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WilderSueden27 Aug 2022 11:02We already had a brief discussion about this topic in the construction costs thread this week, but now I want to address it separately. Originally, we weren’t sure whether we even wanted cooling, especially after experiencing another “summer of the century”… so I definitely want to have a plan for it. Here are the basic details:
- Northwest inland area of Lake Constance at 660m (2,165 ft)
- KfW40+ monolithic construction with ground-source heat pump, 2 full stories plus attic, both floor slabs made of concrete
- Shading is planned; almost all rooms have windows with different orientations, allowing shading without making the rooms completely dark
- I will mainly be working from home (and working from the garden is not an option)
The actual cooling demand is still unclear. Compared to the current situation, it will certainly improve significantly due to the elevation, distance from the lake, and open surroundings, which should reduce heat and allow much better cooling at night. The main goal is to eliminate peak temperatures; maintaining a constant 22°C (72°F) indoors is not the objective. Daytime temperatures of 25-26°C (77-79°F) are acceptable.
In principle, I also think that with proper shading we are not in a bad position; the roof should prevent heat from pressing into the living areas.
For a few years now, our office has had underfloor cooling, which can be implemented quite efficiently using the ground-source heat pump, so that was our first approach. Unfortunately, the cost for the cooling increased from the original estimate of 2,000 to about 4,000. That seems a bit too expensive for me. Therefore, the next idea was to simply get one of those portable monobloc air conditioning units and somehow seal the hose at the window. You could get a good unit for well under 1,000€. A split air conditioner would of course be more practical, but it would require a core drill (expensive), and I’m unsure where it could be installed. Ideally, it would be installed in the upper hallway, but there we have a large fixed glazing panel in the stairwell. If it had to be somewhere, it would probably be in a corner of the study (labeled Child 2 on the plan), where the architect has drawn in the bed. But then only the study would be cooled. Also, is that even easily possible in an energy-efficient house like this, or would I run into problems with the KfW funding (keyword: deterioration prohibition)?
At the moment, I’m leaning towards the portable solution because it’s affordable and flexible. Any opinions or questions?
- Northwest inland area of Lake Constance at 660m (2,165 ft)
- KfW40+ monolithic construction with ground-source heat pump, 2 full stories plus attic, both floor slabs made of concrete
- Shading is planned; almost all rooms have windows with different orientations, allowing shading without making the rooms completely dark
- I will mainly be working from home (and working from the garden is not an option)
The actual cooling demand is still unclear. Compared to the current situation, it will certainly improve significantly due to the elevation, distance from the lake, and open surroundings, which should reduce heat and allow much better cooling at night. The main goal is to eliminate peak temperatures; maintaining a constant 22°C (72°F) indoors is not the objective. Daytime temperatures of 25-26°C (77-79°F) are acceptable.
In principle, I also think that with proper shading we are not in a bad position; the roof should prevent heat from pressing into the living areas.
For a few years now, our office has had underfloor cooling, which can be implemented quite efficiently using the ground-source heat pump, so that was our first approach. Unfortunately, the cost for the cooling increased from the original estimate of 2,000 to about 4,000. That seems a bit too expensive for me. Therefore, the next idea was to simply get one of those portable monobloc air conditioning units and somehow seal the hose at the window. You could get a good unit for well under 1,000€. A split air conditioner would of course be more practical, but it would require a core drill (expensive), and I’m unsure where it could be installed. Ideally, it would be installed in the upper hallway, but there we have a large fixed glazing panel in the stairwell. If it had to be somewhere, it would probably be in a corner of the study (labeled Child 2 on the plan), where the architect has drawn in the bed. But then only the study would be cooled. Also, is that even easily possible in an energy-efficient house like this, or would I run into problems with the KfW funding (keyword: deterioration prohibition)?
At the moment, I’m leaning towards the portable solution because it’s affordable and flexible. Any opinions or questions?
In a project with estimated total costs well over 500,000 (five hundred thousand), you want to implement a "DIY solution" because of a 3,000 (three thousand) difference. Consider if, as an outsider, you wouldn’t find that "crazy."
My choice would clearly be either air conditioning with core drilling or Passive Cooling through the ground-source heat pump.
My choice would clearly be either air conditioning with core drilling or Passive Cooling through the ground-source heat pump.
WilderSueden schrieb:
That’s why the next idea was simply to get one of those portable monoblock air conditioners and somehow seal the hose at the window.Really a bad idea. You wouldn’t drive around permanently with a spare tire either. That’s only meant for the trip to the workshop.A split air conditioning system is the simplest, most efficient, and effective solution. A core drill hole for this usually isn’t a big deal. It doesn’t have to be a 200mm (8 inches) hole in the masonry.
i_b_n_a_n schrieb:
In a project with estimated total costs well over 500,000 (approximately 500k), you want to install a "makeshift solution" just to save 3,000 (approximately 3k). Think about whether you, as an outsider, wouldn't find that "crazy."
My choice would clearly be either air conditioning with core drilling or passive cooling using the ground source heat pump. And above all, why only now, when it’s almost too late? Why choose ground source at over 40°C (104°F)? An air-to-water heat pump would have been enough. Then, with the saved drilling costs, you could have installed "real air conditioning," if necessary.
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WilderSueden27 Aug 2022 14:15i_b_n_a_n schrieb:
In a project with total costs estimated to be well over 500k, you want to install a “DIY solution” just to save 3k. Don’t you think an outsider would find that “crazy”? Probably yes. And of course, 3k more for a project with a total budget of 550k (all in, including kitchen, land, additional costs...) is not huge. On the other hand, I once again feel like the planning costs are getting out of hand. Something for cooling here, more for the bathroom there, the garden is becoming more elaborate (partly voluntary, partly because of the terrain) and more expensive than planned. Underfloor heating for the screed is currently still unpredictable. Tiles and flooring are arriving the Saturday after next; I certainly won’t get those prices from 1.5 years ago anymore... and so quite a few costs add up... There is still some buffer left, but I’d rather not use it if I have the option.
driver55 schrieb:
And especially, why only now, when the chance is almost gone? Air conditioning was not really a priority for us, and there was always the option of underfloor cooling if we decided to go for it. I would have gone with that now too, but the price no longer appeals to me.
driver55 schrieb:
Why even geothermic with over 40°C (104°F)? An air-to-water heat pump would have sufficed. The money saved on drilling could then have gone into “real” air conditioning, if needed. The general contractor installs it as standard, so I gladly accepted that. Yes, financially it was probably not the ideal solution, but at that time there was also the BAFA subsidy, so the extra cost wouldn’t have been as high as it is now, and I found it much more appealing than the 40,000€ BAFA-eligible air-to-water heat pump everyone else tried to sell me. Today, I would probably plan it differently.
In this respect, the opportunity has passed, the drilling was done at the end of May.
Back to the split air conditioning system you all vote for... what would be a realistic price under the current conditions? And could that cause issues with KfW funding? How much more expensive would it be if installed later as a retrofit?
We are currently in the rough installation phase between the electrician and the heating/plumbing. The electrician is almost finished and said he would do the rest after the plumbing work. That’s a problem because a decision might have to be made quickly if needed.
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