The Crime Prevention Website


In the UK about 30% of homes have some kind of domestic alarm system; some of whom pay monthly or annually for their alarm system to be monitored by a third party. One of the biggest growth areas for home security in 2016 is the (DIY) Smart Home Security System. Thousands of people are purchasing these systems instead of the more traditional professionally installed alarm system. 

They seem attractive for a number of reasons which may include: 

  • Making optimal use of the dwelling’s existing internet connection (it’s already there so why not make the most use of it)
  • Ease of installation, more often DIY, although some professional alarm companies are installing them
  • Opportunity to greatly extend the system bit-by-bit and therefore affordably to include devices such as internal and external cameras, some of which have the ability for two-way conversation
  • Low starting installation costs, although extending the systems can soon start adding to the initial starting price
  • None, or very low ongoing costs to the user. The user may have to pay an annual subscription to access images off the Cloud or pay for a SIM 

There are some disadvantages which may include: 

  • The inability to obtain automatic police response to an alarm activation due to the system not meeting the relevant British and or European security standards required by the police or because it is a self-installed system. Some smart home security systems that are installed professionally will meet with police requirements
  • A lack of reliability of the technology, such as software glitches, non-compatibility issues, connectivity issues, radio or electrical interference (search internet for evidence of this)
  • False alarms due to the poor locating and or installation of the various devices by the self-installer
  • A potential failure of the system to send alert messages if internet connection is lost
  • A potential failure of the system to operate if mains power is lost (Backup batteries are supplied with most starter kits, but not all)

The Components of a Smart Home Security System (SHSS) 

The Hub

Mains powered

Smart Home Security Systems (SHSSs) comprise a number of detection devices (powered by BATTERY or MAINS), which are connected to a hub (sometimes referred to as a ‘gateway’). 

It is through the hub that the whole system is controlled via a user interface which could be a wall-mounted terminal (key pad), mobile phone software, a tablet computer, or a web interface. Simple arming and disarming can also be achieved using control fobs, which most manufacturers provide. 

Activation of the various sensors will be signalled to the hub and the hub will carry out the programmed task, which could be to sound the alarm, send a message to the user or switch on a device (normally one plugged into a smart plug outlet) or a combination of these tasks, depending on the product’s specifications and the chosen settings. 

The number of detection devices that can be connected to the hub will vary with manufacturer and vary greatly from as few as 20 to as many as 200. Whilst 200 might sound impressive it is unlikely that most homes would require as many and even then there are limits based on the type of detector. For example, movement detectors and CCTV cameras would use up more of the hub’s capacity than door contacts. 

The effective range of the hub where a clear signal from the various detection devices can be detected will vary from system to system, but some system manufacturers supply mains operated (with battery backup) repeater relay transmission devices enabling the user to extend the system to cover garden outbuildings for example.  

Most hubs contain an internal siren, although the loudness of the siren, expressed in Decibels (Db) varies considerably across makes. Many systems give you the option of connecting up an independent internal siren, which tend to be louder.

Wireless Signal Relay Transmission Device

Mains powered

Used to extend the range of the your SHSS. These ‘repeater’ devices are ideal for larger sites where you are protecting outbuildings and in buildings where the signals may be disrupted by metal structures, e.g. steel walls and metal reinforcement in concrete walls.

Detection Devices

The variety of detection devices (described below) that you can use with your chosen SHSS differs greatly from system to system. Bear in mind too that your Smart Home System can be used for other purposes, such as for communication, remote control of appliances and environmental control.

Movement Sensors (PIRs)

Battery powered

This sensor usually uses a passive infrared detector (PIR).  These devices can be used to activate an alarm or switch on a light or other device (via the hub) when motion is sensed.  Some devices are ‘pet-friendly’ insomuch as they are designed to ignore smaller moving bodies of heat usually expressed in kilograms. Using one of these devices will mean that you lose out on some sensitivity. For example, one company produces a pet-friendly detector that will ignore pets up to 36KG (more than 5 ½ Stone), which is a very big dog, but could also be a 10-year-old child working with an adult burglar.  

Movement sensors (PIRs) tend to be located into the corner of a room to maximise the field of view of the detector. Bear in mind that the detector is receiving information from its surroundings rather than sending information out. The detection pattern is not unlike the fingers and thumb of several fanned out hands, one on top of the other and hinged from the wrist. The detector is looking for the movement and change of heat across its fingers of detection against the background ambient temperature of the room. They are more sensitive to movement across the detectors’ field of view than towards it.

