ᐅ Mechanical ventilation with heat recovery instead of solar thermal energy?

Kabelmodem87 schrieb:
Yes, I would be interested in that too

It's a pity that no feedback has been given so far. The answers would be highly interesting for many others as well, even if only as an indication.

My own rough calculation using the Energy Saving Ordinance Excel tool from the University of Kassel showed that with gas plus controlled residential ventilation without solar, even with better insulation (KfW55 standard) and air tightness testing at the Ht value (0.24), we are more than 15% below the Energy Saving Ordinance 2016 target (0.35) in terms of heat transfer coefficient, but not for the annual primary energy demand.

The Renewable Energy Heat Act requires, as a valid alternative measure, a 15% lower annual primary energy demand than the Energy Saving Ordinance 2016 and a 15% better insulation value than the Energy Saving Ordinance 2016.

According to the Energy Saving Ordinance 2016, our allowable annual primary energy demand is a maximum of 49.38 kWh/(m²a) (49.38 kWh per square meter per year). However, the house only achieved 52.85 kWh/(m²a). This means that it does not even meet the Energy Saving Ordinance 2016.

We would have met the 2014 Energy Saving Ordinance maximum of 65.84 kWh/(m²a), but that no longer counts. Back then, even as an alternative measure (85% = 55.96 kWh/(m²a)), it would have been sufficient without solar.

If a detailed thermal bridge calculation is carried out, our house (depending on the results of this calculation) would speculatively reach 48.40 kWh/(m²a), which would only just comply with the Energy Saving Ordinance 2016.

So, based on my rough inputs into the Excel calculator, I see no way to forgo solar under the Renewable Energy Heat Act since 2016 if you want to use gas.

Our energy consultant is currently doing calculations but hasn’t really given us much hope for this.

That’s why information or calculations from other builders or contact details of their energy consultants would be all the more interesting.

Wait and see what the energy consultant says. They will know a few tricks.

When I look at my thermal insulation certificate and see all the factors involved... for example, auxiliary energy (circulation present yes/no), night setback, solar gains... The ventilation system also has a significant impact on energy demand through heat recovery. Photovoltaic systems also have a positive effect, if that is an option.

Masonry:
17.5 cm (7 inches) aerated concrete / Ytong
16 cm (6.3 inches) double-layer mineral fiber mat
3 cm (1.2 inches) construction joint
11.5 cm (4.5 inches) facing bricks

U-value: 0.15

Roof or ceiling:
Mineral fiber – 20 cm (7.9 inches) and 10 cm (3.9 inches) – WLG 035

U-value: 0.12

So, from my perspective, standard.

HausbauTiNa schrieb:
Masonry:
17.5 cm (7 inches) aerated concrete / Ytong
16 cm (6.3 inches) double-layer mineral fiber mat
3 cm (1.2 inches) working joint
11.5 cm (4.5 inches) facing bricks

U-value: 0.15

Roof or ceiling:
Mineral fiber – 20 cm (7.9 inches) and 10 cm (3.9 inches) – thermal conductivity 0.035

U-value: 0.12

So, in my view, standard.

Our wall construction looks exactly the same.
In the roof or beam layer, we have 24 cm (9.4 inches) insulation with thermal conductivity 0.035.

Therefore, we can also do without a solar panel system and instead install a central ventilation system.

We wanted to combine a gas condensing boiler with a controlled mechanical ventilation system with heat recovery. Our architect says this is not sufficient to meet the requirements.
So, in the end, we will still have to install the unpopular photovoltaic system along with the income surplus calculation (EÜR) for the tax office.
This time with a battery storage.

A photovoltaic system has no impact on primary energy demand. You probably mean solar thermal.
I would have this calculated in advance rather than blindly trusting the architect. In my opinion, it should definitely be possible if you invest a bit more in insulation as well. This usually results in a much more sensible overall package, since solar thermal often does not pay off and, unlike controlled mechanical ventilation, does not offer any additional benefits.