Most conservatories now have Argon filled, warm-edge spacer bars with low emissive glass sealed units, Planitherm sealed units achieve a U-value of about 1.0W/m2K.
This coupled with the same roof glass, insulated cavity walls and insulated slabs below the screeded floor make the rooms liveable...
Basically, conservatories are exempt from Building Regs.
It needs to be single storey, constructed at ground level, and less than 30 sq metres of floor area.
It also requires a lockable barrier between the house and conservatory.
If the existing central heating system is extended to heat it, it...
Nothing to stop you having under floor heating or Dimplex electric wall mounted heaters.
Hot water radiators may be used if they have isolation valves and temperature thermostats