Movement Sensors (PIRs) Ceiling mounted

Battery powered

As the name suggests this device is usually fitted to the centre of a ceiling and has a 360° field of detection

Movement Sensors (PIRs) Curtain

Battery powered

This detector is similar to the ones described above, but its detection area is in the form of a narrow beam that creates an invisible ‘curtain’ across the protected area. This device is sometimes used to cover the underside of a skylight or maybe a patio door. Any movement through the ‘curtain’ will trigger the alarm or activate whatever the user has selected (depending on the system’s available settings).

Door and Window Contacts

Battery powered 

These are similar to the contacts you would have with a more traditional alarm. It is a two-piece magnetic switch that will trigger an alarm (or other device) when the two parts are moved apart. Some of the smart contacts include sensors that can also monitor vibration and temperature. They can be used on doors (usually towards the top of the door to avoid accidental damage), windows and cupboards; anything really that opens like a door or window. If your dwelling is next to a railway line, a very busy road with HGVs passing by or under the flight path of an airport this might be a problem if your contact contains a vibration detector. A period of testing may be sensible.

Glass Break Sensors

Battery powered

These acoustic sensors are useful for homes with large areas of glass, such as patio doors and conservatories. The best ones work by ‘listening out’ for an initial impact and then the noise generated by breaking glass. This ‘double detection’ (dual technology) will reduce the chance of false alarms. Manufacturers test them on various types of glass and so should work on plate (float), laminated, toughened and wired. These detectors are rather different to the volumetric types (PIRs) in that they detect the initial intrusion of the thief while the thief is still outside the building trying to get in.

Vibration Sensors

Battery powered

As the name suggests these devices detect vibrations. They are often adjustable and are normally used on solid objects such as safes and drawers and in places where a more conventional door/window contact is unsuitable. Once again, it may be sensible to test these devices, especially if you live nextdoor to a railway line or very busy road.

CCTV Cameras

CCTV (Video) Camera

Mains or battery powered

Most, but not all SHSS starter kits are supplied with a camera, either video or snap shot. Most are mains powered with backup battery, but some rely on battery power only. If this is something that interests you then you must study the specifications in detail as there is a great deal of variance.  Normally the camera is triggered by the in-built passive infrared detector. Most have a night vision mode where recordings will be in black and white and some will have a built-in microphone and speaker enabling you to speak to another person who is in the dwelling or an intruder (via your phone). They tend to record a wide field of view (from 110° to 128°) and so if you are after evidential quality images (See below) then the location of the camera will have to be carefully considered. In some cameras the video or images are stored on an SD card inside the camera, but in other cases the video is stored externally, such as on the Cloud.  In some cases you may have to pay an annual subscription to access historical images on the Cloud. If the image is stored on an SD card and nowhere else then the camera/SD card could be stolen.

CCTV Snap Shot Camera

Battery powered (possibly mains) 

Some SHSS starter kits are supplied with a snap shot camera, which is generally cheaper than video. It could be argued that camera location for a snap shot camera is even more important as the majority of these cameras only take a limited number of shots.  These are also activated by an in-built passive infrared detector although some may be activated by the tripping of other detectors if the programming allows, which could be case for video cameras also.

External CCTV Cameras

Mains or battery powered

Either fixed, pan and tilt and or zoom and often fitted with an in-built microphone and speaker. These will be weather resistant and controllable via your mobile phone or tablet. Allows you to talk to a caller at the front door (if that’s where you’ve located the camera) and with a pan, tilt and zoom function allows you to ‘follow’ an intruder once an alarm has been triggered using your mobile device. Check the weathertightness specifications of the cameras and, if possible, try to locate them in sheltered positions.

Covert CCTV Cameras

Mains or battery powered

I’ve have thus far not found any covert/disguised cameras supplied with the SHSSs I have looked at.

Other Security Devices

Smart Power Outlets

Mains Powered

These are adaptors that plug directly into a power socket into which you can plug appliances such as table lamps or maybe even coffee makers! These devices allow you to turn lights on and off around the dwelling when you are not there. They are often programmable allowing you to use them just like a timer switch.

Smart Fobs 

Battery powered

These small devices can be attached to a key ring, dog collar, child’s school bag etc and are simply used to sound an alarm (usually on your phone) should the fob be detected as moving into or out of the range of the hub. Look out for the operating temperature for these devices as some won’t work under 5°C.

Panic Buttons 

Battery powered

As the name suggests this device is a simple panic button with which to set off the alarm. They are usually located in the bedrooms of the house and by the front door. The ‘best’ types are those that have the button recessed into the body of the device to reduce accidental activation.

Various Smart Light Bulbs

Mains powered

These are bulbs (more correctly ‘lamps’), which are directly connected to the hub allowing you to turn them on and off from your phone (providing the wall switch has been switched on).

