Saturday, November 10, 2007

The Window Challenge

When aggressive goals rule, determining which window takes the “Best of Show” in the Green event was the intent of my trip to Germany this past weekend. While en route to Lautenbach, Germany I picked up Barbara Kingsolver’s book “Animal, Vegetable, and Miracle” to augment the trips goal of finding more ways to achieve the perfect ecological balance. The book turned out to be the perfect complement to the weekend’s pursuit of finding the “best” windows in the world.

Before I begin, let me introduce you to the cast of characters for this trip:

The first character is Sam Bontrager, better known to many as “Sammy,” or, if you are one of those that have been lucky enough to know him well, “Geisbock.” Sam is an architect with whom I worked for five years at SEH before he took a job with another Minneapolis firm. We have managed to collect a number of stories together through a variety of life’s adventures. Among many fine attributes, he is fluent in spoken and written German. So when I asked for his help in interpreting some technical information about the German windows, he came to my rescue. It just so happens that to satiate his desire to travel, he works for NW Airlines on weekends primarily to avail himself of free travel opportunities for employees. With one desire supporting another, it wasn’t long before he had concocted a free flight to Germany, with me covering the hotel and food expenses of the trip. Sam’s fluency in German and his 100% German DNA came in handy. (Did you know Germans call their cell phones handy’s?).

Klaus Muller, is the window expert and a staunch environmentalist. I think Klaus was green before blue and yellow were even created. Klaus owns Muller windows a small environmentally friendly window manufacturing company whose niche is creating the most energy efficient/ecologically friendly window possible. He is a 35-year-old partner in a three generation family-owned company that is nestled in the foothills of the Black Forest. It is apparent that the Fertile Crescent is still alive and well in this area of Germany. Muller Windows has partnered with several other small, local window manufactures to market their product under the Optiwin label. Their particular niche within this group is to promote these environmentally higher performance windows in the international arena, with specific sights on the US market.
Giving a Readers Digest’s version of what I discovered may not be possible, but here’s my attempt to keep is short and sweet,

Hummmmm, what is the operational definition of “finest”, “best” or “top” when discussing green or environmental friendly windows? The highest ranking requirement, at least for our project in a very cold weather climate, no surprise, is its ability to insulate from the cold. Second most important is the passive solar gain, or what Klaus taught me, the “g” factor or the energy gaining potential of a window, this a W/(mK) unit of measure. The other factors pale in comparison, but are worth mentioning:

Integration into a building design that is aggressive about reducing energy useage.
Use of sustainable/renewable materials
Reuse of waste byproducts

Isolative quality:

Kingsolver describes in her book the benefits of knowing who and how the farmer produces the food you eat. Well, after this weekend I believe these same benefits are present regarding knowing the products for the building industry as well. Sam and I spent three days with Klaus and his family getting to know them and seeing first hand how they walk the talk. There wasn’t a question that he answered without backup material and supporting data to substantiate performance. Below is a copy of the McKinsey Quarterly report that Klaus gave me to describe to us why Muller windows believes that making the insulation value of a window is of highest importance. This chart is making the argument that increasing building insulation provides the biggest bang for the buck in saving long-term operating costs and reducing our negative environmental impacts.

The Passivhaus Institute was founded by Wolfgang Feist, who Klaus endearingly calls the “Pope” of green design in Germany. The Passivhaus Institute is a non-profit, non-commercial organization that has set a very high standard for energy efficiency of buildings. You can read more about it at this web site I will henceforth refer to this institute as the passive building institute, because I believe haus in Passivehaus leaves a somewhat inaccurate impression that the institute deals only with residential construction, which is not the case. Simply put, you set an aggressive bench mark, such as 5 kBTU/ft2 yearly for conditioned spaces, this can only be acquired through very aggressive building design and construction measures of occupied space. A building is certified by Passivhaus Institute to meet these standards only after an stringent energy modeling has been completed and air tightness testing has occurred of the completed building. Over 6,000 buildings in Germany and Europe have been certified through the Passive Building Institute and one in the US. There are three more in the US in the design and or early construction phases.

