Dear community,
Our building specification includes a controlled ventilation system for our future KfW 70 house. Our developer now wants to sell it to us as having slots on the outside of the windows, where air is drawn into the window frame and then released back into the room through slots at the top of the frame. Although the slots can be opened and closed, this system is supposed to operate without any fans. The best part is that these slots are only cut after the blower door test.
1. Question: Is this sufficient to achieve KfW 70 standard?
2. Question: Is it allowed to cut the slots only after the blower door test?
Thank you very much for your feedback.
Best regards,
Michael
Our building specification includes a controlled ventilation system for our future KfW 70 house. Our developer now wants to sell it to us as having slots on the outside of the windows, where air is drawn into the window frame and then released back into the room through slots at the top of the frame. Although the slots can be opened and closed, this system is supposed to operate without any fans. The best part is that these slots are only cut after the blower door test.
1. Question: Is this sufficient to achieve KfW 70 standard?
2. Question: Is it allowed to cut the slots only after the blower door test?
Thank you very much for your feedback.
Best regards,
Michael
B
Bauexperte11 Mar 2012 23:39Hello,
What kind of system/provider is that supposed to be?
Kind regards
mik schrieb:
Our builder now wants to sell it to us so that there are slots on the outside of the windows, where air is drawn into the window frame and then released back into the room through the slots at the top of the frame...
What kind of system/provider is that supposed to be?
Kind regards
Hello,
I suspect Nibe or SE with a heat pump will be involved.
If it’s Nibe, you’re buying a money pit (operating costs)!
Best regards
mik schrieb:That should not be the case with this description!
...our construction description includes a controlled supply and exhaust ventilation system for our future KfW 70 house.
mik schrieb:Sounds like you got a bad general contractor! Have you already signed the contract?
...Our general contractor now wants to sell it to us like this,...
mik schrieb:What is important to you? Whether he meets it on paper (window dressing), or if it is actually sensible and economical for you?
...1st question: can he achieve KfW 70 with this?
I suspect Nibe or SE with a heat pump will be involved.
If it’s Nibe, you’re buying a money pit (operating costs)!
Best regards
What you’re referring to are so-called window frame vents, which, as far as I know, are the minimal solutions to protect a well-sealed house from mold. In bathrooms, you probably won’t need to install vents. Our house provider installs them in all windows unless you actively opt out.
We also received an offer for KfW 70 and later upgraded to KfW 55. As a result, in addition to a solar system, we had to retrofit a Zehnder ComfortAir 350.
You can find the exact requirements for KfW 70 on the KfW website. It is a comprehensive list of measures, ranging from insulation of the floor/basement to windows and walls. Everything must comply with the standards. Your supplier must guarantee this contractually.
Note: If you plan to have more windows in a room, adjustments are usually necessary.
Regarding the blower door test: Of course, the vents should only be opened after the test, otherwise your house would be artificially made leaky. That is actually the purpose of the vents.
Personally, I’m not a big fan of these vents. I’d rather invest in a proper ventilation system with heat recovery. Unless you can ensure that ventilation is always done properly at your place—in that case, they are better than nothing.
We also received an offer for KfW 70 and later upgraded to KfW 55. As a result, in addition to a solar system, we had to retrofit a Zehnder ComfortAir 350.
You can find the exact requirements for KfW 70 on the KfW website. It is a comprehensive list of measures, ranging from insulation of the floor/basement to windows and walls. Everything must comply with the standards. Your supplier must guarantee this contractually.
Note: If you plan to have more windows in a room, adjustments are usually necessary.
Regarding the blower door test: Of course, the vents should only be opened after the test, otherwise your house would be artificially made leaky. That is actually the purpose of the vents.
Personally, I’m not a big fan of these vents. I’d rather invest in a proper ventilation system with heat recovery. Unless you can ensure that ventilation is always done properly at your place—in that case, they are better than nothing.
M
MüllerausKaarst20 May 2012 21:41Our house under construction is being equipped with an air-to-water heat pump and a ventilation system with heat recovery from Tecalor.
The ventilation system has three outlets in the living room on the ground floor and extracts air in the kitchen and bathroom.
On the upper floor, fresh air is supplied to two rooms while it is extracted from two others.
The used air warms the incoming fresh air through the heat exchanger, supporting the heating system.
This provides a constant supply of fresh air without the need to open windows and helps save on heating costs.
However, the system can be adjusted or turned off if you prefer open windows in the summer.
Best regards from the Rhineland
Ralf
The ventilation system has three outlets in the living room on the ground floor and extracts air in the kitchen and bathroom.
On the upper floor, fresh air is supplied to two rooms while it is extracted from two others.
The used air warms the incoming fresh air through the heat exchanger, supporting the heating system.
This provides a constant supply of fresh air without the need to open windows and helps save on heating costs.
However, the system can be adjusted or turned off if you prefer open windows in the summer.
Best regards from the Rhineland
Ralf
MüllerausKaarst schrieb:
Our house under construction is being fitted with an air-to-water heat pump .....from Tecalor Unfortunately, full modulation is an unknown term there. It uses outdated "On/Off" technology.Best regards
Similar topics