BlowerDoor Test Problems?

2017-11-08 13:36:20

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

Now I have hung the meter box on the (unplastered) interior wall and possibly did not consider the following.

Unfortunately, during the shell construction, we missed applying a smooth finish at the points where the interior walls connect to the exterior wall. Basically, as an airtight layer between the exterior wall and the connection to the interior wall. (Brick: Poroton)

Now I am wondering how problematic this could be for the blower door test?
Do I have to plaster behind the meter box now? Do I also have to install airtight boxes in the interior walls?

I have absolutely no sense of how much pressure loss is allowed or what impact this could have.

Thanks to all of you for any answers!

2017-11-09 13:55:09

Kfw 40 needs, I think, <1.5

I don’t know how big the difference between solid wood and Poroton is.
We are building a passive house and need <0.6. That’s why we had a test before the walls were covered and the screed was poured. The house was still a shell inside, the insulation was just being installed outside.

Sockets normal.
All exterior water taps, sockets, lamp cables, etc. were laid and sealed.
All joints between interior wall and exterior wall, ceiling on exterior wall, exterior wall on foundation slab, etc. were taped with sealing tape.

From experience, I say seal the joint surfaces of exterior wall and interior wall 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.

2017-11-09 20:09:51

Technical Data Sheet KFW 153

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

But since KFW 40+ (ventilation system is 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 (power storage)
• A ventilation system with heat recovery
• A visualization of power generation and power consumption via a corresponding user interface
The electricity creditable in the balance from renewable energies must be generated on the property in immediate spatial connection with the building or its ancillary structures (garage, carport, shed, etc.). This includes e.g. electricity from photovoltaic systems or small wind turbines or combined heat and power systems that are operated 100% with renewable energies.
The electricity generated at the building or its outbuildings should be predominantly used in the building itself. Self-consumption of electricity must be ensured by a prioritization circuit. There must be a physical connection between producers, storage, and consumers (heating, ventilation, lighting, household processes, and household appliances). In grid-feeding photovoltaic systems, the maximum power output at the grid connection point must be limited to 60% of the installed capacity.
The ventilation system with heat recovery must have a heat supply rate of at least 80%. The ventilation system must be able to ensure the planned outdoor air volume flows (nominal ventilation) for the entire balanced building usable area as specified in DIN 1946-6. The ventilation system must be balanced. [The airtightness of the building envelope must be proven by measurement with n50 ≤ 1.5 h-1 (recommendation: n50 ≤ 0.6 h-1)].

That is quite mild. As previously stated, Passive Houses allow a maximum of 0.6.

2017-11-09 20:42:25

Technical datasheet KFW 153

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

That's pretty harmless. As previously mentioned, passive houses allow a maximum of 0.6.

That all doesn't sound very good when you consider that I want to do most of it myself. I hope everything works out the way I imagine.

Thanks for the assessment regarding airtightness.

I spoke with a well-known electrician. He said it’s not that serious. For solid construction, he doesn’t use airtight boxes. He uses normal boxes and foams them with non-expanding PU foam. He says that’s sufficient.

I know the topic is controversial. I will try it anyway...

2017-11-09 21:24:12

That doesn't sound very good, considering that I want to do most of it myself. I hope everything works out the way I imagine.

It doesn't sound good that these contents seem to surprise you if you want to do all this yourself.

To put it differently, since you are already in the middle of it, has the project been properly registered at all? The application must be made before the start of the project or contract signing. What does your KFW assessor say about your explanation?

2017-11-09 21:40:50

It does not read well that these contents seem to surprise you if you want to do all of this yourself.

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

That was not meant that way. I am fully aware of everything stated there.

We have an energy consultant who created the corresponding thermal insulation certificate for us. All necessary documents were submitted to and approved by the KFW.

So everything is fine.

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BlowerDoor Test Problems?

Schluffi0815

haydee

Alex85

Schluffi0815

Alex85

Schluffi0815