DOMESTIC SMOKE ALARMS

Transcription

1 DIgest DG 525 DOMESTIC SMOKE ALARMS Emma Warren Smoke alarms in homes can save lives, are easy to use and are inexpensive. If correctly specified, installed and maintained, they will give an early warning of fire that can allow occupants to safely escape, while nuisance alarms are minimised. This Information Paper provides guidance on the different types of smoke alarm available, and on correctly specifying, locating, installing and maintaining fire detection and alarm systems. It reviews a number of the recommendations given in relevant regulatory guidance, as well as the use of third-party-approved fire detection and alarm products and installers. The information provided will be of particular interest to UK house builders, building control officers, specifiers, manufacturers, building owners and the fire and rescue services, and may also be of use to similar professionals in other countries subject to local code or national legislative requirements. INTRODUCTION The number of UK homes fitted with smoke alarms has risen from just 8% in 1988 to 91% in 2008 [1], as a result of the changes to the Building Regulations Approved Document B Fire Safety [2] in This has led to a dramatic reduction in deaths and injuries from household fires, but there are still more than 200 deaths and some 7500 injuries from the 36,000 dwelling fires attended by fire and rescue services every year [3]. Many of these casualties could be avoided if people had early warning of fire and were able to escape in time. Smoke alarms that are appropriately selected, located, fitted and maintained can dramatically improve fire safety in homes A suitably specified, located and maintained smoke alarm can provide this warning by detecting smoke in the early stages of the fire and sounding an alarm. UK fire statistics show that you are almost twice as likely to die in a domestic fire where there is no working smoke alarm as you are where one is present [3]. TYPES OF SMOKE ALARM Domestic smoke alarms are simple, self-contained but often interconnected units, incorporating a smoke detector, power source and alarm sounder. Smoke detectors There are two types of smoke alarm in common use: one is fitted with an ionisation smoke detector, the other with an optical or photoelectric detector.

2 2 DOMESTIC SMOKE ALARMS DG 525 Figure 1: Inside a smoke alarm that uses an ionisation detector Figure 3: Inside a smoke alarm that uses an optical detector Figure 2: Ionisation smoke chamber Apollo Fire Detectors Ltd 1997/RHD/JDR Figure 4: Optical smoke chamber Apollo Fire Detectors Ltd 1997/RHD Ionisation detectors Ionisation detectors (Figure 1) make use of the radioactive element Americium 241. Americium emits alpha radiation that can only travel a few centimetres in air and can be stopped by a sheet of paper, and so is safe for use in the home. The radiation passes through an air-filled space in the detector (the ionisation chamber), enabling a small current to flow between two electrodes. If smoke enters the chamber it absorbs the alpha particles. This reduces the ionisation and interrupts the current, setting off the alarm when a preset threshold level is reached (Figure 2). Optical or photoelectric detectors An optical detector (Figure 3) contains a light source, typically an LED, collimated into a beam using a lens. A photosensor is fitted at an angle to this light beam. When smoke particles enter the device they scatter the light, directing some of it towards the sensor and setting off the alarm (Figure 4). Combination and other alarms Smoke alarms that contain both ionisation and optical detectors are available. They offer increased alarm sensitivity across a range of fire types (smouldering and flaming) as a result of the detectors differing capabilities (see Ionisation or optical detector alarms? below). Heat and carbon monoxide (CO) detectors are also available for use in domestic properties, but are considerably less sensitive than smoke alarms and should therefore be used in conjunction with, not instead of, smoke alarms. Heat and CO detectors are increasingly fitted where ionisation and optical devices are not suitable for example, heat detectors are recommended for installation in kitchens. An important recent development has been the introduction of multisensor smoke alarms to the domestic market. They contain more than one type of sensor, eg a combined optical/heat detector or optical/co detector. Interconnection Smoke alarms throughout the dwelling can be wired together, enabling them all to sound when one device alarms. This gives more efficient warning and greater escape time to occupants, and can reduce the risk to both life and property. Radio signals can also be used to connect smoke alarms, allowing the benefits of interconnection without the disruption and expense that wired connection can entail. This makes smoke alarm installation simpler, enabling dwelling occupiers to install interconnected smoke alarm systems themselves under the manufacturer s instructions. Wireless smoke alarms may be preferred for aesthetic reasons, particularly in listed or historic dwellings, and can also be used during construction or refurbishment to protect a property in which wiring has not yet been installed.

