markus-db
2016-07-16 14:55:36
- #1
Hello dear forum members,
I have already read quite a bit in the discussion about ground and air heat pumps here, but it mostly involved construction projects in the size range of 150-200 m2. Since we are planning to build somewhat larger, I wonder if that makes a difference in the consideration and have therefore created this thread.
Briefly the most important key data for the construction project:
- Construction project on the outskirts of Berlin
- New single-family house, not KFW 55 (because according to the energy consultant, an additional ventilation system costing over €20,000 would be required, which we do not want)
- Exterior walls aerated concrete 36cm, no extra insulation
- No chimney planned/wished for
- approx. 300m2 heated living area from ground floor to attic (GF, FF, attic)
- approx. 100m2 heated basement area (BS)
- total heated area thus 400m2
- Heating exclusively planned via underfloor heating (BS-attic completely)
We have decided against a gas heating system because although it is currently possibly more economical than a heat pump (of any kind), the idea of sustainability plays a role for us and therefore we are also accepting additional costs (especially investment costs).
For this reason, we have developed the following two variants with our energy consultant:
Always included is a photovoltaic system (nominal output approx. 4.5 kWp) with buffer storage (probably in the range of 7.5 kWh) – the "idea": We produce the electricity for the heat pump ourselves. This will of course not cover the entire demand of the heat pump (see below), but even if we reach 50% on an annual average, that is already something. (If too much electricity is produced in summer, it will of course be sold.)
Variant a) Ground source heat pump: According to the heat load calculation, we need a system with approx. 18 kW output and must carry out boreholes totaling 440m depth in the area. This is divided into 5 boreholes of 88m each.
We have an offer here, but unfortunately individual items are not visible. Without going into too much detail (because the forum is not supposed to judge my offer), the costs for the boreholes, a Vaillant heat pump with 19.7 kW / Cop 4.7 (unfortunately it is not clear under which standard), 300l buffer storage, 500l fresh water preparation + all additional costs amount to €42,500 gross.
Variant b) Air source heat pump: Here, of course, the borehole is omitted. The heat pump is a heat pump from Heliotherm with 18.5 kW / Cop 4.14 (A2/W35) in fully modulating design, connection is hydraulically decoupled, buffer and water storage analogous to a), total costs: €25,000 gross.
(Additionally, about €18,000 for just over 400 m2 underfloor heating costs plus €15,000 for photovoltaic, but these are the same in both variants and so I leave them out.)
So what remains at the end of the day for the heating system:
- Costs for ground source heat pump: €42,500
- Costs for air source heat pump: €25,000
- Difference: ground source is €17,500 more expensive in investment costs
- However, the air heat pump is less efficient than the ground source heat pump, especially in winter when it is needed, so ground source is cheaper in ongoing consumption
Now I have the following questions for the experts:
- Do these considerations make sense overall?
- Is the idea of covering part of the power demand of the heat pump with one’s own photovoltaic system wise?
- From your point of view, is an additional cost effort of €17,500 for the ground source heat pump variant worthwhile (also considering the heat load of approx. 18 kW)?
- What other factors should I pay attention to?
The overall goal is: to realize a sensible but also as sustainable as possible energy system for the future, which of course does not cause unnecessary costs (since unfortunately I have not won the lottery and the money is therefore finite).
Sorry that the post has become somewhat longer, but I wanted to be as precise as possible. If you need more information, please let me know.
Thanks!
I have already read quite a bit in the discussion about ground and air heat pumps here, but it mostly involved construction projects in the size range of 150-200 m2. Since we are planning to build somewhat larger, I wonder if that makes a difference in the consideration and have therefore created this thread.
Briefly the most important key data for the construction project:
- Construction project on the outskirts of Berlin
- New single-family house, not KFW 55 (because according to the energy consultant, an additional ventilation system costing over €20,000 would be required, which we do not want)
- Exterior walls aerated concrete 36cm, no extra insulation
- No chimney planned/wished for
- approx. 300m2 heated living area from ground floor to attic (GF, FF, attic)
- approx. 100m2 heated basement area (BS)
- total heated area thus 400m2
- Heating exclusively planned via underfloor heating (BS-attic completely)
We have decided against a gas heating system because although it is currently possibly more economical than a heat pump (of any kind), the idea of sustainability plays a role for us and therefore we are also accepting additional costs (especially investment costs).
For this reason, we have developed the following two variants with our energy consultant:
Always included is a photovoltaic system (nominal output approx. 4.5 kWp) with buffer storage (probably in the range of 7.5 kWh) – the "idea": We produce the electricity for the heat pump ourselves. This will of course not cover the entire demand of the heat pump (see below), but even if we reach 50% on an annual average, that is already something. (If too much electricity is produced in summer, it will of course be sold.)
Variant a) Ground source heat pump: According to the heat load calculation, we need a system with approx. 18 kW output and must carry out boreholes totaling 440m depth in the area. This is divided into 5 boreholes of 88m each.
We have an offer here, but unfortunately individual items are not visible. Without going into too much detail (because the forum is not supposed to judge my offer), the costs for the boreholes, a Vaillant heat pump with 19.7 kW / Cop 4.7 (unfortunately it is not clear under which standard), 300l buffer storage, 500l fresh water preparation + all additional costs amount to €42,500 gross.
Variant b) Air source heat pump: Here, of course, the borehole is omitted. The heat pump is a heat pump from Heliotherm with 18.5 kW / Cop 4.14 (A2/W35) in fully modulating design, connection is hydraulically decoupled, buffer and water storage analogous to a), total costs: €25,000 gross.
(Additionally, about €18,000 for just over 400 m2 underfloor heating costs plus €15,000 for photovoltaic, but these are the same in both variants and so I leave them out.)
So what remains at the end of the day for the heating system:
- Costs for ground source heat pump: €42,500
- Costs for air source heat pump: €25,000
- Difference: ground source is €17,500 more expensive in investment costs
- However, the air heat pump is less efficient than the ground source heat pump, especially in winter when it is needed, so ground source is cheaper in ongoing consumption
Now I have the following questions for the experts:
- Do these considerations make sense overall?
- Is the idea of covering part of the power demand of the heat pump with one’s own photovoltaic system wise?
- From your point of view, is an additional cost effort of €17,500 for the ground source heat pump variant worthwhile (also considering the heat load of approx. 18 kW)?
- What other factors should I pay attention to?
The overall goal is: to realize a sensible but also as sustainable as possible energy system for the future, which of course does not cause unnecessary costs (since unfortunately I have not won the lottery and the money is therefore finite).
Sorry that the post has become somewhat longer, but I wanted to be as precise as possible. If you need more information, please let me know.
Thanks!