ᐅ Retrofitting an air conditioning system – will that affect KfW funding?
Created on: 10 Jun 2021 21:02
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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
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
D
Deliverer22 Jun 2021 21:45Are low-temperature radiators excluded from the cooling system? If not, don't they cause the lower limit temperature during cooling to be raised, since condensation happens much faster on those devices?
Otherwise, I hope you weren't afraid that I would confront you! I'm not upset with anyone who doesn't have air conditioning. ;-) And I also understand that there can be significant differences between houses and lifestyles. In the best case, you need neither heating nor air conditioning. But that is usually not the case on average.
Otherwise, I hope you weren't afraid that I would confront you! I'm not upset with anyone who doesn't have air conditioning. ;-) And I also understand that there can be significant differences between houses and lifestyles. In the best case, you need neither heating nor air conditioning. But that is usually not the case on average.
Deliverer schrieb:
However, the two systems complement each other very well: The "Dicke Berta" (heating system) can, for example, extract a solid 5 kW of heat energy from the house. At the same time, a small, energy-efficient air conditioning unit can dehumidify the air, which also works very well across rooms.
So the answer is yes. Both. Does your statement/recommendation also apply when using a central mechanical ventilation system with heat recovery, which should dehumidify the air anyway?
Deliverer schrieb:
I would install it right away. Cheaper, cleaner, and currently even subsidized. Two friends have recently built houses, both (against my advice) did not install air conditioning (since the insulation is so good!!). One family has been sleeping in the basement for days, the other has no basement and is suffering. (Admittedly, no one has admitted I was right yet ;-) Admittedly, I probably count myself among those, as we are currently building a KfW55 (timber frame) house with mechanical ventilation with heat recovery but had initially planned to forgo air conditioning. However, for the past few days, I have seriously been considering taking advantage of the current stage of shell construction to install one directly.
Since I have not looked into the details or obtained any quotes yet, can a rough estimate be made regarding costs and subsidies? The latter, of course, depends on the system and is not fixed.
What kind of ballpark figures would one expect for a new build?
Thanks in advance!
netuser schrieb:
a central controlled residential ventilation system, which should dehumidify the air anyway? Without a dryer and/or active cooling, the controlled residential ventilation system can naturally only dehumidify the air during winter. In summer, the system works exactly the opposite and actually brings even more humid air into the house.
netuser schrieb:
however, they wanted to do without an air conditioning system. For the past few days, though, I have seriously been considering taking advantage of the opportunity during the shell construction phase to install one directly. Take advantage of the opportunity. Take another moment to honestly reconsider. If necessary, consult a physics book and please set aside any prejudices. Air conditioning systems are not inherently bad or the ultimate climate villains.
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pagoni202023 Jun 2021 12:32netuser schrieb:
For several days now, I have been seriously considering taking advantage of the opportunity during the shell construction phase to install one directly. That is exactly the choice I made. I have two quotes and it will be installed. It’s simply that humidity affects me and ruins my enjoyment. For that reason, my preferences have been more towards Scandinavia or Patagonia rather than Asia.
I know people who are less bothered by it; for example, my wife likes to sit directly in the sun, while I always prefer the shade. At cafés, we always look for places where both options are available 🙄
I think that although many calculations can be done here, ultimately the personal comfort is what really matters to me.
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Deliverer23 Jun 2021 13:26netuser schrieb:
What are the approximate costs for a new build in this case? So far, I have only done retrofitting, unfortunately. The rule of thumb is about 1000 € per kW of cooling capacity. So, a 2.5 kW unit from a well-known manufacturer (Mitsubishi Electric, Daikin...) should cost less than 3000 € in total, all included.
For a new build, the installation of the cooling system might be somewhat cheaper because there is no need to install cable ducts, and the hole in the wall is already there. On the other hand, someone else has to chase the walls and possibly perform core drilling... So, it probably balances out.
The main advantage is that the installation won’t be visible in the end, and all holes will be neatly sealed. Also, the electrician can install a separately protected circuit cleanly. Maybe even add a meter (out of curiosity) next to it on the DIN rail.
And most importantly: the condensate water can be drained directly without a pump.
Especially in a well-insulated new build, you should pay attention to the lower performance limit (just like with a heat pump for heating). If you are willing to operate the air conditioning as sensibly as the heating (turn it on, let it run continuously), and you don’t aim for 18°C (64°F), you don’t need a 5 kW unit. Units between 2.5 and 3.5 kW are definitely sufficient.
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