ᐅ Excessive Electricity Consumption in Single-Family Home Construction – Experiences

There are 2 Daikin Altherma 3 H HT 14 kW units, each with a 9 kW backup heater (electric heating element). Air-to-water heat pump

NikSindi schrieb:

Am I responsible for managing these during the construction phase?

What does the contract say? Usually, yes.

What is the energy consumption for such a screed program? If you spread your 46,000 kWh over one year, that would mean a continuous consumption of 5.25 kW running 24/7/365. However, the screed program normally only runs for a few weeks.

I honestly can’t imagine how consumption could reach that level.

I also have no idea what our consumption was during the construction phase, since the temporary construction power was supplied directly by the shell contractor and was basically included in the shell construction price. So, we didn’t have a separate billing for temporary power at all.

NikSindi schrieb:

A few weeks ago, we received our construction electricity bill showing that we supposedly consumed
46,000 kWh, you can imagine the amount charged.

Based on the information you gave, or rather the lack of it, it’s not possible to provide a qualified answer.

NikSindi schrieb:

For our renovation, the screed was poured in May 2021, including the heating program using an air-to-water heat pump.

NikSindi schrieb:

September 2020 to February 2021 (without significant electricity consumption)
Then from the end of March 2021 to November 2021.
Due to a missing meter, we only received our meter in April 2022. That means from November to April, while the house was occupied, electricity was supplied via construction power.

So, from September 2020 to February 2021, construction work was recorded on the meter, but only usual construction equipment was running (drills, mixers, lighting, etc.). How was heating handled? Was there any heating at all? That could already explain a significant amount of electricity consumption, since that covers a whole winter. Then there was the screed heating phase over the summer. How large is the house and the screed area? Generally, the screed heating phase in May with an air-to-water heat pump should not consume that much, around 1,000 kWh per 100 m² (1,000 kWh per 1,076 ft²).

BUT then you heated the house through another entire winter and also lived in it. So this is no longer construction power but the electricity you need for regular use, and I have a rather unfortunate suspicion...
You mentioned this is not a new build. What is the energy standard of the house and how large is it? Was the underfloor heating insulated properly against the ground? It is difficult to change the structural build-up height in existing buildings.
Your system—two large air-to-water heat pumps each with 10 kW (13.4 hp) heating capacity—suggests a very large house, a low energy standard, or poor planning. What are the exact details here?
These are all factors that could explain the high consumption, but without data, it’s impossible to calculate or evaluate anything.

NikSindi schrieb:

Since April, we have been living normally and see that so far, with heating and hot water in occupied conditions, we have consumed 5,000 kWh.

If you subtract about 1,500 kWh for household electricity without heating (which is already quite high), that leaves 3,500 kWh.
From April to September, the heating demand should be very low, mostly just in April, so the majority would be for hot water. 3,500 kWh corresponds to roughly 12,000 kWh of heat output (due to high COP in April for heating and also high COP in summer for domestic hot water). Other new builds consume this amount for heating and hot water over a whole year, which is already quite high for a typical single-family home.
Again, data about the house and usage (number of occupants, special equipment, electric car?) is missing, so it can’t be properly assessed.

NikSindi schrieb:

There are two Daikin Altherma 3 H HT 14 kW units each with 9 kW backup heaters (heating rods). Air-to-water heat pumps.

That’s quite a lot of capacity for a single-family home.

DaGoodness schrieb:

What is the energy consumption for a screed drying program like that?

Our screed drying program used 2200 kWh over December and January. (185 m² (1991 sq ft) of screed)

DaGoodness schrieb:

What is the energy consumption for such a screed system?

We had a thread on this topic last week (?) and I did some quick research. As a rule of thumb, up to 20 kWh/sqm (square meter), depending also on the weather. 46,000 kWh is way beyond reasonable.