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
K
Knallkörper18 Mar 2018 19:24Alex85 schrieb:
His building loses energy not only through the walls but also through the floor, roof, windows and doors, thermal bridges, and ventilation.That is correct. That is why the change in energy demand is so small when expressed in absolute numbers. However, there is still an error in the calculation.
K
Knallkörper19 Mar 2018 11:19Yes, the actual curve resembles that of an exponential decay. Whether it could be distinguished from a linear function over such a small interval is debatable.
However, the numbers from the first post do not support this. I will try to explain it differently. Each time I increase the insulation thickness by 2cm (1 inch), there is a reduction in energy consumption. Each increase has a similar but smaller effect than the previous one. Unless I am completely mistaken, the numbers in the original post contradict this relationship.
However, the numbers from the first post do not support this. I will try to explain it differently. Each time I increase the insulation thickness by 2cm (1 inch), there is a reduction in energy consumption. Each increase has a similar but smaller effect than the previous one. Unless I am completely mistaken, the numbers in the original post contradict this relationship.
A
Aliban201419 Mar 2018 15:50Without detailed information about the concrete walls, without plaster, and without guaranteeing the accuracy of the entries on the U-value calculator website, the following example U-values would result
(according to the energy saving regulations, exterior walls exposed to outside air may have a maximum U-value of 0.28)
24cm (9.5 inches) concrete: U-value 3.65
24cm (9.5 inches) concrete + 12cm (4.7 inches) EPS insulation 035: U-value 0.270
24cm (9.5 inches) concrete + 14cm (5.5 inches) EPS insulation 035: U-value 0.233
24cm (9.5 inches) concrete + 16cm (6.3 inches) EPS insulation 035: U-value 0.206
24cm (9.5 inches) concrete + 18cm (7.1 inches) EPS insulation 035: U-value 0.184
If lower quality insulation is chosen (EPS 040 or EPS 045), the U-values will accordingly be higher.
Whether it becomes economically worthwhile in the long run depends especially on future heating electricity costs, I think, since these could also (considerably? Crystal ball!) be above 0.30€/kWh. The insulation costs, on the other hand, are a "one-time expense."
Just based on feel, I would go with 16cm (6.3 inches) of insulation.
I also find it difficult to see a clear financial benefit from the calculations. I rather doubt that it would play any role when selling the house.
(according to the energy saving regulations, exterior walls exposed to outside air may have a maximum U-value of 0.28)
24cm (9.5 inches) concrete: U-value 3.65
24cm (9.5 inches) concrete + 12cm (4.7 inches) EPS insulation 035: U-value 0.270
24cm (9.5 inches) concrete + 14cm (5.5 inches) EPS insulation 035: U-value 0.233
24cm (9.5 inches) concrete + 16cm (6.3 inches) EPS insulation 035: U-value 0.206
24cm (9.5 inches) concrete + 18cm (7.1 inches) EPS insulation 035: U-value 0.184
If lower quality insulation is chosen (EPS 040 or EPS 045), the U-values will accordingly be higher.
Whether it becomes economically worthwhile in the long run depends especially on future heating electricity costs, I think, since these could also (considerably? Crystal ball!) be above 0.30€/kWh. The insulation costs, on the other hand, are a "one-time expense."
Just based on feel, I would go with 16cm (6.3 inches) of insulation.
I also find it difficult to see a clear financial benefit from the calculations. I rather doubt that it would play any role when selling the house.
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