Below are a couple images of the project.

View from the front

Entry

The CoreHaus has found a new owner and it looks like it will be well loved. I’ll respect the new owner’s privacy but I will say that the house will definitely be in good hands. We both look forward to seeing how the house will be used but also appreciate spaces prior to furniture and personal belongings filling the voids, so here are some photos they took prior to moving in.

View to the living area

First floor bedroom with translucent closet doors

Kitchen

View into the yet-unfinished courtyard

I’ll follow up with a few “conclusion” posts but closing the sale is definitely an occasion worth marking. Congrats and a big thank you are due to the buyer!

Discounted tickets are available through August 12th for the annual BIG (Build It Green) tour put on by the city of Portland on September 25th. This will another chance to see and learn about the CoreHaus and twenty other “green” homes in the Portland area. I believe all three Portland Passive Houses under construction will be on this tour, so it’s a great time to learn more about this building standard.

For more information, visit http://www.portlandonline.com/bps/index.cfm?c=41893. Oh, and for the discounted tickets enter in discount code: PREBIG.

Last week we finished up siding. For most of the house we chose durable, low-maintenance cementitious siding. Near the front door and along the side yard, however, we used reclaimed wood from the house that used to be at this location. We took the old structural 2×4s, many of them old-growth fir, and cut them in half to expose the grain. We left the sides of each plank as-is, as well as nail holes and other signs of its previous use, to show the history of the wood. In the photo you can also see the beginnings of the canopy that we are currently installing.

http://www.youtube.com/watch?v=Q1XEpXKbT5c

I have paid a lot of attention on this blog to the energy and environmental performance features and their progress. But how is the place looking? You can always get the latest exterior shots on the “Construction Progress” page, but I haven’t posted many interior images yet. With the hanging and finishing of the sheetrock over the past week or so, the interior is really starting to come together. Here are a couple of pictures:

From the front door

The is what you’ll see when you first walk in the front door. The living/dining area is straight ahead, and the stairs are to your left. There is a protective covering over the stairs now, but they will be open so you’ll be able to see through them when we’re done.

View from kitchen

Here’s the view from the kitchen. From here, about where the kitchen sink will be, you’ll look out over the dining area and out to the landscaped yard beyond. A fence and landscaping will block the view of the neighbor.

View from the landing

 There is a large landing at the top of the stairs that can be used as a sitting or office area. It is open to the two-story volume for lots of light.

There’s still a lot of finish work to do but I’m quite pleased with how the space is coming together.

One of the most important components of a Passive House is a HRV, a Heat Recover Ventilator.

“What is a Heat Recovery Ventilator?” you might ask. In short, it is the lungs of the house. Airtight houses such as these require means of providing fresh air, and, while of course windows can be opened or a whole-house fan could be used, these aren’t good methods when the temperature outside isn’t what you’d like it to be. The HRV brings in outside air and exhausts stale air at a controlled rate. It passes through filters and a heat exchanger that, when desired, transfers the heat from the warm outgoing air to the cold incoming air without cross-contamination. This way you get fresh air without heat loss- pretty good deal, huh?

With such an important task to perform, we wanted to get the best unit available. The most important characteristics are a high motor efficiency and good heat recovery abilities. To get the best, a building code appeal was needed. The Zehnder ComfoAir 350 from Germany is well tested and widely used in Europe but has not yet been UL-listed, so it isn’t normally allowed. However, with its track record and performance characteristics it was easily approved by the appeal committee and we set about installing the system.

The Zehnder HRV is particularly ingenious in its design. Each supply or return register is connected back to the main unit (located in the utility room) via a 3” flexible duct. The ducts’ size and flexibility is a big advantage since they fit in standard walls and eliminate the more common metal ducting, which is bulky, often leaks, and requires a sheet metal worker. The ducts are flexible yet smooth on the inside, so the air moves freely and the system stays clean. The whole system essentially snaps together. Of course, with 13 ducts converging in the same place at the unit, it looks a lot more complicated than it really is.