3 DOMESTIC SMOKE ALARMS DG Power sources Smoke alarms can be powered by batteries either standard 9V or rechargeable lithium batteries or by mains power. Mains-powered smoke alarms, which need to be installed by qualified electricians, are generally more reliable and are available with a battery backup in case of power cuts. In 2008, battery-powered smoke alarms failed to operate in 36% of UK fires where a smoke alarm was present, mainly because of missing or flat batteries. Over the same period, only 15% of mains-powered smoke alarms failed to operate, mainly because the smoke did not reach the detectors [3]. The introduction of 10-year rechargeable lithium batteries for smoke alarms has allowed greater reliability by reducing maintenance requirements. In many smoke alarms, the battery lifetime is now as long as the alarm lifetime. An additional option is a smoke alarm that plugs into light sockets and uses rechargeable batteries that charge when the light is on. SELECTING SMOKE ALARMS BS :2004 (Fire detection and fire alarm systems for buildings Code of practice for the design, installation and maintenance of fire detection and fire alarm systems in dwellings) [4] provides detailed guidance on the use of smoke alarms in new and existing dwellings, both for single-family properties and for houses in multiple occupation (HMOs). When introduced in 1995, BS became a key set of recommendations for building professionals, detection- and alarm-system designers, installers, landlords and others with an interest in fire safety in the home. In the 2004 update, recommendations were made more stringent, eg by increasing the minimum level of protection required in new buildings, recommending standby power supplies for mains-powered smoke alarms and increasing the emphasis on reducing the number of false alarms. The current standard for smoke alarm devices is BS EN 14604:2005 (Smoke alarm devices) [5]. This specifies the requirements, testing methods, performance criteria and manufacturers instructions for both optical and ionisation devices for use in residential buildings. It is used throughout the European Economic Area. Other available guidance on smoke alarm selection includes the listings of third-party-assessed and approved manufacturers and products such as those produced by the Loss Prevention Certification Board (LPCB), which are outlined below. Current UK fire safety regulations are summarised in Box 1. Ionisation or optical detector alarms? While the two main types of detector are both generally suitable for use in homes, each has advantages depending on the particular circumstances. BS recommends that the choice of smoke alarm for a space should consider both the likely type of fire (flaming or smouldering) and the need to avoid false or nuisance alarms. Box 1: UK fire safety regulations The fire safety requirements in the British Isles vary across the different regions/nations, as follows: England and Wales: guidance on complying with the requirements in the building regulations is provided in Approved Document B (2006) [2]. Scotland: the document used is Section 2 of the Domestic Technical Handbook [6]. Northern Ireland: Technical Booklet E (2005) [7] is used. Republic of Ireland: Technical Guidance Document Part B (2006) [8] is used. These documents outline the requirements for new buildings, extensions, alterations and changes of purpose. In the UK, existing dwellings are covered by the Housing Health and Safety Rating System (HHSRS) [9] under the Housing Act 2004 [10], and in the case of HMOs and some other multiple-occupancy properties, fire safety duties are also imposed by the Regulatory Reform (Fire Safety) Order 2005 [11]. Ionisation detectors more rapidly detect the small smoke particles produced by fast-flaming fires, and are therefore recommended where these present the greater risk to occupants such as in living rooms. Optical detectors respond more quickly to smouldering fires, which produce larger smoke particles. They are recommended for areas such as bedrooms where, for example, a cigarette dropped onto furniture or bedding will result in a smouldering fire. Optical detectors are more effective at detecting particles at a distance from the fire, where the particles are likely to have coalesced to reach a greater size [12]. They are therefore recommended for circulation spaces in homes eg halls and landings which are more distant from likely fire ignition sources. Optical detectors are also recommended in areas of high air flow, where ionisation detectors can experience problems because the ions may be blown out of their ionisation chambers. Ionisation detectors being quick to react to small particles are more likely to respond to fumes such as those produced by cooking, and are therefore more prone to nuisance alarms when installed in circulation areas [13]. Neither type of smoke alarm is suitable for installation in cooking areas, as nuisance alarms would be too frequent. Heat alarms are therefore recommended for the kitchen, the room in a dwelling where most fires start [3]. In the past, ionisation detectors have been used more widely because they are cheaper to produce than optical detectors. However, in recent years increased security concerns have made the storage, transport and disposal of the radioactive material used in ionisation detectors a more complex and expensive issue. Third-party certification Third-party certification is an assessment and approval process carried out by an independent body that is not associated with either the manufacturer or the customer, in order to confirm that a product meets and will continue to meet a specified standard.

