Rethinking Automatic Domestic Fire Suppression
Commercially, automatic fire suppression is well established. From restaurant kitchens to data centres, a wide range of solutions can be seen in the market, from traditional sprinklers to inert gas and chemical systems. In UK homes, by contrast, only manual suppression methods like fire extinguishers and blankets have any real presence, with very few homes having sprinkler installations (either water or watermist). On reflection it is a little surprising that only manual fire fighting solutions which require an occupant to “step up” and take action, are found in homes, where occupants have little or no training, while workplaces, where training can be guaranteed, tend to be automatically protected.
Many fire risk assessors and fire/rescue services now consider fire extinguishers a risk in homes because they encourage untrained people to tackle a fire when the best course of action would be to leave the premises.
The reality is that steps to protect life are normally driven by an economic cost-benefit analysis. In a factory, warehouse or hotel, the cost of lost business or stock, or simply insurance premium savings, can justify the installation of a full sprinkler system. It is not surprising, then, that sprinkler installations for commercial buildings frequently follow strict standards drafted by fire risk underwriters like Factory Mutual rather than looser regulatory requirements.
Does this mean that automatic fire suppression in the home is not economically viable? For sprinkler systems, a BRE report commissioned by the Department of Communities and Local Government states just that. Although they can be cost-effective in high rise buildings and in care homes, they are represent poor value in typical houses and flats. It therefore makes sense that legislation today (in the form of Approved Document B) only mandates more cost-effective measures such as smoke and heat alarms, and passive fire protection such as fire doors and walls.
The result has been an increasing “automatic fire suppression gap” between homes and commercial buildings. Yet low-cost automatic suppression is needed: in terms of fire, you are probably considerably safer in a typical stadium or shopping mall than in the average home. The gap is widened by the stark differences in fire risk and escape between homes and workplaces, because…
Not everyone lives with a fire safety officer
In domestic settings, most occupants can’t identify hazards the way Fire Safety professionals can. With so many flammables and heat sources in a kitchen, even something as innocuous as a badly placed kitchen roll can be dangerous. By contrast, businesses are required to assess fire risks regularly and carefully, adjusting working practices and using signage to avoid the vast majority of hazards. The presence of adult work colleagues in a commercial environment also helps to professionalise behaviour and the approach to risk, resulting in a higher level of hazard avoidance and elimination. In the home, by contrast, a parent may be simultaneously cooking and caring for children alone hob, with no-one to act as “backstop” and no procedures to prevent accidents.
In the event of fire, leave the building
Building Regulations Approved Document B seeks to enable an occupant to escape safely from a building in the event of a fire. It does this primarily through alarm systems, combined with passive fire protection to slow the spread of fire by "compartmentation". These measures are, in theory, more than adequate for the average person in a building that has been built, maintained and undergone remedial work following the requirements of the Building Regulations. Nevertheless, fleeing and even surviving a domestic fire can be challenging compared to commercial settings:
- Small rooms and lack of forced ventilation mean smoke can accumulate;
- There is no control over “lone working” in the home;
- With no automatic suppression, alarms and passive measures provide little comfort foroccupants who may well be elderly or immobile;
- Alarms are regarded as a nuisance and are often disabled;
- The efficacy of passive protection is highly dependent on the proper installation, and is often silently ruined by remedial works or refurbishments – especially in private homes where the building contractor may not have had deep passive protection training.
Why are cost effective solutions not available for homes?
The lack of effective risk assessment in homes has driven the fire protection industry to develop solutions primarily for commercial applications, rolling these out to homes in only in a few special cases, largely unmodified. With no real targeted product development it should not surprise us that, as discussed above, today’s commercial sprinkler solutions are not well-suited to the home. The poor cost/benefit ratio of domestic sprinkler systems can be attributed to several factors. Firstly, with no attempt to prioritise key risk areas like the kitchen, risk/benefit ratios are inherently poor. Secondly, low UK mains pressures and the need to activate many nozzles at once demands a large, expensive pump and potentially a substantial tank. Thirdly, sprinkler systems are inherently bespoke and carry a substantial survey and design cost. Finally, total life cost is increased by the need for periodic system testing. Although many of these costs also apply to commercial premises, in domestic settings such expenditure is both optional and harder to dilute into the overall costs of a development.
