Figure 48. The corner seen in figure 47 as it looks now. The bamboo is temporary (long story) and will be relocated in a couple of months.
The house was move-in ready at the end of September 2010 and we've been living in the house since then. Most things turned out great, but some are still waiting to be completed. Things having to do with the heating/warm water/air systems as well as the lighting and the cabinetry. We hope they'll get done in the next couple of weeks.
Figure 47. The topping-off tree (Richtbäumli) was put up last week!
By tradition, when the roof is finished, a little spruce decorated with ribbons is put up to mark this occasion. The roofing work is the most dangerous and trying part of the construction, so the completion of this is a significant achievement.
Figure 48. The weatherproofing continues.
Majcoat[1] by Siga is a "driving rain-proof and diffusion-open breathable membrane" that creates a windtight envelope.
Figure 49. Close-up of the seams between sheets. The indentation on the left side is for one of the rain gutters.
Wigluv[2] also by Siga is used to seal the overlap areas between the sheets.
Figure 50. I can't resist showing how neatly all the tools and materials were put away for the long (Easter) weekend. This is a corner of one of the bathrooms.
[1] Link to the page about Majcoat.
[2] Link to the page about Wigluv.
Figure 45. Some of the windows waiting to be installed.
Figure 46. Storms were expected over the weekend so the house was wrapped up tightly.
Figure 43. A peek into the installation, upper floor before they started to put the roof on. View towards the east.
Figure 44. One of the roof elements being placed.
Figure 42. A peek into the installation, upper floor. View towards the east.
The first batch of wood elements were trucked to our site yesterday and the woodworkers started their work. This photo is from the end of the working day today, after the upper floor was mostly put together. This stage should be completed by Thursday.
Preparations were made last week to be ready to install the house elements this coming week. So far, the weather forecast is promising...
Since my last update, the scaffolding has been installed in preparation for the wood envelope. The wall elements will be moved into place with the crane and the installers will have the scaffolding to walk around on to access the exterior of the thing. Now we're just waiting for a few clear days.
Figure 39. The concrete shell has been treated against water penetration and extruded polystyrene insulation panels have been mounted. In the foreground is the roof of the technical room, soon to become the floor of the garage.
Figure 40. View from the other side.
Figure 41. Closer look at the ducts for the ventilation system.
The concrete foundation and retaining walls were completed before the winter holidays. Here are a couple of photos showing them at different parts of the process.
Figure 37. Concrete foundation/shell. The black stuff is a bituminous paint.
Figure 38. Most of the backfilling had been done by the time I took this photo. In the foreground the top of the rainwater reservoir tank can be seen. A little patio will be built on top of the area.
No, I haven't abandoned this blog project despite the evidence so far. When I started the blog I wasn't working and I had lots of time to spend on the write-ups. But now that I'm gainfully employed, I can't seem to be able to find a decent chunk of time to work on this anymore. I'm going to try harder: let's see how it goes. So, here's a little report from our trip to Hecht in Sursee to check out the wall construction process.
Figure 34. The upstairs west wall can be seen in the back. The opening is where the door to the patio will be installed. The piece in the foreground is the downstairs south wall. More photos of it below.
Figure 35. One part of the downstairs south wall being loaded onto the trailer. At the bottom left of the photo you can see a wall element edge-on with one layer of insulation.
Figure 36. The same wall, seen from the other side. The rectangular openings are for the ventilation system, as are the round holes. When the thing is assembled, the round holes will be inside the floor and the vents for fresh air will be connected to them.
A little diversion away from our house building story. I had the pleasure of visiting the first Solar Decathlon competition in Washington DC back in 2002 and now I try to follow it "virtually". The winner of the 2009 competition is Team Germany from the Technische Universität Darmstadt with their surPLUShome. Incidentally, Darmstadt is the home of the Passivhaus Institut I've mentioned on this blog before.
Here is a description of the event from Wikipedia:The international and biennial event is sponsored by the United States Department of Energy and the National Renewable Energy Laboratory (NREL). Competing colleges and universities build solar powered homes and operate them on the National Mall for 3 weeks every other year.
