ᐅ Energy Saving Regulation 2016 or KfW 55 Standard for a Bungalow with Air-to-Water Heat Pump and Controlled Mechanical Ventilation, Optional Photovoltaic System

Created on: 5 Jun 2019 08:25
M
micric3
Good morning,

We are currently in the preliminary planning phase and are being flooded with information from various builders.

The topic of the "Energy Saving Ordinance 2016 or KfW 55 standard" especially leads to additional discussions.

The current concept for a household of four is as follows:
- Underfloor heating + air-to-water heat pump / controlled mechanical ventilation system combo, for example Vaillant recoCOMPACT (alternative: Nibe 730/750)
- Photovoltaic system ready for later retrofitting
- No gas connection possible/available

Opinions from some builders:
- KfW 55 was only attractive because of the low interest rates compared to traditional bank loans
- Currently, few are building to KfW 55 standard; the Energy Saving Ordinance 2016 is 'back in trend'

Calculation from another builder:
30 cm (12 inches) exterior masonry instead of 24 cm (9.5 inches) exterior masonry (both according to Energy Saving Ordinance 2016) = (costs €3,750)
(Additional costs for KfW 55 with 36.5 cm (14 inches) exterior masonry, floor slab insulation, increased roof insulation, and KfW 55 calculations and documentation were (costs €14,680))

I would like to hear some opinions on this:

Good luck
Michael
E
Egberto
5 Jun 2019 14:21
The Energy Saving Ordinance is appropriate, but you will never recover €15,000 through heating savings alone,...
S
Snowy36
5 Jun 2019 14:44
What material do you want to build the house from, did I miss that? Ytong, aerated concrete?
M
micric3
5 Jun 2019 15:04
Aerated concrete is at least according to the offer

@fragg: I couldn’t quickly find it from Vaillant, but the Nibe F730 has exactly this exhaust air heat pump, so why should it be worse than using outdoor air? The system is basically the same

Diagram of a heating system with flow/return, cold and domestic hot water, connections XL1-XL4
N
nix zu schwör
5 Jun 2019 15:26
In principle, the planner should point out the issue of depreciation, since in about 1–2 years the Passive House standard will apply under the Energy Saving Ordinance.

Therefore, a KfW55 house should generally be recommended, as this should help keep depreciation in check before the house is occupied.

The question is how the house is verified—that is, how good the building envelope really is. This means without a high primary energy factor, such as with electricity or even with photovoltaic systems.

This can be clearly seen through the room heating load according to DIN EN 12831.
Note: not the building heating load. The sum of the room heating loads is usually higher than the building heating load, in the case of a KfW55 house by up to a third or more.
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boxandroof
5 Jun 2019 15:30
The house’s exhaust air alone is not sufficient to operate the heat pump. In that case, either additional electric heating must be used, or the heat pump can also draw from outdoor air. I’m not sure if the latter applies here. The latter option increases complexity, initial costs, and depreciation expenses, while pure electric heating just generates additional costs.

There are few reasons to justify using such a heating system. However, general contractors seem to prefer it quite often.

With a standard mechanical ventilation system with heat recovery, the heat in the exhaust air is not lost either.
L
Lumpi_LE
5 Jun 2019 15:31
KFW 55 as a benchmark is rather unimportant. For an air-to-water heat pump, I would consider the heating load more important and limit it to 5 kW. That would certainly also be a KFW 55 house.