Energy Saving Ordinance 2016 or KFW 55 for bungalow with air-water heat pump & controlled residential ventilation, optional photovoltaic

  • Erstellt am 2019-06-05 08:25:46

boxandroof

2019-06-10 20:51:13
  • #1
You are mixing heating load with heat demand here. Even if it pays off, you won't become rich from the measure.

It depends on the overall concept and its goals: which heating system, subsidies, threshold values to reach the next level, or to take the smaller heating system. If you push insulation to the limit, you no longer need a conventional heating system, so it might pay off again.

You will insulate the slab either above or below the concrete, below is better, both are possible.
 

nix zu schwör

2019-06-23 12:08:12
  • #2
@

A consulting engineer is liable, as with any chamber profession.

Especially with the heating system, you save significant amounts over decades.

Where did you hear that nonsense, that is complete rubbish, neither condensing technology nor heat pump technology has a lifespan of several decades. You'll be happy if you make it through 1.

The annual performance factor is close to 5, as we have planned the heating surfaces, hydraulics, and the building accordingly.

You only achieve an annual performance factor of 5 with expensive geothermal probes, consequently, the investment is much more expensive and the consumption is often only equal to gas, which will hardly be sustainable with the increases in electricity costs. With an air heat pump, you can only dream of half that. The test parameters are also fixed, otherwise the specification would make no sense, therefore the COP is also not taken into account.

@

You can't skip the insulation, it must already be proven for the Energy Saving Ordinance 2013. Furthermore, you forget the thermal bridge surcharge, because with that you can no longer apply an optimized flat rate for the building. This means not only your calculation is wrong but that no KfW house is achievable, no matter how poor.

@

Heating load calculation DIN EN 12831 with mh software is already the right step.

Many still have not understood that the sum of the room heating loads is generally significantly higher than the building heating load according to Energy Saving Ordinance 2013, which is only roughly estimated here and the parameters in the building itself are not taken into account at all.
 

ares83

2019-06-23 12:35:43
  • #3

In practice, it looks different. We also have an annual performance factor well above 4, and that with an air-to-water heat pump. Your aversion to the technology somewhat clouds your view of reality.
 

boxandroof

2019-06-23 13:42:25
  • #4
Of course not. The decision for a specific type of heating and its follow-up costs usually does not end with the replacement of the boiler or whatever. An annual performance factor of 5 is not only achievable with expensive geothermal probes. 4.5 as an annual performance factor for an air-to-water heat pump is a realistic goal and would be my standard in new buildings; we are well above that. However, you will not find anyone liable for that. My planner also came to me with various "wisdoms" about the annual performance factor, after which I (out of necessity) took care of various details myself.

By the way, BAFA only subsidizes air-to-water heat pumps from a calculated annual performance factor of 4.5.
 

nix zu schwör

2019-06-24 12:57:05
  • #5
@

There are standard values and no practical values, since ideal and identical conditions can be assumed in the standard. Because the COP value is at least 1 point higher than the annual performance factor value, this only confirms the poor annual performance factor of the air heat pump. Radiators and thus a higher flow temperature than 35° are excluded anyway.



BAFA grants funding from a COP of 3.1, which corresponds to an annual performance factor of around 2.1, since an annual performance factor of 2.5 was not sustainable in the past and temperatures below 7° are no longer considered.

Quote BAFA:
....for determining the subsidy for the heat source "air", the heating capacity at A-7/W35 is used.

because hardly any air heat pump could demonstrate such a value. Only with an achievable annual performance factor for ground probes above 4.5 would the kWh be cheaper than with gas. Due to the current electricity price, the trend is already towards an annual performance factor of 5.0.
No heat pump with ground probes currently achieves more than an annual performance factor of 5.5-6.0. Regarding the 6.0, I only know of a research project. No idea if it still exists.

Here the politically artificially raised primary energy factor for electricity does not apply, because it is about the hard costs and not how air heat pumps are made attractive to builders.

Therefore, the change to only approve passive houses in new construction from 2020/21. Because no matter which current heating system is used, all are significantly more expensive than the old systems, simply because the service life is far too short.
 

boxandroof

2019-06-24 13:11:54
  • #6
I agree with you on the policy, and that lifespan is a factor in the economic efficiency consideration, especially when the heat pump is purchased at a high price. However, nothing can be said about this in general terms. Regarding the other generalized statements about standards and COPs, I have nothing sensible to add.

At [BAFA] there is an annual performance factor calculator. Subsidies for new buildings are granted from an annual performance factor of 4.5 for air-water heat pumps including hot water generation. The value is purely theoretical and has become difficult to achieve since the last change in the funding guidelines. But still not impossible. So much for the theory.

Enough has already been written about practice.
 

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