Combination of split air conditioner, gas, solar

Hello housebuilding colleagues,

We have been living at just under 300 meters above sea level since 2014, solidly built.
The house is rather simple in shape.
Normal gable roof without dormer or skylight (On the upper floor one window per room on the gable side)

Styrofoam was not an option for various reasons, hence the rather expensive monolithic plan blocks with Lambda 0.08.

Size: 111 sqm living space.
Exterior wall: 36.5 cm Ytong // Lambda 0.2 W/m²K
Floor slab insulated with XPS // 0.21 W/m²K
Ceiling in the upper floor slanted with 24 cm // Ceiling insulated with 34 cm mineral wool // 0.12 W/m²K
The door + windows are triple glazed and gas-filled // total including frame 1.05 W/m²K

Heat generator:
Gas condensing boiler: Viessmann Vitodens 300
System control: Vitotronic 200
Solar 5 sqm: Vitosol 200-F
solar storage: Vitocell 100-W 300 liters

The solar system is only for hot water (without heating support)
Our gas boiler is switched off for heating from May to September and uses about 100 kWh during the summer.
In winter, the solar system barely manages to heat hot water (2 people), so it mostly runs on gas.

Ventilation is via decentralized Lunos e² with 90% heat recovery.

We have an average consumption of 8000 kWh of gas per 12 months.
In the harsh February, it is 45-75 kWh daily, depending on the cold.

The attic is often unbearably warm, so we would like to air condition the bedroom, children’s room, and office with split air conditioning units.
And also put an indoor unit in the living room with open kitchen on the ground floor right away.

Outdoor unit
CU-4Z68TBE

Master bedroom (12 sqm east-south)
CS-Z20XKEW

Children’s room (12 sqm west-north)
CS-Z25XKEW

Office (12 sqm south-west)
CS-Z35XKEW

Living room (35 sqm + 15 sqm kitchen)
CS-Z35XKEW

I would also like to use this for heating, not just cooling. Now that gas has become very expensive, this certainly pays off with such a high-quality modern air conditioning system. Of course, it is nonsense if it is -10 degrees outside. However, if the gas supply were suddenly shut off for us private individuals, I would have a working fallback, even if the usual 23 degrees cannot be reached everywhere with only one unit on the ground floor. But as emergency operation, certainly appropriate.

What do you think of the expansion plans?

Is photovoltaics an option for you? We also heat in winter with our split systems when the sun is shining. There are many great videos about this on YouTube, just search for "DIY Wärmepumpe".

My brief recommendation: Do it. Even just for the gain in living comfort in summer. We have installed split devices as Quick Connect ourselves in all relevant rooms and are totally happy with it.

Is photovoltaic an option for you? We also heat in winter when the sun is shining using our split systems. There are many great videos on YouTube about it, just search for "DIY heat pump".

My brief recommendation: Do it. Alone because of the gain in living comfort in summer. We installed split units as quick connect in all relevant rooms ourselves and are totally happy with them.

A photovoltaic system for around another €8,000 is too much for me now.
I want to first see how much the split AC units consume and can always still do it when I have no more liabilities. I am currently still paying it back.

Even with a loan of 20K for a larger photovoltaic system at 3-4% interest, I predict a payback period of under 20 years ;-)

Even with a loan of 20K for a larger photovoltaic system at 3-4% interest, I predict a payback period of less than 20 years ;-)

I agree. As long as humanity doesn’t eventually achieve nuclear fusion, electricity prices will continue to move northward.

I now have an offer.

€11,500 for the split air conditioning system

3 indoor units
Panasonic Etherea Z 2.0kw
1 indoor unit
Panasonic Etherea Z 3.5kw
1 outdoor unit
Panasonic 6.8kw

Thanks to [BEG EG Förderung] -35%,
= €7,475

Application will be submitted on Monday.