As office building insulation requirements improve and the capacity of heating (whether wet or air systems) is reduced, why are 82/71°C water temperatures still used instead of more economic temperatures such as 60/50°C? Flow rates would remain unaltered and boilers would operate in condensing mode, with the only downside being larger heat exchangers and not being able to incorporate domestic hot water generation on to central boiler plant.
There is an historical reason for the use of the 82/71, which equates to the old British legacy of 180/160°F. All radiator system were designed around these parameters and have continued to do so. Obviously the hotter the radiators, the smaller the surface area and resultant wallspace. Conversely to achieve the same output at the reduced mean temperature suggested would significantly increase the radiator size.

Granted that the insulation levels are driving down the heating requirements for buildings. However within the heating requirements are constraints on the time to bring a building upto temperature based upon a minimum outside temperature. With lower mean temperatures, this time is extended, or the system is on continuously - not normal in most applications.

System designs can be configured to meet the lower mean temperature criteria and in doing so must use condensing boilers, as conventional boilers are restricted from operating at these temperatures. But as you have noted, these low temperatures are not ideal for the generation of dhw, although advances are being made with the ability to override the low temperature operation to satisfy a dhw priority.

To answer your final question, CIBSE are on the case promoting Best Practice in system design, but it's horses for courses with the odds shifting very gradually to lower temperatures driven by legislation.

Source

Building Sustainable Design