In order for a window or door to qualify for the Passivhaus building certification, they have to be tested using one of the most stringent window testing labs in the world. Unfortunately for us, no North American wood window can meet or exceed these PassivHaus measures, nor do we have any US made window wood or material that meet these standards. North American windows come close with some of the fiberglass windows now being produced in Boulder Colorado and in Canada. The R factor of the Mueller window is R 7.1 the center of glass is R factor is R 9.47.

It turns out that a “one size fits all” window in terms of energy performance is the only window supplied by most large US window manufacturer (e.g., Anderson, Pella, Marvin). For these companies, it makes sense from a business model to build something that is multipurpose for the US window market, but from a user/buyer having one general all purpose window design that is best used in a temperate climate, greatly inhibits making appropriate choices for what is best in very cold weather climates such as northern Minnesota.

As of this date, my research on high performance windows has not lead me to any companies that can produce the required very high performance as an all-wood window. There is a window called Alpen Fiberglass Windows that have the highest performance window on the market, but they are made outside the US in Canada, and at least for me, they do not represent the most ecologically friendly choice regarding the material used to create them.

As a side note, during my attendance of the GreenBuild conference in Chicago this year I attended the presentation of the 2007 products of the year award session and Alpen Windows was honored with being selected as one of the top ten picks. GreenSpec and Environmental Business News sponsor this selection process. Criteria for their selection process and why they have it is described on their web site at Alpen’s window have an amazing performance of R 20 for the center of glass and R10 for the unit. See attached performance information. When I questioned Alex about the environmental friendliness of fiberglass, he supported my judgment that it is not the best material regarding ecological manufacturing processes, however performance of wood windows has not achieved these higher standards so the tradeoff is a judgment call.
Here is more specific information on the window performance values.

I am seriously thinking of using the glazing product from Alpen windows with the wood frame and sash from Mueller as an approach to our project. Interestingly, Alex Wilson, the presenter also made the statement that unfortunately there are no US windows made that compete with these performance levels.

Additionally it appears that the small, more custom fit window manufacture doesn’t appear to exist in our local market place.

PS: Apparently, low e glass is the standard for all windows in Germany, largely because it is required by law. Low e glass has a R factor of 2.84 to give you a bench mark to compare the difference in the windows.

Passive Solar gain or “g” factor:

The ability of a window to capture as much of the longer wave lengths of the sun that will reduce the heating demands of the building comes in a strong second regarding factors for quality.

The higher the “g” factor the better it will perform in cold climates and the lower the g the better it will perform in warm climates.

The equivalent “g” factor in the US is the Solar Heat Gain Coefficient and again the higher the SHGC the better the window is especially for the south facing glass.

Integrated Design

Touting R or U values, without the realistic R or U values that include the window assembly, is like judging a book by its cover. The real story is how it performs in an assembly. It is pointless to put quality windows in an assembly that greatly reduces its performance. So, unless you are committed to high performance buildings, “one size fits all” windows might be the better investment. Klaus provided data on the loss’s that occur due to the materials adjacent to the window and the need to cover part of the jambs of his windows with insulation to assure the highest R value possible. We will be changing the precast sill to a metal sill to reduce the material that is of low insulating value with a combination of materials that is higher. I will post the window details finished for your review.

Additionally, he reminded me that sealing the inside of the building in lieu of the outside is more important, this prevents the moisture from getting into the insulation and walls. He showed us a material that he uses to create the interior window framing to make a water proof barrier that is demanded by the Passive Building Design.

Use of sustainable materials

The ability to have a wood window that doesn’t need painting, use of wood that is air not kiln dried, comes from a sustainable forest, and uses cork as the insulating material is a prototype window that is hard to beat. Small amounts of metal and sealant are currently used in his windows and are not what Klaus considers as sustainable material, however, but seem necessary until we create a better way to manage the movement of water into and through wood surfaces.

Klaus calls this his ecological window and uses three different three types of wood in them: larch for the exterior wood, pine for the interior, and cork for the insulation. The natural oil finish over the fir interior surface complete the assembly in what appears to be the best answer to a achieving an ecologically friendly window that I have come across to date. My eyes and ears are still wide open though.

