ᐅ What modifications are necessary for installing a heat pump in a 1960s terraced/mid-terrace house?

I want to convert a mid-terrace house with the following basic data from electric heating to an air-source heat pump:

- Living area: 80 sqm (4 rooms, 1 bathroom)
- Fully basemented with a laundry room and a small workshop (the largest basement room with access to the garden has potential for a small granny flat or a party room)
- On the ground floor are only the kitchen and the living room. The upper floor has 3 bedrooms and the bathroom.
- Final energy demand of the building: 224 kWh/(sqm a). According to the owner, the total electricity costs with the night storage tariff are about €150 monthly.

Since the mid-terrace house is a real bargain in a good location and I no longer want to rent, I have considered the following measures:

1. The attic cannot be converted due to the low height, so I would lay 20 cm (8 inches) of walkable stone wool insulation boards on the floor (above them is a Harz-style double roof)
2. Replace windows as well as entrance and balcony doors with triple-glazed units
3. Mill space into the screed for underfloor heating (about €40 per sqm), install the underfloor heating and lay tiles on top. If the screed is unsuitable for milling, the surface heating could go into the walls. Large radiators outside are not feasible due to limited living space.
4. Install the following air-source heat pump: Viessmann Vitocal 200-S heat pump, 7.0 kW, Z016960, 300 L Vitocell 100-W, CVAA (only 35 dB at 3 m distance)

Then I would see if that is sufficient. If not, I would additionally:

5. Install a wood stove in the living room for cold days
6. Insulate the two exterior walls with 18 cm (7 inches) of insulation material WLS 025
7. Insulate the basement ceiling with 8 cm (3 inches) of insulation material WLS 024

I do not have enough space for pellets or oil. For a gas heating system, I would first need a gas connection and would also have less space due to the radiators. Additionally, the heat pump can also provide cooling, which is important to me.

Since I am not an expert, my questions are: Is this completely unrealistic, or could it work because the mid-terrace house has fewer exterior walls? Have I missed a better measure or a more suitable/cheaper heat pump? Is the Panasonic Geisha 5 kW louder? Would solar thermal with a south-facing orientation help?

I estimate costs around €40,000 (before subsidies) for the first four measures plus bathroom renovation. But currently, I give my landlord €5,000 annually and have significantly less than 80 sqm as well as no terrace or garden.

Best regards
Kaban4ik

It is advisable to consult a technical, independent expert who is not affiliated with any sales interests.
Heat pumps, especially air-source heat pumps, require conditions that are favorable for heat pump operation, which are often not present in existing buildings. If these conditions are not met, it can quickly become a costly mistake.

That's right. Here, I consider the basic conditions and the planning to be reasonable. With the planned insulation, it will not be a problem to achieve low supply temperatures with underfloor heating.

However, you should definitely inform yourself thoroughly and/or consult a true expert. Do not rely on rough estimates or "we've always done it this way."

It could work.
What does the masonry look like?
The biggest weak point after the planned measures is probably the basement ceiling.
Insulating from below should be relatively easy, but closing off the stairs to the basement might be more difficult.
Can you place the outdoor unit in a way that it doesn’t annoy you or the neighbors too much?

I might have missed it, but how is the heating currently set up? Night storage heaters?

Insulating the basement ceiling and the top floor ceiling should definitely be done, regardless of the heating type planned. The effort-to-benefit ratio should be best here.

Do you have the building plans and therefore know what was installed under the screed? I see this as a potential issue: the underfloor heating should lose as little heat as possible into the concrete slabs below. While the concrete would act as a good heat store, it would also create high thermal inertia.

Is the current screed already cracked? I mean, since you’re doing a full renovation, a crew (e.g., from the Czech Republic) can remove the screed entirely within a few days, allowing you to rebuild properly with insulation under the screed and underfloor heating. At the same time, you could also install network cables in every room or renew water pipes.

Is exterior wall insulation allowed given the row house setup? Are there strict regulations regarding uniform façade design?

Are the windows and doors still original from 1960?

Kaban4ik schrieb:

before deducting subsidies

Are you referring to the KfW funding? In that case, you need to work with an energy consultant anyway, who will advise you on the best way to insulate. If you seal everything, don’t forget about ventilation.