Join Joerg Birkelbach for a hands-on workshop and presentation about exciting new air sealing products and techniques developed for the European building industry and now available in the United States; all are welcome.
The two events will be held in Seattle and Portland.
Here is a continuation of our global survey of houses that are both high performance and high design. See the previous blog entry for the introduction.
Stroh Haus, Eschenz, Switzerland
Designer: Felix Jerusalem, Zürich, Switzerland
Completed: 2006
Construction: Compressed Straw fiber panels
Energy use: 15 kWh/m²a
Minergie energy standard
GV5ER8CCB42C
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Passive House in Skibet, Denmark, designed by aart Architects
We enjoy hearing about buildings with impressive performance data or interesting wall assemblies. However, what gets us far more excited are high performance buildings that are simply beautiful.
In their early stages, green building movements such as Passive House tend to attract visionary but often more technical thinkers. Advances in socially and environmentally responsible buildings often come at the cost of thoughtful design, as designers, builders and clients, filled with a sense of purpose, strive to meet new technical or environmental challenges. Unfortunately, architecture is seldom green, and far too often, green buildings are not architecture. The Brute Force Collaborative don’t mince their words when they claim that “most homes being built are horrendous and almost as many being peddled as green are really just greenwashed and appalling.” Therefore we applaud those who bridge the gap and manage to do both: practice the art of crafting beautiful spaces that also happen to not require barrels of oil to build and occupy.
Veteran Passivhaus architect Walter Unterrainer is quoted in Michelle Kaufmann’s blog echoing this sentiment: “While Walter commends the Passivhaus intentions, he says that it is about more than that. It is about good design. ‘Designing a Passivhaus is easy. But we need to make sure we are designing good Architecture as well.’ It is much more than just calculations and scientific numbers. ‘Good architecture is not a scientific result.’”
Our cedar siding, which we acquired from Enyeart Cedar, has finally arrived on site for our Passive House, and is in the process of being installed. We are using 4″ tongue and groove boards in a horizontal rainscreen application.
Our cedar arrived prestained and ready to go. Since we are using two tones of stain on the building, it was quite a challenge to find a set of colors that worked well together and that everyone on the team agreed to. We found that testing stains is extraordinarily difficult since paint shops don’t offer samples, and most brands only sell their stains in gallons. We were not willing to take a leap of faith and order 15,000 linear feet of stained wood based solely on 1″ color swaths on a paper brochure, so our decision to go with the “Olympic” brand was largely due to the fact that they were one of the only brands that offered quart-sized samples.
The garage siding is mostly completed by now, and the main house is quickly catching up. Here are our latest photos:
Some samples of exterior wood stains on cedar. Many of these were blends we made from existing tones in an attempt to find the right combination of tones.
In order to protect the decks below the balconies from water we opted to detail our two balconies as closed assemblies with tiled surfaces and built-in gutters. The balcony surface slopes away from the glass doors toward a linear gutter which spans the balcony’s front edge, making it easy to keep our door frames protected, even in snowy conditions.
A curb was built around the balcony perimeter in order to give the balcony an even and level edge. The surface was covered in a self adhesive waterproofing (Jiffy Seal 140/60) and all edges, curbs, and connections to the gutter were additionally reinforced with a liquid waterproofing (PTL 1350TG) to create a continuous seal.
The finish surface is ceramic tile, but since one can count on some water getting through the grout, we placed a drainage layer between the waterproofing and the tile – the “Ditra Drain” from Schlüter, which is a polyethylene honeycomb mat that will allow water to drain into the gutter. This gives us three lines of defense against water infiltration.
diagram of our balcony waterproofing system
Prior to applying the siding, we had several more layers to add. All necessary penetrations for wiring were made for exterior lighting and to power the sunshade motors. All of these penetrations were carefully sealed and gasketed in order to maintain our high level of air tightness. Since the exterior siding will be 5 1/2 inches outboard of the outer layer of sheathing, all attachments that need to fasten directly to the structure, such as the attachment of the metal brackets that will support the sunshades, were made at this point.
