Hello everyone,
I already have several energy performance certificates showing that for KfW55, a final energy demand of about 17 kWh/m²a (5.2 kBtu/ft² per year) has been calculated. This corresponds to an annual final energy demand of 2550 kWh/a (8700 kBtu/year) for a heated area of 150 m² (1615 ft²). The insulation, air-to-water heat pump, etc., also match my planned new build in timber frame construction. Here are my questions, as I feel a bit stuck:
1.) Has anyone had experience with similar figures and can confirm that these calculated values are realistic in practice?
2.) Can these numbers really be accurate, that only 2550 kWh/a (8700 kBtu/year) are needed? With electricity costs of €0.22, that would be only €560, and heat pumps produce more kilowatts of heat per kilowatt of electricity consumed.
3.) How exactly are the seasonal performance factors (seasonal COPs) calculated based on this final energy demand?
I have different seasonal performance factors for various heat pumps. I want to calculate the annual electricity demand in order to estimate running costs and assess from when a ground-source heat pump becomes worthwhile.
Split heat pump: 3.34
Monobloc heat pump: 3.67
Ground-source heat pump with horizontal loop: 4.67
Thank you very much
I already have several energy performance certificates showing that for KfW55, a final energy demand of about 17 kWh/m²a (5.2 kBtu/ft² per year) has been calculated. This corresponds to an annual final energy demand of 2550 kWh/a (8700 kBtu/year) for a heated area of 150 m² (1615 ft²). The insulation, air-to-water heat pump, etc., also match my planned new build in timber frame construction. Here are my questions, as I feel a bit stuck:
1.) Has anyone had experience with similar figures and can confirm that these calculated values are realistic in practice?
2.) Can these numbers really be accurate, that only 2550 kWh/a (8700 kBtu/year) are needed? With electricity costs of €0.22, that would be only €560, and heat pumps produce more kilowatts of heat per kilowatt of electricity consumed.
3.) How exactly are the seasonal performance factors (seasonal COPs) calculated based on this final energy demand?
I have different seasonal performance factors for various heat pumps. I want to calculate the annual electricity demand in order to estimate running costs and assess from when a ground-source heat pump becomes worthwhile.
Split heat pump: 3.34
Monobloc heat pump: 3.67
Ground-source heat pump with horizontal loop: 4.67
Thank you very much
I can't find any information on what percentage is added for that.
Would my calculation then be correct?
140 m² (1507 sq ft)
48.5 kWh/m²a heating demand
6790 kWh/year
Heat pump | Annual Performance Factor | kWh/year | $0.24/kWh
Split | 3.34 | 2032.93 | $487.90
Mono | 3.67 | 1850.14 | $444.03
Ground source (Sole) | 4.67 | 1453.96 | $348.95
And the 17 kWh/m²a (5.2 kWh/sq ft/year) come from the electricity generated by the photovoltaic system, which reduces the annual electricity demand?
Would my calculation then be correct?
140 m² (1507 sq ft)
48.5 kWh/m²a heating demand
6790 kWh/year
Heat pump | Annual Performance Factor | kWh/year | $0.24/kWh
Split | 3.34 | 2032.93 | $487.90
Mono | 3.67 | 1850.14 | $444.03
Ground source (Sole) | 4.67 | 1453.96 | $348.95
And the 17 kWh/m²a (5.2 kWh/sq ft/year) come from the electricity generated by the photovoltaic system, which reduces the annual electricity demand?
Yes; especially since it needs to be checked whether the annual performance factor is achieved. I’m not exactly sure how the photovoltaic electricity is considered, but as you said, it is definitely possible.
Additionally, there is hot water. Depending on demand, this can account for a large portion of the total electricity costs.
Additionally, there is hot water. Depending on demand, this can account for a large portion of the total electricity costs.
I used about 2000 kWh of electricity in my first year for a slightly larger KfW 70 house with a ground source heat pump, covering both heating and hot water. Therefore, the figures mentioned in the original post seem roughly accurate, as the system technology appears to have been taken into account.
S
Sebastian792 Dec 2015 19:34However, both in the pink and green forums, it is mentioned that the values from the Energy Saving Ordinance certificate have little to do with reality and hardly allow any conclusions to be drawn about the actual consumption.
Sebastian79 schrieb:
However, in both the pink and green forums, people say that the values from the energy saving regulation report have nothing to do with reality and that they hardly provide any indication of the actual consumption. Nothing like that has been claimed here. In the pink and green forums, the discussion usually isn’t about energy consumption, but about choosing a suitable heating appliance. In that context, an important figure is the heating load, to ensure the appliance is properly sized. Regarding heating load, having 200 m² (2,150 sq ft) of solar panels, optimal orientation, and large windows for solar gain (which can be beneficial for the energy saving regulation report) doesn’t help much if it’s −20°C (−4°F) on a cold winter night.
For overall energy consumption, the certificate does provide some indications — of course, user behavior (hot water usage, maintaining 26°C (79°F) in the living room) isn’t included there. But for a very rough comparison, it is sufficient. I believe it gets you into the right general “order of magnitude” (in a colloquial sense).
Besides, actual consumption varies significantly with the weather. I have logged the heating degree days from last year and can use that data for more precise long-term comparisons or to share some data if needed.
Similar topics