High-density housing in Kowloon has been blamed for heating up the peninsula, after a study found that densely populated areas were more than five degrees hotter than elsewhere. Environmental group Green Power found that the western and central parts of Kowloon were a lot warmer than the east. It said the so-called 'heat island effect' was partly responsible for smog build-up and increased energy consumption. Readings were taken at 16 sites along a 3,180-metre stretch from western Kowloon, near Kowloon Station, to Hunghom Pier on August 14 last year and July 15 this year. It was found that Hunghom was an average 5.5 degrees cooler than central Kowloon and 3.9 degrees cooler than near Kowloon Station. The highest temperature of about 37 degrees was taken at the junction of Wylie Road and Gascoigne Road, in the heart of the peninsula. Dr Cheng Luk-ki, head of research for Green Power, said the temperature differences were probably due to high-density housing on the central and western part, plus prevailing easterly breezes. 'There are massive areas of road surface in western Kowloon which absorb excessive heat, while high-density buildings could trap the heat within the area,' he said. Dr Cheng said the resulting higher energy consumption in urban areas, due to increased use of air-conditioners, increased the heating effect further. The green group suggested planting more trees to cool down urban areas. Developers should also use less heat absorbent construction materials. Better urban design could also minimise the effect. Leung Wing-mo, senior scientific officer of the Hong Kong Observatory, said although temperatures in Hong Kong in general had been rising, it was difficult to distinguish the impact of global warming from the heat island effect. In the first half of this year, the observatory recorded an average temperature of 22.9 degrees, 1.9 degrees higher than normal and the highest since records were first kept in 1885. The observatory said the high temperatures could also be due to the El Nino effect and fewer cold fronts coming from the mainland. A spokesman for the Environmental Protection Department said they had not investigated the heat island effect. But they said the Buildings Department offered guidelines to developers on building materials to minimise heat absorption.