ISLAMABAD The Headquarters building of the Capital Development Authority (CDA) plunged into darkness at 8:30 p.m. the other night when it observed 'World Earth Hour by switching all the electrical lights off in the premises of the building. Chairman CDA Imtiaz Inayat Elahi switched off all the essential and non-essential lights between 8:30 p.m. to 9:30 p.m. of the building and lit the candles as a symbolic act to observe The Earth Hour-2011. Many officials of the Authority including Member Planning and Design Tahir Shamshad attended the well-turned-out ceremony. Highlighting the importance of the event, Imtiaz, urged the residents of the federal capital to take a firm stand against climatic changes. The Earth Hour was a great concept and would help conserve power and prevent loadshedding, he said in addition the event was organised to create awareness on climate change and global warming. Imtiaz said the civic agency was already taking appropriate measures to conserve electricity in the backdrop of ongoing electricity crises in the country. CDA is the first ever municipality of the country that is going to replace streetlights with light emitting diode (LED) system, he added. He said the CDA was adopting the sound principal of sustainable urban development, conservation natural resources, restoration of natural ecosystem and minimising the use of non-renewable resources.