Retrofit underfloor heating??

Hello,

after several years, we have finally found our own home. The little house was built in 1981 and is still in good condition; we could actually move in right away.

There is a gas heating system and radiators... however, we have been "spoiled" by underfloor heating for years. Now, as laypeople, we are trying to weigh the pros and cons... not so easy. I think IF you decide on it, it should be done before moving in. Because once you live in the house (with 4 people), it only gets more complicated.

One point we can’t quite estimate: Does underfloor heating save so much energy that it is worthwhile? What kind of acquisition/installation costs should I roughly expect? My husband and father are handy and could do quite a bit themselves.

Total living area 186 m² (where either only the ground floor or ground floor + upper floor with 65 m² each are relevant). The house also has a basement.

Which type of underfloor heating would be recommended for retrofitting? I don’t know the ceiling height at the moment, but it was neither noticeably high nor low.

A very important point: According to calculations, the house has an EEK "G" with a consumption of 217.2 kWh/(m²a). Can anyone say something about this? What does that mean concretely?

It has double-glazed wooden windows installed; I think replacing them would also make sense so as not to heat the garden...

We will probably hire an energy consultant who can take a closer look at the house and give us tips. But I am already grateful for your help!

Regards Schnie

Good evening,

One point we cannot quite assess: Does a underfloor heating save so much energy that it pays off? Total living area 186 m² (where either only the ground floor or ground floor + upper floor with 65 m² each are relevant). By the way, the house has a basement.

In new buildings yes, in existing buildings it depends on the overall situation.

What type of underfloor heating would be recommendable for retrofitting? I don't know the ceiling height currently, but it was neither notably high nor low.

Underfloor heating, as the name says, goes into the floor. So it depends on whether the floor slabs have enough thickness to accommodate the carrier including plastic pipes. So a lot of dirt would be coming your way; probably also new interior doors.

Another alternative would be electrically operated underfloor heating. It is very flat but has the disadvantage that it is very costly for an entire house. "Can" be an alternative in connection with photovoltaics plus storage.

A very important point: According to calculations the house has EEK "G" with a consumption of 217.2 kWh/(m²a). Can anyone say something about that? What does that mean concretely?

The energy efficiency of buildings is classified in an energy certificate according to the Energy Saving Ordinance by the energy efficiency classes A to I. The classification is based on the primary energy demand. This considers thermal insulation, the technology used, and the environmental compatibility of the energy carriers employed.

G - typical for partially modernized older buildings: thermal insulation measures on partial areas and/or new more efficient central heating

We will probably hire an energy consultant who will take a closer look at the house and give tips. But I am already thankful for your help!

That is a good way, because nobody can really advise you here as the extent of partial modernization, building fabric etc. is not known. Bottom line, the energy consultant may even recommend that you initially make no changes.

Rhenish greetings

Correct me if I am wrong, but as a rule, the heating pipes are not installed in the ceiling (concrete) but rather – on an insulating layer – in the screed. Therefore, the ceiling thickness should be irrelevant at first. Conversely, it would also be anything but economical to tear out the screed in a well-maintained house, insulate, and then lay new screed after installing heating pipes.

However, there are also systems for retrofitting (with milling into the existing screed). The problem, however, could be that there is not enough (or no) insulation under the screed, so that the heating radiates both upward and downward – which is actually not desired.

Best regards

K1300S

Hello you two,

thank you for your help.

I had almost feared that retrofitting underfloor heating in an existing house would be very complicated and expensive.

We will probably get a quote, but internally I am already saying goodbye to the idea...

The thing is also (actually an advantage) that except for one room the floors are still in great shape. Parquet and light tiles.
It would actually be a shame to tear them out...

Nevertheless, I will shed some tears for the underfloor heating... not least because I am allergic to house dust.

Hello,

Correct me if I am wrong, but as a rule, the heating coils are not installed in the ceiling (concrete) but - on an insulating layer - in the screed. Therefore, the ceiling thickness should not matter at first.

We mean the same thing. By floor slabs I mean the ceiling above the basement; ground floor; upper floor, attic (the latter probably a collar beam layer). It does depend on whether a 15 cm or rather a thicker concrete/wooden ceiling was installed at the time of construction. If it is a frugal use of ceiling thickness (insulation?) and screed, I am rather pessimistic about the retrofitting of a conventional underfloor heating system.

Conversely, it would also be anything but economical to tear out the screed in a well-preserved house, insulate, and then lay new screed after installing heating coils.

Ack - therefore also the hint at a "possible" statement from the energy consultant to leave everything as it is.

Rhenish regards

Oh, it’s not that expensive. We also bought an old house and the screed downstairs is being removed (or was), because a thick insulation layer is necessary and the screed just gets in the way. On the ground floor, however, the new underfloor heating can simply be placed on top of the old tiles. Altogether, there is a 4.5 cm build-up height upstairs (2.5 cm underfloor heating including insulation and 2 cm screed). Downstairs it’s 13 cm, but that includes 11 cm insulation and 2 cm screed. Material costs for 100 sqm are just under 3000 euros (without screed), installation 1000 euros. However, it hasn’t been done yet because, yes I can confirm, it is a bit tricky to clear 100 sqm after moving in. The furniture has to go somewhere, we are still figuring out how to do that. I don’t find it expensive, though you may need to expect additional costs for the heating system. We bought a new pellet boiler and buffer tank anyway, but a mixing valve and a new pump still had to be added. The cost for the latter and two distribution boxes was also just under 1000 euros (including piping).