Hello,
I am planning to build in the near future and cannot decide between gas and geothermal energy. The single-family house with KfW 70 standard (basement, ground floor, first floor, and attic conversion) has 163 sqm (1754 sq ft) of living space and will be occupied by 2 people. Underfloor heating is also planned. What is the most cost-effective way to heat domestic hot water and the heating system? What is the best investment and why?
Good luck
I am planning to build in the near future and cannot decide between gas and geothermal energy. The single-family house with KfW 70 standard (basement, ground floor, first floor, and attic conversion) has 163 sqm (1754 sq ft) of living space and will be occupied by 2 people. Underfloor heating is also planned. What is the most cost-effective way to heat domestic hot water and the heating system? What is the best investment and why?
Good luck
We are currently facing this difficult decision as well. However, we have already narrowed it down to three systems, and I find myself daily wavering between these two options. We plan to build in the summer of 2012, and here are some key details about the house:
Solid construction with 30cm (12 inch) Poroton bricks + 10cm (4 inch) ETICS polystyrene insulation
Approx. 135 sqm (1,450 sq ft) living area
Triple glazing
Decentralized ventilation system Schiedel AERA Comfort (without heat recovery, as we are not convinced by it; we do not want fresh air coming through a duct system but want to minimize ventilation heat losses)
Roof truss with 20cm (8 inch) insulation between rafters
BRAAS roof tiles
Basement built as a waterproof shell, 30cm (12 inch) concrete + 10cm (4 inch) perimeter insulation, floor insulation in basement screed
Large window area facing south, with dormer windows facing north as well
Designed for 2 adults and 2-3 children
Now, here are my thoughts on the heating system:
We want a heat pump, that is certain (so please don’t try to convince me otherwise ;-).
a) Ground-source heat pump (Alpha Innotec) with borehole drilling (probably up to about 80m (260 ft) with 45W/m efficiency, clay soil)
b) Air-to-water heat pump with COP >3.5 (Alpha Innotec) in monovalent operation
c) Air-to-water heat pump with COP >3.5 (Alpha Innotec) + solar thermal system to support heating (8-12 sqm (86-129 sq ft) collectors)
Possibly, a traditional tiled stove in the living-dining area for support during the transitional seasons.
Climatically, we are not located in a particularly favorable region, meaning average temperatures tend to be moderate to lower compared to climatically advantaged regions, for example, in southern Germany.
Apart from investment costs, I would be interested in what makes the most sense energetically. Of course, investment costs are also important, and naturally, a standalone air-to-water heat pump would be the "cheapest" option... but would that be "economical" for our planned house?
We would like to achieve KfW 70, which should be doable. Do you see any chance of reaching KfW 55, and what would be required to achieve that?
Thank you very much in advance for your help!
Solid construction with 30cm (12 inch) Poroton bricks + 10cm (4 inch) ETICS polystyrene insulation
Approx. 135 sqm (1,450 sq ft) living area
Triple glazing
Decentralized ventilation system Schiedel AERA Comfort (without heat recovery, as we are not convinced by it; we do not want fresh air coming through a duct system but want to minimize ventilation heat losses)
Roof truss with 20cm (8 inch) insulation between rafters
BRAAS roof tiles
Basement built as a waterproof shell, 30cm (12 inch) concrete + 10cm (4 inch) perimeter insulation, floor insulation in basement screed
Large window area facing south, with dormer windows facing north as well
Designed for 2 adults and 2-3 children
Now, here are my thoughts on the heating system:
We want a heat pump, that is certain (so please don’t try to convince me otherwise ;-).
a) Ground-source heat pump (Alpha Innotec) with borehole drilling (probably up to about 80m (260 ft) with 45W/m efficiency, clay soil)
b) Air-to-water heat pump with COP >3.5 (Alpha Innotec) in monovalent operation
c) Air-to-water heat pump with COP >3.5 (Alpha Innotec) + solar thermal system to support heating (8-12 sqm (86-129 sq ft) collectors)
Possibly, a traditional tiled stove in the living-dining area for support during the transitional seasons.
Climatically, we are not located in a particularly favorable region, meaning average temperatures tend to be moderate to lower compared to climatically advantaged regions, for example, in southern Germany.
Apart from investment costs, I would be interested in what makes the most sense energetically. Of course, investment costs are also important, and naturally, a standalone air-to-water heat pump would be the "cheapest" option... but would that be "economical" for our planned house?
We would like to achieve KfW 70, which should be doable. Do you see any chance of reaching KfW 55, and what would be required to achieve that?
Thank you very much in advance for your help!
Hello,
Best regards.
Behaim schrieb:The question can only be answered reliably once the actual demand has been calculated!
....Independently from the investment costs, I would be interested in what makes the most sense energetically. Of course, the investment costs would also be interesting,...
Behaim schrieb:The same applies here: first calculate and identify where the main issue lies! Ht', Qp'', or even both. Sometimes, achieving KfW 55 requires only minor additional effort.