Smart Door Locks

Battery powered

There is a growing availability of these types of smart locks with at least one that is approved by the police Secured by Design project. Some can be used in conjunction with a multipoint lock and others are replacements for mortice locks and rim nightlatches. It is important to tell your insurer if you have a smart door lock as they may have their own security requirements. For an example of a smart door lock please see those manufactured by Yale*.


Internal Siren 

Battery powered

Although most hubs have an internal siren they tend not to be loud and therefore many manufacturers offer a much louder (deafening) internal siren as an optional extra. Unlike some of the hubs that are free standing these will be screwed into the wall or ceiling and so can’t be thrown into a sink of water quite so easily. If using one it is recommended that it is installed at the top of a high internal wall or on a high ceiling so that attack is less likely. The sound output of these internal sirens tend to be in the region of 110Db to 120Db

External Siren (alarm box)

Battery powered

Most SHSSs provide external sirens, but normally as an optional extra. This website recommends an external siren for the reasons described below. The sirens’ sound outputs are usually around the 110Db mark; loud enough to be heard by all the nearby neighbours. Many have strobe lights that flash when the alarm is triggered and some have permanently operating lights in order to bring the siren’s presence to the notice of the potential thief.

External Decoy Siren (dummy alarm box)

Battery powered or no power

If your chosen SHSS provides dummy sirens as an optional extra then do purchase one for use on a rear or side wall of the dwelling. Some have permanently operating lights in order to bring the siren’s presence (and a potential alarm system) to the notice of the potential thief. Obviously some people will simply put up dummy alarm boxes on their external walls in the hope that their presence alone will deter the burglar.

Setting and unsetting devices

Key Pad

Battery powered

This device, which may be part of a basic starter kit, but is normally offered as an optional extra, is similar to the key pad you would have with a traditional alarm system. It allows you to arm and disarm the system using a PIN and part set the system. ‘Part set’ in this context means the ability to set part of the alarm system at night. For example, you could programme external devices, such as door and window contacts or external cameras to be operative, but not the internal cameras or movement sensors allowing you to walk around the inside of the alarmed house at night. You can also use key pads at the various entrances to the dwelling allowing you to enter from the back or side door rather than the normal entry/exit route through the front door. Some of the key pads also have a panic button.

Operating Fobs

Battery powered

These small devices provide an alternative means of arming and disarming the alarm and will be familiar with people who have a traditional wire-free alarm system. The device usually includes a panic button so that the alarm and its siren can be activated if you are in trouble right outside your home - by the car for example.

RFID Arming/Disarming Proximity Tag

Battery powered 

Some SHSSs supply proximity tags that enable you to arm and or disarm the alarm system by swiping the device across the hub or key pad. Some will also automatically unlock an electronic door lock, which could be on your front door; a feature you might want to turn off in certain circumstances.

Other useful devices

Smoke Detectors

Battery powered

In most cases, when this device detects smoke, it will make a sound at the unit just as a conventional smoke detector, but will also send an alarm signal to the hub/control panel. Invariably this will result in the activation of all connected sirens and you will be sent a message to your smartphone.

Water Detectors

Battery powered

These detectors are designed to alert the user when water is detected and are therefore particularly useful for properties that have a high risk of flood. They can also be used in places where there is stored water, such as close to boilers and water cylinders.

Smart Thermostats

Mains or battery powered

Various devices used to remotely control the heating of your dwelling via your smartphone.

Some Considerations before Purchase

Check that your chosen system’s backup battery has a sufficient operating life. 

If there is a power cut while you are away, perhaps on holiday, you will need your SHSS to keep operating. Fortunately most SHSSs include a backup battery in the hub enabling them to operate during a power outage.  A reasonable expectation for the battery backup is 12 hours as most power cuts are usually resolved within that time period. However, if the power cut continues or there is a fault on your electrical system while you are away or there has been a surge (often associated with a thunderstorm) it is possible that some trips switches may have been fired leaving you with no power to some or all of your electrical circuits.  This would cause problems for both a traditional alarm and a SHSS and is the reason why you should always have at least two keyholders on hand to deal with such problems as they arise. 

Most SHSSs will send you messages warning the user of low battery levels and loss of mains power enabling you to take some action, such as calling your keyholder if you are away. 

Most of the individual detection units, such as the door and window contacts and passive infrared detectors will continue to operate normally during a power cut as they are powered by batteries anyway. However, some mains operated cameras will stop working during a power cut as will a few of the mains operated hubs unless you have purchased a separate backup battery pack. There are some SHSS that do not have a backup battery in the hub and so have to be bought in addition to the basic starter packages.

Will your chosen system still be able to signal a problem/intrusion if the internet connection is lost? 

