The ubiquitous SMS (Short Message Service) is turning out to be quite an environment-friendly tool for a junior college. It has helped to cut down on unnecessary use of air-conditioning and slash utility bills by an average of $10,000 a month.

The project won St Andrew's Junior College (SAJC) the Gold Innergy Award at the recent Ministry of Education's (MOE) ExCEL Fest 2007 - a festival that seeks to develop the spirit of innovation and enterprise in schools. In all, some 81 awards were presented to MOE staff during the event. These included the Best Suggestion Award and the Thinking Culture Award, in addition to the Innergy Award.

SAJC had moved into spanking new premises at Potong Pasir in 2006, the buildings boasting larger and more numerous rooms, as well as better equipment and facilities. Moreover, all the tutorial rooms, as well as lecture theatres and offices are air-conditioned. Electricity bills were expected to increase, but not by the whopping 40 per cent - from an average of $25,000 a month to $35,000.

Mr Sia Lai Chai, the Head of Department of Education Technology, realised that the bulk of the electrical wastage occurred in the big lecture theatres. "Air-conditioners were being turned on by individual students and small groups of students outside of lecture times without regard to energy consumption. And they were not being turned off after usage as well."

Such unauthorised usage was tricky to prevent - how could air-conditioners be turned off and on at the authorised times, yet be flexible enough to accommodate changes in schedules?

Mr Sia came up with the idea of using an automatic scheduling system that sent out SMS messages to devices embedded in the air-conditioners, to turn them on and off.

He found a component called a "GSM telemetry device" in a catalogue. After doing some research, he called the school's air-conditioning contractor to install the necessary circuits. Meanwhile, he wrote simple scheduling scripts that enabled an existing SMS server to send out the necessary commands to activate the GSM telemetry device in the air-conditioners. An online booking and logging system was also created so that the school technician could use it to create ad hoc bookings.

When the system was ready for use, Mr Sia sought the permission of the management to implement a usage policy whereby the air-conditioners could be switched on only when more than 50 per cent of the seating capacity in any given lecture theatre was taken up.

This usage policy coupled with the new SMS GSM power-saving system has been operational since late February, and the results have been staggering. Significant improvements have shown up in the utility bills, with average savings of $10,000 per month from April to July.

This effectively brought the bill down to the level spent at the old premises. Not bad for an idea that cost some $6,100 to implement - $2,100 for the three GSM devices in the five lecture theatres; and $4,000 for cabling works by the air-conditioning contractor. The monthly recurrent costs? Just $10 for each of the three SIM cards used to send out the messages from the SMS server.