One of the burning houses had an activated automatic sprinkler system installed while the other was left unprotected.

Firefighters hope the charred remains of the living room in the unprotected house will convince government departments, local authorities and developers that all new buildings should be fitted with sprinklers.

Assistant divisional officer of the fire service John Murtagh said: 'Survivors in this room would have been nil and the likelihood is that anyone upstairs wouldn't have got out or would have had to be rescued.'

More than 100 people watched the demonstration at two Douglas Corporation houses in Hazel Crescent, Pulrose, which are scheduled for demolition.

Firefighters had planned to leave the fires to burn for 15 minutes – the time it would take for an alarm to be activated and fire crews to arrive – but it spread so quickly in the unprotected house the blaze was put out after only five minutes.

During that time thick black smoke poured from the roof, ground floor and upstairs windows, and the fire, with temperatures reaching more than 1,000C, reached the back door.

Meanwhile, at the neighbouring property, the sprinkler in the living room was activated when the temperature reached 71C, reducing it to 20C.

Mr Murtagh said: 'The house on the left will be fairly unscathed – a bit of air freshener, new sprinkler head, dehumidifier and a Hoover and everyone's happy.

'On the right, black ash furniture, new carpets, ceilings and floors and, unfortunately, probably new occupants,' he added.

Mr Murtagh said he hoped to dispel myths about sprinklers, including that they would cause flooding or go off throughout the whole house.

'A sprinkler system is the best for life and property safety,' he said.

Mr Murtagh explained that sprinklers only go off when enough heat is generated in each room – and would only cause only a small amount of water damage.

The demonstration was held in partnership with Douglas Council, the Department of Local Government and the Environment's building control division and the Homesafe Group, which fitted the sprinklers.

George Waft MLC, political member of the Department of Home Affairs, said: 'The demonstration shows that the sprinkler system outdoes any other protection provided at the moment. Smoke alarms are only able to make people aware of a fire.'

Douglas Council leader David Christian said if the local authority was to fit sprinklers in new build and existing council properties they would need DLGE to fund the work.

But he added: 'The council recognises that fire sprinkler systems can protect both property and life and we are pleased to have this unique opportunity to witness their effectiveness first hand.'

Firefighters will visit 10 primary schools next week to raise awareness of fire safety in the home as part of National Schools' Fire Safety Day.

They will talk to year two pupils about what to do if a fire breaks out.

For further information or to arrange a home fire safety visit contact the risk reduction team on 647303.