Smart air conditioning sensors make KMB buses go green
Kowloon Motor Bus is determined to keep its cool when it comes to the environment.
All of its 3,600 air-conditioned buses now have sensors that fine-tune the inside temperature in response to the atmosphere outside.
The sensors save fuel as air conditioning is used only when it is needed.
Principal engineer Shum Yuet-hung said the cabin temperature was affected by the number of passengers, the air flow at bus stops and the temperature difference between inside and outside.
'The ambient sensor fine-tunes the temperature in the bus automatically to suit different cooling requirements based on the temperature difference,' he said. 'It enables the air-conditioning system to adjust its cooling according to actual needs and this helps save energy.'
Mr Shum said fuel consumption increased 1 per cent when the outside temperature increased by one degree Celsius.
'If the air conditioning is set at a certain degree and does not change, energy will be wasted in cool weather.'
KMB sets its air conditioning at 23 degrees and the humidity level at 40 per cent to 70 per cent.
The bus company said the device came into its own in spring, autumn and on rainy days, when there were big temperature differences between day and night.
The sensor aims to keep the temperature inside the bus at between 22.5 degrees and 25.5 degrees, depending on the temperature outside.
KMB introduced an enhanced air-conditioning system in 2005, which includes the ambient sensors.
The system's 'intelligent' temperature control makes adjustments every four seconds.