Heat Pump.

Gideon: 
 

Underfloor heating in a heat pump context seems to mean heated water tubes under the floor?

What floors does it work with? 

Here in Germany, it is laid in screed over concrete.

We have suspended wooden floors with a void underneath. 

So do I, in the main building. 

I can't see how it would work as well. The point of the layout in the screed is to warm it up more-or-less uniformly, conductively. If you have wood-on-stays then it is air, even if rockwooled. 

My attached building is 1960's and has screed-on-concrete. But radiative heating. Installing underfloor heating means new floors. I've been into the costs and I can't see it working out.

There is I suppose room under the ground floor for warm air ducts, but that's not ever suggested in UK, AFAIK? 

Andy C and then, more extensively, Denis McM introduced this on the “Electric Heatpumps” thread. Synopsis: installing ducted air heating/exchange does cost real money. I haven't costed it for my entire house, although I did discuss it in depth with an installation engineer in September 2020 when I was trying to figure out how to get 6 ACH in my music room (80 m^3) to give us space to practice indoors with flutes (result: too much money. A 500 m^3/hour UV-C disinfectant device would have been cheaper at €5K).

Gideon: 
 

Underfloor heating in a heat pump context seems to mean heated water tubes under the floor?

What floors does it work with? 

Here in Germany, it is laid in screed over concrete.

We have suspended wooden floors with a void underneath. 

So do I, in the main building. 

I can't see how it would work as well. The point of the layout in the screed is to warm it up more-or-less uniformly, conductively. If you have wood-on-stays then it is air, even if rockwooled. 

My attached building is 1960's and has screed-on-concrete. But radiative heating. Installing underfloor heating means new floors. I've been into the costs and I can't see it working out.

There is I suppose room under the ground floor for warm air ducts, but that's not ever suggested in UK, AFAIK? 

Andy C and then, more extensively, Denis McM introduced this on the “Electric Heatpumps” thread. Synopsis: installing ducted air heating/exchange does cost real money. I haven't costed it for my entire house, although I did discuss it in depth with an installation engineer in September 2020 when I was trying to figure out how to get 6 ACH in my music room (80 m^3) to give us space to practice indoors with flutes (result: too much money. A 500 m^3/hour UV-C disinfectant device would have been cheaper at €5K).