4 4 DOMESTIC SMOKE ALARMS DG 525 Manufacturers of third-party-approved smoke alarms will have had their products rigorously tested and approved by certification bodies such as the LPCB, and are subject to a combination of regular company audits and schedules of ongoing tests. This gives users the confidence that the alarms will perform as expected, provided they have been correctly installed and maintained. LPCBapproved smoke alarm manufacturers and products and detection- and alarm-system installers are listed in the LPCB Red Book (see While not required by law in the UK, third-party certification offers a number of benefits to specifiers. Expensive mistakes, for example, can be avoided by using products that have been independently shown to be effective. Specifying third-party-approved products also reduces risks, mitigating accusations of negligence by proving due diligence. There are also benefits for manufacturers, including the potential to improve global sales the use of thirdparty-approved products is often specified, and in some territories is mandatory. It can also add value to products, and reduce liability by proving due diligence. SPECIFYING FIRE DETECTION AND ALARM SYSTEMS BS assists with the specification of fire detection and alarm systems by defining grades of alarm system and categories of protection required. Which grade of alarm system? BS grades fire detection and alarm systems from Grade A to Grade F, taking such issues as power source reliability and the level of control and monitoring possible into account. In general, the greater the fire risk and the more demanding the application, the more comprehensive the system needs to be. The grades used are outlined below: Grade A: fire detection and alarm system with control and indicating equipment compliant with BS EN 54-2:1998 [14] and power supply compliant with BS EN 54-4:1998 [15], designed and installed in accordance with BS :2002 [16]. Grade B: fire detection and alarm system comprising fire detectors (other than smoke/heat alarms) and sounders, with control and indicating equipment compliant with BS EN 54-2 and power supply compliant with BS EN Grade C: detectors and sounders (can be combined in smoke/heat alarms) connected to a common power supply, with a standby supply and central control equipment. Grade D: system of interlinked (wired or radio) mainspowered smoke alarms (plus heat alarms if required), each with backup power. Grade E: system of interlinked (wired or radio) mainspowered smoke alarms (plus heat alarms if required), with no backup power. Grade F: a fire detection and alarm system comprising one or more battery-powered smoke alarms (plus heat alarms if required). Higher-grade systems (A C) Large buildings, buildings containing a considerable number of dwelling units and those where the fire risk is particularly high may justify Grade A or B systems. Where a system is designed for property protection, insurers may require a Grade A system, although in smaller properties Grade B or C systems may be sufficient. Grade D systems Grade D is the minimum type of system for new dwellings that complies with the guidance in Approved Document B. The use of mains-powered alarms that each incorporate a standby supply should address the problems outlined below, but if ready access to control is considered necessary a Grade C or higher system will be needed. Grade E systems Grade E systems are not suitable in new dwellings. Mainspowered smoke alarms are potentially more reliable than battery-powered, but are not suitable where the power supply may be intermittent due either to the inability of residents to pay for it or the unreliability of mains supply. Grade F systems Grade F systems should not be installed in new dwellings, but may be considered for existing dwellings if there is a reasonable certainty that batteries will be replaced this is a key issue with battery-operated smoke alarms. Occupants on a tight budget, for example, may find it difficult to afford replacement batteries. In addition, some occupiers might remove the batteries to prevent false alarms or to use in other battery-powered items, and then forget to replace them. What category of protection? BS defines three categories of fire detection and alarm system that are concerned with protecting life (L) in dwellings (D). These are based on the areas in which the detectors and alarms are required, and therefore the level of protection the system offers (Figure 5). They are: Category LD1: detectors throughout the dwelling in all circulation spaces comprising the escape routes, and in all rooms or areas in which a fire might start (other than bathrooms, toilets and shower rooms). Category LD2: detectors installed in all circulation spaces comprising the escape routes, and in all rooms that present a high fire risk to occupants. Category LD3: a system of detectors in all of the circulation spaces comprising the escape routes from the dwelling. BS also defines two categories of fire alarm system installed to protect property in dwellings: PD1 and PD2. Category LD1 and LD2 systems While a Category LD1 system offers the most protection in terms of early fire detection, a good level of protection can be obtained using an LD2 system, which may contain detectors in the kitchen and living room, for example, in addition to the circulation areas.