Some SHSSs have the ability to send alert messages to your mobile phone via the mobile phone network if you lose your connection to the internet. There will be a small annual fee to pay for the SIM card. Although the loss of internet connection for long periods of time is unusual it does happen as in this recent example in 2016 

.....Whilst work was being carried out by Network Rail in the early hours of Wednesday October 19, cables used by a number of internet providers were damaged, leaving residents across West Drayton and Uxbridge (West London) without internet. 

A Network Rail spokesperson said  “While work was taking place in the early hours of Wednesday morning we damaged cables which are used by a number of different communications providers. The cables were not highlighted in the thorough surveys we carried out prior to the work." 

The connection was restored after six days on Tuesday 25th October.

Is your chosen system supplied with external alarm sirens and or dummy sirens or are they offered as extras? 

For your SHSS to act as a burglary deterrent and dissuade criminals from breaking in the potential burglar needs to know that a SHSS is in use. This is best achieved by fitting bright siren (alarm) boxes onto the external walls of the dwelling. It is preferable that the alarm box carries the name of the manufacturer of the system. At the very least the system should be supplied with stickers/decals that can be displayed on doors/windows at likely entry points. 

With one or two exceptions basic starter SHSS kits rarely include external sirens or dummy sirens. Therefore, before you purchase, make sure sirens are offered as optional extras. Follow the practice of the traditional alarm industry and (subject to the type of dwelling) install the sounding siren to the front elevation of the property and the dummy siren to the rear. If stickers/decals are supplied; use them. 

There is no evidence to suggest that visible alarm boxes attract thieves – quite the reverse. However, if you have installed an alarm or a SHSS make sure: 

  • You use it on all occasions
  • The physical security of the dwelling is of a high standard or at least meets with the requirements of your insurer’s conditions of cover
  • You practice sensible crime prevention techniques, such as leaving/turning internal and external lights on and off to give the impression your empty dwelling is occupied 

Alarm systems and SHSSs must be seen as just one part of an overall security package; all of which must work together to ensure the risk of crime is as low as it can be reasonably expected to be.

Will your chosen system operate at the temperatures you can expect in the dwelling that is to be protected? 

Always check the specifications of the hub and devices to ensure that they will operate efficiently in the range of temperatures that your dwelling may experience. For example: There are systems where the hub will not work below 0°C. Whilst this is unlikely to be a problem with a dwelling that is normally occupied it may be a problem if that dwelling is unoccupied for most of the year or is, perhaps, a holiday trailer.

Internal CCTV Cameras and Evidential Quality Images 

The Metropolitan Police define two images that are useful for a police investigation: 

Recognition quality: A person's face occupies at least 50% of the screen, the viewer can confirm with high probability that they have seen the person before. 

Identification quality: A person's face occupies at least 100% of the screen height. Picture quality should be good enough that the identity of the person can be established beyond reasonable doubt. 

It is not for me to tell you how to use your internal CCTV cameras as you may have installed the system simply to monitor activity in your occupied or unoccupied house for any number of reasons. However, if it your intention to obtain evidentially useful images then you should consider the following points: 

  • Before purchase think about whether you want your camera to take a series of shots or a period of video. Some cameras may do both via the settings of your system, but you will have to read the specifications of each before making your decision
  • Because your objective is to obtain a facial image of the intruder you will have to work out the direction from which an intruder might come and where he/she might go once they are inside the dwelling. So, ask yourself which are the most likely doors and windows that will be forced open by an intruder and do not dismiss the fact that you may need to purchase an additional camera or cameras in order to achieve your objectives.
  • Bear in mind that one of the main causes of poor recordings of images is overexposure to sunlight or electric light. Wherever possible try to avoid pointing cameras towards doors and windows if the sun shines through them as the image of an intruder may become silhouetted and evidentially useless
  • Most SHSS cameras have a wide field of view to enable general monitoring of a room. There is nothing wrong with this, but if you are trying to obtain an evidential quality image then you may have to try different locations for the camera in order to obtain the best images
  • In some circumstances it would make sense to position a camera close to a place where most burglars will venture, such as the dressing table where jewellery may be kept or, perhaps, the safe. In this instance it would be useful if SHSS manufacturers supplied covert cameras. Unfortunately I have yet to find a SHSS covert camera and so you might want to think about disguising one yourself. 

For a more comprehensive guide to domestic CCTV cameras please see CCTV for Home and Business on this website.

Further Information 

The Consumers' Association 

The Consumers’ Association’s Which? Magazine featured Smart Home Security Systems in their January 2017 issue. With my assistance Which? tested and evaluated several starter kits and the results of these findings are presented in this magazine. 

Smart Home Security Systems was also featured on the Which? website in late December 2016. 

In order to receive the magazine or read the website feature in full you will have to subscribe to Which? (Link above) 

* The inclusion of Yale’s smart door locks is not an indication of this website’s recommendation for these products or sponsorship of this website by Yale.

Updated February 2017