All commercial, institutional and hotel buildings, which use hot water, will have to install a solar water heating system of adequate capacity. The existing buildings which do not have this facility will provide it within one year from the date the orders are notified in the official gazette. UT Chief Administrator Sanjay Kumar had issued orders regarding amendments in its building bylaws for commercial and residential units on Tuesday. As per rules, the orders will be notified by December 22, 60 days after being issued. The orders are mandatory for residential buildings as well, constructed on a site of one kanal and above. While a one kanal house will have to make provision for a solar water heating system with capacity of at least 100 litres, houses constructed on an area of two kanal or above will have to install the same with a minimum capacity of 200 litres. The existing houses are required to provide these facilities within two years from the date the orders are notified in the official gazette, that is December 22. Talking to Newsline, Sanjay Kumar said: