ᐅ Reliability of an energy calculation for KfW 55 – is it too high?
Created on: 20 Jun 2016 18:01
W
WT1987
Hello everyone,
For our new build with 2 full floors and a basement, we have now received a calculation for the entire KfW application. However, it seems to me that the numbers are being calculated quite high or may even be incorrect.
Some data about the house:
Is that the electricity consumption I should expect, or am I misunderstanding something? That seems very high!
Thank you in advance.
For our new build with 2 full floors and a basement, we have now received a calculation for the entire KfW application. However, it seems to me that the numbers are being calculated quite high or may even be incorrect.
Some data about the house:
- Architect’s plan shows living area: ground floor 75m² (807 ft²) & upper floor 70m² (753 ft²) (difference due to open space)
- Clear ceiling height: ground floor 2.7m (8 ft 10 in) & upper floor 2.5m (8 ft 2 in)
- Basement is unheated, air-water heat pump located in the basement
- Attic is not developed
- Air-water heat pump with ventilation system including heat recovery
- The expert assessor calculates a usable floor area of 277m² (2,982 ft²), which seems very high to me! He then uses this to estimate electricity consumption and arrives at a final energy demand of 4,860 kWh/year
Is that the electricity consumption I should expect, or am I misunderstanding something? That seems very high!
Thank you in advance.
T
toxicmolotof21 Jun 2016 15:15Our house has 7 rooms (+2 hallways).
S
Sebastian7921 Jun 2016 15:17My imagination is poor – you had a cube-shaped building with a recessed top floor, right?
T
toxicmolotof21 Jun 2016 15:23No, it was not a cube, but yes, a setback upper floor with a partial 3m (10 feet) recess, meaning that on the ground floor every room has a floor and a ceiling and at least two exterior walls, and on the upper floor a ceiling and at least two exterior walls. In total, there are 17 exterior surfaces and 42 exterior edges.
toxicmolotow schrieb:
The KfW standard is not meant to compare the money saved.
The absolute value already provides a lot of information (under laboratory conditions).
A typical house of this design would require even more energy. That’s what it shows.
Anyone wanting a nice, individual house design (or forced to by building authority requirements) has to pay the price for it.
Considering that each of our rooms has four external walls, I find the value very good. I can’t imagine 7 rooms, 2 floors, and each room having 4 external walls either. Three, yes, but four?
Edit. You were faster. But then it’s not 4 full walls, more like about 3.4.
S
Sebastian7921 Jun 2016 15:24Ah, then I misunderstood – that makes sense. Some people and what they know about their house – old number crunchers 😀.
T
toxicmolotof21 Jun 2016 15:29There are only two rooms that do not have four exterior walls (bathroom and children's room), but the hallway and the living room each have five.
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