dertill
2018-10-09 07:44:56
- #1
For a difference of 1 W/m²K in the U-value of a component, an energy saving of 70 kWh/m² (surface area, not living area) per year can be assumed.
When insulating an exterior wall with an area of 100m² with a U-value of 1.5 down to a value of 0.5 W/m²K, the energy demand decreases by approximately (1.5 - 0.5) * 100 * 70 = 7,000 kWh.
In your example, the change in the U-value is from 0.26 to 0.21, so a difference of 0.05 W/m²K. This results in a saving (for 100m² wall area) of 0.05 * 70 * 100 = 350 kWh per year. At production costs of 10 ct/kWh, that is 35 euros per year... Better to use the warm edge spacer in the windows than the thick stone. That probably yields a similar amount.
When insulating an exterior wall with an area of 100m² with a U-value of 1.5 down to a value of 0.5 W/m²K, the energy demand decreases by approximately (1.5 - 0.5) * 100 * 70 = 7,000 kWh.
In your example, the change in the U-value is from 0.26 to 0.21, so a difference of 0.05 W/m²K. This results in a saving (for 100m² wall area) of 0.05 * 70 * 100 = 350 kWh per year. At production costs of 10 ct/kWh, that is 35 euros per year... Better to use the warm edge spacer in the windows than the thick stone. That probably yields a similar amount.