I have read several times that heat pumps are favored by the Energy Saving Ordinance, but I have never seen any specific details. Could someone please explain how exactly this preference is applied?
There have been no direct subsidies for them for quite some time, so that can’t be what is meant.
There have been no direct subsidies for them for quite some time, so that can’t be what is meant.
@DerBjoern thanks for the explanation. I still don’t quite understand it. 🙁
Do you mean that the stated final energy demand is lower than the actual value because the heat pump’s annual performance factor is included in the calculation?
To give you our calculated figures:
Final energy demand: 10.9
Primary energy demand: 26.1
This makes sense to me since it was multiplied by a factor of 2.4.
Was the figure of roughly 33 divided by the annual performance factor (for example, 3) to get the 10.9 beforehand?
Do you mean that the stated final energy demand is lower than the actual value because the heat pump’s annual performance factor is included in the calculation?
To give you our calculated figures:
Final energy demand: 10.9
Primary energy demand: 26.1
This makes sense to me since it was multiplied by a factor of 2.4.
Was the figure of roughly 33 divided by the annual performance factor (for example, 3) to get the 10.9 beforehand?
D
DerBjoern20 Nov 2014 10:42It is defined as follows:
Primary energy
(In the case of natural gas, this includes the energy contained in the gas plus the energy required for extraction, processing, and transportation to the consumer)
Final energy demand
This is the actual energy delivered to the house connection point. In other words, the kWh value shown on your meter.
Heat demand or heating demand
This refers to the amount of energy needed to maintain the building’s temperature and to heat the domestic hot water.
The annual performance factor (annual coefficient of performance, COP) basically represents the efficiency of the heat pump alone over the course of a year. However, this is only indirectly considered in the energy saving regulations. In these regulations, the factor from primary energy to heat or heating demand is used. This is called the system factor. The system factor describes how much primary energy is required to generate heating energy. It is not only composed of the annual performance factor and the primary energy factor, but also takes into account whether the heat generator (the heating system) is located inside or outside the insulated building envelope. It also considers whether, for example, a ventilation system with heat recovery is installed or not, as well as the energy demand for domestic hot water circulation, etc., or gains from solar thermal systems. So, the system factor covers the entire package. It reflects the total primary energy needed to keep your house and domestic hot water at the required temperature. Naturally, the heat generator and the primary energy factor play a major role in the system factor.
Your primary energy demand is therefore the product of the system factor and the sum of heating demand and domestic hot water demand.
In other words, Primary energy = system factor * (heating demand + domestic hot water demand).
Depending on the defined primary energy factor, certain heat generators are naturally better suited to keep the building’s required primary energy demand low.
As far as I know, you cannot convert this directly, but of course, the annual performance factor affects the conversion. If you want a realistic value for the building’s heating demand, the only reliable method is a heating load calculation.
In theory, the final energy demand should be the value you ultimately read from your meter. It is theoretical because calculations based on energy saving regulations are not always very close to reality, and there can be some deviations in practice.
Are the numbers you mentioned actual data? Does 26.1 mean 26.1 kWh/m² per year or 26,100 kWh as the annual primary energy demand for the entire building?
Primary energy
(In the case of natural gas, this includes the energy contained in the gas plus the energy required for extraction, processing, and transportation to the consumer)
Final energy demand
This is the actual energy delivered to the house connection point. In other words, the kWh value shown on your meter.
Heat demand or heating demand
This refers to the amount of energy needed to maintain the building’s temperature and to heat the domestic hot water.
The annual performance factor (annual coefficient of performance, COP) basically represents the efficiency of the heat pump alone over the course of a year. However, this is only indirectly considered in the energy saving regulations. In these regulations, the factor from primary energy to heat or heating demand is used. This is called the system factor. The system factor describes how much primary energy is required to generate heating energy. It is not only composed of the annual performance factor and the primary energy factor, but also takes into account whether the heat generator (the heating system) is located inside or outside the insulated building envelope. It also considers whether, for example, a ventilation system with heat recovery is installed or not, as well as the energy demand for domestic hot water circulation, etc., or gains from solar thermal systems. So, the system factor covers the entire package. It reflects the total primary energy needed to keep your house and domestic hot water at the required temperature. Naturally, the heat generator and the primary energy factor play a major role in the system factor.
Your primary energy demand is therefore the product of the system factor and the sum of heating demand and domestic hot water demand.
In other words, Primary energy = system factor * (heating demand + domestic hot water demand).
Depending on the defined primary energy factor, certain heat generators are naturally better suited to keep the building’s required primary energy demand low.
Was the figure changed from about 33 to 10.9 before (for example with an annual performance factor of 3) because it is divided by the annual performance factor?