In the search for a solution which will be cost effective for domestic settings, some characteristics of the home must be considered:
- Not every room carries the same fire risk: about two-thirds of fires start in the kitchen, normally from cooking or from appliance faults. In studio flats, there may only be a single room needing fire protection.
- Plumbing for water based suppression systems is not available everywhere in the home, and space for gas or powder cylinders may be limited.
- Major disruption to the home may not be practical in a retrofit situation, especially in the case of elderly or disabled, where temporary relocation may be inadvisable.
Recently, several automatic fire suppression devices have arrived in the market to address these needs. Rather than tackling the whole home, these lower-cost, easy-to-retrofit, low maintenance devices focus on a specific location: a bedsit, the kitchen, or even just the cooker hob. We can loosely classify them as “fire suppression appliances” or “FiSAs”.
Plumis’s Automist is an example of such a product. It is a high-pressure mist device which mounts between a kitchen sink and tap. In the event of a fire, a heat alarm is triggered at the standard 57°C and a high pressure pump under the sink powers mist throughout the volume to be protected. The system is focused on the kitchen but can also cover many studio flats or open plan lounges.
Automist’s cost effectiveness is achieved by being provided as a complete “ready to install” kit, focused on the room with the highest fire risk and with no specialized fire installation or customization required. The draw-back is that it can only be installed where there is a tap available and thus cannot fit every room of the home.
What about Standards?
Product standards are often based on well established methodologies to achieve a certain functionality. Sprinklers systems, for example, have clear guidelines on the maximum nozzle spacing and layout, required flow and even activation temperatures to ensure that a qualified person is able to replicate the setup successfully. Since this approach is not directly transferable to the FiSA product class, one of two scenarios will develop as FiSAs mature. It may be that certain types of FiSA succeed above all others in the marketplace. If this happens, FiSAs will follow sprinklers, with a “dominant design” being embodied in a set of standards. Alternatively, if today’s varied designs continue to proliferate, a generic standard will be drafted around a set of repeatable fire performance criteria, independent of the device’s design.
The lack of appropriate standards today has been an impediment to system developers working at the cutting edge, because FiSA engineers not only have to develop new products and bring them to market: they must also find new ways to demonstrate that their solution is effective. At Plumis we felt that video of a system in action could be compelling, but would need to be backed by objective data. We therefore based our test setup on well-established standards wherever possible, drawing elements from BS 9251:2005* and DD 8458-1** as well as less well known documents, such as the Scandinavian “Easily installed automatic extinguishing systems***”
To independently evaluate fire performance, Plumis sought the assistance of the Building Research Establishment (BRE) and agreed on the use of Fractional Effective Dosage (FED). This method predicts how long it would take a person to lose consciousness, suffer burns, pain and ultimately die, due to oxygen deprivation, inhalation of toxic gases, and/or exposure to high temperatures. BRE also ran control tests to compare the fire spread and life risk with no fire suppression system in place. In the absence of suitable standards, these comparative FED measurements provide objective effectiveness data (see Plumis’s website) and have also allowed limitations to be discovered and converted into recommendations for installers on the use of automatic door closers and on permissible room configurations.
In fire protection, cost-effectiveness is always in tension with full coverage. To date, this has meant that cost-effective solutions were not generally developed or deployed in domestic settings. Plumis believes that a cost-effective fire suppression solution can provide most of the benefit of full-home coverage for a fraction of the cost and may enable protection to be provided in places which otherwise would have none at all. This is especially worthwhile in high-risk environments like student accommodation, in small self-contained living areas like studio flats, and for vulnerable people such as the elderly or disabled.
Automist is available to pre-order in the UK at www.plumis.co.uk.
For further information, please contact Plumis Ltd. at: fireprotection@plumis.co.uk.
Footnotes
* “Sprinkler systems for residential and domestic occupancies, Code of practice”
** “Watermist fire suppression systems for residential and domestic occupancies – Part 1: Code of practice for design and installation”
*** Swedish Rescue Services Authority (Räddnings Verket) and the Norwegian Directorate for Civil Protection and Emergency Planning (DSB) [2007]; recommended by the International Watermist Association
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