A Mist Opportunity? Retrofitting, when traditional sprinklers demand too great a water supply
The renewed focus on fire safety has seen London Assembly’s Planning Committee recently investigate whether additional Automatic Fire Suppression Systems – for brevity let’s call them sprinklers – should be deployed in London. Their work looked at the costs and benefits of sprinklers both in new build and retrofit, with a view to changing the fire safety landscape first in London, and then across England through the Building Regulations.
The costs of installing sprinklers in new homes can be relatively low, particularly in flats where it can be limited to around 1 to 2 per cent of the total development cost. Houses benefit less from shared infrastructure such as pumps and tanks and are therefore more expensive to equip, while retrofit in any property type tends to be significantly more expensive again.
The report concludes that while full coverage of all English homes should be aimed for, the costs and the impact on the installation industry are unrealistic on short- and medium timescales: even when only London’s buildings above 10 storeys are considered, retrofitting sprinklers would cost up to £500 million. The committee therefore proposed a short-term focus on vulnerable tenants and existing high-risk buildings, and a £50 million retrofit fund, to be spent over 5 years. The committee also envisages folding sprinkler installations into ongoing building refurbishment programmes and suggests that the Government mandate this in care homes, sheltered housing and high-rise.
The report’s conclusions about the importance of sprinklers chime with many experts’ views; for example Dany Cotton, Commissioner of London Fire Brigade, told the Assembly that “fire sprinklers are key going forward” in making London’s buildings safe.
This consensus makes it almost inevitable that in the next few years, a wave of retrofit projects will bring sprinklers to existing high-risk buildings. Particularly in the most challenging projects, installers will be under pressure to constrain costs with innovative solutions.
In high rise buildings, the typical fire suppression system is the traditional sprinkler, where each ceiling-mounted nozzle can spray around 60 litres per minute, in the form of large droplets. These systems are designed to allow for several nozzles activating during a fire. In retrofit projects, however, the challenges of upgrading the water supply, providing pumps and tanks, and installing several nozzles in each ceiling, can bring significant cost and complexity. The main alternative to traditional sprinklers is watermist technology. Offering lower water usage and flexible hoses that are easier to work with, watermist systems nevertheless share many of the limitations of traditional sprinklers and represent an evolutionary rather than revolutionary advance.
With flexible hoses that are easier to work with, watermist systems also offer water consumption as low as 12 or even 6 litres per minute. Flow is not necessarily a guide to performance, as some systems use the watermist in a more targeted way, and others have room size limits that may not be mentioned in promotional material. Specifiers should check that the system performs to BS8458 for the room sizes required and that a neutral third party such as BSi or LABC has endorsed the test performance.
Watermist has been used in tower block retrofit projects for several years, and some systems are particularly amenable to retrofit. At Surrey Towers, in Addlestone, heightened concerns over fire and a consultation with Surrey Fire and Rescue led to the extensive use of an innovative watermist system in the building. Installations took place to fit in with major internal works and re-lettings, minimising disruption to tenants.
We hope that most people will never need the Automatic Fire Suppression Systems that are now being retrofitted into homes, but even the majority of households that never experience a fire can gain huge benefits from sprinklers. Under the Building Regulations and British Standards, homes that have fire suppression can go open plan, eliminating the wastage of space on dingy hallways and bringing a more modern and spacious aesthetic. We urge property owners to make the most of their fire suppression retrofits: with some co-ordination, they have the opportunity to create homes that are not only safer, but also more liveable and attractive.
The above article was provided by Plumis Ltd as part of the LABC Warranty ‘Future of Construction’ blog series. To learn more about Plumis please visit www.plumis.co.uk