Nid yw’r gwelliant o fewn cymhwysedd deddfwriaethol y Cynulliad Cenedlaethol.  Fodd bynnag, mae’r pwerau newydd i Weinidogion Cymru wneud rheoliadau adeiladu ar gyfer mesurau oddi ar y safle i leihau carbon yn golygu bod ganddynt y pŵer i’w rheoleiddio a bod y Cynulliad Cenedlaethol yn cael craffu arnynt.  Byddwn yn ymgynghori ar fesurau oddi ar y safle i leihau carbon yng Nghymru cyn arfer y pwerau newydd i wneud rheoliadau adeiladu.  Rwyf felly wedi cytuno bod Llywodraeth y DU yn gwneud darpariaeth ar gyfer rhoi pwerau i Weinidogion Cymru wneud rheoliadau adeiladu ar gyfer mesurau lleddfu carbon oddi ar y safle yn y Bil Seilwaith.
The amendment is outside of the National Assembly’s legislative competence. However, the new powers for the Welsh Ministers to make building regulations for off-site carbon abatement measures would mean that their regulation would be within their power and be subject to the scrutiny of the National Assembly. We will consult on off-site carbon abatement measures in Wales before exercising the new powers to make building regulations. I have, therefore, agreed that the UK Government make provision for powers for the Welsh Ministers to make building regulations for off-site carbon abatement measures in the Infrastructure Bill.