Hello,
We are planning to build an urban villa. According to the building description, it will be constructed with 17.5 cm (7 inches) calcium silicate bricks and a 14 cm (5.5 inches) external thermal insulation composite system (ETICS), with a hipped roof at a 22-degree pitch.
The ceiling height should be 2.5 m (8.2 ft) for the 138 m² (1,487 ft²) living area.
The heating system specified in the building description is a Vaillant AuroCompact with a stratified storage tank (150 liters (40 gallons)), underfloor heating on both floors with individual room controls, and 2 solar panels (each 2.51 m² (27 ft²)).
We have now inquired about the additional cost if we want to upgrade to a KfW 70 energy standard house.
The following offer was made to us:
Increase insulation thickness from 14 to 16 cm (5.5 to 6.3 inches), install an air-to-air heat pump heating system (manufacturer not yet specified), and upgrade windows to triple glazing (currently Veka with double glazing, Ug 1.0). The price is €12,500. Is this justified? I find it a bit high, especially considering that the gas connection costs have already been offset in the calculation.
Unfortunately, I don’t know the heating load.
Regards,
Kay
We are planning to build an urban villa. According to the building description, it will be constructed with 17.5 cm (7 inches) calcium silicate bricks and a 14 cm (5.5 inches) external thermal insulation composite system (ETICS), with a hipped roof at a 22-degree pitch.
The ceiling height should be 2.5 m (8.2 ft) for the 138 m² (1,487 ft²) living area.
The heating system specified in the building description is a Vaillant AuroCompact with a stratified storage tank (150 liters (40 gallons)), underfloor heating on both floors with individual room controls, and 2 solar panels (each 2.51 m² (27 ft²)).
We have now inquired about the additional cost if we want to upgrade to a KfW 70 energy standard house.
The following offer was made to us:
Increase insulation thickness from 14 to 16 cm (5.5 to 6.3 inches), install an air-to-air heat pump heating system (manufacturer not yet specified), and upgrade windows to triple glazing (currently Veka with double glazing, Ug 1.0). The price is €12,500. Is this justified? I find it a bit high, especially considering that the gas connection costs have already been offset in the calculation.
Unfortunately, I don’t know the heating load.
Regards,
Kay
Bauexperte schrieb:
Hello,
That’s correct, and in the combination presented, it doesn’t make sense.
If you assume a “typical” GBR/solar system, this is a bold statement; it largely depends on the house’s orientation to the sun. Theoretically possible, but in practice quite rare. Additional measures are often required.
Best regards, BauexperteOf course, it’s not always easy, but if thermal insulation and efficiency are prioritized from the start with your builder/architect, KfW70 should also be achievable with gas/solar. If the roof is poorly positioned and receives very little sun, that’s a different matter 😉
Regarding my heating cost estimate, around 3,300 kWh per year are needed for heating and hot water. 63% of the hot water is covered by the solar system. Since I like to keep the temperature at about 24°C (75°F) and also have continuous ventilation, I estimate around 5,000 kWh.
It doesn’t really matter whether it’s 400 or 600 euros, an investment of over 30,000 euros can hardly ever pay off, even if heating costs dropped to 100 euros per year.
B
Bauexperte1 Dec 2013 00:28Hello,
I have just read this ...
Filled aerated concrete?
What costs 40,000 euros and how do you arrive at heating costs of €500 per year (including hot water)?
Regards, Bauexperte
I have just read this ...
Nutshell schrieb:
KfW55 new build without basement, 1.5 storeys, knee wall 70cm (28 inches), 112sqm (1205 sqft) living area, 4 floor-to-ceiling, 2 small and 5 standard windows
Roof orientation 30° west / 60° south
Exterior wall 36.5cm (14 inches) aerated concrete:
0.2 W/m²K
Filled aerated concrete?
Nutshell schrieb:
Something like this currently costs an estimated 40,000 euros and is hardly worth it, considering about 500 euros heating costs per year 🙂
What costs 40,000 euros and how do you arrive at heating costs of €500 per year (including hot water)?
Regards, Bauexperte
Nutshell schrieb:
.... 63% of the domestic hot water demand is covered by the solar thermal system... Please install a heat meter in the solar thermal system and later compare the actual yield with the 63% figure!Best regards
Bauexperte schrieb:
Hello,
I just read this now...
Filled aerated concrete?
What costs 40,000 euros and how do you arrive at heating costs of €500 per year (including hot water)?
Regards, BauexperteThe aerated concrete has a lambda value of 0.08 W/mK.
Filled? These are solid blocks without any air gaps or insulation wedges inside.
The larger investment I mentioned as an example, between 30,000 and 40,000 euros, would be a conversion to a zero-energy house, including photovoltaic panels and a heat pump.
I haven’t requested a concrete quote for this yet, as it is currently quite uneconomical.
The estimate of €500 is partly based on experience from other homeowners who chose this house,
and also on the calculated energy demand, which suggests it could even be less, although I still find that hard to imagine. Let’s say it’s €1,000 per year in the worst case. Even then, it would take 30 to 40 years for the zero-energy conversion to pay off. Considering interest and maintenance costs, I probably will never see the return on investment.
Nutshell schrieb:
...The estimate of 500,- is partly based on the experiences of other homeowners who chose this house,... A reliable transferability to other construction projects is impossible! Nutshell schrieb:
...In addition, the calculated energy demand shows, ... Which one? On what basis was it calculated?Best regards
Nutshell schrieb:
...until the net-zero energy renovation pays off,... Such terms should be used with great caution. These slogans are often found in colorful advertising brochures, of course without any liability or guarantee! ;-) When referring to annual energy balances, such approaches can indeed be economically viable. However, true self-sufficiency is certainly not achievable at present!
Regards
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