So what that the new Part L signifies the end of fan coils (7 April)? About time, too.

In modern mechanically ventilated and cooled office buildings where the internal loads

are 35 W/m虏 or more and fabric and infiltration losses are tiny, what sense does it make to be running the chiller for almost all the occupied hours? For about 75% of the time the external air temperature is below 16掳C and all the building's heating and cooling needs can be catered for by fans and heat recovery devices.

The issue that seems to me to create the biggest sea change within the new regs, and of which I have seen no other mention, is contained in clause 64. By either limiting total gains to 35 W/m虏 or requiring internal temperatures to be below 28掳C for all but 20 hours a year, the concept of a naturally ventilated office type building in the south of England becomes history. The problem is:

  • As soon as occupancy levels exceed one person with a PC per 8 m虏 and the lights are on, with no solar gain you have exceeded the first criteria
  • Given that in warm years the external temperature frequently exceeds 25掳C for more than 20 hours, then on a summer day (where the only driving force is the stack effect generated by a maximum 3K temperature differential) there is no hope in a typical office of generating the necessary air changes from natural ventilation.
One final point is that our energy consumption could be reduced if individuals were more

tolerant to temperature variations. This is precisely the opposite effect to that created when it is almost impossible to find a new car that does not offer "climate control". I would like to see a vehicular version of Part L that imposes the same dramatic improvements in performance as those required for buildings. Maybe then we would understand what King Canute learned long ago - that as true control of the elements is not achievable, we need to adapt to the changing climate, not vice versa.

Richard Spinney, Henderson Green

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