MEET the new generation of "clean technology": Robots that trundle along as they clean and polish the floor, rubbish bins that move around on their own, and sensors that tell you whether a bin needs to be emptied.
Some of this sounds like science fiction. But technology firms at the CleanEnviro Summit Singapore exhibition at the Marina Bay Sands exhibition hall this week are already trying to sell such labour-saving gizmos to local cleaning companies, which are facing a manpower crunch.
Cleaning firm Clean Solutions has its Intellibot robotic cleaner, a shopping cart-size machine that can clean an area the size of 10 Housing Board four-room flats each hour.
The $70,000 machines, which sense obstacles with sonar or sound waves and stop when a person gets in their way, are already being used at Changi Airport.
Sensor firm Cre8 Technology, meanwhile, is showing off a remote-controlled miniature trash bin. One day, said director Gregory Ong, a swarm of self-propelling bins could station themselves where they are needed most.
The company is also pitching other sensor technologies, which can alert a cleaner or building manager when a rat trap finds its prey, count how many people use a toilet or tell how often rats move in and out of a bin.
"It saves you having to check repetitively, so your time can be better spent doing things that really matter," Mr Ong said.
Pest control firm Origin Environmental Consultancy is one of the first buyers.
Its director Deanne Ong said: "In the past, when you wanted to identify whether a rat was in a trap, you had to go and check by smell. Now, the sensors are doing the work for us."
The sensors mean that Origin can cut down the number of people at a client's site from 12 to 10.
Waste management firm Ausko, too, has a sensor that can be mounted in a bin to tell how full it is, so cleaners can decide how frequently the bin needs to be emptied.
Such labour-saving devices, however, do not come cheap.
Ausko's sensors, for instance, cost $300 each - or cheaper in bulk - and cleaning firms must also subscribe to tracking software.
But president of the Environmental Management Association of Singapore, Mr Milton Ng, pointed out that labour costs are going up anyway.
"Salary is going to catch up, and the labour market is tight," he said. "We have no choice but to adopt these technologies in the next few years."