Normally a ventilation system is separate from the heating system. However, since we have such low heat loads, we can provide most of the heat for the house with a 1,000 watt in-line duct heater (see picture). Compare that to a typical hairdryer at 1,875 watts! Supplemental heat will be provided in the bathrooms for those extra cold mornings.

This heater, at about half of the power of a hairdryer, heats the whole house

The next step is to get the HRV tested and balanced, which will be performed by Zehnder. But we’re looking forward to getting it fired up to see how it works!

If you are familiar with Passive House at all (or have been following this blog), you’ll know that one of the biggest challenges (and biggest danger to body hair- see The Goo Factor) is meeting the air tightness standard of 0.6 air changes per hour.  Fail this test and there is no need to submit for certification. Practically every decision that has been made so far has been affected by the need to make the house airtight.

Today Earth Advantage Institute came out to perform the preliminary blower door test. This test is performed just before insulation and drywall are installed so that any potential problem areas can be corrected before everything is covered up. Needless to say, Bart and I were very excited to see if the results of our work had paid off.

A blower door test is relatively simple. A large fan with measuring equipment is attached to an exterior door frame and the house is either pressurized or de-pressurized. The electronics control the fan speed to provide a constant pressure of 50 Pascals. The amount of air that is measured passing through the fan is equivalent to the amount of air that is leaking elsewhere through the building. Using this number and the volume of the house the air changes per hour rating is calculated.

Enough technicalities… what were the results? I’m happy to report that we easily passed the test with a score of about 0.31 air changes per hour, well below the Passive House threshold.

I’m finally back in business after the death of a camera – it’s hard to have a blog about construction without photos! Anyway, the new camera arrived so I can post some of the progress.

In the photo below you can see some of the house’s latest additions- a front door and stairs! The door is white now but it’s going to be a light blue color like the watercolor rendering to add some color. We’re pretty excited about the stairs. As one of the first things you’ll see as you enter the house, we wanted to make them a sculptural element. Unfortunately the photo was taken after the stair tread covers where put on (to protect them during construction) so you’ll just have to wait to see how they turn out. We’re having a cable rail fabricated which should finish off the stairs nicely.

View of the entry from the living room

Solar Oregon’s Goal Net Zero tour last weekend went well and there was a lot of interest in Passive House building techniques. About 80 or so people showed up. Here’s a photo from the event.

Goal Net Zero Tour at the CoreHaus

It’s not too late to get your tickets for Solar Oregon’s Goal Net Zero 2010 tour THIS Saturday, May 8! The CoreHaus is one of the four homes included in this tour.  Using Passive House techniques to slash energy use is a perfect and vital first step toward reaching net zero. The Goal Net Zero tour is more than a tour of houses- also included is a workshop on latest design strategies, an organic lunch, and transportation. For more information, visit http://solaroregon.org/workshops-and-education/tours/goal-net-zero-2010. Hope to see you there!

Meet Tinkerbell, the jobsite cat. Tinkerbell, or so we’ve named her for the bell she wears around her neck, belongs to the next door neighbor. However, she has decided that CoreHaus is her domain. She showed up a few months back as a lightning-quick kitten who would dart in and out of the job shed too quickly for us to even catch her. She’s growing up now and has become more comfortable prancing around the shed (including finding a comfortable place to relieve herself) and the house as if she owns the place.

Tinkerbell is one of the most precocious, curious cats we have met. She enjoys chasing flies, jumping on unsuspecting people’s backs, and exploring. Sometimes we find her in places we aren’t even sure how she got to, mewing for somebody to help her down from an awkward location. She isn’t particularly coordinated either- she was inspecting our laptops on a desk yesterday and managed to fall off the table butt-first, taking a tangle of cords and chargers with her.

Yesterday and today was spent having the roof installed. To obtain the most durable, lowest maintenance roof we chose to use standing seam metal from Custom Bilt Metals. While certainly not the cheapest product upfront, it should last several decades and has one of the lowest long-term costs of any roofing product. The light color was chosen to reduce the heat island effect.

