Condenser vs vented
Even over here, condensers were more of a stop gap solution that just stuck.
Vented dryers are per load more efficient than condenser.
They are usually faster and gentler even in compact models.
Most of our housing stock wasn't build with dryers in mind, so no venting.
And since our small flats were usually the places you didn't want to hang clothing around, condenser quickly caught on.
Our energy labeling system actually gives a slight edge to condensers over vented ones. Idea is that the heat from the condenser heats your house compared to vented dryers sucking in cold air.
So vented dryers - even though they used slightly less per kg - got a C while condensers got a B.
Heat pump dryers turned the whole dryer conundrum on it's head.
In the beginning they were slow (about 50% longer cycles, or more), expensive (about twice the initial investment) and due to electricity rates not quickly viable.
They were kind blocking their own road to success: Those who could have gotten a quick ROI were large families with a lot to dry - but exactly these people were put off by long drying cycles.
Over the next 10 years they were optimised further and further.
BSHs blueTherm/EcoLogixx dryers were probably the most sold dryers for a long time - they were affordable, relatively quick and overall a good value.
Since the early 2010s, even more so 2015ish, something amazing happend.
Even cheap brands cracked the code to the dryer that has become more or less standard today.
The dryer has to be very well sealed (condensation efficiency class A, which means that for all moisture removed from clothing, over 90% is collected).
It uses a single speed compressor at about 500W or so.
The motor is an inverter driven design that runs both drum and fan - only using about 100W peak.
Reversing is kept minimal to none on the normal cycles. The fan wheel is optimised for one direction to improve airflow.
That gives you label drying times usually around 150min for 8kg and 90-100min for 4kg.
Efficiency class A+++.
That all means that day to day loads are usually all done below 2h with usually not more than 1kWh and at no more than 140F.
And all that for 500€ or even less if lucky if you are ok with lower end brands.
Before you needed inverter compressors and long cycle times, but just by thermodynamic optimisation, you no longer needed fancy tech to get the perfect efficiency rating in reasonable drying times.
If you are cheap, entry level machines can be had for an extra of 50-100€ over similar normal dryers.
Since even those basically cut usage in half, the usual run time until you break even is about 600-800h, a life expectancy even the cheapest machines will fullfill.
TL;DR:
Our heat pump dryers have gone from a novelty to an option for eco careing people with the hope to maybe break even to the only really viable option no matter the price point.
Over the next few years the environmentally very bad refrigerant R134a will be phased out and replaced by more reasonable alternatives makeing these dryers from start to finish the only logical solution in almost any regard.
My bet is that commercial equipment will be further developed so that the required cycle times can be reached while still being reasonably efficient and financially viable.
Once that tech is there it will be cheapend and scaled down and then US full size heat pump dryers will become an actual thing.
