ᐅ Blower Door Test Issues?

Hello,
we have just finished the shell and roof of our KFW40+ house.

Now I have mounted the electrical panel on the (unfinished) interior wall and might not have considered the following.

Unfortunately, during the shell construction, we missed applying a smooth plaster layer at the points where the interior walls meet the exterior wall. This would serve as an airtight layer between the exterior wall and the interior wall connection. (Masonry: Poroton)

Now I am wondering how problematic this could be for the blower door test.
Do I need to plaster behind the electrical panel now? Do I also need to install airtight electrical boxes inside the interior walls?

I have absolutely no idea how much pressure loss is acceptable or what impact this might have.

Thanks for any answers!

I believe KfW 40 requires less than 1.5.

I’m not sure how big the difference between solid wood and Poroton is.
We are building a passive house and need less than 0.6. That’s why we did a test before the walls were covered and the screed was installed. The house was still a shell inside, and the insulation was just being applied outside.

Standard electrical outlets.
All exterior faucets, outlets, lamp cables, etc. were installed and sealed.
All joints between the interior wall and exterior wall, ceiling to exterior wall, exterior wall to foundation slab, etc. were taped with sealing tape.

From my experience, I would say just seal the joint surfaces between exterior and interior walls and that’s it. At least with solid wood, the interior and exterior plaster as well as the insulation don’t seem to change the values much.

Your architect or energy consultant should be able to tell you exactly.

Technical Data Sheet KFW 153

Requirements for the airtightness of the building envelope according to Annex 4 of the Energy Saving Ordinance do not apply if no ventilation system is installed and no reduced air exchange rate is used in the efficiency house verification. However, the airtightness of the building envelope of a KfW efficiency house must be measured. If a mechanical ventilation system is installed, airtightness of the building envelope must be demonstrated by measurement in accordance with Annex 4 of the Energy Saving Ordinance.

But since KFW 40+ (ventilation system mandatory anyway):

Additional requirements for a KfW Efficiency House 40 Plus
A KfW Efficiency House 40 Plus meets the requirements of a KfW Efficiency House 40 and includes the following plus package:
• A power-generating system based on renewable energy
• A stationary battery storage system (electricity storage)
• A ventilation system with heat recovery
• Visualization of electricity generation and consumption via an appropriate user interface
The electricity credited in the balance from renewable energies must be generated on the property in direct spatial connection with the building or its ancillary structures (garage, carport, shed, etc.). Examples include electricity from photovoltaic systems, small wind turbines, or combined heat and power systems that operate 100% on renewable energy.
Electricity generated at the building or its outbuildings should be predominantly used within the building itself. Self-consumption of electricity must be ensured by a priority control system. A physical connection must exist between generators, storage units, and consumers (heating, ventilation, lighting, household processes, and appliances). For grid-feeding photovoltaic systems, the maximum power feed-in at the grid connection point must be limited to 60% of the installed capacity.
The ventilation system with heat recovery must achieve a heat recovery rate of at least 80%. The ventilation system must be capable of delivering the planned outdoor air volume flows (nominal ventilation) for the entire calculated building usable area as specified in DIN 1946-6. The ventilation system must be properly adjusted. Airtightness of the building envelope must be demonstrated by measurement with n50 ≤ 1.5 h-1 (recommendation: n50 ≤ 0.6 h-1).

This is quite moderate. As previously mentioned, passive houses allow a maximum of 0.6.

Alex85 schrieb:
Technical Data Sheet KFW 153



But since KFW 40+ (ventilation system mandatory anyway):



That is quite manageable. As mentioned before, passive houses allow a maximum of 0.6.

It all sounds a bit challenging, considering I want to do most of it myself. I hope everything works out the way I envision.

Thanks for the assessment regarding airtightness.

I spoke with a well-known electrical installer. He said it’s not that critical. For solid construction, he doesn’t use airtight boxes. He uses standard boxes and foams them with non-expanding PU foam. He thinks that will be sufficient.

I know this topic is controversial. I’m going to try it anyway...

Schluffi0815 schrieb:
That doesn’t sound very promising, especially since I plan to do most of it myself. I hope everything works out the way I imagine.

It’s concerning that this information seems to come as a surprise to you if you intend to handle most of the work yourself.

On a different note, since you are already in the middle of the process, has the project been properly registered? The application must be submitted before starting the project or signing any contracts. What does your KFW consultant say about your execution plan?

Alex85 schrieb:
It doesn’t sound good that you seem surprised by this content if you want to do everything yourself.

To put it differently, since you are already in the middle of it, has the project been properly registered? The application must be submitted before starting the project or signing the contract. What does your KfW assessor say about your execution?

That wasn’t what I meant. I am fully aware of everything mentioned there.

We have an energy consultant who prepared the required thermal insulation certificate for us. All necessary documents were submitted to and approved by KfW.

So everything is fine in that regard.