The scheme has four certification levels namely the Certified, Gold, GoldPlus and Platinum ratings, in increasing order of stringency. The basic or Certified level is mandated for all new buildings and existing buildings undergoing major retrofitting, with a gross floor area greater than 2000 m2, through the Building Control (Environmental Sustainability) Regulations under the Building Control Act. Singapore has also set a target to have 80% of its building stock Green Mark certified by 2030.