The Government is defending its decision to put under floor heating in four new prisons.

National is critical of the move, claiming that many working New Zealanders cannot afford such luxury and will not be happy to think that they are funding through their taxes comforts for hardened criminals.

But Associate Corrections Minister Mita Ririnui has told Parliament the Government is acting within the law as the current Building Code requires an adequate interior temperature of no less than 16 degrees in public buildings, including prisons.

Mr Ririnui says Auckland Hopsital's mental health unit and a large number of childcare centres and retirement homes also have under floor heating.