Nutshell
2014-04-23 20:08:53
- #1
I assume this is about a new build, single-family house.
Anyone aiming for a Kfw loan should have the house achieve 70, 55, or 40% of the primary energy demand of the "[Energieeinsparverordnung Referenzgebäude]."
In addition, the transmission heat loss must be lower.
Since the house must be seen as an overall concept, you can't just say "Put Styrofoam on the wall and that's it."
The U-values of all components must be considered.
So first describe what you plan to do...
Living area in sqm?
When do you want to start building?
Single-family detached house or semi-detached, townhouse?
Prefer radiators, underfloor heating, or air heating?
Before you start building and especially before you sign the contract for a turnkey house... Please inform yourselves much, much more!
I am currently also building... a single-family house with 112 sqm living area, without skylights, without bay windows, without conservatory, without dormer, without knee wall, without garage, without basement... with underfloor heating, solar for hot water, gas condensing boiler, decentralized ventilation system with heat recovery and soundproofing.
Small but fine and achieves KFW 55 without slapping Styrofoam on the exterior walls. (Problems with moisture, ants, pests, wasps, woodpeckers, algae decay etc. are more than enough in our neighborhood, luckily we can do without them)
The foundation slab should therefore be equipped with XPS perimeter insulation accordingly.
The walls should have a good U-value, so at least 36.5 cm thick walls.
Example: 36.5 cm wall with Lambda 0.09 = U-value 0.237
= with 125 sqm exterior wall and 20°C temperature difference, 14.1 kWh heating demand in 24 hours.
Example: 36.5 cm wall with Lambda 0.08 = U-value 0.211
= with 125 sqm exterior wall and 20°C temperature difference, 12.6 kWh heating demand in 24 hours.
Example: 36.5 cm wall with Lambda 0.07 = U-value 0.186
= with 125 sqm exterior wall and 20°C temperature difference, 11.1 kWh heating demand in 24 hours.
So you can save about 20% losses by investing more money in better bricks.
But now there’s still the roof, foundation slab, windows.
If all of this is executed with high quality (thermal bridges are avoided)
and the ventilation works with heat recovery... it should already be more efficient than many, many other houses!
Besides, you also save quite a bit in investment costs if you do without frills like a basement, conservatory, blah blah. Especially since many errors happen with basements!!
(A tool shed in the garden also does the job!)
Anyone aiming for a Kfw loan should have the house achieve 70, 55, or 40% of the primary energy demand of the "[Energieeinsparverordnung Referenzgebäude]."
In addition, the transmission heat loss must be lower.
Since the house must be seen as an overall concept, you can't just say "Put Styrofoam on the wall and that's it."
The U-values of all components must be considered.
So first describe what you plan to do...
Living area in sqm?
When do you want to start building?
Single-family detached house or semi-detached, townhouse?
Prefer radiators, underfloor heating, or air heating?
Before you start building and especially before you sign the contract for a turnkey house... Please inform yourselves much, much more!
I am currently also building... a single-family house with 112 sqm living area, without skylights, without bay windows, without conservatory, without dormer, without knee wall, without garage, without basement... with underfloor heating, solar for hot water, gas condensing boiler, decentralized ventilation system with heat recovery and soundproofing.
Small but fine and achieves KFW 55 without slapping Styrofoam on the exterior walls. (Problems with moisture, ants, pests, wasps, woodpeckers, algae decay etc. are more than enough in our neighborhood, luckily we can do without them)
The foundation slab should therefore be equipped with XPS perimeter insulation accordingly.
The walls should have a good U-value, so at least 36.5 cm thick walls.
Example: 36.5 cm wall with Lambda 0.09 = U-value 0.237
= with 125 sqm exterior wall and 20°C temperature difference, 14.1 kWh heating demand in 24 hours.
Example: 36.5 cm wall with Lambda 0.08 = U-value 0.211
= with 125 sqm exterior wall and 20°C temperature difference, 12.6 kWh heating demand in 24 hours.
Example: 36.5 cm wall with Lambda 0.07 = U-value 0.186
= with 125 sqm exterior wall and 20°C temperature difference, 11.1 kWh heating demand in 24 hours.
So you can save about 20% losses by investing more money in better bricks.
But now there’s still the roof, foundation slab, windows.
If all of this is executed with high quality (thermal bridges are avoided)
and the ventilation works with heat recovery... it should already be more efficient than many, many other houses!
Besides, you also save quite a bit in investment costs if you do without frills like a basement, conservatory, blah blah. Especially since many errors happen with basements!!
(A tool shed in the garden also does the job!)