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

Hello everyone,

I need to reach out to the forum because I would like to get your opinions and advice.

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

The main electricity meter shows 18,000 kWh.
This seems extremely high to me, and I cannot figure out where such consumption could come from.

Could the meter from the energy supplier be faulty?
Could a device, for example the heat pump, refrigerator, stove, etc., be malfunctioning and therefore drawing more electricity?

I am still quite puzzled.

Best regards

Write something about the pump settings.

For example, flow temperatures, domestic hot water temperature.

Does the ground source heat pump have an auxiliary heating element?

Hello,

are you referring to the main meter for the heat pump?

Don’t you have separate meters for yourself and the granny flat?

In that case, you wouldn’t be able to bill accurately – would you?

Also, there are small measuring devices for end appliances, available as plug-in meters (under 10€), which can perform short- or long-term measurements.

Just buy two and plug one in behind each cooling device. Let them run for a week, then read the values and be surprised.

Could you briefly tell me what settings you need to get an idea?
Yes, it has a heating element, which we initially used for drying heating.
However, I have since deactivated it.

What does it mean when a device is defective? Is everything dependent on a single meter?

So, 9000 kWh per year for two families with heating? That sounds normal.

In our case, we use 4500 kWh of household electricity for five people, one of whom lives in the granny flat.

That means two refrigerators or two kitchens, and with babies and children, there’s more laundry, plus a heater above the changing table.

How many square meters are heated, including the basement and utility rooms?

superzapp schrieb:

Are you referring to the main meter of the heat pump?

No, I mean the main meter from the energy provider at the connection point.

superzapp schrieb:

Don’t you have separate meters there for yourself and the secondary apartment?

Ah, there’s our next problem, which our former developer (who sold his company before finishing the project) didn’t consider.
We have one meter from the energy provider for the total electricity. Then the electrician installed a meter in the meter cabinet for the electricity used within the apartment.
However, no one seemed to consider that hot water, heating, and cooling run on electricity through the heat pump.
So the secondary apartment has the meter for electricity consumption (2,500 kWh (8,202,000 BTU) in one year), but everything else runs through the heat pump, which, in turn, is connected to the main meter :-( On top of that, we have been chasing the energy provider for a year trying to get a separate meter for the heat pump.
Sounds complicated, doesn’t it? For me, it’s a total nightmare because I’m a bit lost when it comes to utility billing.

superzapp schrieb:

Also, there are small measuring devices available for end appliances as plug-in meters (under $10) that can perform short- or long-term measurements.
Just buy two and plug them in behind each cooling device. Let them run for a week, read off the data, and be surprised.

Yep, I got myself some now and haven’t found anything surprising so far… except for the FLM, which is the exhaust module for heat recovery ventilation. At night, from 9:00 pm to 9:00 am, it draws 150 W, and during the day only 20 W. We have this device twice: one for the secondary apartment directly connected to the heat pump, and one in my living unit in a separate room. So that’s 300 W at night and 40 W during the day. That’s quite a chunk of power. It’s set up so that I bring in cold air through the fresh air vents at night in summer, and only minimal warm air during the day.
Of course, that’s also a problem, because the FLM for the secondary apartment should be on the secondary apartment’s electricity meter. Right now, they both run completely on the main meter.

This should have been set up differently from the start, I know that, but I relied too much on the planner and architect without questioning them. How could I, I had no idea about heat pumps, ventilation systems, or secondary apartments. Only now am I starting to get familiar with all this stuff as I have to deal with it.