The point of the competition is not to create new building technologies. On the contrary, entrants have to use commercially available products to demonstrate that a sun-powered home can be commercially reproduced.
Link → US Department of Energy's Solar Decathlon Homepage
Figure 33. The new calculated energy balance for the house. The numbers are in kWh/(m2). Compare to figure 23.
Back in April I had started to write a little about the calculations of the projected energy usage that had been done based on the components making up the house. Since then much has changed and the structure of the house is now going to be made entirely of wood[1]. The windows have been upgraded to have better energy performance. We also have a new energy planner who is a better fit for our project. He changed the heat pump to a better-tested model, added 4 m2 of solar collector (for hot water) and an Erdregister (earth tube heat-exchanger). The result of all these changes is that we now have an optimized system with lower numbers. Numbers that put us firmly in Minergie-P territory!! Read on for more information...
First, the quantities listed in the diagram above are:
- QiP: heat generated by the residents.Also back in April, in post 021, I had written about the requirements of Minergie. Here again is the relevant equation (refer to the old post for details):
With the new construction plan, the various energy demands are computed to be:
This gives a weighted energy demand of 20.7 kWh/(m2·a). The limit for Minergie-P is 30 kWh/(m2·a), so we are comfortably within this requirement. This is great news!
[1] In the earlier plan, the lower level was going to be made of concrete and bricks, and the upper level out of wood.
Figure 31. The excavator operator checks his work against the plans from time to time.
Figure 32. The trench for the sewer pipes has been dug.
Figure 30. View from the south-west, looking at the excavator sitting on the north part of the land.
A lot of things have happened over the last couple of months but I wanted to wait until the dust settled (so to speak) to do an update. It's high time for it now, as yesterday the ground preparation work started.
We hadn't had the land mowed in months and the ground cover was really quite dense so the first thing that was done was that the sod was turned over using this excavator. I think most of the top layer will be stored on the site, to be used to fill in after the construction ends. The material that is dug out from lower down will have to be transported away and dumped.
There was a misunderstanding somewhere and it appears that the overall cost for the district heating system would exceed that of the version with a heat pump. I still don't understand this clearly so I obviously cannot explain it. So, it's back to the air-source heat pump, though perhaps not the one by Heliotherm.
I'm looking at some of the results of performance tests of these devices done by independent labs[1] to see if I find a favorite. One new issue that I've become aware of is that our technical room[2] is a little on the small side. The heat pump and its associated plumbing will fit, but we really could use the space if we can save it. Also, this type of installation requires large openings from the room to the outside and because this room is partly underground, construction elements called Licht- or Kellerschächte[3] have to be used. I have a great aversion to these things, partly from the maintenance point of view. To circumvent both these problems, I think a unit that is installed outside the house is called for (we had been considering only internal units so far). I have yet to find any indications that they're less effective than the ones installed inside.
[1] One such facility is in Switzerland → Wärmepumpen-Testzentrum WPZ.
[2] Here's a link to an old sketch → Figure 7g. The lower level.
[3] I'm not sure these things even exist in the same form in the Anglo-world. You can do an image search with the keyword "Kellerschacht" or "Lichtschacht" to see some examples.
Back in March (link to the post here), I had written that we would be using a heat pump made by a company called Heliotherm to heat the house and warm water. That model had been suggested to WA by the company that did the first round of energy calculations for us. Since then, there have been some significant changes in the construction elements, and a new energy calculation is being done by a different firm. Also, a new opportunity became available in May, that of district heat[1]. Earlier in the year REFUNA, the company that runs this network, was in the process of adding capacity and they couldn't promise that they could serve us. By May they were able to give us a positive answer.
The advantages of this type of heating system is that they're generally more energy efficient and cleaner than local systems and boilers. They take up less room for installation and are very low maintenance. Wikipedia had a good write up on it, see the link in the footnotes below. In our case, the costs associated with the installation and hook-up should be below that of what it would be for the heat pump system because a lot of the necessary earth removal work will have to be done for the other connections anyway.
