unlawful condition? - Public forum - Planning Advisory Service (PAS)

I've come across an eyebrow-raising condition imposed by a Council very recently on a scheme for a handful of new houses. The condition requires the houses to be Code 3 compliant, but the council has no policy requiring this (either in the development plan or in an SPD), and the reason for the condition is 'to comply with PPS1: Climate Change Supplement'. As far as I can see the application didn't proposed that the houses meet Code 3. Observations?