5 DOMESTIC SMOKE ALARMS DG Figure 5: Smoke alarm coverage provided by the three BS categories of fire detection system If the risk to occupants from fire in any part of the building is high, eg if an occupant suffers from a disability, a Category LD1 or LD2 system should be considered, based on a full risk assessment that takes account of all of the fire protection measures and fire safety systems in place. Category LD3 systems A Category LD3 system is the minimum that is required in new dwellings in order to comply with the guidance in Approved Document B. This system protects the escape routes for occupiers not directly involved in the fire, but may not provide protection to those in the fire s immediate vicinity. Meeting the needs of the various building types BS provides recommendations on the minimum grade and category needed to protect different types of housing. These apply to buildings where details of the occupants are unknown, such as in newbuilds or buildings with high occupant turnover. For a specific property where occupant needs are known, the recommendations can be modified to a higher standard based on a risk assessment. Recommendations for existing properties depend on whether they meet the for fire in BS :1990 (Fire precautions in the design, construction and use of buildings Code of practice for residential buildings) [17], or in national building regulations. These include recommendations on fire-rated partitions, ceilings and doors. If there is some doubt as to whether a dwelling complies with these regulations, the more stringent recommendation for dwellings that do not comply should be followed. The recommendations for the minimum grade and category of system in single-family dwellings and shared dwellings (no more than six people sharing in a similar manner to a family, eg student houses) are outlined below (Tables 1 and 2). There may be requirements in addition to the recommendations for minimum protection in Tables 1 and 2. These are detailed in BS , and include issues such as the type and placement of alarm and battery lifetime. Where occupants or property are considered to be at high risk, these recommendations may not be sufficient and a risk assessment should be carried out. Houses in multiple occupation For the purposes of fire safety, HMOs can be defined as dwellings in which three or more unrelated persons live, who do not form a single household. The minimum levels of protection for HMOs are outlined below (Table 3). Reducing nuisance alarms in larger HMOs In larger HMOs, a mixed alarm system one with a mixture of system grades for different needs, such as Grade D systems in individual dwelling units with a Grade A system in communal areas is recommended. This is because many nuisance alarms can result from several households undertaking activities such as cooking, which can disrupt all occupants of a HMO if a simpler single-grade system is used. The result can be that occupants disable or ignore alarms, and therefore jeopardise their own safety. An example of a mixed system that could meet the needs of a large HMO is a Category L3 system recommended by BS (Fire detection and fire alarm systems for buildings Code of practice for system design, installation, commissioning and maintenance) [16]. This includes interlinked smoke detectors in the communal escape routes, and smoke, heat or CO detectors in the adjoining rooms. In addition, the individual dwelling units will be protected with stand-alone smoke alarm

6 6 DOMESTIC SMOKE ALARMS DG 525 Table 1: Minimum fire protection by grade and category of fire alarm system for dwellings with no floor greater than 200 m 2 in area Class of building Owner-occupied bungalow, flat or other one-storey dwelling Rented bungalow, flat or other one-storey dwelling Owner-occupied maisonette or two-storey dwelling Rented maisonette or two-storey dwelling New dwelling Existing dwelling meeting Existing dwelling not meeting Grade Category Grade Category Grade Category D LD2 F LD3 D LD2 D LD2 F LD3 D LD2 D LD2 F LD3 D LD2 D LD2 D LD3 D LD2 Three-storey dwelling D LD2 D LD3 D LD2 Four- or more storey dwelling B LD2 D LD2 B LD2 Table 2: Minimum fire protection by grade and category of fire alarm system for dwellings with one or more floors greater than 200 m 2 in area Class of building Bungalow, flat or other one-storey dwelling New dwelling Existing dwelling meeting Existing dwelling not meeting Grade Category Grade Category Grade Category D LD2 D LD3 D LD2 Maisonette or two-storey dwelling B LD2 B LD2 B LD2 Three- or more storey dwelling Grade A, Category LD2 system with detectors sited as per BS for a Category L2 system Table 3: Minimum fire protection by grade and category of fire alarm system for HMOs Class of building One- or two-storey HMO with no floor greater than 200 m 2 in area New dwelling Existing dwelling meeting Existing dwelling not meeting Grade Category Grade Category Grade Category D LD2 D LD3 D LD2 All other HMOs Individual dwelling units D LD2 D LD3 D LD2 Communal areas Grade A, Category LD2 system with detectors sited as per BS for a Category L2 system systems in each self-contained unit. Such a system would provide a warning to residents of the HMO before the escape routes become smoke filled, but would reduce the number of nuisance alarms. There are other solutions for reducing nuisance alarms, such as systems with a short delay (typically no more than two minutes) in triggering the smoke alarms in dwelling units other than that in which the alarm was initiated. This enables the occupier to investigate and reset the smoke alarm if there is no cause for concern. In most HMOs, it is appropriate to include manual call points in the fire detection and alarm system. Responsibility Responsibility for fire safety in a HMO is considered under the Management of Houses in Multiple Occupation Regulations 2006 [18]. Under these regulations, the manager of the HMO is responsible for ensuring that fire alarms and equipment are maintained in good order. However, in a mixed system the occupiers of each unit may be responsible for maintaining the smoke alarms within their own dwelling unit and should be made aware of this responsibility even though a separate system is installed to protect escape routes. Detailed guidance on meeting fire safety requirements for different types of HMO and shared housing can be found in LACORS Housing: fire safety [19]. INSTALLATION AND SITING The correct installation of a fire detection and alarm system is extremely important for its effective performance in practice. The system must be installed in accordance with manufacturers instructions, and be properly sited. To ensure this, it is recommended that systems are designed and installed by third-party-certificated contractors, such as those approved to LPS 1014 (Requirements for certificated fire detection and alarm system firms) [20]. Manufacturers instructions for securing alarms to ceilings or walls, which typically requires mechanical fixings, should be followed. Deviation from these can

