ᐅ Underfloor Heating or Air Heating in New Construction? (KFW55)

Hello everyone!

Our building project is becoming more concrete, and we have been considering for some time which heating system to use.
The options we are looking at are:

Schwörerhaus "Wärme GewinnTechnik" WRG134HK:

• Air-to-air small heat pump (integrated into the ventilation system)
• Additional small PTC heating elements at the outlets
• Summer bypass available (slightly cooling effect)
• Domestic hot water via: "Drinking water heat pump Aerotop DHW250"
• Water tank: 250 liters (66 gallons) with electric auxiliary heating
• Cost approx.: 12,000 Euros

Underfloor heating:

• Air-to-water heat pump Buderus "Logatherm WLW196i IR"
• Here too, there is supposed to be a possibility for a slight cooling effect
• Annual performance factor specified as ">=4.5"
• Domestic hot water also provided by this unit
• Water tank: 300 liters (79 gallons) (no mention of electric auxiliary heating)
• Cost approx.: 25,000 Euros

A few more details about our house:

• Ground floor area: 74.07 m² (797 sq ft)
• Usable floor area: 116.29 m² (1,252 sq ft) plus 69 m² (742 sq ft) cellar
• Built on a slope facing south
• Located near the Sauerland region – winters can be cold, wet, and long

There are many details to consider, so now the question is: How would you decide... and why?
What would you recommend?

Underfloor heating... Air is a poor medium for heating or cooling...

What you apparently save in initial costs will sooner or later be spent on the heating system... and when selling or renting the property later, the house will be valued lower because there is no "real" heating system installed.

Definitely option 2! Option 1 is initially cheaper, but later it will cost you a fortune in electricity bills!

I do not yet see option 1 being feasible with the KfW 55 construction standard, as this is more suited for passive houses with extremely low heating demands. Otherwise, the air-to-air heat pump effectively turns into an electric heater with very low comfort.

All right, thanks for your assessments so far!

We had similar concerns regarding the air heating system. Additionally, there are frequent reports of dry air, especially when it’s cold outside.

At first glance, it is incredibly affordable, but as you already mentioned: probably not in the long run after all :-/

Do you have any experience with the offered Buderus LW heat pump? Is the unit any good?

I personally have no experience with this Buderus unit, but professionally I am somewhat familiar with heat pumps: these split systems are generally quite similar in terms of COP and such. Therefore, the manufacturer does not really matter much in this regard. Perhaps for future repairs, it might be wise to choose one of the major manufacturers, simply so that they still exist after 10 years. Much more important is a complete system that is precisely tailored to the actual heating and hot water needs of the building. Also essential is a heating engineer who is well experienced in sizing, installation, and so on, and who lives within a reasonable distance so they can respond quickly if there is a fault...