As far as I know, you cannot convert this directly, but of course, the annual performance factor affects the conversion. If you want a realistic value for the building’s heating demand, the only reliable method is a heating load calculation.
Do you mean that the specified final energy demand is lower than in reality because the heat pump’s annual performance factor is included in the calculation?
In theory, the final energy demand should be the value you ultimately read from your meter. It is theoretical because calculations based on energy saving regulations are not always very close to reality, and there can be some deviations in practice.
Are the numbers you mentioned actual data? Does 26.1 mean 26.1 kWh/m² per year or 26,100 kWh as the annual primary energy demand for the entire building?
D
DerBjoern21 Nov 2014 11:44I’m not a professional either. I’m a homeowner who has just read extensively on the subject. (I am an engineer myself, but in a completely different field.) I just wanted to understand the matter and be able to reasonably verify what I’m being told.
Can you possibly provide more details about the planned house? Size, insulation, building services (air-source heat pump or ground-source, planned mechanical ventilation with heat recovery)? Are you building through an architect, a general contractor, or a developer?
The value of 26.1 kWh/m²a (8.3 kBtu/ft²/year) already sounds very low. And 10.9 kWh (10.9 kWh) final energy as well. Passive house? The system energy factor is also quite low.
No, 5070 kWh (5070 kWh) would be the primary energy. However, you only pay for what is shown on the meter. Based on the conversion factor alone, that would be 5070 kWh / 2.6 = 1950 kWh (1950 kWh). But as I said, you can’t directly translate that into real-world consumption. It’s not really suitable for that.
Can you possibly provide more details about the planned house? Size, insulation, building services (air-source heat pump or ground-source, planned mechanical ventilation with heat recovery)? Are you building through an architect, a general contractor, or a developer?
The value of 26.1 kWh/m²a (8.3 kBtu/ft²/year) already sounds very low. And 10.9 kWh (10.9 kWh) final energy as well. Passive house? The system energy factor is also quite low.
So, according to the formula above, Primary Energy = 0.550 * (6791 + 2428) = 5070. But what does that tell me? Should I expect an electricity consumption of 5070 kWh per year for heating and hot water? Or can you not say that?
No, 5070 kWh (5070 kWh) would be the primary energy. However, you only pay for what is shown on the meter. Based on the conversion factor alone, that would be 5070 kWh / 2.6 = 1950 kWh (1950 kWh). But as I said, you can’t directly translate that into real-world consumption. It’s not really suitable for that.
DerBjoern schrieb:
Can you maybe share more details about the planned house? Size, insulation, building services (air-source heat pump or ground-source, mechanical ventilation with heat recovery planned?). Are you building through an architect, a general planner/general contractor, or a developer?
The value of 26.1 kWh/m²a (8.2 BTU/ft²a) already sounds quite low. And 10.9 kWh final energy use as well. Passive house? The system efficiency factor is also quite low.It is a timber frame house from a large southern German company. The insulation consists of 16 cm mineral wool and 16 cm wood fiber insulation board. The mechanical ventilation with heat recovery basically also serves as the heating system, so there is no separate hydronic heating. The living area is 154 m² (1,658 ft²). It was not designed as a passive house, but only as a KfW 40 standard.
D
DerBjoern25 Nov 2014 08:11Okay, you should be able to find enough information on the builder’s construction method and the installed heating system on the internet.
E
ErikErdgas11 Dec 2014 20:54Hello,
Regarding primary energy demand, the factor method naturally favors wood as a renewable resource, but meeting the limits for subsidies is one thing, and comparing investment costs and ongoing expenses is another.
Therefore, heating load calculations with the different systems should be performed for a proper comparison.
For an initial comparison, however, you can use the calculated final energy demand and the costs for energy supply per kWh. Then, consider the usual service life of 25-30 years, as well as the purchase costs and annual maintenance and repairs. I would omit price increases for now. This way, you can compare the different systems in terms of cost and then discuss only the shortlisted systems further with a heating engineer.
Best regards, Erik
Regarding primary energy demand, the factor method naturally favors wood as a renewable resource, but meeting the limits for subsidies is one thing, and comparing investment costs and ongoing expenses is another.
Therefore, heating load calculations with the different systems should be performed for a proper comparison.
For an initial comparison, however, you can use the calculated final energy demand and the costs for energy supply per kWh. Then, consider the usual service life of 25-30 years, as well as the purchase costs and annual maintenance and repairs. I would omit price increases for now. This way, you can compare the different systems in terms of cost and then discuss only the shortlisted systems further with a heating engineer.
Best regards, Erik
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