The Gas Interlock System must be CE marked.

A gas interlock system is required to be fitted within every new commercial kitchen which has been built since 2001 or has had any major refurbishment since the release of BS6173:2001.

There are a couple of different ways which a gas interlock system can check that the ventilation is in operation. Firstly, air pressure differential switches can be fitted in the ducting and will physical check for airflow before allowing the gas solenoid valve to open. Alternatively, a more modern method is to use current monitors which will check for a power supply going to the fan and control the gas solenoid valve accordingly. If either at start-up, or during the course of the operation, the fans fail or are turned off the gas solenoid valve will automatically close.

Another aspect of BS6173:2009 is gas pressure proving. The standard states if any of the catering equipment does not have a flame failure device a gas pressure proving system should be installed. A gas pressure proving system will check for any leaks on the pipework or on the appliances at start-up, in the event where a gas leak is detected then this will not allow the gas solenoid valve to open.

The majority of appliances which have been built within the last 10 years should have flame failure devices fitted, however in a kitchen where every appliances does have flame failure devices fitted then gas proving is often still recommended to carry out a gas check on the line and ensure the safety of kitchen staff in the area.

It states gas should not be available within the commercial kitchen if the ventilation is not in operation, and this should be controlled by a gas interlock system. IGEM/UP19 once again states that the gas interlock system can check the ventilation using either air pressure differential switch or current monitors.

IGEM/UP19 does clarify a number of things which are listed in BS6173:2009 however it makes a lot more references to carbon dioxide monitoring within a commercial kitchen. CO2 Monitors should be considered within a commercial kitchen, which hasn’t had any major refurbishment, and there is no gas interlock system is fitted as a means of indicating to staff when the carbon dioxide is increasing and to notify them that they should increase the ventilation within the area.

Also, IGEM/UP19 states that a carbon dioxide monitor should be fitted when there is a variable speed controller to control the ventilation. Where variable speed controllers are fitted the end user has the ability to have all the gas appliances in operation but just trickle the ventilation at a low speed and therefore the CO2 is likely to increase. The CO2 Monitor should alarm at first and second stage, the first stage warning staff at 2800ppm to let them know that they should increase ventilation. In the event where the CO2 continues to rise and the ventilation is not increased, once the CO2 Monitor reaches 5000ppm then (where applicable) the gas solenoid valve shut be closed.

Positioning of the CO2 Monitors within the commercial kitchen is included within DW172 – Edition 2.

DW/172 was revised in January 2018 in order to reflect current legislations and the latest cooking techniques and design of catering equipment, by all sections of the catering industry.

The sections that have been modified and amended are –

• The appliance coefficient schedule has been significantly expanded and modified
• Modification to Grease Separation
• The lighting section has been modernised
• New section for Solid Fuel Equipment
• New section for Demand Controlled Kitchen Ventilation Systems
• Gas Interlocking
• Modifications to Pollution Control
• New Section for Recirculation Systems
• Modifications to Cleaning and Maintenance
• Control Panels

IGEM/UP/11 shows that it is mandatory in science laboratories to have the ability to isolate the gas supply, whether this be by means of a manual valve (ECV) such as a quarter-turn fitted by the entrance to the room, or an automatic isolation valve (gas solenoid valve) linked with an emergency stop button. However, in section 6.2.4 it does state where a gas solenoid valve is installed then a “downstream integrity check) must be included otherwise known as a gas proving test.

A gas pressure proving system will check for any leaks on the pipework or on the benches at start-up, in the event where a gas leak is detected then this will not allow the gas solenoid valve to open. There must be a means of isolation fitted in a “readily accessible position” which most often is by each main exit(s) to the room, so there is a way of shutting off the gas supply in the event of an emergency.

IGEM/UP/11 goes on to discuss the requirements for CO2 and ventilation in a home economics room to ensure the safety of the children and to ensure air quality is at a safe level. For a new installation, where ventilation is installed to extract combustible gases then this should be interlocked by means of air pressure differential switch or current monitor. Where mechanical ventilation is fitted purely for climate control within the room then the need to interlock the ventilation with the gas supply should be analysed by means of a risk assessment.

In the event where the ventilation requirements cannot be met then a carbon dioxide monitor should be installed at seating height (roughly 1.5 metres from floor level). The CO2 monitor should alarm at 2800ppm to notify the teachers or occupants to increase ventilation, where the CO2 levels in the room continue to rise and exceed 5000ppm then the gas supply should be automatically isolated.

Although it is not mentioned within IGEM/UP11, it is very popular in science laboratories to also control the electric and water supply to the benches through the gas proving system.

Building Bulletin 100 states that school plant rooms (where they are part of the main building) should be classed as a high fire risk and therefore recommends the following precautions –

• An emergency knock-off button should be installed at the entrance of the boiler room and connected up to the isolation valve so there is a way of isolating the gas supply in the event of a emergency.
• Heat detectors should be included over each boiler. If the boiler was ever to catch fire, the heat detector would automatically alarm and cause the gas solenoid valve to shut off.
• The gas solenoid valve can be automatically reset in the event of a power failure to reduce the risk of frozen pipework in cold periods, however in the event of a genuine alarm the system must be manually reset to restore the gas supply.
• Gas Detectors are recommended to be connected to a gas detection system, in the event where a gas is detected then this should cause the system to give out an audible alarm and shut off the fuel supply in the boiler room. The most common detectors used are carbon monoxide and natural gas. However, for LPG installations an LPG detector should be considered.

