ᐅ Retrofitting an air conditioning system – will that affect KfW funding?

Created on: 10 Jun 2021 21:02
H
Helado
Good evening everyone,

Since October, we have been living in a prefabricated house built by Hanse Haus. We have been living here for about 5 months now and are very pleased.

However, at the moment, the indoor temperature in each room is between 26°C and 28°C (79°F and 82°F), even though it is similarly warm outside. The only way we can lower the temperature is by opening the windows at night.

We have a KFW55 standard and a Stiebel Eltron LWZ 5s Plus. Unfortunately, it does not have an active cooling function, but we have installed and activated the summer cassette in the menu settings. So far, this has not produced the desired result. The temperature remains the same.

We are now considering adding air conditioning, but we have been clearly advised that this might mean no longer meeting the KFW energy-saving regulation standards, and therefore, it might affect the eligibility for subsidies. Fortunately, it is not very hot outside at the moment, but when it reaches 35°C (95°F) outdoors, the temperature inside the house can easily rise to around 30°C (86°F), which is not exactly comfortable.

Does anyone have advice or experience with retrofitting air conditioning (in specific rooms) or with the same heating system?

Thanks & best regards
Helado
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ypg
16 Jun 2021 12:13
Why not simply use thermal protection in front of the windows (lowering the roller shutters) and add some plants in front of the patio door? This is actually the common practice, proven effective for centuries.
You don’t always have to rely on technology that tends to complicate the purpose and implementation.
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Dogma
16 Jun 2021 12:14
K1300S schrieb:

Sure, but keep in mind that somewhat thicker pipes need to be installed.

I believe this is about a split air conditioning system, not a chilled water system. For the latter, each indoor unit requires its own line (liquid and gas).
AllThumbs schrieb:

I'm currently considering preparing the bedroom, children's room, and office. The living room is adjacent to the utility room, so something could still be added later...

We have one outdoor unit and five indoor units. The outdoor unit is what really costs money; the indoor units are comparatively inexpensive. So it makes sense to install them all at once.
K1300S16 Jun 2021 12:20
Of course, and I wasn’t referring to that air hose, but the pipes are overall quite a bit thicker than, for example, an electrical cable.
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Dogma
16 Jun 2021 12:22
That’s correct; I believe they had insulation of about 5cm (2 inches) and 3cm (1 inch).
K1300S16 Jun 2021 12:24
In our case, the slots were about 8 cm (3 inches) wide and 8 cm (3 inches) deep. That means a significant part of the wall was missing, and the opening was approximately 10 cm (4 inches) in diameter.
Mycraft16 Jun 2021 12:30
In our experience, a 50mm (2-inch) HT pipe is sufficient to connect everything for an indoor unit.
ypg schrieb:

That is actually the common practice. It has proven reliable for centuries.
However, houses were built differently centuries ago compared to today. Either the walls were so thick and the windows so small that sunlight stayed outside, or the walls were so thin and permeable that air exchange happened quickly. Insulation panels designed to retain heat were also nowhere to be found.