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((andreas))10 Aug 2018 12:58Hello everyone,
We are currently in the early stages of planning our single-family home, still focusing on the basic room layout.
I am currently considering the type of heating system.
My gut feeling is swinging between an air-to-water heat pump and a ground-source (also called water-to-water) heat pump.
Unfortunately, there is no gas connection available, otherwise that would definitely be another option.
Using a calculation tool, I have entered the following parameters:
Living area 180 m² (will likely be somewhat smaller)
Electricity (heat pump): €0.20 / kWh
Gas: €0.06 / kWh
Specific heating demand 60 kWh/m²*a
Gas boiler efficiency 96%
Gas boiler standby losses 8%
Heating costs:
Gas heating: €740 / year
Air-to-water heat pump: €497 / year
Ground-source heat pump: €488 / year
First question: Are air-to-water and ground-source heat pumps really that close in cost? If so, you can save yourself the question of economic efficiency and drastically shorten your considerations at this point. Or do I have a calculation error here?
I am also interested in the topic of cooling with the heat pump. Both types can provide cooling if designed accordingly, with ground-source heat pumps likely being somewhat cheaper to operate. Does anyone have an estimate of how much energy cooling with a heat pump consumes? A rough figure or rule of thumb would be sufficient for now.
Thanks very much for your input.
We are currently in the early stages of planning our single-family home, still focusing on the basic room layout.
I am currently considering the type of heating system.
My gut feeling is swinging between an air-to-water heat pump and a ground-source (also called water-to-water) heat pump.
Unfortunately, there is no gas connection available, otherwise that would definitely be another option.
Using a calculation tool, I have entered the following parameters:
Living area 180 m² (will likely be somewhat smaller)
Electricity (heat pump): €0.20 / kWh
Gas: €0.06 / kWh
Specific heating demand 60 kWh/m²*a
Gas boiler efficiency 96%
Gas boiler standby losses 8%
Heating costs:
Gas heating: €740 / year
Air-to-water heat pump: €497 / year
Ground-source heat pump: €488 / year
First question: Are air-to-water and ground-source heat pumps really that close in cost? If so, you can save yourself the question of economic efficiency and drastically shorten your considerations at this point. Or do I have a calculation error here?
I am also interested in the topic of cooling with the heat pump. Both types can provide cooling if designed accordingly, with ground-source heat pumps likely being somewhat cheaper to operate. Does anyone have an estimate of how much energy cooling with a heat pump consumes? A rough figure or rule of thumb would be sufficient for now.
Thanks very much for your input.
Please try searching first, there are lots and lots of threads on this topic.....
Have you gotten a quote for drilling the geothermal borehole? For us, it was $15,000 just for that, so unfortunately it was off the table... otherwise, I would have found the technology great.
For us, it would have paid off only after about 20 years or so... too long for me.
Have you gotten a quote for drilling the geothermal borehole? For us, it was $15,000 just for that, so unfortunately it was off the table... otherwise, I would have found the technology great.
For us, it would have paid off only after about 20 years or so... too long for me.
The calculation looks a bit odd to me. For the air-to-water heat pump, you have an annual performance factor (COP) of about 4.3. That’s an ambitious value that only a few air-to-water heat pumps manage to achieve; a ground-source (brine-to-water) heat pump can easily reach that. To me, the energy consumption figures are too close together. How did you arrive at these numbers?
The 20 cents per kWh for the heat pump electricity is only available with a special tariff that requires a second meter specifically for the heat pump, which comes with additional costs. The ground-source heat pump is probably more expensive upfront but also receives more subsidies. If you have a larger garden, a horizontal ground collector might be an option. Some people in Lower Saxony do this, making the geothermal heat pump much more affordable.
The 20 cents per kWh for the heat pump electricity is only available with a special tariff that requires a second meter specifically for the heat pump, which comes with additional costs. The ground-source heat pump is probably more expensive upfront but also receives more subsidies. If you have a larger garden, a horizontal ground collector might be an option. Some people in Lower Saxony do this, making the geothermal heat pump much more affordable.
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((andreas))10 Aug 2018 14:32I understand that the 20 cents applies only with a second meter. That probably makes sense for a heat pump heating system as well.
We currently rent and have an air-to-water heat pump with a second meter, so I based the 20 cents on what we are currently paying plus a small additional charge. I consider the extra costs negligible or compensated by a planned photovoltaic system.
I calculated everything using a tool I found online. However, it might produce inaccurate results. The outcomes surprised me as well, which is why I started this thread.
I have also thought about using a ground collector. The plot is large enough, about 700 m² (7,535 sq ft). The house and garage together will cover less than 150 m² (1,615 sq ft) of floor area.
We currently rent and have an air-to-water heat pump with a second meter, so I based the 20 cents on what we are currently paying plus a small additional charge. I consider the extra costs negligible or compensated by a planned photovoltaic system.
I calculated everything using a tool I found online. However, it might produce inaccurate results. The outcomes surprised me as well, which is why I started this thread.
I have also thought about using a ground collector. The plot is large enough, about 700 m² (7,535 sq ft). The house and garage together will cover less than 150 m² (1,615 sq ft) of floor area.
A second meter and photovoltaic system are mutually exclusive. The heat pump will not be able to use electricity from that.
Such a meter usually costs around 80-100€ per year, which accounts for roughly 20% in your calculation.
A geothermal (ground source) system is about 20% more efficient, while running costs are realistically quite similar. However, it all depends on the drilling costs. Subsidies are much higher for geothermal systems, so it may already be worthwhile.
It’s not just about costs. Geothermal can also provide passive cooling if desired, and you avoid having an unattractive (outdoor unit) and potentially noisy/vibrating device on the house.
Such a meter usually costs around 80-100€ per year, which accounts for roughly 20% in your calculation.
A geothermal (ground source) system is about 20% more efficient, while running costs are realistically quite similar. However, it all depends on the drilling costs. Subsidies are much higher for geothermal systems, so it may already be worthwhile.
It’s not just about costs. Geothermal can also provide passive cooling if desired, and you avoid having an unattractive (outdoor unit) and potentially noisy/vibrating device on the house.
((andreas)) schrieb:
I consider the additional costs negligible or offset by a planned photovoltaic system With that, the second meter doesn’t really make sense anymore.
For a standard air-to-water heat pump, I would estimate an annual performance factor (coefficient of performance) of about 3.5, and for a ground-source water-to-water heat pump around 5.0, meaning for each kWh of electricity, you get 3.5 or 5.0 kWh of heat. So, based only on your heating energy demand of 10,800 kWh (180m (590ft) × 60), this results in just over 3,085 kWh per year with an air-to-water heat pump, and just over 2,100 kWh per year with a ground-source heat pump. Hot water demand is additional. Since you’re using only one meter because of the photovoltaic system, the cost per kWh is then 26 cents.
Just a rough estimate for illustration.
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