Hello everyone,
After getting in touch with about half a dozen home builders and having a clear idea of our project (i.e., wishes versus what is feasible), we have now narrowed it down to two builders. Both use different methods to achieve KfW70 energy efficiency standard.
We plan to build a single-family house with approximately 135 m² (1453 sq ft) of living space, including the basement.
Builder A (A* House):
This will be a timber frame construction. They rely on a gas condensing boiler + solar system + controlled ventilation (mechanical supply and exhaust ventilation). The recommendation here was to use gas with an underground gas tank as the solution (which would offer the advantage of being able to choose the supplier). Overall, the conversation seemed the most competent to me, at least judging by my limited knowledge.
Builder B (L* Solid Construction):
Although this is also a prefab manufacturer, they build solid construction (if that term can be used here). According to the representative we spoke with today, the Klimapor walls (which look like a rice cake) are built without membranes, so a mechanical ventilation system is not necessary. To meet the KfW70 standard, they would install an air-to-water heat pump.
In most other aspects, including pricing, both are quite similar. Now we are unsure how to proceed. Builder B told us today that omitting a ventilation system only has advantages. From what I have found so far in my research, the prevailing opinion is different. With a mechanical ventilation system, you supposedly cannot just open the windows whenever you want, or it would affect the costs and performance of the system or limit its purpose. On the other hand, you save on the gas connection costs. Also, since the walls don’t have membranes, the ventilation system would not be necessary anyway. This sounds somewhat... odd to me.
Now we are quite uncertain. We usually sleep with the window open (summer and winter). In the summer, we basically keep the balcony doors open all the time in the living room. We do not want to give that up.
What should we do? Are Builder B’s claims correct or nonsense? Has anyone had experience with this topic or with these builders?
We would be very grateful for any advice!
Best regards, Andi
After getting in touch with about half a dozen home builders and having a clear idea of our project (i.e., wishes versus what is feasible), we have now narrowed it down to two builders. Both use different methods to achieve KfW70 energy efficiency standard.
We plan to build a single-family house with approximately 135 m² (1453 sq ft) of living space, including the basement.
Builder A (A* House):
This will be a timber frame construction. They rely on a gas condensing boiler + solar system + controlled ventilation (mechanical supply and exhaust ventilation). The recommendation here was to use gas with an underground gas tank as the solution (which would offer the advantage of being able to choose the supplier). Overall, the conversation seemed the most competent to me, at least judging by my limited knowledge.
Builder B (L* Solid Construction):
Although this is also a prefab manufacturer, they build solid construction (if that term can be used here). According to the representative we spoke with today, the Klimapor walls (which look like a rice cake) are built without membranes, so a mechanical ventilation system is not necessary. To meet the KfW70 standard, they would install an air-to-water heat pump.
In most other aspects, including pricing, both are quite similar. Now we are unsure how to proceed. Builder B told us today that omitting a ventilation system only has advantages. From what I have found so far in my research, the prevailing opinion is different. With a mechanical ventilation system, you supposedly cannot just open the windows whenever you want, or it would affect the costs and performance of the system or limit its purpose. On the other hand, you save on the gas connection costs. Also, since the walls don’t have membranes, the ventilation system would not be necessary anyway. This sounds somewhat... odd to me.
Now we are quite uncertain. We usually sleep with the window open (summer and winter). In the summer, we basically keep the balcony doors open all the time in the living room. We do not want to give that up.
What should we do? Are Builder B’s claims correct or nonsense? Has anyone had experience with this topic or with these builders?
We would be very grateful for any advice!
Best regards, Andi
P
perlenmann7 Nov 2013 14:01Sounds really outrageous! First of all, I would say: DO NOT SIGN ANYTHING!
Regarding the controlled mechanical ventilation system, what some sellers say is sometimes unbelievable—I’ve experienced it myself, and I almost got convinced. But I managed to change my mind and decided to go with a controlled mechanical ventilation system. And I’m glad I did. The main purpose of controlled mechanical ventilation is fresh air. In winter, the outside air is naturally cold, so it’s great to have fresh, preheated air continuously and automatically. In summer, the ventilation system runs at a minimum. I still don’t need to air out after showering—I go straight to work. And when it’s not too warm outside, we keep the patio door open all day, or the bedroom windows.
What’s important is not to achieve the “KfW 70” value, but how this value is achieved!!!
Instead of a solar thermal system, for example, you can reach this value by increasing insulation (or something along those lines). The controlled mechanical ventilation lowers the value just as much, as does switching from gas to a heat pump.
Whether all this makes economic sense is another matter entirely.
Regarding the controlled mechanical ventilation system, what some sellers say is sometimes unbelievable—I’ve experienced it myself, and I almost got convinced. But I managed to change my mind and decided to go with a controlled mechanical ventilation system. And I’m glad I did. The main purpose of controlled mechanical ventilation is fresh air. In winter, the outside air is naturally cold, so it’s great to have fresh, preheated air continuously and automatically. In summer, the ventilation system runs at a minimum. I still don’t need to air out after showering—I go straight to work. And when it’s not too warm outside, we keep the patio door open all day, or the bedroom windows.
What’s important is not to achieve the “KfW 70” value, but how this value is achieved!!!
Instead of a solar thermal system, for example, you can reach this value by increasing insulation (or something along those lines). The controlled mechanical ventilation lowers the value just as much, as does switching from gas to a heat pump.
Whether all this makes economic sense is another matter entirely.
Bauer78 schrieb:
Hey everyone,
I hope the decision hasn’t been made yet.I think the original poster has already made their decision, whatever it may be. The initial thread is now 1.5 years old.
P
perlenmann7 Nov 2013 15:01Man, I just fell for such an old chestnut 🙄
@Bauexperte: Then you have to change post 1 as well 🙂 otherwise the edit doesn’t make any sense
@Bauexperte: Then you have to change post 1 as well 🙂 otherwise the edit doesn’t make any sense
B
Bauexperte7 Nov 2013 16:19perlenmann schrieb:
@Bauexperte: Then you need to update Post 1 as well 🙂 otherwise, the edit doesn't make senseThank you for your note. Also done :-)Regards, Bauexperte
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