ᐅ KfW 55 or just the Energy Saving Regulation – Gas heating and minimal ventilation?
Created on: 16 Feb 2018 10:23
S
Sony70
Hello dear forum members,
We will start building our house in September and have already signed a contract with the builder for a KFW 55 house with a central ventilation system and an air-source heat pump.
However, just the day before yesterday, the question arose again—after we realized that the kitchen extractor hood can only be installed as recirculation and not as exhaust due to the ventilation system and the negative pressure caused by an exhaust extractor hood—whether we should build a house more like in the past, meaning not so airtight that we would need a ventilation system, and use gas heating. Initially, this was our plan, but the sales representative at the builder advised against it. Since houses nowadays are so airtight, a ventilation system is necessary. That results in dry air, so additional measures are required. Also, the air-source heat pump is expensive, consumes a lot of electricity or makes you dependent on electricity prices, and with all its electronics, it is quite prone to malfunctions. If it breaks down, significant replacement costs are to be expected.
Yesterday, I spoke with the site manager at the builder about this issue. We discussed this question as well. He said that he would personally build his own house without ventilation and with gas or oil heating. Now the question is: Is this still allowed nowadays under the 2016 Energy Saving Ordinance (EnEV 2016), or will the requirements force me to build such an airtight house again that I would need a ventilation system? Then there is the question of whether I would really save anything overall by switching from the air-source heat pump to gas heating, since I would need an indoor chimney again.
Is it true that if I use gas, I definitely have to install solar thermal panels on the roof, or is there still the alternative of building the house more airtight (which of course would require ventilation again)?
Thank you in advance for your advice.
Best regards,
Sony
We will start building our house in September and have already signed a contract with the builder for a KFW 55 house with a central ventilation system and an air-source heat pump.
However, just the day before yesterday, the question arose again—after we realized that the kitchen extractor hood can only be installed as recirculation and not as exhaust due to the ventilation system and the negative pressure caused by an exhaust extractor hood—whether we should build a house more like in the past, meaning not so airtight that we would need a ventilation system, and use gas heating. Initially, this was our plan, but the sales representative at the builder advised against it. Since houses nowadays are so airtight, a ventilation system is necessary. That results in dry air, so additional measures are required. Also, the air-source heat pump is expensive, consumes a lot of electricity or makes you dependent on electricity prices, and with all its electronics, it is quite prone to malfunctions. If it breaks down, significant replacement costs are to be expected.
Yesterday, I spoke with the site manager at the builder about this issue. We discussed this question as well. He said that he would personally build his own house without ventilation and with gas or oil heating. Now the question is: Is this still allowed nowadays under the 2016 Energy Saving Ordinance (EnEV 2016), or will the requirements force me to build such an airtight house again that I would need a ventilation system? Then there is the question of whether I would really save anything overall by switching from the air-source heat pump to gas heating, since I would need an indoor chimney again.
Is it true that if I use gas, I definitely have to install solar thermal panels on the roof, or is there still the alternative of building the house more airtight (which of course would require ventilation again)?
Thank you in advance for your advice.
Best regards,
Sony
You don’t need a chimney for gas, but rather a LAS (air/exhaust system, commonly called a chimney). This is not more complicated and only slightly more expensive than a vent pipe (wastewater vent) through the roof.
Therefore, no significant additional costs are to be expected here.
However, you do need a gas connection plus a meter, which depending on the supplier can easily start at around 3,000 (three thousand) or more, depending on distance and other factors.
Don’t get me wrong, but this statement shows a lack of understanding. No matter what kind of house you build, especially if it is supposed to meet KFW requirements, it will be as airtight as a plastic bag, or, if poorly executed, then not so airtight.
About 1,000, but nowadays I wouldn’t want to build without humidity recovery.
Only an energy consultant from the general contractor or an independent expert can help you with that. The ST is naturally the path of least resistance for everyone.
Therefore, no significant additional costs are to be expected here.
However, you do need a gas connection plus a meter, which depending on the supplier can easily start at around 3,000 (three thousand) or more, depending on distance and other factors.
Sony70 schrieb:
whether we should still build a house like before, meaning not so airtight,
Don’t get me wrong, but this statement shows a lack of understanding. No matter what kind of house you build, especially if it is supposed to meet KFW requirements, it will be as airtight as a plastic bag, or, if poorly executed, then not so airtight.
Sony70 schrieb:
(how much more does it cost with humidity recovery)
About 1,000, but nowadays I wouldn’t want to build without humidity recovery.
Sony70 schrieb:
to achieve KFW 55 here, or do we need the ST for that?
Only an energy consultant from the general contractor or an independent expert can help you with that. The ST is naturally the path of least resistance for everyone.
Sony70 schrieb:
we cannot apply for the KfW loan nor receive the additional 5000 subsidy. This amount doesn’t even cover the extra effort, so it’s just a bonus if you happen to plan measures that meet the KfW55 standard anyway. I think aiming for that standard just because of the subsidy is nonsense. In my view, KfW55 offers from developers are primarily a sales argument with the message “comply with a future standard today = create higher value stability.” The builder/homebuyer is meant to have the romantic idea that they will pay off their little house faster because they will owe much less to the utility company.
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11ant schrieb:
I don't follow that conclusion: the same control command can also result from the hood being turned on. Well, and where does the air that the extractor hood pulls out come from? That's why linking it to the window is the right approach.
A bit off-topic:
We are currently planning/buying an apartment.
Energy Saving Ordinance 2014, no KfW standard with heat recovery. The developer says in this context that a recirculation system is completely sufficient or can even be omitted because the system gets the necessary air.
Is this correct or just nonsense?
We are currently planning/buying an apartment.
Energy Saving Ordinance 2014, no KfW standard with heat recovery. The developer says in this context that a recirculation system is completely sufficient or can even be omitted because the system gets the necessary air.
Is this correct or just nonsense?
Cooking fumes mainly consist of moisture, odors, and grease. These three components need to be removed somehow. Moisture can be easily ventilated out through the ventilation system. Odors may take longer to eliminate than with a ducted extractor, but that’s not a problem; if it bothers you, you can simply open a window as usual. However, grease cannot be ventilated out and will instead settle on various surfaces and become sticky if not cleaned off promptly. A good recirculating hood with an activated carbon filter can help reduce odors while dealing with grease.
I am planning to buy a recirculating hood. Currently, we have a ducted extractor, and I find it incredibly annoying to always have to open the window (even at -20°C (–4°F)). However, I would not completely give up on using an extractor.
I am planning to buy a recirculating hood. Currently, we have a ducted extractor, and I find it incredibly annoying to always have to open the window (even at -20°C (–4°F)). However, I would not completely give up on using an extractor.
So far, we have been cooking without an extractor hood. It works perfectly fine. After cooking, we just wipe down the surrounding cabinets. Eventually, we will get a proper one.
So, just open the windows, do a little cleaning, and that’s it. That’s why I would never give up my beloved ventilation system.
So, just open the windows, do a little cleaning, and that’s it. That’s why I would never give up my beloved ventilation system.
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