We're now busy finishing the kitchen and the bathroom (I'll have more on that in a couple of weeks, the shower stall I wrote about earlier, is going to be real interesting, different from what I had in mind initially, as that wasn't going to work), then we have to do around 500 square feet of oak floor, sand and oil all the floors, and then mid-January the plumber is coming to connect us to the water mains, and we should be able to move in before the end of the month.
I hope we'll make it. I have no (mental) energy left! As expected.
OK, we made it!
It was a nightmare with Murphy's Law doing its thing at every turn, but we managed to finish things enough to be able to move in, exhausted and all. Here's a couple of images with the oak floor installed and oiled:
An interesting period starts now, as we're testing and tweaking all the new stuff, like the heat pump that heats our water, the rain water pump, the heating and most of all, the device I looked forward to most: the Ökolüfter decentral heat recovery ventilation system I described almost two years ago in
this comment (tempus fugit).
Here are a couple of images, and my experiences so far below that:
Basically, the upper fan sucks in air from the house through a polyethylene membrane in the metal drum, and the lower fan presses fresh air through the same membrane. This sucking and pushing causes the drum to turn, and so the membrane takes up around 90% of the heat of the air leaving the house, the drum turns to the next fan and the membrane transfers this heat to the incoming air. Some humidity is transferred as well, so the house doesn't dry out (a big downside of heat recovery ventilation systems).
And it works! There is definitely enough fresh air coming in, even at the Ökolüfter's lowest position, which is around 80 m3/hr. Now, our house has a volume of around 225 m3, which amounts to an
air change rate of 0.35. The inventor of the passive house, Dr. Feist, required an air change rate of 0.3-0.4, so we're already doing good.
Some say you should have an air exchange of at least 30 m3/h per person, a Swiss institute mentioned 22-36 m3/h per person, others say more. I just look at the Green Eye CO2 measuring device I bought a while ago:
With 80 m3/h (perhaps slightly lower) we have a total CO2 concentration that varies between 800 and 1100 ppm every day. Below 1000 ppm is 'normal' according to the Green Eye, above that is 'poor'. I'd like the concentration to be lower than 800 ppm (my brain needs oxygen for the translation work and blogging I do), but for that I'd need to increase the Ökolüfter's air exchange rate. The downside of that is that the device becomes a lot less quiet when turned up.
I'm very sensitive to these kinds of noises (the PC I built myself for instance is almost 100% passive, with the only moving part a big CPU fan that kicks in at a certain temperature) and so I'm happy with 80 m3/h for now. But I will try to reduce the noise level and have asked the manufacturer for advice.
If anyone would like to have more details on the installation process, just let me know.
The great thing about heat recovery ventilation systems is that you don't lose a lot of energy while letting fresh air into your home. During the first few days of living in our home we had to ventilate all the time by opening the windows, because the CO2 concentration was exceeding 2000 ppm, which is really unhealthy. This was a real PITA, and we also lost a lot of heat in the process. That's not so great as the outside temps are freezing at night and during some days as well.
This has been our view ever since we moved in last week:
Beautiful, but somewhat cold.
However, thanks to the Ökolüfter and just two infra red heating panels with a total capacity of 1100 W, we manage to keep the temperature between 18 and 20 °C! That's really the result I was hoping for. It means that we'd need to heat the house with 1000-1500 W for 2 months at most, and that's it. Of course, this amounts to 12-18 kWh a day (and add to that what the heat pump needs to heat the 300 L water storage tank), which IMO is too much. Sure, we have 5.25 kWp of PV capacity, but it produces less than 5 kWh per day right now, which means this energy will have to be produced by coal.
We're going to see how things go for a while longer this winter (I'm hoping for some very low temps as a test), and then we'll have to decide before next winter whether we want to install the wood oven system (20% of the wood energy goes to heating the air, 80% to heating water using a water heat exchanger in the 300 L water storage tank) I wrote about
here.
So, this is our building project so far. I hope to have the energy to set up a website/blog that describes the alternative building aspects of the project, with a lot of data, etc. It's amazing what one can accomplish on the eco/energy level for a reasonable price. Not easy, but doable. I hope it will prove to be a solid foundation for a healthy, sustainable lifestyle that inspires others.