I'm actually very pleased about this development as I was not so happy about the air-source heat pump. At very low ambient temperatures, they basically become electric heaters.
[1] District heat is also known as waste heat, or utility-supplied heat. The term in German is Fernwärme, literally "distance" heat or warmth. REFUNA gets its heat from the waste heat of the nuclear reactor in Beznau near where we'll be. The Wikipedia article mentions this → District heating
This is a case where we've had a really big change in our opinion, catalyzed by the suggestions of WA. Our original thought was plaster walls painted white (or in shades somewhere between white and grey in some rooms) with a dark industrial-type floor (more about the floor in another post).
WA suggested that this combination is a dime a dozen and that a much better choice for our house would be to leave the wood of the construction elements visible. Our first reaction to this was quite negative as the examples we had seen so far were too rustic and we didn't really like them except maybe in small chalets surrounded by fields of snow and pine trees. This discussion kept coming up and we kept shaking our heads and finally we went to see a house with an application similar to ours. Actually, if I understand it correctly, ours will be one grade higher than what we saw. The manufacturer, Pius Schuler[1], has recently started producing panels with knot-free, A-grade wood on the visible side which is quite smooth and we were pleasantly surprised and agreed that it does look very nice and airy. The company also has a planning service and they're (re)designing the walls for our house right now. I'll put up detailed drawings once the design is decided. Quite possibly the energy performance will be much better than that of the version I had written about before. More on that topic later.
Figure 28. A close up of a AB-grade Pius Schuler panel in spruce and fir. One half of the panel has been treated with a UV protectant to prevent darkening.
Figure 29. Interior of a house built using Pius Schuler panels in larch. Our version in spruce or fir should be lighter, and have less variation in the strips. More images can be found at the Schuler website.
[1] Pius Schuler is well-known in the Swiss low-consumption wood construction circles → Examples of houses built using Pius Schuler wall elements
I've mentioned a few times already that it is crucial that a good plan be made for shading the (transparent elements of the) house from the sun in the summer to avoid overheating. Generally speaking, this topic is especially relevant in these times of rising global temperatures and there is a strong effort underway to find the best (low-energy) solutions. Organizations such as the European Solar Shading Organization (ES-SO) have some information in English on their websites[1]. Minergie in Switzerland provides guidelines for good practice. See Figure 22 in Post 29 to get an idea of the size of the problem for our house, as calculated for a particular set of parameters.
The German Institute for Standardization (DIN = Deutsches Institut für Normung) provides a useful listing of the rough efficiency factors for different types of shading systems as given in Table 4 below (visit the ES-SO link to see illustrations of these systems). Of course, the actual numbers will vary with the details of the type of materials used. In general, the best systems are those that are installed outside the glazing. For residential applications, roller shutters[2] seem to be the usual choice over here. Aesthetically they're not my favorite as I find them chunky and obstructive. A better alternative are external venetian blinds, with adjustable louvers that allow a view of the outside. They're rather high-maintenance from a cleaning point of view but WA assure us that in our locality we won't have to clean them more than once every couple of years.
| Reduction factor | ||
|---|---|---|
| Type of shade | Fc | |
| No shading | 1 | |
| Internal installation or between the glass panes | ||
| White or reflective surface with low transparency | 0.75 | |
| Light colors or low (less than 15%) transparency | 0.8 | |
| Dark colors or high transparency | 0.9 | |
| External installation | ||
| Rear-ventilated adjustable louvers | 0.25 | |
| Blinds and materials with low transparency, rear-ventilated | 0.25 | |
| Blinds, general | 0.4 | |
| Shutters, roller shutters | 0.3 | |
| Overhangs | 0.5 | |
| Awnings, ventilated | 0.4 | |
| Awnings, general | 0.5 | |
[1] A nice list of the different types of shading systems can also be found at their site → European Solar Shading Organization
[2] Actually, I'm not sure this is the right term for the objects I'm thinking of which are called Rollläden in German
There are so many details of the house under consideration right now that it doesn't make sense to talk about them until we come to some sort of agreement. I'm going to try to write updates as we get close to decisions, to keep a record of the evolution of the process. First up, a discussion of the choice of roof and siding material.