7 DOMESTIC SMOKE ALARMS DG result in failure in situ of the devices, or in them falling from a height causing a safety risk to building occupants and possible damage to the device. Such damage may lead to problems that include overheating batteries, false alarms, exposed electrical connections and fire detection failures. Siting of alarms Nuisance alarms can result from poor smoke alarm siting, which may induce occupants to remove batteries or damage the devices. In the UK in 2008, 39% of the battery-powered smoke alarms that failed to trigger during a fire did so because of a missing battery or some other act to disable the smoke alarm [3]. BS recommends that smoke and heat alarms be ceiling mounted where possible, at least 300 mm from walls or light fittings. In circulation spaces, no point should be more than 7.5 m from a smoke alarm, and there should be at least one smoke alarm in every hallway and corridor. No bedroom door should be more than 3 m from a smoke alarm, and there should be a smoke alarm between each bedroom and every other room (other than bathrooms, toilets and shower rooms). For Category LD1 or LD2 systems, no point in a room that is being protected should be more than 7.5 m from an alarm. More detailed guidance is included in BS Audibility requirements BS recommends that a smoke alarm sounder should provide at least 85 db at the door of each bedroom unless there is an alarm or sounder within the bedroom if there is a fire anywhere in the dwelling. For some HMOs in which high levels of background noise or other factors mean that greater audibility is required, a sound level of 75 db at the bedhead is advised. BS notes that, in practice, this is unlikely to be accomplished without a sounder or alarm within the bedroom. MAINTENANCE Poor smoke alarm maintenance can result in the increased frequency of nuisance alarms or in smoke alarm failure during a fire. Routine testing should be undertaken weekly to ensure that no major failure has occurred, as recommended by fire and rescue services throughout the UK. Grade A systems should be tested as recommended by BS All other systems should be tested by operating every alarm in the building. With smoke or heat alarms, this can be done by operating the test button on each device. If the building has been unoccupied for a period in which power could have failed, the system should be tested on reoccupation of the dwelling. Recently developed handheld remote programming and testing tools can be used to test smoke alarms, allowing testing to be undertaken on alarms that are difficult to reach or by people who are less mobile. Grade A, B and C systems should be serviced at least every six months, as recommended in BS , and in accordance with the installer s or manufacturer s instructions as appropriate. It is recommended, particularly for Grade A systems, that this is undertaken by a third-party-approved contractor with specialist knowledge of fire detection and alarm systems, such as those approved to LPS Smoke alarms in Grade D, E and F systems should be cleaned in accordance with the manufacturer s instructions at regular intervals, often six-monthly. The build-up of dust and other background particles in the optical or ionisation chamber can make the detector more sensitive, and therefore more prone to false alarms [21]. Alternatively, dust build-up can block up the entry paths for smoke into the detector, making it less sensitive and less likely to react to a fire. If experience shows that the build-up of dust is likely to affect the performance of the device, cleaning should be undertaken more frequently. A recent innovation drift compensation uses microprocessors to monitor slow changes in background particulates, and adjust the sensitivity of the smoke alarm accordingly. Smoke alarms using standard 9V batteries should have replacement batteries on at least a yearly basis, and smoke alarms should be replaced after 10 years of use. SUMMARY The widespread use of domestic smoke alarms has done much to improve fire safety in UK homes. But while new technologies are delivering more reliable smoke alarms systems, the correct specification, installation and maintenance of alarms remains vital to ensuring that they perform properly. The two commonly used types of smoke alarm employ either ionisation or optical smoke detectors to give early, and sometimes life-saving, warning of fire. BS , a key source of guidance on the use of domestic smoke detectors, recommends that the choice of smoke alarm should consider both the likely type of fire (flaming or smouldering) and the need to avoid false or nuisance alarms. The use of smoke alarm products and installers with third-party certification is recommended. Product manufacturers and installers that comply with thirdparty-certification schemes, such as those operated by the LPCB, are subject to independent and ongoing assessment in order to ensure the consistency of product and performance. Grades of alarm system and categories of protection required are defined by BS , and can be used to simply and clearly specify effective alarms systems (eg Grade D, Category LD2). BS also provides recommendations on the minimum grade and category needed to protect different types of housing, including houses in multiple occupation. To ensure that they work well and that nuisance alarms are minimised, smoke alarms must be located and installed correctly; they must be regularly tested and cleaned, and the reliability of their power sources ensured.

