Alternatives to gas, how are they calculated?

Hello everyone,

we currently live in a house (built in 2015, rented) with the following consumption values:

[*]Household electricity: 3,000 kWh per year

[*]Air heat pump: 4,300 kWh electricity per year, heating output 13,000 kWh

[*]Solar thermal: 1,000 kWh solar thermal

For our planned house, there is gas available, but we are also open to alternatives. We would have estimated gas costs of 800 euros per year for heating demand and might spend another 5,000 euros for the gas heating system.

Now, we have looked into solar (i.e., photovoltaic and thermal) to use it as support or as an energy source for an air heat pump, but financially it just doesn’t add up. Additionally, our house with a pitched roof will be oriented exactly north-south; that means one roof side faces east, the other west.

[*]For the photovoltaic system, I initially thought of a battery so that the electricity is not fed into the grid for a ridiculously low price and the generated electricity could be used for the air heat pump. But such a battery quickly costs over 6,000 euros; in other words, for the price of the battery, you could buy gas for 8 years. In other words, even if it were a magical battery that would supply the entire electricity for the air heat pump free of charge, it would first have to last 8 years. Not to mention that the air heat pump itself is also more expensive than the gas heating system.
[*]I am skeptical about solar thermal because during the summer months, with correspondingly high solar radiation, you need the least hot water. Electricity, at least household electricity, is always needed.
[*]Is it even possible, when building according to the Energy Saving Ordinance only, to install a gas heating system without putting anything on the roof? Or does that not work with the maximum allowable primary energy demand?
[*]How does it look if we only use an air heat pump (like today in the rental house)? Somehow it is so expensive that it never pays off compared to gas (regardless of whether photovoltaic or thermal is on the roof). Gas is just too cheap...

We are quite undecided about how to proceed sensibly. What would you do?

First answer. You are right. From a commercial perspective, alternative energy sources will never be profitable compared to gas.
Second answer. The legislator knows this too. Therefore, through the Energy Saving Ordinance, to obtain a building permit, we are forced to use an alternative renewable energy source. This can be solar thermal hot water in addition to gas. Or controlled residential ventilation. Or PVI systems. Or the use of district heating from biogas. Or any other.
None of it adds up financially.
What to do? Commercially speaking, you take the cheapest. 5 sqm solar panels on the south or west roof, then you have hot water from the sun. And you think you are saving....Karsten

One must consider the time. Towards the end, so about 20 years later, it is relatively irrelevant what one takes, the projections show that it is relatively irrelevant. The difference in costs over 20 years is marginal. Assuming the systems last 20 years without major defects.

First answer. You are right. From a commercial point of view, alternative energy sources will never be worthwhile compared to gas.

Is that so? The payback period is – if I remember correctly – about 15 years (gas vs. air-water heat pump). Admittedly, quite general, but as a rough estimate. However, here often only the boiler versus heat pump and corresponding consumptions are calculated. The fact that gas also necessarily requires a chimney, which costs money, is often not modeled. Maintenance costs for heat pumps are often criticized, but the regular visit by the chimney sweep is omitted.

For me personally, it makes little sense to rely on a scarce energy source (oil, natural gas) that will inevitably become more expensive. Of course, certainty comes from looking into the crystal ball, but it is currently broken.

I have actually thought about gas too, and I don’t want to demonize it, but pretending it is the only sensible and economical solution is simply nonsense in general. It depends too much on the framework conditions what is economical (usage behavior, number of occupants, insulation standard, house location, etc.).

So firstly, his current heat pump seems to have a fairly decent, but not a very good annual performance factor. What helps you further is a proper full cost calculation. Everything that is needed is listed there and that over 20 years. An example is the already mentioned chimney, the maintenance, the basic fee for the gas meter and of course the expected consumption. You proceed the same way with the heat pump. As a price increase, you can basically choose what you want to apply, but I would take the average of the last ten years. You can’t do more than that. Especially with price development, it’s a guessing game. Personally, I would also try to go in the direction of a heat pump when building new. But only if I get a general contractor who doesn’t charge an unjustified 10,000€ surcharge.

If the gas or oil price rises, the electricity costs also rise