Next came curb flashing and the additional 4″ of EPS foam insulation that will further minimize our thermal bridges and help bring our heating loads down to the levels required to meet the Passive House Standard. Over this we applied weather wrap and the furring strips that will support our siding.
These unistrut brackets will support the sliding 'barn door' style exterior sunshades. The brackets themselves will be hidden.
We would like to introduce our design for the Salamander House, the other custom home project of ours which we are designing to meet the Passive House standard.
The Salamander House, currently in design development, is to be located on a remote forested lot 10 miles west of Hood River on the Washington side of the Columbia overlooking the Columbia River Gorge. The house, which will be nestled into the slope of the property and resting underneath an oak forest canopy, will boast spectacular views south over the river towards Oregon, but will also pose quite a challenge due to the remoteness and steepness of the site. The entire property has a slope of 28 degrees (53%).
spectacular view from the future living room
Understanding that generally the more local option is the more sustainable one, we initially struggled a little with our decision to order our windows from Europe. Our friends at Brute Force Collaborative recently posted a fascinating blog entry in which they investigated the carbon footprint associated with shipping high performance windows all the way from Europe. Can the superior performance of European Passive House Certified windows over the best windows available in the North American market justify the energy expenditure of an international shipment? Their conclusions are surprising. Check out their post here:
Can European windows actually save carbon?
Their study is especially relevant to us at Root Design Build since the European brand they used in their comparison is the “Internorm Varion” window line we used for our own “Shift House”.
To tape or not to tape? Because the installation method of our windows was not typical in this part of the world, we did run into some differing opinions on how to best seal the window assembly. The big issue here is to avoid trapping moisture – whether coming from rain infiltration, diffusion from building materials, or air leakage – inside the wall assembly. Standard windows with flanged frames are typically taped and/or caulked from the outside, generally allowing moisture buildup in the gap between wall and window to escape toward the inside. However, for inset windows such as ours that are not attached to the exterior surface, it was recommended that we place the primary air seal (silicone or tape) on the interior side of the window frame. This is to pressure moderate the cavity, and to prevent warm, moist interior air from getting into that gap where it would condense as it cools. The bigger point of contention regarding the assembly, however, was what to do on the outside of the window frame. Do we seal the exterior perimeter with tape?
RDH Group, our local building science experts who have given us much invaluable advice on our foundation, wall, and roof assemblies, weighed in on this issue. Their concern with installing seals on both sides of the frame was that this would create an un-drained pocket between the window and the surround, a condition they typically discourage. A seal on the outboard side of the window, in addition to the interior seal, would create the potential danger that if the outside seal fails, water may become trapped between the two seals.
They felt that our interior seal plus spray foam already gave us two air seals and a thermal barrier around the window, and recommended that the exterior side be protected solely by the cladding or other “shedding” surface, allowing the cavity to weep out excess moisture. And If any seal was applied to the exterior, at least the seal at the sill of the window should remain open to drain any water that might get into the space.
Window installation sprayfoamed but not sealed from the exterior
Originally, as you can see in earlier renderings, the exterior was designed to be clad in white stucco with some highlights of dark-stained wood siding. We felt that this high contrast between the two materials, and the smooth continuous surface created by the stucco, would accentuate the reading of the shift – of the building sheared in half and offset to reveal the balconies. Additionally, we felt that the monolithic look of stucco seemed appropriate cladding to represent our thick 14″ walls, and we were drawn to the material since its use would have been a nod to the predominant building practices of our home countries (Germany for me, Serbia for VJ and Milos).
However, as the design evolved, we began to lean more toward cladding the building only in cedar siding. We felt that the simplicity of cladding both the house and garage in only one material would benefit the design, that as a renewable northwest material, natural cedar would be more responsive to the surrounding buildings, and that it would be more expressive of the green building practices we are incorporating. Additionally, since we have 4 inches of EPS foam (see details) between the siding and our structure, we realized that it would be exceedingly challenging to adequately attach an assembly of materials as heavy as stucco to the side of the building.
So here is our revamped look, using horizontal 4″ tongue and groove cedar siding with two semi-transparent stains. What do you think?
rendering of the south face with sunshades open
