 Certified Passive House projects, is its intrinsic HIGH embodied energy. We try to use as little foam as possible, foam processing and energy consumption in the manufacturing process is not a pretty thing, not for human health and not for the environment. In our project we have air tight construction, paired with an open diffusion wall (a wall that can last over 200 years) with dense pack cellulose or fiberglass, both of which have extremely reduced carbon footprints and cost in comparison to SIPs. Also we don’t expose OSB to the weather side, an element of longevity in my opinion. There are many cases where SIPs don’t last the test of time on there outer skins. In our more recent Certified Passive Houses, we have gotten away from any foam at all, which is very exciting!

At one time, SIPs were a good upgrade to achieve a more energy efficient home, albeit expensive and not accessible for many people. It’s possible there are acceptable uses for them still but, I have yet to find an opportunity where I couldn’t get better performance for less cost and embodied energy on a project. The PHPP modeling software gives us the opportunity to model homes with an accuracy that can’t be touched with ANY other modeling tools available on the market, the kind of information it yields allows us to run iterations and see curves of return on investment with material choice and very subtle design tweaks (the kind that can’t just be rule of thumb). With that, we’ve determined our current construction method to be the most cost-effective, highest performing approach with the least environmental impacts. It just can’t be beat so far.

NPR Interview: Passive House Project

adminZeta — Fri, 24 Sep 2010 16:02:35 +0000

NPR contacted The Artisans Group the other day to interview us about one of our Passive House projects. It’s gotten great press lately having been on the front page of the Olympian in the same week!

We’re pretty excited that Passive House is getting this exposure. It’s such a perfect approach to building homes in our region and it’s particularly exciting to think that building this way could have mainstream appeal. Finally.

Listen to the segment here![audio:http://artisansgroup.com/blog/wp-content/uploads/2010/09/Tessa-on-KOUW-09-23-102.mp3|titles=NPR Interview with The Artisans Group- 9.23.10]

Quick Passive House Refresher

adminZeta — Tue, 14 Sep 2010 00:17:59 +0000

It’s so simple it’s elegant.

Passive House, or Passivhaus as it’s known in Europe, is not a brand name, but rather a design and construction method. It is a measurable approach to energy efficient design and construction that critically relies upon the following to be performed with precision:

Energy modeling the home during design-stage
using the Passive House Planning Package software
Create an airtight building envelope
Insulate with super insulation, WAY more than
is found in a typical building
Install extremely efficient doors and windows
Capture the heat that exists in ventilated air, and use it
to heat fresh, filtered air which comes into the home constantly
Have third-party professionals verify the performance of the home

Passive Houses are mechanically very simple and exceptionally efficient. Due to careful energy modeling, the heating or cooling systems are tiny and are often not needed for much of the year. Also, heat from appliances, cooking and humans are often all that’s needed to keep a Passive House cozy!

That’s pretty much it… but, if you want to know more… please read on.

How is energy performance measured?

The Passive House Planning Package (PHPP) is a complex and proven modeling tool created by the Passivhaus Intstitut of Darmstadt, Germany. Based on hundreds of specific data points, the PHPP predicts energy consumption and performance of a Passive House prior to project ground-breaking. The PHPP considers localized climate data, solar orientatation, comfort criteria, seasonal shading conditions, as well as the internal heat gains mentioned above. The PHPP is empowering as a comprehensive design tool, allowing for the optimization of any project to its architectural design, specific site, building assembly components and budgetary constraints. A few examples, the specificity of the PHPP results calculate valuable information such as potential overheating periods in a given year; it offers the ability to model cross-ventilation or night-flushing to mitigate active cooling needs. We can also accurately determine the size of solar array required to make the project carbon neutral.

What does a Passive House Cost?

The cost to build a Passive House often saves a homebuyer money up front when compared to other methods of construction. In some cases it can add 5%-10% which typically pays back in less than ten years because of extreme energy cost savings. A Passive House is built usually with commonly available materials. The major differentiators of building a PH are in the detailing: no thermal bridging, order of materials in assemblies (consider the building science more thoroughly), super insulation and super efficient windows and doors. In response to the growing national interest in Passive House as the most cost effective, sensible solution to net-zero energy housing, the Washington State University Energy Extension Program has adopted the North Residence as a pilot project this year. They will be collecting data throughout the next year pertaining to energy usage, comfort and indoor air quality.

Required Performance Characteristics

To achieve Passive House Certification, a home must meet specific performance characteristics set forth by the Passive House Institute:

Annual heat requirement of 4.75 Kbtu’s per square foot per year
Primary energy demand under 38 Kbtu’s per square footage of treated floor area
Airtight building shell ? 0.6 ACH @ 50 pascal pressure, measured by blower-door test

In addition, the following are recommendations, varying with climate:

Window u-value 0.8 W/m2/K
Ventilation system with heat recovery with 75% efficiency with low electric consumption @ 0.45 Wh/m3
Thermal Bridge Free Construction 0.01 W/mK

If you want to read more about Passive House, please [click here] for more topics. Enjoy!