Fire alarm power efficiency

2021

The Fire Industry Association’s CEO Ian Moore, explains the importance of ensuring efficient power for fire and security alarm systems in line with environmental concerns…

Environmental friendliness is second nature to us all now. Going further than moral responsibility, the EU sets much publicised carbon targets to insist we improve green building technologies. Reusable power such as solar, wind and geothermal as the input is a great start, as is maintaining that power by making buildings “efficient” e.g. insulation, LED lighting etc. No opportunity to improve efficiency should be ignored however small it is in comparison with the step changes made by these significant alterations. The built environment accounts for over 40% of overall energy consumption in Europe and over 35% of CO2 emissions so it is clear that even minor changes when multiplied out will be worth pursuing.

Fire and security systems are now common place in all new buildings. With the focus on technological advances and compliance to a range of standards, there is little attention paid to energy efficiency. Modern fire detection and alarm systems have always had a degree of energy efficiency in their design as they need to have a secondary source of standby power (usually batteries) and in most cases with the requirement of running the detection system for a minimum of 24 hours and more importantly sounding alarms for a minimum of 30 minutes, a significant power requirement is required.

Staying with fire detection and alarm systems; within EN 54-4 (BS EN 54-4:1998 to give it its national name) it is detailed how the batteries should be maintained at the correct level of charge and how fast they must be recharged. The traditional method has been by trickle charging or float charging the batteries. Basically a float charger will charge a battery at a similar rate as a battery self-discharges, thus maintaining a full capacity battery. However, the main difference between a trickle charger and a float charger is that a float charger has circuitry to prevent battery overcharging.

The more advanced manufacturers incorporate battery management software (including in some cases algorithms) to define how the power is used to charge and maintain the batteries. As an example, EN 54 states that the batteries must be charged to 80% capacity within 24 hours. Batteries do not like fast charging (heat is also an issue, in fact EN 54-4 specifies that the charging characteristic is temperature compensated to achieve the expected life of the battery) so just enough to comply is required to prolong battery life. Once this level is achieved a variety of modes can be applied to limit the amount of power used to charge the last 20% (within an additional 48 hours).

Lead acid battery type is the industry standard but is known not to be the most efficient (or for that matter the lightest or smallest which creates its own problems in storage) so advances in this technology will also reap its own rewards. Maintainers should not be tempted to replace batteries earlier than is required as this will minimise the energy wasted in production or recycling of the battery and reduce the impact on the environment. Measuring the battery capacity using a proprietary tool can allow better judgement to be made of continued battery serviceability.

There has been some great work done by a number of power supply manufacturers in the field of efficiency, but to keep within the strict guidelines of the EN 54 standard there is only so far that optimisation can go. Design for energy efficiency is now even more complicated with designers and manufacturers being required to consider the whole life cycle implications of product design. So it may be that one technology solution uses more material or energy during manufacture that is compensated by consuming less energy during use and end of life disposal or recycling; of course the converse may be true. This should now be part of product design processes.

It’s not just new builds that can gain by using more efficient power supplies, some of the efficiencies quoted by various manufacturers will give you a return on investment in a matter of months, therefore replacing what is already fitted (even if working correctly) should not be excluded from the thoughts of users.

So if you’re looking to save a bit more energy, then ask the question of your fire alarm and security system supplier – every little bit helps!

Ian Moore

CEO

Fire Industry Association (FIA)

Tel: +44 (0)203 166 5002

info@fia.uk.com

www.fia.uk.com

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