Re: FRA airport is very nearly in compliance with this law....
Not really any good. Laws of physics being what they are, if you turn down the flow temperature your boiler will run longer to provide the same heat. Sensible thing to do is turn down the TRV's and thermostat and wear a bit more. Disclosure - I have worked in the design and construction industry for 40 years and had several qualifications relating to low energy / heat loss design. There is a lot of possibly well meaning but mainly useless information out there due to the impending cost rises.