ᐅ Gas heating plus photovoltaic system possible without proof

Created on: 12 Dec 2019 16:30

Hello, I have a question and urgently need your expertise.

I am planning a new build using monolithic construction with Poroton 36.5cm (14.4 inches) blocks without an external thermal insulation composite system.

Now, instead of an air-source heat pump, I would like to install a gas heating system. Unfortunately, my architect’s 2016 energy calculation software only offers the option of a solar thermal system. This is how compliance with the energy-saving ordinance (EnEV) is demonstrated. However, for me, solar thermal is becoming outdated, and I would prefer gas combined with photovoltaic panels. Allegedly, this should be possible with a gas heating system and 10m² (108ft²) of photovoltaic without further proof…

Can anyone provide more details or a tip on where I can officially verify this?

The calculations of the various options currently show the following for our house…

1. With air-source heat pump
Primary energy demand is 36.2 kWh/m²*a and
corresponds to KfW Efficiency House 55.

2. Option: Gas + Solar + Ventilation system
Primary energy demand is 45.1 kWh/m²*a and
corresponds to KfW Efficiency House 70.

3. Option: Gas + Ventilation system
Primary energy demand is 58.10 kWh/m²*a
Efficiency house rating is 82.1% and proof of compliance not achieved.

4. Option: Gas with solar thermal
Primary energy demand is 52.9 kWh/m²*a, requirement value 53.1 — > energy-saving ordinance fulfilled.

Dr Hix5 Jan 2020 15:17

#13

Subwoofer schrieb:

If you can trust the energy consultant.

This is where things should start.

I have already dealt with several representatives of this profession, and unfortunately, many have little knowledge of the subject and/or no interest in delivering anything beyond the standard approach. They can manage their software solutions reasonably well and put together some results for a flat fee. But then it follows that “If the software doesn’t know it or can’t handle it, it doesn’t exist.” The result is often an overuse of materials when trying to meet certain thresholds (“No, we definitely need solar thermal as well”).

For example, we had this experience with the so-called “shower pipe.” This component is apparently still somewhat rare and therefore does not appear in many programs’ drop-down menus under standard solutions for renewable energy. The result: three out of four energy consultants either could not or did not want to include it.

Another example concerns thermal bridges (in the context of KFW funding), for which the KFW offers no less than four options for consideration. However, the energy consultants always calculated with the flat rate of 0.1 (for older buildings); everything else was considered new construction.

Or, as already mentioned, the representation of actual technical system parameters—it is too much work, so standard values from the DIN standard of 2001 (?) are used, meaning on paper they work with technology almost 20 years old.

hegi___5 Jan 2020 15:48

#14

Nordlys schrieb:

Try planning the whole thing with 36.5cm (14 inches) Ytong blocks instead of Poroton. I think that might work.

Ytong is not necessarily better than Poroton!

Nordlys5 Jan 2020 15:56

#15

Try it. You have to do the calculations. For us, it would have been possible with a so-called insulated ground slab using gas. It was too expensive for us. Gas combined with solar was simply the most cost-effective.

Subwkloofer5 Jan 2020 15:58

#16

Well, we already have a basement and also need to consider insulation above the basement ceiling.

ᐅ Gas heating plus photovoltaic system possible without proof

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