Good morning,
We are planning to build a house for five people. Until now, we didn’t have to deal with this at all and have been living comfortably in our detached house that is already 40 years old.
Now, due to work reasons, we need to move again.
However, we have some time since we are currently still commuting (almost 3 hours every day).
The financing is basically secured, as we can sell our current house. The rest is mostly covered by the car costs we save.
We already have three offers: two for solid construction and one from a prefabricated house manufacturer.
The most cost-effective option so far is the following:
Increased thermal insulation of the base slab, highly insulating brick masonry, increased insulation of the facade, as well as insulation in the upper floor roof area as needed.
Efficient heat pump (Tecalor THZ 304/404 SOL including a three-year manufacturer warranty) with a 235-liter (62-gallon) hot water tank and preparation for cooling and connection of a solar system. Controlled ventilation with cross heat exchanger for up to 90% heat recovery, including pollen and fine dust filters. WEB module (Internet Service Gateway) with remote diagnostics and maintenance. Underfloor heating on the ground floor (except utility room) and upper floor, including room thermostats integrated into the switch program. Climate protection windows, triple-glazed (Ug 0.7-0.9), with mushroom-head locks and security fittings.
Built as a KfW 55 (energy-efficient) house. However, as I have read in construction blogs, this is done only with 17.5 cm (7-inch) Poroton bricks and exterior insulation with polystyrene.
Now comes my question: How should we approach this? Does it make sense to build it this way? The many posts confuse us completely.
Maybe you could at least point us in the right direction at first.
Best regards, Xinette
We are planning to build a house for five people. Until now, we didn’t have to deal with this at all and have been living comfortably in our detached house that is already 40 years old.
Now, due to work reasons, we need to move again.
However, we have some time since we are currently still commuting (almost 3 hours every day).
The financing is basically secured, as we can sell our current house. The rest is mostly covered by the car costs we save.
We already have three offers: two for solid construction and one from a prefabricated house manufacturer.
The most cost-effective option so far is the following:
Increased thermal insulation of the base slab, highly insulating brick masonry, increased insulation of the facade, as well as insulation in the upper floor roof area as needed.
Efficient heat pump (Tecalor THZ 304/404 SOL including a three-year manufacturer warranty) with a 235-liter (62-gallon) hot water tank and preparation for cooling and connection of a solar system. Controlled ventilation with cross heat exchanger for up to 90% heat recovery, including pollen and fine dust filters. WEB module (Internet Service Gateway) with remote diagnostics and maintenance. Underfloor heating on the ground floor (except utility room) and upper floor, including room thermostats integrated into the switch program. Climate protection windows, triple-glazed (Ug 0.7-0.9), with mushroom-head locks and security fittings.
Built as a KfW 55 (energy-efficient) house. However, as I have read in construction blogs, this is done only with 17.5 cm (7-inch) Poroton bricks and exterior insulation with polystyrene.
Now comes my question: How should we approach this? Does it make sense to build it this way? The many posts confuse us completely.
Maybe you could at least point us in the right direction at first.
Best regards, Xinette
We are currently planning to build as well (there is something missing in the floor plan).
"Increased thermal insulation of the facade" <-- What exactly does that mean? Compared to what?
"Efficient heat pump" – this refers to an air-to-water heat pump... which is generally somewhat controversial – it depends on where you plan to build... the warmer the better.
"However, as I read in construction blogs, only with 17.5 cm (7 inches) Poroton brick and then exterior insulation with Styrofoam." ... that wouldn’t be my choice, but without knowing the thickness of the Styrofoam, this is not very helpful.
The worse the insulation, the more critical the performance of an air-to-water heat pump.
Overall, this sounds like very effective advertising wording.
Back to the air-to-water heat pump:
tecalor GmbH THZ 404 SOL 2.82 3.46 4.19 1 6.38 kW EN 14511 5.0 K
Your pump has a COP of 2.82 at -7°C (19°F) – what does this mean? It produces 2.82 kWh of heat from 1 kWh of electricity. What does that imply? If your house ends up with a heating demand of about 20,000 kWh, you would consume approximately 7,100 kWh of electricity, which translates to around $150 per month in heating costs. Heating with gas would cost about $109. (I checked the local utility’s website for reference.) This is roughly a worst-case scenario. If you look around, some people report consumption of up to 7,000 kWh of electricity for their air-to-water heat pump... which is obviously not ideal and does not contribute to low operating costs, but rather ensures that the builder easily meets funding program standards (heat pumps are calculated much more favorably than gas).
This changes, of course, if you build a passive house or similar (very good insulation) – then these systems can be worthwhile, especially since they also handle ventilation. If you are thinking more idealistically, ground-source heat pumps would probably be preferable – they cost significantly more but have COPs around 5.
"Increased thermal insulation of the facade" <-- What exactly does that mean? Compared to what?
"Efficient heat pump" – this refers to an air-to-water heat pump... which is generally somewhat controversial – it depends on where you plan to build... the warmer the better.
"However, as I read in construction blogs, only with 17.5 cm (7 inches) Poroton brick and then exterior insulation with Styrofoam." ... that wouldn’t be my choice, but without knowing the thickness of the Styrofoam, this is not very helpful.
The worse the insulation, the more critical the performance of an air-to-water heat pump.
