Hello everyone,
since I couldn’t find any thread under the keywords “basement envelope” in the title, I’m quickly creating one myself:
Current status: A single-family house of about 170 sqm (1,830 sq ft), two stories, is planned with 36 or 42 cm (14 or 17 inches) insulated bricks (probably with perlite). We have not yet carried out the heating load calculation according to the energy-saving regulation, but that will happen in the next few weeks. Nevertheless, at the moment, a ground loop heat pump with ring trench collector is the favorite heating system, along with the planned underfloor heating in all rooms on the ground floor and upper floor. Additionally, a central ventilation system with heat recovery is planned for all rooms on both floors.
Now to the main point. Originally, I had planned the ventilation system with heat recovery also for all basement rooms.
Since there are two home office spaces, a hobby room, and corresponding children’s rooms planned on the ground floor and upper floor, we cannot do without a basement that would include a guest room (also desired), heating and utilities, and storage spaces (please no “you don’t need a basement” discussions, just constructive contributions on whether the basement with the only partially used living space “guest room” should be within or outside the thermal envelope).
Now my question is whether the mostly uninhabited and only rarely used basement (actually only on a few days when the guest room with visitors is needed, but I don’t know exactly how many days per year on average) should be included in the thermal envelope or not. At first, my gut feeling says no, which would mean that the ground floor slab / basement ceiling should be insulated accordingly.
But then, for ecological reasons, I obviously cannot implement the ventilation system for the entire house (including basement). The question is also what kind of heating I should install in the basement guest room (underfloor heating outside the envelope is a no-go). Additionally, how strongly should the basement be insulated if it is outside the thermal envelope (perimeter insulation)?
Of course, in that case, I would have to insulate the basement entrance door accordingly to prevent heat loss or cold air infiltration.
Or is it more cost-effective and ecological to include the mostly uninhabited basement in the thermal envelope, connect it to the central ventilation system, and also install the underfloor heating circuits there? And then insulate the externally waterproofed concrete basement with perimeter insulation? What do you recommend here?
Best regards
ludwig88sta
since I couldn’t find any thread under the keywords “basement envelope” in the title, I’m quickly creating one myself:
Current status: A single-family house of about 170 sqm (1,830 sq ft), two stories, is planned with 36 or 42 cm (14 or 17 inches) insulated bricks (probably with perlite). We have not yet carried out the heating load calculation according to the energy-saving regulation, but that will happen in the next few weeks. Nevertheless, at the moment, a ground loop heat pump with ring trench collector is the favorite heating system, along with the planned underfloor heating in all rooms on the ground floor and upper floor. Additionally, a central ventilation system with heat recovery is planned for all rooms on both floors.
Now to the main point. Originally, I had planned the ventilation system with heat recovery also for all basement rooms.
Since there are two home office spaces, a hobby room, and corresponding children’s rooms planned on the ground floor and upper floor, we cannot do without a basement that would include a guest room (also desired), heating and utilities, and storage spaces (please no “you don’t need a basement” discussions, just constructive contributions on whether the basement with the only partially used living space “guest room” should be within or outside the thermal envelope).
Now my question is whether the mostly uninhabited and only rarely used basement (actually only on a few days when the guest room with visitors is needed, but I don’t know exactly how many days per year on average) should be included in the thermal envelope or not. At first, my gut feeling says no, which would mean that the ground floor slab / basement ceiling should be insulated accordingly.
But then, for ecological reasons, I obviously cannot implement the ventilation system for the entire house (including basement). The question is also what kind of heating I should install in the basement guest room (underfloor heating outside the envelope is a no-go). Additionally, how strongly should the basement be insulated if it is outside the thermal envelope (perimeter insulation)?
Of course, in that case, I would have to insulate the basement entrance door accordingly to prevent heat loss or cold air infiltration.
Or is it more cost-effective and ecological to include the mostly uninhabited basement in the thermal envelope, connect it to the central ventilation system, and also install the underfloor heating circuits there? And then insulate the externally waterproofed concrete basement with perimeter insulation? What do you recommend here?
Best regards
ludwig88sta
L
ludwig88sta23 Dec 2019 10:32-XIII- schrieb:
We didn’t do any calculations because from the very beginning, it was the only option for us to have everything within the thermal envelope. I estimate the additional costs to be around 4500 for insulation and 6000 for building services. The floor area is 10 x 12 m (33 x 39 ft). Okay, how did you ultimately insulate the exterior walls of the basement? Did you also use waterproof concrete?
ludwig88sta schrieb:
Okay, how did you finally insulate the exterior walls of the basement? Did you also use waterproof concrete?We have groundwater pressure and a hillside. Since our architect is very cautious, we used waterproof concrete plus a bituminous tanking system. Everything is then covered with 16cm (6 inch) XPS insulation.
face26 schrieb:
and then consider whether to exclude it from the thermal envelope. How much saving is that supposed to bring?Completely excluding it means saving the insulation on the basement perimeter walls, while the insulation of the ceiling just shifts between the basement ceiling and the slab-on-grade. Including only that room individually and not the rest of the basement doesn’t really work—or only in theory: properly executed insulation in this case would require “thermal breaks” in the slab, which in my opinion no sensible builder would attempt.https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
ludwig88sta schrieb:
You conduct the heat from the electric heater through the WU concrete (whose U-value I don’t know, but it’s probably quite high) directly to the ground outside.Correct, just like in millions of undamaged houses in Germany. Then the heater simply runs at a higher setting and consumes more electricity. But that doesn’t really matter because you only want to heat the room for a few days a year.
L
ludwig88sta23 Dec 2019 14:13rick2018 schrieb:
How do you thermally separate the basement then?
Insulation on the ceilings and walls and a separate entrance, or an additional inner door? I don’t think you save much except on comfort. As @Pinky0301 also mentioned, there are airtight and insulated basement entrance doors, so an additional inner door isn’t necessary.
And insulation at the basement ceiling or ground floor slab makes sense, yes.
@Tassimat I should probably get cost estimates for both options. Then it’s really a matter of budget and preference. Including the basement in the thermal envelope is likely more expensive but offers better comfort and perhaps more future-proofing (if in 20 years a great battery storage is developed that works less efficiently at low temperatures compared to room temperature). Retrofitting would be hardly possible.
Though comparing the annual electricity costs for heating the basement stove during the relatively rare overnight stays of guests to the additional costs of including the basement in the thermal envelope is probably unnecessary, as the difference will be clear. But as I said, it’s about comfort and “done is done, because retrofitting isn’t really an option.”
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