8 8 DOMESTIC SMOKE ALARMS DG 525 REFERENCES * 1 Department for Communities and Local Government (DCLG). Fire statistics monitor. Issue 02/11. London, DCLG, 24 June Department for Communities and Local Government (DCLG). The Building Regulations Approved Document B: Fire safety. Volume 1: Dwellinghouses; Volume 2: Buildings other than dwellinghouses (2006 edn). London, DCLG, Department for Communities and Local Government (DCLG). Fire statistics, United Kingdom London, DCLG, BSI. Fire detection and fire alarm systems for buildings Code of practice for the design, installation and maintenance of fire detection and fire alarm systems in dwellings. BS :2004. London, BSI, BSI. Smoke alarm devices. BS EN 14604:2005. London, BSI, Scottish Government Building Standards Division. The Building (Scotland) Amendment Regulations Domestic Technical Handbook. Section 2: Fire (2011 edn). Edinburgh, Scottish Government, Department of Finance and Personnel Northern Ireland. The Building Regulations (Northern Ireland) Technical Booklet E: Fire safety (2005 edn). Belfast, TSO, Department of the Environment, Heritage and Local Government. Building Regulations (Republic of Ireland) Technical Guidance Document Part B: Fire safety (2006 edn). Dublin, TSO, The Housing Health and Safety Rating System (England) Regulations SI London, TSO, The Housing Act Chapter 34. London, TSO, Regulatory Reform (Fire Safety) Order SI London, TSO, Fleming J M. Photoelectric vs. ionization detectors: a review of the literature. Proceedings of the Fire Suppression and Detection Research Application Symposium, National Fire Protection Research Foundation, Orlando, FL, February Available at: 13 National Institute of Standards and Technology (NIST). Performance of home smoke alarms. NIST Technical Note Washington, DC, NIST, December 2007 revision. 14 BSI. Fire detection and fire alarm systems Control and indicating equipment. BS EN 54-2: A1:2006. London, BSI, BSI. Fire detection and fire alarm systems Power supply equipment. BS EN 54-4:1998. London, BSI, BSI. Fire detection and fire alarm systems for buildings Code of practice for system design, installation, commissioning and maintenance. BS :2002. London, BSI, BSI. Fire precautions in the design, construction and use of buildings Code of practice for residential buildings. BS :1990. London, BSI, The Management of Houses in Multiple Occupation (England) Regulations SI 372. London, TSO, Local Authorities Coordinators of Regulatory Services (LACORS). Housing: fire safety. Guidance on fire safety provisions for certain types of existing housing. London, LACORS, Loss Prevention Certification Board (LPCB). Requirements for certificated fire detection and alarm system firms. LPS Watford, BRE Global, Available at: 21 Dziekan M. Where there s smoke there s (not always) fire: an inside look at smoke detectors. The Citizen Scientist, 23 July Available at: weeklyissues/ /feature1/index.html. Acknowledgements The preparation and publication of this Digest was funded by BRE Trust. The author also wishes to thank FireAngel (Figures 1 and 3) and Apollo Fire Detectors (Figures 2 and 4) for supplying the images used in this Digest. * All URLs accessed May The publisher accepts no responsibility for the persistence or accuracy of URLs referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. BRE is the UK s leading centre of expertise on the built environment, construction, energy use in buildings, fire prevention and control, and risk management. BRE is a part of the BRE Group, a world leading research, consultancy, training, testing and certification organisation, delivering sustainability and innovation across the built environment and beyond. 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