Several city hotels,institutes and IT companies switched off their electrical supply to mark Earth Hour on Saturday. The National Defence Academy (NDA) saved more than 1,600 units of power by shutting down all the non-essential lights on its campus. Lt Gen Jatinder Singh,commandant,NDA,said,Such initiatives have certainly kindled the spirit of conserving the environment amongst the entire fraternity. The Courtyard by Marriott Pune City Centre switched off all the power supplies from 8.30 to 9.30 pm. Courtyard by Marriott Pune,Hinjewadi,celebrated by cutting a cake and serving their guests a candle light dinner. Earth Hour should be observed to spread awareness for a greener future, said Vineet Mishra,general manager,Courtyard by Marriott Pune City Centre.