Overall, this sounds like very effective advertising wording.
Back to the air-to-water heat pump:
tecalor GmbH THZ 404 SOL 2.82 3.46 4.19 1 6.38 kW EN 14511 5.0 K
Your pump has a COP of 2.82 at -7°C (19°F) – what does this mean? It produces 2.82 kWh of heat from 1 kWh of electricity. What does that imply? If your house ends up with a heating demand of about 20,000 kWh, you would consume approximately 7,100 kWh of electricity, which translates to around $150 per month in heating costs. Heating with gas would cost about $109. (I checked the local utility’s website for reference.) This is roughly a worst-case scenario. If you look around, some people report consumption of up to 7,000 kWh of electricity for their air-to-water heat pump... which is obviously not ideal and does not contribute to low operating costs, but rather ensures that the builder easily meets funding program standards (heat pumps are calculated much more favorably than gas).
This changes, of course, if you build a passive house or similar (very good insulation) – then these systems can be worthwhile, especially since they also handle ventilation. If you are thinking more idealistically, ground-source heat pumps would probably be preferable – they cost significantly more but have COPs around 5.
Does this mean, conversely, that with a better wall and a possible gas heating system, we can also achieve the KfW55 standard? Does the cross-flow heat exchanger make sense as well?
We plan to install a wood stove. It can provide additional heating during cold winters.
Could you also tell me something about a ground source heat pump?
Is it worthwhile? What geological conditions do we need to consider?
Thanks in advance.
We plan to install a wood stove. It can provide additional heating during cold winters.
Could you also tell me something about a ground source heat pump?
Is it worthwhile? What geological conditions do we need to consider?
Thanks in advance.
Geothermal heat pumps are expensive... about 20,000€ (approximately $22,000) more compared to gas - it only pays off after 12-15 years (at least for deep drilling). If you have a large property, surface collectors can also be installed underground – this is usually cheaper. But I would suggest talking to heating specialists – one for gas and one for geothermal – to get a better idea.
Yes, KfW 55 is possible with gas as well – but it’s a bit more challenging. You might want to read on Wikipedia what it actually means. It definitely makes more sense to focus on proper insulation rather than just aiming for the "KfW 55" label. The subsidies can partly be offset by all the inspections and assessments involved.
In my opinion, a fireplace in the living room is not a substitute for heating – if anything, it should be connected to the heating system, which would be a bit more expensive – and always keep in mind, if you don’t get wood cheaply, it usually isn’t really worthwhile.
I believe cross-heat exchangers are just one type of design – without a heat exchanger, the heating system wouldn’t work, since that’s the basic principle of heat pumps. You extract heat from one medium and use that energy to provide heat to the house, for example.
Yes, KfW 55 is possible with gas as well – but it’s a bit more challenging. You might want to read on Wikipedia what it actually means. It definitely makes more sense to focus on proper insulation rather than just aiming for the "KfW 55" label. The subsidies can partly be offset by all the inspections and assessments involved.
In my opinion, a fireplace in the living room is not a substitute for heating – if anything, it should be connected to the heating system, which would be a bit more expensive – and always keep in mind, if you don’t get wood cheaply, it usually isn’t really worthwhile.
I believe cross-heat exchangers are just one type of design – without a heat exchanger, the heating system wouldn’t work, since that’s the basic principle of heat pumps. You extract heat from one medium and use that energy to provide heat to the house, for example.
BeHaElJa schrieb:
In my opinion, a fireplace in the living room is not a substitute for heating ...We have a fireplace – and nowadays (the outdoor temperature in the evening is not low enough for the heating to kick in and make the room truly warm) it is enough to raise the house temperature by about 3 degrees Celsius (5°F).
What else could you want? Or rather: what more do you expect from a fireplace?
Unfortunately, I can’t say anything about heat pumps, but basically, nowadays an energy standard like KfW 55 is not financially worthwhile unless you have extra money or do it out of conviction. There are many discussions about this here in the forum.
Best regards,
Yvonne
The heat pump is not exactly a top performer in terms of efficiency; there are significantly better options available. According to the BAFA heat pump list, the COP values for the Tecalor 304 are 2.72 / 3.4 / 4.14. Good or efficient values would be more like >3 / >4 / >5. There are plenty of models that can achieve these numbers. I recommend taking a close look at the BAFA list. Top models come, for example, from Heliotherm, Weider, or Ochsner.
If it really has to be Tecalor, then at least consider the much more efficient TTL 15 IS-2 model. As mentioned: compare the values!
Nothing is worse than getting stuck with high operating costs from an inefficient heat pump that was expensive to buy.
A ground source heat pump can indeed be more efficient, but it heavily depends on where you live in Germany.
In volcanically active areas, such as the Eifel region, or along the Upper Rhine Graben, where the continent is pulling apart, ground temperatures are significantly higher.
If it really has to be Tecalor, then at least consider the much more efficient TTL 15 IS-2 model. As mentioned: compare the values!
Nothing is worse than getting stuck with high operating costs from an inefficient heat pump that was expensive to buy.
A ground source heat pump can indeed be more efficient, but it heavily depends on where you live in Germany.
In volcanically active areas, such as the Eifel region, or along the Upper Rhine Graben, where the continent is pulling apart, ground temperatures are significantly higher.
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