Where energy efficiency measures are undertaken correctly, there is a real opportunity to have a positive effect on the building, provided that two key principles are observed:
Lle bo mesurau effeithlonrwydd ynni'n cael eu cyflawni'n gywir, mae yna gyfle go iawn i gael effaith gadarnhaol ar yr adeilad, ar yr amod y cydymffurfir â dwy egwyddor allweddol: