Hello dear readers,
We are currently making concrete plans for our new build next year. Key details: single-family house, about 130sqm (1400 sq ft), with a basement.
Bien-Zenker has made it to our shortlist. The price-performance ratio seems reasonable, we like the floor plan, and it is also a well-established large home builder.
For heating, we were offered a brine-to-water heat pump with underfloor heating (which we wanted) and a controlled mechanical ventilation system with heat recovery.
Our budget is limited, and we would go for the so-called Efficiency House 55 thermal wall with a U-value of 0.142 W/(sqm·K).
Overall, the house would meet the Efficiency House 70 standard.
I’m no expert, but compared to other manufacturers, this value is average. The "standard wall" from Kampa, for example, would be better.
What do you think about this building services offer overall?
Is the heat pump cost-effective over the years compared to the standard gas condensing boiler?
Many thanks from a beginner for your support and answers.
We are currently making concrete plans for our new build next year. Key details: single-family house, about 130sqm (1400 sq ft), with a basement.
Bien-Zenker has made it to our shortlist. The price-performance ratio seems reasonable, we like the floor plan, and it is also a well-established large home builder.
For heating, we were offered a brine-to-water heat pump with underfloor heating (which we wanted) and a controlled mechanical ventilation system with heat recovery.
Our budget is limited, and we would go for the so-called Efficiency House 55 thermal wall with a U-value of 0.142 W/(sqm·K).
Overall, the house would meet the Efficiency House 70 standard.
I’m no expert, but compared to other manufacturers, this value is average. The "standard wall" from Kampa, for example, would be better.
What do you think about this building services offer overall?
Is the heat pump cost-effective over the years compared to the standard gas condensing boiler?
Many thanks from a beginner for your support and answers.
Does no one have any comments on this?
Another question I have is whether the heat pump can also easily provide domestic hot water, since the temperature of around 60°C (140°F) is significantly higher than the supply temperature of underfloor heating.
Would solar panels on the roof possibly make sense for the summer?
Thank you very much for your opinions...
Another question I have is whether the heat pump can also easily provide domestic hot water, since the temperature of around 60°C (140°F) is significantly higher than the supply temperature of underfloor heating.
Would solar panels on the roof possibly make sense for the summer?
Thank you very much for your opinions...
Cascada schrieb:
No one has anything to say about this? Many things can be said, but it is questionable how reliably such issues can be resolved in a forum, as it requires considerable effort if it is to be truly effective. Heat pumps can definitely be an alternative to gas condensing boilers, but this requires adherence to specific conditions. Whether a ground-source heat pump with the additional costs of source development is necessary in this case should be clarified in advance. After all, a heat pump generally offers the possibility to do without a less efficient solar thermal system. 😉
I have just completed an expert report on such a solar thermal system showing that the energy yield was only slightly higher compared to the additional auxiliary energy consumption involved. In other words, a wasteful investment!
Cascada schrieb:
...Another question I have is whether hot water supply can easily be provided by the heat pump, since the temperature of about 60 degrees is significantly higher than the supply temperature of underfloor heating. A heat pump becomes more efficient the smaller the temperature difference between the heat source and the consumer. Heat pump hot water preparation is certainly possible, but temperatures of 60°C (140°F) can drastically reduce the annual performance factor, depending on how large the share of hot water preparation is in the total annual final energy demand.
Cascada schrieb:
...Does it possibly make sense to install solar panels on the roof for summer use? Primary energy-wise, yes; economically, usually not! Best regards
@ €uro,
Thank you very much for your post.
From what I understand, the conditions with a KfW 70 standard and underfloor heating should be fine. A controlled ventilation system with heat recovery would also prevent ventilation heat losses. What exact figures would be needed for a reasonably accurate calculation? A quick question: solar thermal system? Solar panels on the roof?
Regarding the heat pump for domestic hot water: what solution would be advisable here? An electric water heater in the bathroom and under the sinks in the bathroom/toilet/kitchen? I assumed 60°C (140°F) because of legionella prevention. In theory, the temperature could be 10-15°C (18-27°F) lower to have a more comfortable shower experience.
I was thinking about the solar panels on the roof to produce almost exclusively hot water in summer. But according to your statements, that wouldn’t make much economic sense.
