ᐅ Heating screed with a heating device versus a heat pump – costs?

Hello,

Two weeks ago, the screed (cement screed) was poured in our new single-family home (about 130 sqm (1400 sq ft) floor area).

Our general contractor (GC) now offers us the following options:

1) Heating the screed using a 19 kW heating device, starting in 10 days.

2) Heating the screed via underfloor heating powered by a heat pump after the heat pump is installed in mid-October.

According to our contract, I am responsible for paying the heating costs, while the GC covers construction electricity. The house completion date is set for February 2023 in the contract.

Option 1: The GC says I must pay for the construction electricity used by the heating device because it counts as heating costs. Until now, I assumed that heating costs cover the energy needed to keep the workers working, but not the energy used specifically to heat the screed. If I prefer option 1, I understand that I will have to cover these costs, but the GC will still complete the house by February using the cheaper option 2.

How expensive would option 1 be? What is the cost of construction electricity, and how much electricity is needed to operate the heating device until the screed is dry?

According to the GC, option 1 would allow me to move in this year, which could save me about one month’s rent for my current apartment—around 650 euros—and avoid the risk that the heat pump might not be installed by mid-October, as required for option 2.

Option 2: After the heat pump is installed in mid-October, if the screed is heated via underfloor heating, does the GC cover the electricity used for this? Would this electricity still be measured by the construction electricity meter (paid by the GC according to the contract), or would it already be charged through my new private electricity meter?

How much electricity would be needed to heat the screed this way, and if I had to pay for this electricity, approximately how much cheaper would option 2 be compared to option 1?

Which option would you choose?

difficult to quantify. For us, the heat pump didn’t use much energy. And it was August.
I would prefer option 1. Do you know when the heat pump will be delivered and installed? Can he guarantee that 100%?
A dry screed is important to be able to proceed with the next work stages.
Therefore, my favorite is option 1.

Note, this is just an amateur opinion: I heard from our plumber that heating the screed using a heat pump (in case of a ground source heat pump) can potentially cause the borehole of the probe(s) to freeze due to the extended period of high energy demand, which might “damage” it. I am not aware of such concerns with air-to-water or air-to-air heat pumps.

If there are no worries regarding this, I would also choose option 2, as it should account for about one-third to one-quarter of the electricity costs—unless time is extremely critical (such as for screed curing, tiling, and other subsequent work).

Regardless of the option, the electricity costs will likely fall on you, either directly or indirectly for heating.

Directly via the heating unit for a 2-week heating period = 19 kW × 24 h × 14 days ~ 6380 kWh? ≈ around 2 k (currency unspecified).
However, your general contractor (GC) or builder should be able to provide you with this data, at least approximately.

P.S. We allowed our screed to dry naturally and calmly (without heat pump, without electricity) 😉

Costs will likely be passed on to you either way, I assume. But that is fairly common.
Option 2 carries the risk that subsequent work steps could be significantly delayed, especially if it is still unclear when the heat pump will actually be installed. On the other hand, the screed will probably dry without heating, although more slowly. I can’t say if that is a good thing.
Option 1 sounds expensive. However, with an air-to-water heat pump, the heating element is usually also activated during the screed drying program → which is also relatively costly.

When we built our first house, we ran the screed drying program on the heat pump and I believe we used around 1100 kWh.
But that was in the middle of summer. In winter, it can be significantly more expensive.

Best regards

Electricity for the hot water heater is usually never included. At least in our case, it was clearly communicated from the beginning that it has to be provided by the builder and that heating is only done with the hot water heater (geothermal heating, see post #3).
Since we will soon be installing the screed, I asked the general contractor about the expected electricity consumption. They estimated a demand of 1000 to 2500 kWh, which also depends heavily on the weather. The construction power electricity price was apparently raised by EnBW to about 40 cents. So, I expect a cost of around one thousand euros.
However, this also depends greatly on which heating program is used. Some still operate at high temperatures even with modern heating systems, which are often not actually reached in practice.

A more sensible use of resources would, of course, be heating with a heat pump. On the other hand, this means you complete your heating cycle a few days faster, which would be worth a few extra euros to me in the current situation.

kati1337 schrieb:


During the construction of our first house, we had the screed program running on the heat pump, and I think we used around 1100 kWh.
But that was in the middle of summer. In winter, costs can be significantly higher.

Were you able to run the air-to-water heat pump using a low-cost private electricity contract (in my case, it would still be an old contract that I could transfer after moving, at 23 cents per kWh), or did you have to use construction electricity (which is probably much more expensive? How much should one expect to pay)?

A cost comparison would be interesting.

For option 1, 2000 euros were mentioned above – roughly how much would option 2 likely cost?