Hello,
we have just received quotes from house construction companies. The exterior walls are specified as 17.5 cm (7 inches) thick. This seems a bit thin to me. Can anyone help me with their knowledge or experience? We are building a bungalow-style house with a heat pump (if that is relevant...).
we have just received quotes from house construction companies. The exterior walls are specified as 17.5 cm (7 inches) thick. This seems a bit thin to me. Can anyone help me with their knowledge or experience? We are building a bungalow-style house with a heat pump (if that is relevant...).
For an energy-efficient construction, a U-value of the exterior wall and roof assembly below 0.17 W/m²K for the entire component (...not just the insulated section...) should be aimed for.
In the case of a bungalow design, the surface-to-volume ratio (the ratio of the exterior surface area to the building volume) is less optimal, so a low U-value of the building envelope is essential for energy-efficient construction.
Heat pump! – With a well-insulated building envelope, the heating load decreases, creating ideal conditions (low temperature difference) for particularly energy-saving operation and better seasonal performance factors of a heat pump. If the building is less well insulated and a more cost-effective heat pump is used (for example, an air-to-water heat pump), frequent use of the electric heating element may occur, resulting in energy consumption that can even exceed that of a condensing gas boiler.
Regards
T.H.
In the case of a bungalow design, the surface-to-volume ratio (the ratio of the exterior surface area to the building volume) is less optimal, so a low U-value of the building envelope is essential for energy-efficient construction.
Heat pump! – With a well-insulated building envelope, the heating load decreases, creating ideal conditions (low temperature difference) for particularly energy-saving operation and better seasonal performance factors of a heat pump. If the building is less well insulated and a more cost-effective heat pump is used (for example, an air-to-water heat pump), frequent use of the electric heating element may occur, resulting in energy consumption that can even exceed that of a condensing gas boiler.
Regards
T.H.
T.H. schrieb:
....If the building is less well insulated and the heat pump used is a more budget-friendly compromise (for example, an air-to-water heat pump), the electric backup heater may be used frequently, resulting in energy consumption that could exceed that of a condensing gas boiler. That is not correct! The energy consumption of a heat pump, regardless of the type, is always lower compared to a combustion-based heat source such as a gas condensing boiler, provided that environmental energy sources are utilized! However, operating costs can be higher if the system is inadequately or poorly designed. Energy is measured in kWh, not in currency! Furthermore, air-source heat pumps are fundamentally not a compromise, as the somewhat lower annual performance factor compared to, for example, brine systems often does not justify the additional costs for ground or water source installation. Nevertheless, air-source heat pumps only make sense if all boundary and framework conditions are suitable and if the overall system has been precisely sized and designed. Unfortunately, it is still common to find general contractors building projects where air-source heat pump combination units are installed without sufficient dimensioning. In such cases, operating costs may become uncomfortably high due to the resulting low annual performance factor.Hello,
I believe the question about the correct wall thickness has already been discussed here about 936 times. Somehow, the conclusion is always the same: this question cannot be answered universally. It depends on your specific requirements.
The material plays a major role — calcium silicate blocks, aerated concrete, fired clay blocks, wood. All these materials meet different demands in different ways. Keywords here are sound insulation, thermal insulation, and structural stability.
Then, your building has to be considered as a whole. The interaction between the building structure and building services must fit together perfectly.
In general, the only thing that can be said is that it makes sense to design the building envelope so energy is hardly needed to heat your house.
Best regards
I believe the question about the correct wall thickness has already been discussed here about 936 times. Somehow, the conclusion is always the same: this question cannot be answered universally. It depends on your specific requirements.
The material plays a major role — calcium silicate blocks, aerated concrete, fired clay blocks, wood. All these materials meet different demands in different ways. Keywords here are sound insulation, thermal insulation, and structural stability.
Then, your building has to be considered as a whole. The interaction between the building structure and building services must fit together perfectly.
In general, the only thing that can be said is that it makes sense to design the building envelope so energy is hardly needed to heat your house.
Best regards
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