One thing that may be apparent visually, and also contributes to its long-lasting potential, is the lack of penetrations. Air admittance valves have replaced plumbing vents, and there are no skylights, vents, or other holes in the roofing that cause maintenance and durability issues. Photovoltaic (PVs), if added in the future, can be simply clipped to the standing seams and will not require any roof penetrations as well. Roofing is one area where simple is certainly better.

Installing the metal roof

Making the stair treads

- Roof overhang framing: Since there will be four inches of exterior insulation on the roof, the supports for the overhang are located about the roof deck. These were installed and now we are ready to have the insulation and roofing installed.

Roof overframing- will be covered by 4 inches of insulation prior to roofing

- Appeals: Our two building code appeals- to use Air Admittance Valves (AAV’s) to eliminate plumbing vents on the roof and to use a non-UL listed Heat Recover Ventilator, the Zehnder ComfoAir 350, were both approved- thanks to local Passive House pioneer Tad Everhart’s hard work.

- Plumbing and mechanical rough-in: in progress. We received our Zehnder Heat Recover Ventilator- the lungs of the house- and are currently working on the installation. There are a ton of ducts that go into the system- hence the post title. It is a pretty slick system though- more on this later.

Flexible ducting for the Heat Recover Ventilator

The weather has certainly slowed us down, but fortunately, there is plenty of indoor work to be done! With a day or two of decent weather we’ll have the roof installed.

By now, you have probably heard about the all-important blower door test that we will need to pass to meet Passive House standards. The actual test isn’t performed until the building is completely sealed and all systems (mechanical, plumbing, electrical) are installed. Well, the anticipation was too much to bear and we decided to try out our own version of the test- the Sucker Door Test.

With two on-horsepower fans in hand, we set out to find, and fix, any air leaks that could cause us problems during the actual test. By creating a strong vacuum in the house, we were able to locate areas that were leaking air. The pressure created was so strong that our ears popped and it was impossible to open doors or windows once the fans were turned on!

Using a “smoke pencil” (http://www.chimneyballoon.us/smokepencilstick.html), we traced the inside of the house. Anytime the smoke moved rapidly we knew to look for a leak. From the outside leaks were apparent by the hissing sound they made. The most significant leak we found, not surprisingly, was around the patio door. While fully weather-stripped, the door still allowed a fair amount of air to pass through. Other leaks included:

-          Door latch and deadbolt holes in the frame

-          Small holes in the underslab vapor barrier at the edge of the foundation

-          Corners of operable windows

-          Connection between the window frame and the nailing flange

-          Horizontal tape joints where the plywood had a crack on the outermost layer

After sealing up the known leaks, very little air was being moved by the fans. If we can control new wall penetrations, I feel good about our prospects for a successful blower door test.

Today we initiated what is now called “the goo factor.”

Using construction adhesive, we have been building the walls, floor, and roof… The glue will not go or stay where you want it; especially when it’s raining. Once the glue slapped into submission, the sheathing is laid into place. The glue rises up in defiance. It squishes out everywhere; everywhere you need touch; and then onto your lunch. It’s on our shoes, hands, pants, shirt, hair, nose, and other unmentionable places. Once the walls are standing and the joists laid, out comes the spray foam and caulking. Every place that wasn’t smeared with glue to stop air leaks receives a healthy dose of the latter. Caulking is even better at sneaking onto any surface which needs to be bump, touch or shoved.

The last few days has introduced me to a new method of stripping all the hair and some skin off my already weathered hands. Grace Vycor tape doesn’t adhere well to plywood. The solution to this challenge is to apply a primer to the plywood. Grace sells Perma-A-Bond WB primer. They should rename it “just plain sticky stuff.”

We roll it on all the seams of the plywood and window openings in preparation for the tape. On the roof, I quickly discover you should not step on the primer – my foot gets stuck, which precipitates a nice test of the fall gear. The tape could be used in any salon instead of wax. It is only 4” wide and 75’ long. Just one quick pull and you would have a total body wax. When added to the primer the hair isn’t the only part of the dermas which is removed, several layers of skin are also stripped away.

