Reconsidering the smoke alarm in the smart home

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Fire Protection

Reconsidering the smoke alarm in the smart home US Correspondent Catherine Levin reports on smoke alarm innovation Stateside

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r Larry McKenna works at the US Fire Administration. He has dozens of smoke alarms in his home and insists his family tell him when they go off so that he can take notes. With such a love for smoke alarms and a collection that goes back to the 1960s when smoke alarms cost $85, it is comforting that Larry found his way to the USFA to be their resident expert in this field. With a $700,000 budget (including some funds from the CPSC), Larry found himself directed to the foothills of East Tennessee, an unlikely place to find smoke alarm innovation, but the home of the Oak Ridge National Laboratory. Made famous as the home of the Manhattan Project, the development of the atomic bomb in World War Two, Oak Ridge is now a vast scientific research complex, part of the US Department of Energy. Dr Bruce Warmack, a 38-year veteran of ORNL, is a passionate scientist and an expert in sensor technology. He was intrigued by a request by Larry at the US Fire Administration to see if he could improve the performance of smoke alarms to increase their sensitivity and specificity. He and his team have achieved both with the smart smoke alarm. When I spoke to Bruce, he talked a lot about toast and training. How do you get your smoke alarm to know the difference between burnt toast and a real fire? You need a microcontroller, “it’s the brains”, says Bruce. The mathematical formula inside the microcontroller that Bruce has developed “improves the intelligence of the sensors in the smoke alarm without changing the sensor technology”, which he says makes it very attractive to commercial partners.

Linear Discrimination Analysis So if the sensors in the smoke alarm can talk to the microcontroller first before talking to the alarm and double check if the readings fit with the profile of smoke or heat from a fire rather than the distraction of burnt toast, then most of those false positives should disappear. It is called a rather fancy name, Linear Discrimination Analysis, which at its heart means it can differentiate between different types of smoke. The mathematics inside is trained by how sensors have reacted in test scenarios. ORNL is not in the business of developing commercial products but rather coming up with scientific solutions that the private sector can explore and exploit. ORNL is now in 42 | January 2015 | www.fire–magazine.com

“Innovation in smoke alarm technology goes beyond the sensors. Getting smoke alarms to talk to each other through wireless networks in the home has been a key development”

dialogue with manufacturers about licensing this technology. A process of testing, certification and full production will then follow with it being available to consumers within one to two years. Innovation in smoke alarm technology goes beyond the sensors. Getting smoke alarms to talk to each other through wireless networks in the home has been a key development. For example, in the US, Kidde sells through outlets like Home Depot a battery operated wireless inter-connectable ionization smoke alarm for around $25. Competing with five dollar ionization smoke alarms, it is not hard to see why consumers would prefer these to wireless alarms retailing for five times as much. But both have weaknesses: they are single sensor and they have short life replaceable batteries. Whilst a single sensor smoke alarm may be the best solution for particular circumstances in the home, it does require the consumer to know when ionization is better than photoelectric and vice versa. That is asking a lot of people. The move to multiple sensor smoke alarms allays some of this but ultimately if the wrong type of sensor is in the wrong place in the home, it will become a nuisance. The point about short life replaceable batteries is important. When a smoke alarm is poorly located it is more likely to go off when it does not need to and it is common to take the battery out to prevent nuisance alarms. Thinking about relocating the smoke alarm and putting those batteries back in is less common and not doing so can result in tragic consequences as the Fire Service knows all too well. Long-Life Alarms A smoke alarm with a short life replaceable battery is cheaper than a sealed smoke alarm with a ten-year battery. But why have them at all? Would it not be better to remove short life battery alarms from the market through changes to the standards governing their manufacture? Getting the balance right between cost and functionality is crucial in terms of fire safety outcomes here. This debate is not new but perhaps it needs to be resurfaced by the fire sector if further inroads are to be made into reducing fire statistics. Innovation is not just limited to the technology inside the smoke alarm. There is a wide range of activity by the industry to try and differentiate the aesthetics of their products in


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