Energy conservation and waste heat recovery are important global issues of our times. Attock Oil Refinery Limited (ARL) is pioneer in crude oil refining in Pakistan. After thorough surveys and analysis Heavy Crude Unit (HCU) was selected for energy conservation and waste heat recovery. A detailed study of the plant led to the identification of potential zones for energy conservation and waste heat recovery. Energy conservation was done in the ‘pre-heat train'' which exchanges heat between the products at high temperature and crude at low temperature. By increasing the heat exchange here, both the amount of fuel burnt in the heater to heat crude and the coolant used to cool products could be reduced. Waste heat recovery was done on the flue gases of the combined stack of two heaters which were being exhausted into the atmosphere at a temperature well above its due point temperature. Recovered heat could be used to heat up the intake air for combustion in the heater which was being used at ambient temperature, saving fuel and environment, hence addresing economic and global warming issues.