Shanghai will again implement power-saving measures this summer, requiring companies to shift working hours or even shut. For about three months from June 15 the city will require high energy-consuming factories or those that produce a lot of pollution to shut from 8am to 10pm every day. At least 1,500 companies would be affected, the Shanghai Daily said yesterday. Other companies would have to shift working hours to periods of lower electricity demand, reports said, without giving figures for the number of firms affected. Shanghai has already announced that more than 3,000 companies will give workers mandatory week-long holidays this summer to save power. If temperatures top 35 degrees Celsius, shopping malls, office buildings, hotels and entertainment spots such as nightclubs and karaoke parlours would have to turn off central air-conditioning for 18 hours a day, running it only from 6pm to midnight, reports said. Shanghai also would raise the average price businesses pay for power by 25 per cent to 0.035 yuan per kilowatt hour this summer, the New Times said. Prices for households would be unchanged. The city introduced similar measures last summer, but Shanghai's power demand is forecast to be higher this year. Foreign companies said the city's power shortage remained a serious blot on the business landscape. 'There's no respite. Last year's summer was relatively mild so we got lucky, but who knows this year,' said one US business executive. Official estimates put peak electricity demand this summer as high as 19,000 megawatts, up more than 12 per cent, resulting in a shortfall of 2,000mW.