The pièce de résistance is the contact cement. Its name says it all, a little on your knuckle, a little on the wall, contacts the knuckle to the wall, and now the knuckle is part of the wall. To apply the contact cement we use a paint roller, pour out the contact cement on the one and half feet of under-slab vapor barrier sticking out from under the exterior wall, and start rolling. We roll up the walls and all over the floppy, unruly, and stiff vapor barrier. We let it dry a little and then stick the 24 mil plastic to the wall. This is the only time I believe the stiff membrane behaved. Just like the knuckle, the plastic became part of the wall.

I can’t wait for the blower door test to find out of all the skin I have put into this building will pay off. And by the way, I spared you the details of removing any remaining skin trying to get the goo off other parts of the body. Don’t ask.

The biggest challenge of constructing a Passive House, it seems, is preparing to meet the air-tightness requirements of 0.6 air changes per hour. This is about 1/10^th of what a house that is considered “tight” achieves. It is particularly difficult since you can’t get a “progress report” to know how you are doing so far as the entire building envelope has to be completed before the blower door testing can take place. We’re not there yet, but with the exterior framing complete we have already taken a lot of steps:

-          Underslab vapor barrier- See earlier posting

-          Framing-to-sheathing glue: Every plywood/framing connection has been glued instead of just nailed. We’ve gone through almost four cases (48 large tubes) of construction adhesive.

-          Gasketing: We used European-style gaskets available from www.conservationtechnology.com at difficult locations such as the floor and roof rim joists.

-          Foam insulation: Wherever we felt uncomfortable about the wood connection we sprayed foam insulation on the interior

-          Caulking: We may caulk the perimeter of the stud bays at the interior prior to installing insulation, but we haven’t decided if this is necessary.

There are much more that will need to be done to win the battle for an airtight house. The next step is to tape all the exterior sheathing joints. Stay tuned for more on this issue.

Bart installing gasketing

Note: Bart Bergquist, the contractor consultant for CoreHaus, is the contributer to this post.

As a builder, there is always a desire to change the world, or at least my tiny corner of it. Building houses both big and small, remodels from bathrooms to complete house makeovers has offered challenges but little in the way of innovation. The best you can hope for with most of these projects is to fulfill a customer’s dream. Yet the yearning exists to change how the world lives through construction.

Over the past several years some incentives and programs have been created to help advance building practices. Leadership in Energy and Environmental Design (LEED) certified building practices have begun to elevate the need to build with a conscience. EarthAdvantage tries to encourage environmental responsible practices with an emphasis on energy-saving homes. Yet most of the certifications are beyond the budgets constraints of a standard home.

German Passive House Institute may answer the need for an energy efficient home. The approach isn’t a set of rules but performance standards to be achieved. These guidelines have spawned a grass roots creativity to build highly efficient houses. My dream to change the world is coming back, but this ideal is too big for a single person to accomplish.

The CoreHaus project may be my defining moment in a long career in the construction industry. Making the difference is the seamlessly combined efforts of a potentially contentious partnership. The team consists of a builder steeped in tradition, a strong-willed architect, and often stubborn engineer. Working to achieve and surpass the Passive House high standards are challenging yet exciting. The materials, systems, and techniques exist to achieve a home capable of being heated with little or no direct heating system. The really fun part is developing new systems which enhance existing strategies and building techniques.

The greatest credit doesn’t comes from the experience my building skills bring to the table but that of developer and architect Rob Hawthorne. His skills as a designer, architect, and now a craftsman are astonishing. Our friendship has created this building more than any of my skills combined. Through the unlikely development of this team my dream to change the world has come back to life.

Our Serious Windows (yes, that’s the actual brand name) arrived today, a few weeks ahead of schedule. Very few windows that meet the efficiency specifications required for Passive House are available in the US. As seen in the chart, their performance is far above those of the major US manufacturers. With a u-value from .11 to .14, these windows are more than twice as efficient as the latest Energy Star windows (which require a u-value of .30). Also, they are manufactured from fiberglass, which is more environmentally friendly in the manufacturing process and more durable than vinyl. Northwest Energy Savers (www.northwestenergysavers.com),  a local dealer for Serious Windows, was a big help and was very patient with my hundreds of questions.