ᐅ Single-family house – 18,000 kWh in two years – what could be the issue?

Ah, Section 2: Does not apply to you. (if there is only one granny flat/apartment and you live in the other part of the house).

Pinky0301 schrieb:

Heating costs read

Not necessary for a basement apartment since the cost outweighs the benefits.

titoz schrieb:

Hello everyone,

I need to reach out to this forum because I could use your opinions and advice.

We (2 adults with 2 small children) have been living for two years in a single-family house with a secondary unit (granny flat). This unit has been rented out for one year (2 adults with a baby).
Our house has a ground-source heat pump (Nibe 1245 PC). It provides hot water, heating, and passive cooling through the underfloor heating system.

The main meter shows 18,000 kWh.
That seems extremely high to me, and I can’t figure out what could be causing it.

Could the utility meter be faulty?
Could an appliance, for example the heat pump, refrigerator, stove, etc., be defective and therefore consuming more electricity?

I’m still at a loss.

Best regards

18,000 kWh for 2 families over 2 years is not unusual depending on heating and usage behavior.

The issue is more that many come from 2-3 room apartments under 100 sqm (square meters) where they only paid for comfort electricity with less than 3,000 kWh, and now every single usage like comfort, hot water, and heating electricity is drawn from the grid.

I was also surprised when after 12 months 7,500 kWh was on the meter, but considering all-inclusive with electric car, XXL fridge, controlled mechanical ventilation, boiling water tap, air-to-water heat pump (LWWP), basement, 22.5°C (72.5°F) indoor temperature in winter, that’s actually reasonable. Without photovoltaic panels, the additional payment in the first year would have been even higher.

If you or the tenants prefer it warmer in the bathroom, take long baths, bake and cook extensively, then 18,000 kWh is nothing.

What @Bookstar is saying is obviously nonsense. Almost everyone with a heat pump knows this—only those who can’t read or have limited technical understanding think otherwise.
So, it’s good that you’re asking.

You need to set up the heat pump properly. This means turning all room thermostats fully up and setting the maximum flow rate. Then definitely lower the supply temperature.
I would bet that most of the consumption comes from domestic hot water production. It always needs to supply hot water to the secondary apartment. This is the biggest cost driver for the heat pump.
My tip would have been to install a very large instantaneous water heater for the secondary apartment’s supply and connect it to the apartment’s household electricity.
This way, you get fresh water at all times and can still properly adjust the heat pump. Maybe that’s still possible.
A separate heat pump tariff rarely makes sense if the heat pump is set up correctly. You can, of course, hire someone who charges for travel and hourly rates and comes a few times, or you can do it yourself.

Joedreck schrieb:

So, what @Bookstar writes is obviously nonsense. Almost everyone with a heat pump knows this. Only those who don’t read or have little technical understanding don’t.
So, it’s good that you’re asking.

So about 90% of heat pump or heating system owners. That’s all I said. First, it needs to be clarified whether it really is the heat pump. If household electricity is included, then 4500 kWh per housing unit would be a very good value.

Bookstar schrieb:

So about 90% of heat pump or heating system owners. That’s all I said. However, first it needs to be clarified whether it’s really the heat pump. If household electricity is included, then 4500 kWh per housing unit would be a very good figure.

I still see it differently, but never mind.

Later, the original poster provided the heat pump’s figures. According to that, the annual performance factor is about 2 if I read it correctly. That would, of course, be completely unacceptable.