Hello,
Attached is the information from our energy consultant. With the installation of a photovoltaic system, we would meet the KFW 55 standard for primary energy demand.
However, the heat transmission loss is too high. We have 36.5cm (14 inches) brickwork and 0.09.
Can someone help me understand how we can reduce this value further? Which measures affect this value?
Thank you, Jörg
Hello,
Achieving KfW 55 standards is not easy (higher investment). For the specific heat demand (qp´´), an additional photovoltaic system is often required here.
The heat transfer coefficient (Ht´) is the second hurdle to overcome. Based on experience, significant improvement is possible when looking at the percentage distribution of total heat loss. Usually, depending on the building construction, improvements can be made in the areas of external walls (AW), ventilation heat losses (DA), and windows (AF) (Fx=1). In some cases, an external wall U-value (AW) of 0.08 W/(m²·K) may already be sufficient. However, a "solid" wall is no longer necessarily required. Therefore, I am not particularly fond of these monolithic external walls.
Furthermore, thermal bridges are important. I suspect the flat-rate allowance of 0.05 W/(m²·K). This means all thermal bridges must comply with DIN 4108 Part 2! Pay attention to the equivalence verification!
If it gets tight, a detailed proof of thermal bridges might also be necessary. However, this is expensive, so it is a rather rare exception.
Ultimately, construction supervision by a certified expert is required. That also costs money. Overall, the subsidy is relatively quickly used up.
Formally, KfW 55 standards save heating energy compared to the Energy Saving Ordinance standard. In practice, however, this only applies if the structural and system execution corresponds to the overall planning.
At this point, one sometimes encounters various "miracles," making the proof essentially a "creative calculation."
Subsidies generally cover the additional effort but usually do not fully compensate for it.
Best regards.
hululu0 schrieb:
Hello €uro, could you please explain that to me once more so I can follow? )
Achieving KfW 55 standards is not easy (higher investment). For the specific heat demand (qp´´), an additional photovoltaic system is often required here.
The heat transfer coefficient (Ht´) is the second hurdle to overcome. Based on experience, significant improvement is possible when looking at the percentage distribution of total heat loss. Usually, depending on the building construction, improvements can be made in the areas of external walls (AW), ventilation heat losses (DA), and windows (AF) (Fx=1). In some cases, an external wall U-value (AW) of 0.08 W/(m²·K) may already be sufficient. However, a "solid" wall is no longer necessarily required. Therefore, I am not particularly fond of these monolithic external walls.
Furthermore, thermal bridges are important. I suspect the flat-rate allowance of 0.05 W/(m²·K). This means all thermal bridges must comply with DIN 4108 Part 2! Pay attention to the equivalence verification!
If it gets tight, a detailed proof of thermal bridges might also be necessary. However, this is expensive, so it is a rather rare exception.
Ultimately, construction supervision by a certified expert is required. That also costs money. Overall, the subsidy is relatively quickly used up.
Formally, KfW 55 standards save heating energy compared to the Energy Saving Ordinance standard. In practice, however, this only applies if the structural and system execution corresponds to the overall planning.
At this point, one sometimes encounters various "miracles," making the proof essentially a "creative calculation."
Subsidies generally cover the additional effort but usually do not fully compensate for it.
Best regards.
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