Hello everyone,
I currently need to decide on the thickness of our ETICS (External Thermal Insulation Composite System) for the facade. According to the energy-saving regulations, I need at least 12cm (5 inches) on my precast concrete elements.
I have now received quotes for 14cm (5.5 inches), 16cm (6.3 inches), and 18cm (7 inches) as well.
According to the architect, the energy demand differs as follows:
Thickness Final Energy Demand Primary Energy Demand
12 cm (5 inches) 17.70 31.87
14 cm (5.5 inches) 17.66 31.78
16 cm (6.3 inches) 17.04 30.67
18 cm (7 inches) 17.01 30.62
The units are kWh/m²a.
So, what now?
The house has a full basement. Basement and roof insulation are not to be considered here. Geothermal energy will be used as the energy source, and a controlled mechanical ventilation system with heat recovery will be installed. The windows have triple glazing. Overall, about 220 m² (2370 ft²) of living and usable space will be fully heated (attic insulated but not heated).
Do I now have to multiply the difference by the living/usable area, apply my average kWh price, and that will be the additional annual cost? Or am I thinking about this incorrectly?
Thanks and regards,
Markus
I currently need to decide on the thickness of our ETICS (External Thermal Insulation Composite System) for the facade. According to the energy-saving regulations, I need at least 12cm (5 inches) on my precast concrete elements.
I have now received quotes for 14cm (5.5 inches), 16cm (6.3 inches), and 18cm (7 inches) as well.
According to the architect, the energy demand differs as follows:
Thickness Final Energy Demand Primary Energy Demand
12 cm (5 inches) 17.70 31.87
14 cm (5.5 inches) 17.66 31.78
16 cm (6.3 inches) 17.04 30.67
18 cm (7 inches) 17.01 30.62
The units are kWh/m²a.
So, what now?
The house has a full basement. Basement and roof insulation are not to be considered here. Geothermal energy will be used as the energy source, and a controlled mechanical ventilation system with heat recovery will be installed. The windows have triple glazing. Overall, about 220 m² (2370 ft²) of living and usable space will be fully heated (attic insulated but not heated).
Do I now have to multiply the difference by the living/usable area, apply my average kWh price, and that will be the additional annual cost? Or am I thinking about this incorrectly?
Thanks and regards,
Markus
Whether something is "worth it" is always a very individual matter.
I would like to be able to estimate if the additional cost (12 to 14: ~650€, 12 to 16: ~1300€, 12 to 18: 2000) pays off or not.
For this, I would consider only the insulation, even though that might not be 100% meaningful. The heat pump is already planned, and I don’t want to open a full cost analysis regarding drilling meters at this point.
So, how can I relate the above values to each other?
Regards,
-Markus-
I would like to be able to estimate if the additional cost (12 to 14: ~650€, 12 to 16: ~1300€, 12 to 18: 2000) pays off or not.
For this, I would consider only the insulation, even though that might not be 100% meaningful. The heat pump is already planned, and I don’t want to open a full cost analysis regarding drilling meters at this point.
So, how can I relate the above values to each other?
Regards,
-Markus-
T
toxicmolotof14 Mar 2018 14:25Considering the heat source and the rather (somewhat) rising rather than falling heating costs, I would go with the 18cm (7 inches).
By increasing the insulation from 14 to 18cm (5.5 to 7 inches) and adding a photovoltaic system, we were able to meet the old energy saving regulations (before 2016) for KfW55 standard. It surprises me that nowadays 12cm (5 inches) is supposed to be enough to comply with the current energy saving regulations.
What does the rest of your heating (energy) concept look like?
Do you know if this would allow you to choose a smaller heat pump? That could possibly save you around 400 euros.
By increasing the insulation from 14 to 18cm (5.5 to 7 inches) and adding a photovoltaic system, we were able to meet the old energy saving regulations (before 2016) for KfW55 standard. It surprises me that nowadays 12cm (5 inches) is supposed to be enough to comply with the current energy saving regulations.
What does the rest of your heating (energy) concept look like?
Do you know if this would allow you to choose a smaller heat pump? That could possibly save you around 400 euros.
We financed without KFW funding and are therefore not bound by any specific requirements.
Geothermal energy and controlled residential ventilation. Underfloor heating throughout the entire house. The heat pump is modulating – with the even smaller model, I would be a bit "cautious" that it might not be sufficient.
How do I calculate this now? With a naive view on the "decimal places," I would have instinctively said 16cm (6 inches) is enough.
Best regards
Markus
Geothermal energy and controlled residential ventilation. Underfloor heating throughout the entire house. The heat pump is modulating – with the even smaller model, I would be a bit "cautious" that it might not be sufficient.
How do I calculate this now? With a naive view on the "decimal places," I would have instinctively said 16cm (6 inches) is enough.
Best regards
Markus
You have an energy demand per square meter for 12 cm (5 inches) and for 16 cm (6.3 inches) of insulation. You multiply the difference by the area to be insulated, and the result is the difference in heating demand that the heat pump has to cover. Let’s assume your heat pump has an annual performance factor (COP) of 4. Then you divide this heating demand by 4 and multiply it by the price you pay for one kWh of electricity.
PS. What type of heat pump did you choose?
PS. What type of heat pump did you choose?
Hello,
Honestly, the differences in the values seem very small to me. If these values are correct, the difference is less than 200 kWh/year between 12 cm (5 inches) and 18 cm (7 inches) of insulation.
So, that’s no more than 200 * 0.3 / 4 = 15 USD difference per year?
Based on my intuition, that doesn’t feel quite right... I would have expected at least 50 to 100 USD in savings. Which still wouldn’t be cost-effective, though!
Regards,
Andreas
Honestly, the differences in the values seem very small to me. If these values are correct, the difference is less than 200 kWh/year between 12 cm (5 inches) and 18 cm (7 inches) of insulation.
So, that’s no more than 200 * 0.3 / 4 = 15 USD difference per year?
Based on my intuition, that doesn’t feel quite right... I would have expected at least 50 to 100 USD in savings. Which still wouldn’t be cost-effective, though!
Regards,
Andreas
I find that a bit strange as well. The values come from the architect – it’s possible he made a miscalculation.
Thermal conductivity is 0.034 W/m*K – thickness as described above. About 237 m² (2550 ft²) of insulation panels.
The heat pump is the Buderus WPS 10-1.
If I base it on the primary energy demand, I get a difference from 12 to 16.
31.87 - 30.67 = 1.2
Difference multiplied by area – so 225 m² (2420 ft²).
1.2 * 225 = 270.
Assumed coefficient of performance (COP) 4
270 / 4 = 67 kWh per year.
30 cents per kWh → 20 € per year.
That’s not cost-effective at all 🙁
Could the original numbers really be correct?
Best regards,
-Markus-
Thermal conductivity is 0.034 W/m*K – thickness as described above. About 237 m² (2550 ft²) of insulation panels.
The heat pump is the Buderus WPS 10-1.
If I base it on the primary energy demand, I get a difference from 12 to 16.
31.87 - 30.67 = 1.2
Difference multiplied by area – so 225 m² (2420 ft²).
1.2 * 225 = 270.
Assumed coefficient of performance (COP) 4
270 / 4 = 67 kWh per year.
30 cents per kWh → 20 € per year.
That’s not cost-effective at all 🙁
Could the original numbers really be correct?
Best regards,
-Markus-
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