Production practices of the window:

The Mueller window is assembled in a factory that is heated by the by waste wood products of his wood window manufacturing process. Because he had more waste than needed to heat his manufacturing facility, he created a small “heating utility company” that serves five other buildings on his street. He sells heat to these buildings from his wood-fired boiler system. Klaus gave us a tour of his 10-year-old wood fired heating system and is shown below in this picture. He thinks he will return his investment for capital output in about 15 years with some help of local governmental support, but return it immediately regarding environmental payback. Emissions are very low using a high temperature combustion for the biomass fuel source. To inaugurate the system he threw a party with live music inside the waste wood hopper.

I need to verify if his building as Passivhaus certified. However, features on his building did include other passive design features such as solar wall for passive gain in the winter and cooling in the summer due to deciduous vines covering the wall, solar shading shutters, etc.

We were able to visit Klaus’ sister’s Passivhaus certified home and were intrigued by the by the supply air vents, the future consideration for turning the house into more than one flat for future older parent care opportunities (cradle to cradle concepts), self closing kitchen drawers that actually pull themselves inward, wood stove that keeps most the heat out of the central living area and into the vestibule, air conditioning unit being supplied by ground source heat pumps, the lack of the need for screens, the need to control fabric breakdown by UV solar radiation, bugler-proof locks, three point locking doors, exterior doors that are the same construction style as the windows thereby keeping the house and all its contents warm, not just the air in the house. We also discussed the idea of “perceived warmth” extensively and how radiant heat from the surrounding building materials can make one feel warm at a lower air temperature. Think of being on a ski hill when the sun is out and how you can feel quite warm, despite the air being very cold. Below are some of the pictures of what I have described above.

Functionality and Aesthetics:

I am going to lump all these into rating criteria, since there really is no good accounting for individual taste. Suffice it to say, the Germans do produce precision made, high quality products when comes to functionality of almost anything. The windows are a tilt and turn style, that allows the window to be open and not be in the path of the user. They have clean lines and little ornamentation to allow for ease of restoration. In my mind, they are indeed a thing of beauty that few would dispute.

Discussion points:

Buying a window 6,000 miles away, when a slightly lower “quality” product can be purchased within 500 miles is arguably a difficult decision to make if energy and reduction of carbon dioxide production is the goal. We have yet to calculate the carbon dioxide generated to ship this windows as well as the reduction in carbon dioxide generation due to it’s high performance over an estimated 50-year window life span. Fiberglass windows of comparable design are available from Canada, but lack some of the sustainable manufacturing practices that Klaus’ windows have to offer. An argument to be made is the need to create a demand for this window in our area so that improved locally produced products become available and thereby making this a more viable choice for Americans.

While Forest Stewardship Council or equivalent certification processes do not exist for German forests, the Germans, and Europeans more generally, have proven themselves by managing for several centuries their renewable forests.

Full circle

After seeing the results achievable by this small German window company, I have come to the conclusion that similar to the unhealthy outcome of our food industry due to a “one size fits all” mentality and monopolizing of the seed industry, an equally unhealthy byproduct of having only a few large manufacturing conglomerates be the sole suppliers of most building products with little variation for application in the highly varied climates in North American. Having only slow moving gorilla company’s that has no mission other than to maximize profits for shareholders as the model for long-term environmental sustainability is not in anyone’s long term best interest. The model of building an economy around the opportunities to reduce emissions in an approach that address’s the business and environmental issues together.


Tom said...

I commend you on your eco-endeavors, but can't see how it is possible to justify the purchase of German windows when, as you stated in the article, the difference between fiberglass and wood can boil down to a judgment call.

Fiberglass is maintenance free, strong, durable, and locally manufactured.

Attempting to further parse the environmental stewardship of various companies strikes me as a bit of over-reach. We all have an environmental impact. The important thing being that we strive for continual improvement; not unattainable and non-existant perfection.

Notwithstanding my petty criticisms, I'm sure your house will turn out wonderfully. What product did you end up specifying for entry doors?


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kanchan tyagi said...

Really very awesome thought is that we have to put Tilt and turn windows in our home because they don't take to much space and look very attractive. So thankful to you for posting this blog.