....We would like to achieve KfW 70, which should be doable. Do you see chances for KfW 55, and what else would be needed to reach this?
Best regards.
Sabine68 schrieb:
..... How naive can someone be to react to such a blatant promotional event? ;-)Admin?
Best regards
Hi,
we have also considered this question. I think it is wrong to look solely at the costs. In addition, I would definitely include the following factors in the decision:
- Reliability
- Performance / Speed
- Cleanliness / Odor impact
- Space requirements
- Safety
- Convenience
If I could choose freely, I would rank them as follows:
1. Gas heating (if gas is available locally; does not apply if a tank needs to be installed first.)
Gas is convenient and clean if you have access to it on-site. It is expensive, no doubt. However, I believe all energy sources will generally rise in price proportionally (demand/supply) – anything else would be a surprise. So, that wouldn’t be a reason against it for me. The gas heating system is compact – a small room or corner is sufficient. It is quite reliable, powerful, and quick in meeting higher demand. Installation effort is manageable, and the technology is well known and proven. The only concern I have is the risk of explosion, but that is quite rare. 😉
2. Geothermal heating
Since we don’t have gas here, we chose geothermal heating.
Advantage: clean, low operating effort; disadvantage: slow response time, high installation effort. Additionally, we planned photovoltaic panels and a fireplace for sudden temperature drops in winter.
3. Air-source heat pump
Similar to geothermal, but for me the significant drawbacks are: unattractive in the garden, noise disturbance (though low), and lower efficiency.
4. Pellet heating / Wood heating:
Advantages: independent from conventional suppliers, I would always choose a stove that can burn regular wood as well, preferably also coal; fast response time, powerful.
Disadvantages: space required for fuel storage, odor impact, ensuring long-term fuel supply, fire hazard and protection need to be considered, labor-intensive (heating daily without an automatic system), I can imagine occasional jamming and less reliable technology, but that’s just speculation.
5. Gas tank
When we compared gas prices for a tank in the garden, we were shocked and immediately set the offers aside. Maybe it was just an unlucky coincidence. In any case, I would not want a gas tank in the garden, and liquefied gas prices are higher than expected. Otherwise, the pros and cons are similar to number 1.
6. Oil heating
Personally, I find oil completely unsuitable. That’s just my personal preference. In fact, it is fast, powerful, proven technology, widely available, installation effort is reasonable, convenient, and reliable—but the smell! I find the smell of oil in the house and garden disgusting, and having a tank in the garden is awful. Oil is also expensive and takes up a lot of space. That’s why oil heating is last on my list.
we have also considered this question. I think it is wrong to look solely at the costs. In addition, I would definitely include the following factors in the decision:
- Reliability
- Performance / Speed
- Cleanliness / Odor impact
- Space requirements
- Safety
- Convenience
If I could choose freely, I would rank them as follows:
1. Gas heating (if gas is available locally; does not apply if a tank needs to be installed first.)
Gas is convenient and clean if you have access to it on-site. It is expensive, no doubt. However, I believe all energy sources will generally rise in price proportionally (demand/supply) – anything else would be a surprise. So, that wouldn’t be a reason against it for me. The gas heating system is compact – a small room or corner is sufficient. It is quite reliable, powerful, and quick in meeting higher demand. Installation effort is manageable, and the technology is well known and proven. The only concern I have is the risk of explosion, but that is quite rare. 😉
2. Geothermal heating
Since we don’t have gas here, we chose geothermal heating.
Advantage: clean, low operating effort; disadvantage: slow response time, high installation effort. Additionally, we planned photovoltaic panels and a fireplace for sudden temperature drops in winter.
3. Air-source heat pump
Similar to geothermal, but for me the significant drawbacks are: unattractive in the garden, noise disturbance (though low), and lower efficiency.
4. Pellet heating / Wood heating:
Advantages: independent from conventional suppliers, I would always choose a stove that can burn regular wood as well, preferably also coal; fast response time, powerful.
Disadvantages: space required for fuel storage, odor impact, ensuring long-term fuel supply, fire hazard and protection need to be considered, labor-intensive (heating daily without an automatic system), I can imagine occasional jamming and less reliable technology, but that’s just speculation.
5. Gas tank
When we compared gas prices for a tank in the garden, we were shocked and immediately set the offers aside. Maybe it was just an unlucky coincidence. In any case, I would not want a gas tank in the garden, and liquefied gas prices are higher than expected. Otherwise, the pros and cons are similar to number 1.
6. Oil heating
Personally, I find oil completely unsuitable. That’s just my personal preference. In fact, it is fast, powerful, proven technology, widely available, installation effort is reasonable, convenient, and reliable—but the smell! I find the smell of oil in the house and garden disgusting, and having a tank in the garden is awful. Oil is also expensive and takes up a lot of space. That’s why oil heating is last on my list.
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