New heat pump for old buildings without renovation

Even if the gas price settles at 15 cents/kWh and electricity drops to 30 cents and you manage to reach 3. But I would be very surprised, with a supply temperature of 50°C with underfloor heating, an air-to-water heat pump hardly achieves more. Unfortunately, physics cannot be fooled, not even by Panasonic.

But everyone can easily calculate that for themselves. In the "old" apartment with, let's say, 16,000 kWh of gas, you pay €2,400. With a factor of 3 for the heat pump, the heat costs you €1,600. So €800 difference per year. Over 20 years that’s €16,000, with an annual price increase of 3-4% (and/or significantly rising CO2 charges), you can consider whether the heat pump makes sense. If it costs €20,000 and I get 30-45% funding on that (no idea how it will develop next year), then the pendulum clearly swings strongly in favor of the heat pump. And if you also have to factor in the alternative investment "old oil/gas heating has to be replaced anyway," then there is no way around the heat pump.

Air-to-air heat pumps (split air conditioning units) in new buildings are certainly the future! No one needs a heat pump with an efficiency standard like EFH40. Split air conditioning units can also really cool in the summer. No more complicated hydraulics with pumps, buffers, etc., more space in the utility room, much cheaper and more comfortable (since you can actually run an ERR effectively here). If I were building new, only air-to-air heat pumps would come into my house. I would do the hot water with instant water heaters. If only those things weren’t always so ugly :p

But you haven’t taken the heating lobby into account here. Buildings are made complex with all sorts of gadgets even if you only have €65 and then only €58 monthly heating costs anyway. They deliberately do the math nicely. Energy consulting is often a sales pitch!

But, I am also somehow part of this lobby. The topic has already reached us. The problem at the moment is the outdoor units that can be combined with a maximum of 5 indoor units. Also, I cannot install an indoor cassette in bathrooms. But there are solutions for such cases as well. In all variants we have calculated (heating only), the air-to-air heat pump (by that I always mean split air conditioning units) is ahead. When thinking about heating, everyone thinks of the installer, who of course in many cases does not have a refrigeration certification ;) The annual performance factor is comparable to air-to-water heat pumps. We have also calculated and equipped renovation projects with it. It works without problems and is a good hybrid option.

Air-to-air heat pumps (split air conditioning units) in new buildings are certainly the future! Nobody needs a heat pump with an efficiency standard like EFH40.

Air conditioning is nothing other than a heat pump – with various advantages and disadvantages (which should not be concealed!). But the thread is about old buildings. And these are about 15 million single-family homes built before 2010 as well as 3.5 million multi-family homes (the majority of which are not energy efficient).

That is exactly why I wrote that we have already implemented projects in the portfolio with this solution. The old heating system remains in place and serves as peak load coverage.

I have a KFW55 house with solar hot water and gas (8600 kWh gas/year heating + hot water) and underfloor heating. The new 6.8 kW split air conditioner with 4 indoor units currently serves as heating. The issue of peak load coverage is one thing, but I will also turn off the air conditioner at -10 degrees and rather switch on the gas.

It is optimal: The gas heating then runs nicely in the optimal condensing range. The heat pump of the air conditioner runs efficiently at moderate temperatures. I can calculate when what is worthwhile using my electricity and gas rates.