ᐅ KfW 70 house, cost comparison between gas condensing boiler and air-source heat pump, cost comparison of ground-source heat pump
Created on: 29 Jun 2012 11:44
M
Musketier
Hello Newsgroup,
we are also planning to build a house in Saxony and are currently still in the offer phase.
It will be an urban villa with exterior walls of about 9x9m (29.5x29.5 ft) on a slab foundation.
The likely future general contractor prefers 36.5 cm (14.4 inches) aerated concrete for the exterior walls without additional insulation.
For heating, a gas condensing boiler and additionally a solar thermal system are planned.
Triple glazing is also included as standard.
Since we are already working through the financing, the question arises whether KfW 70 makes sense.
If we get the financing through the Saxon Development Bank, we would anyway have to provide proof that we build 10% better than the Energy Saving Ordinance.
According to the seller, to achieve KfW 70, the gas condensing boiler would have to be replaced by a heat pump.
I have already read many threads on this and know that an energy calculation is needed (a little hint to €uro) to make precise statements.
Maybe some general answers can be given to my questions.
1. How much more does an air-source heat pump cost compared to a gas condensing boiler?
2. How much more does a ground-source heat pump cost compared to an air-source heat pump?
3. It is often said: If I have a better insulated house, I can save less with an air-source heat pump.
Does this mean, conversely, that the more heating energy I use, the more worthwhile an air-source or ground-source heat pump becomes?
Is there approximately a break-even point for a particular heating type?
4. According to €uro, a solar thermal system is generally uneconomical.
Is it then worthwhile to install an air-source or ground-source heat pump without a solar thermal system?
Would KfW 70 still be achievable?
Thank you very much in advance
Musketier
we are also planning to build a house in Saxony and are currently still in the offer phase.
It will be an urban villa with exterior walls of about 9x9m (29.5x29.5 ft) on a slab foundation.
The likely future general contractor prefers 36.5 cm (14.4 inches) aerated concrete for the exterior walls without additional insulation.
For heating, a gas condensing boiler and additionally a solar thermal system are planned.
Triple glazing is also included as standard.
Since we are already working through the financing, the question arises whether KfW 70 makes sense.
If we get the financing through the Saxon Development Bank, we would anyway have to provide proof that we build 10% better than the Energy Saving Ordinance.
According to the seller, to achieve KfW 70, the gas condensing boiler would have to be replaced by a heat pump.
I have already read many threads on this and know that an energy calculation is needed (a little hint to €uro) to make precise statements.
Maybe some general answers can be given to my questions.
1. How much more does an air-source heat pump cost compared to a gas condensing boiler?
2. How much more does a ground-source heat pump cost compared to an air-source heat pump?
3. It is often said: If I have a better insulated house, I can save less with an air-source heat pump.
Does this mean, conversely, that the more heating energy I use, the more worthwhile an air-source or ground-source heat pump becomes?
Is there approximately a break-even point for a particular heating type?
4. According to €uro, a solar thermal system is generally uneconomical.
Is it then worthwhile to install an air-source or ground-source heat pump without a solar thermal system?
Would KfW 70 still be achievable?
Thank you very much in advance
Musketier
Musketier schrieb:
...If the general contractor refuses to carry out the calculation before signing the contract, does it make sense to have the calculation done at your own expense first and then offset it if the contract is concluded? Primarily with general contractors or main contractors, the offer is usually a standard package, regardless of whether it meets individual requirements or needs. A reliable general contractor will not refuse an external calculation or sizing, whereas one more focused on their own interests might :-) This is often where the wheat is separated from the chaff ;-) Therefore, smart homeowners often exclude the trades for heating, hot water, and ventilation from the contract upfront and assign them externally with independent planning. Of course, this is somewhat more inconvenient overall ;-)Musketier schrieb:
...I assumed that the closer I get to a passive house standard in terms of insulation, the less sense it makes to have an expensive (in terms of purchase costs) but efficient (in terms of variable costs) heating system. The higher the insulation standard of the building, the lower the efficiency requirements for the system, since absolute values regarding final energy consumption must be paid for.Musketier schrieb:
...by contrast, an uninsulated house should have an expensive but efficient heating system. Correct!Hello,
Since several suggestions have already been made that the decision should be based primarily on the energy calculation, here is also the advice to really obtain the energy calculation as a key basis for deciding on the heating system. It might be worthwhile to additionally consult an independent expert who can support you better on this topic than the sellers or construction managers of the general contractors (GCs).
It also makes sense to have the energy consultation conducted independently from the GC at your own expense if this increases certainty about meeting the requirements for funding and choosing the optimal heating system. Often, this relatively small investment during the planning phase can bring significant advantages during construction and later use, making it worthwhile.
The exact selection of the system, composed of essential components such as investment costs, installation costs, and later operating and maintenance costs, must be compared for the device selection. This should already take place during the planning phase and is rarely offered by a GC. Therefore, the advice is to demand such a comparison—including the impact on funding—from the GC or have it calculated by an external consultant, as quite a bit of funding can be lost otherwise.
Best regards
Since several suggestions have already been made that the decision should be based primarily on the energy calculation, here is also the advice to really obtain the energy calculation as a key basis for deciding on the heating system. It might be worthwhile to additionally consult an independent expert who can support you better on this topic than the sellers or construction managers of the general contractors (GCs).
It also makes sense to have the energy consultation conducted independently from the GC at your own expense if this increases certainty about meeting the requirements for funding and choosing the optimal heating system. Often, this relatively small investment during the planning phase can bring significant advantages during construction and later use, making it worthwhile.
The exact selection of the system, composed of essential components such as investment costs, installation costs, and later operating and maintenance costs, must be compared for the device selection. This should already take place during the planning phase and is rarely offered by a GC. Therefore, the advice is to demand such a comparison—including the impact on funding—from the GC or have it calculated by an external consultant, as quite a bit of funding can be lost otherwise.
Best regards