The unusual angular shape of our house demands a smooth transition between the roof and the walls. Ideally, the cladding should be of the same material and this limits the choice to slate, metal or fiber-reinforced cement board[1]. Factor in the cost, and only the last option remains.
In Switzerland there is only one[2] supplier for this material: Eternit. Eternit cladding stock is composed (by volume) of 40% Portland cement, 11% limestone powder and similar, 2% reinforcing fibers such as PVOH[3], 5% process fibers, 12% water and 30% air in the form of pores. The precursor to this material used asbestos fiber, but since 1991 all Eternit products have been asbestos-free. For more information on asbestos cement, see the report at the link at footnote 2.
I haven't been able to find a good example of an unconventional house completely clad in Eternit boards in a way similar to what we're considering, so below are a couple of examples in slate where the roof-wall differences are eliminated. The details here are not important (for example, our house will definitely have gutters), the point is that the same material covers all the surfaces and the format of the tiles is uniform over the two building elements (roof and walls).
Figure 26. House in Wallis by Nunatak Sàrl Architects[4].
Figure 27. House in Basel by Luca Selva Architects[5].
[1] Faserzement in German, I'm not sure of the generally accepted English translation. Fiber cement board and fibrated concrete are some of the terms I've come across.
[2] An Austrian named Hatschek invented fiber cement (using asbestos) and patented it in 1901. He licensed the production method to only one manufacturer per country and it seems to remain that way. More information can be found in this report which deals with the asbestos aspect → The Tragedy of Asbestos
[3] PVOH is a synthetic polymer → Polyvinyl alcohol
[4] Details at ArchDaily → Zufferey House
[5] Details at ArchDaily → House in Lupsingen
I should say: the one we let get away.
Once in a while, I like to look back at my collection of notes to see how things have come along since we embarked on this house project. I had mentioned before that our architects had originally (in November 2008) presented us with two distinctly different designs to choose from. In the interest of keeping complete records, here are a couple of drawings of the one that we decided against.
Figure 25a. Plan B upper level.
Figure 25b. Plan B lower level.
There were many things we liked in this plan, but in the end we happened to like the other one better. I would have selected this design if we had neighbors living closer to us. In that case, the secluded garden and courtyard would have been more desirable. What is not apparent in these drawings is that the garden and courtyard are actually on different levels (the stairs are not drawn in).
Given the particulars of our land, with the open southern exposure, we think that the design we chose (click here to go directly to the post where I discuss that) makes better use of it. I particularly like that all the rooms, including the main bathroom, have views out on that side.
Which one might you have chosen? Feel free to leave a comment.
Over the last few weeks, our architects — I'll refer to them as WA[1] from now on — collected bids from various planning firms for specific aspects of the house. It seems that construction activity around Switzerland, at least in the part where we live, is still quite intense and several of the companies that WA have worked with in the past decided not to submit bids for our project. Even so, WA made sure there were at least two bids in each category and we had a meeting last week to make the final selections. The categories we covered were as follows:
- the Bauingenieur: the people who calculate things like the statics of the building, in particular the parts in the ground which must be executed in concrete
- the Holzbauingenieur: the people who will do the details of how to construct the house in wood
- the HLS-Planer: Heizung (heating) Lüftung (ventilation) Sanitär (sanitation)
- the Elektroplaner: responsible for planning the electrical network
Once these "third-party" plans are in, they'll be sent out for bids from firms that actually do the work, such as build concrete structures and install plumbing. Meanwhile, WA are looking at every detail of the house and re-evaluating them, looking for the best solutions. New ideas are still being considered. I'll be giving updates here as things are finalized. We had not realized that so much designing would be done after the Vorprojekt (initial project) phase and I must say that we're really, really pleased with all the effort. This is our first experience working with architects and so far it has been excellent!
WA → Walker Architekten