I was generally interested in whether a heat pump can also cover hot water production without negating the advantages compared to a gas condensing boiler, meaning whether a heat pump might pay off not only after perhaps 10 years but possibly never. Economically speaking.
Best regards...
Thank you very much for your post.
From what I understand, the conditions with a KfW 70 standard and underfloor heating should be fine. A controlled ventilation system with heat recovery would also prevent ventilation heat losses. What exact figures would be needed for a reasonably accurate calculation? A quick question: solar thermal system? Solar panels on the roof?
Regarding the heat pump for domestic hot water: what solution would be advisable here? An electric water heater in the bathroom and under the sinks in the bathroom/toilet/kitchen? I assumed 60°C (140°F) because of legionella prevention. In theory, the temperature could be 10-15°C (18-27°F) lower to have a more comfortable shower experience.
I was thinking about the solar panels on the roof to produce almost exclusively hot water in summer. But according to your statements, that wouldn’t make much economic sense.
I was generally interested in whether a heat pump can also cover hot water production without negating the advantages compared to a gas condensing boiler, meaning whether a heat pump might pay off not only after perhaps 10 years but possibly never. Economically speaking.
Best regards...
Cascada schrieb:
... What exact figures would be necessary for a reasonably reliable calculation? Basically, all data related to the building structure, the climate location, and user behavior.
Calculations include: air volumes (if mechanical ventilation with heat recovery is desired or required), design heating load, room heating demands, heating surfaces, and the pipe network. These results are used, among other things, to determine the actual energy demand for heating and hot water. This, in turn, influences the choice of the heat generator.
Cascada schrieb:
...Short question: solar thermal system? Solar [B]Thermal System, as opposed to photovoltaic. Cascada schrieb:
.. what solution would make sense here? Usually, centralized hot water with the same heat generator that also supplies the heating. Cascada schrieb:
...An electric boiler in the bathroom and under the sinks in the bathroom/WC/kitchen? That would be direct electric heating and is hardly practical. Cascada schrieb:
....Theoretically, the temperature could be 10-15 degrees lower for a more pleasant shower experience. Tap water temperatures are typically 45…50°C (113…122°F). Cascada schrieb:
...I was generally interested in whether domestic hot water production can be included when using a heat pump at all,... If the system is precisely planned and calculated, that is absolutely no problem.Regards
Thank you very much for the detailed explanations 🙂
In general, the solution for a KFW70 building is fine, provided the system is properly calculated and sized. That’s what I have gathered so far. Would you also lean towards the brine heat pump solution, or would you still prefer a gas condensing boiler system (also with underfloor heating and controlled ventilation with heat recovery)?
Of course, I’m not calculating short-term here, but in about 10 years, the investment costs should at least break even, meaning the system should then operate “profitably” compared to the gas solution.
Regarding the domestic hot water temperature (outlet temperature): isn’t there a risk of Legionella growth at 45–50°C (113–122°F)? I’m always thinking about 60°C (140°F) in this context.
One more important question: heating the basement. The consultant advised to plan underfloor heating directly in the designated basement rooms. What do you think about that? How should I properly heat a basement that will be used as a hobby room (model railway) in the foreseeable future? The temperature should not exceed 18°C (64°F) much, even in winter. Ventilation would then be done through the basement windows.
Best regards…
In general, the solution for a KFW70 building is fine, provided the system is properly calculated and sized. That’s what I have gathered so far. Would you also lean towards the brine heat pump solution, or would you still prefer a gas condensing boiler system (also with underfloor heating and controlled ventilation with heat recovery)?
Of course, I’m not calculating short-term here, but in about 10 years, the investment costs should at least break even, meaning the system should then operate “profitably” compared to the gas solution.
Regarding the domestic hot water temperature (outlet temperature): isn’t there a risk of Legionella growth at 45–50°C (113–122°F)? I’m always thinking about 60°C (140°F) in this context.
One more important question: heating the basement. The consultant advised to plan underfloor heating directly in the designated basement rooms. What do you think about that? How should I properly heat a basement that will be used as a hobby room (model railway) in the foreseeable future? The temperature should not exceed 18°C (64°F) much, even in winter. Ventilation would then be done through the basement windows.
Best regards…
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