The detectors should be fitted at the following locations –

• Natural Gas – 300mm from the ceiling
• Carbon Monoxide – 1700mm from the floor
• LPG – 300mm from the floor

Building Bulletin 101 discusses both mechanical and natural ventilation within the schools building in great depth, but also makes a number of references to carbon dioxide monitoring. This is based on the need to control carbon dioxide produced by respiration of occupants. In teaching and learning spaces, in the absence of any major pollutants, carbon dioxide is taken to be the key indicator of ventilation performance for the control of indoor air quality.

Carbon dioxide should be measured at seating height and the average concentration should not exceed 1500ppm between the start and end of the day. Building Bulletin 101 states that there should be a carbon dioxide monitor fitted in every learning or teaching space in the school. The CO2 Monitor should give the staff and occupants a visual display of the conditions within the room by means of a traffic light system to notify them if the ventilation should be increased.

The CO2 Monitors can be used to automatically control the ventilation in some situations, but where this is not practical or possible then the monitors can be used just to give indication and then the occupant can act accordingly to reduce the levels of carbon dioxide in the area, for example increasing natural ventilation by means of opening windows and doors etc.

Part F states the below –

1.21 In new buildings, the following types of occupiable room, unless they are rooms of the size described in paragraph 1.22, should have a means of monitoring the indoor air quality. This may be achieved using CO2 monitors or other means of measuring indoor air quality.

1. Occupiable rooms in offices.
2. Occupiable rooms where singing, loud speech or aerobic exercise or other aerosol generating activities are likely to take place. These may include rooms, for example, in gymnasiums, other indoor sports venues, dance studios, theatres, concert halls, public houses, nightclubs, places of assembly, as well as in other types of building.
3. Occupiable rooms where members of the public are likely to gather. These may include rooms, for example, in public buildings, hotels, gymnasiums, indoor sports venues, dance studios, theatres, concert halls, public houses, nightclubs, places of assembly, as well as in other type of building.
4. Occupiable rooms which are maintained at both low temperatures and low levels of humidity. These may include rooms used for chilled food processing and occupied cold stores.

1.22 The guidance in paragraph 1.21 does not apply to the following sizes of room. a. Small spaces up to 125m3 volume, or 50m2 floor area. b. Large spaces over 800m3 in volume, or 320m2 floor area. 1.23 Where CO2 monitors are used, they should meet all of the following.

1. Be non-dispersive infrared (NDIR) type CO2 monitors.
2. Be mains powered.
3. Be placed at breathing height and away from windows, doors or ventilation openings where practicable.
4. Be placed at least 500mm from people where practicable.

Building Bulletin 101 discusses both mechanical and natural ventilation within the schools building in great depth, but also makes a number of references to carbon dioxide monitoring. This is based on the need to control carbon dioxide produced by respiration of occupants. In teaching and learning spaces, in the absence of any major pollutants, carbon dioxide is taken to be the key indicator of ventilation performance for the control of indoor air quality.

As stated in section 2.4, where mechanical ventilation or a hybrid system is used within a teaching space the levels of carbon dioxide over the course of a day should be below an average of 1000ppm and shouldn’t rise above 1500ppm for a continuous period of 20 minutes. However, where only natural ventilation is used then the average should be below 1500ppm and not be allowed to rise above 2000ppm for a continuous period over 20 minutes. Unlike the previous BB101 document, this update makes a number of references to science classrooms and laboratories where gas is used and says that is acceptable for the carbon dioxide levels to rise above the previously listed parameters where an experiment is being carried out or the gas appliances are being used. The carbon dioxide monitor should give an audible and visual alarm at 2800ppm and then be connected to a gas safety system in order to automatically shut off the gas supply when the levels rise above 5000ppm.

In terms of interlocking with the ventilation, in the event where only Type A appliances are used such as Bunsen burners, domestic cookers etc then a CO2 Monitor is only means of interlocking required. However, where any Type B appliances are used, such as kilns, gas fires etc then the gas supply should not be allowed into the area without the ventilation operating and should be monitored using an air pressure differential switch or a current monitor.

Carbon dioxide should be measured at seating height and can also be used to control the ventilation system to regulate the ventilation throughout the day to achieve the levels stated in section 2.4.

Quotes from BB101.

“CO2 levels should be measured at seated head height in all teaching and learning spaces.”

“Where only Type A appliances are used, interlocking may be achieved by environmental monitoring of carbon dioxide as described in IGEM UP 19.”

“When practical activities are not taking place and gas is not in use the ventilation in practical spaces should be controlled to meet the normal CO2 levels for teaching and learning spaces as described in section 2.4.”

“In these practical spaces, higher levels of CO2 are acceptable for the periods of time when Bunsen burners, cookers and other gas-fired appliances are in use as described in section 2.9”

‘All teaching classrooms to have a real-time display monitor that measures the CO2 parts per million (ppm) levels, and temperature (deg C) to alert room occupants when the average concentration of CO2 reaches 1500ppm when measured at 1500mm above floor level.’

To demonstrate compliance with BREEAM WAT 02 requirements:

A water meter is to be supplied to the mains water supply to each building. The water meter should have a pulsed output so the information can be monitored through a BMS (Building Management System.)

For one credit –

• Sub meters are to be fitted to allow the metering of individual water consuming plant or building areas, where demand in such areas will be equal to or greater than 10% of the total water demand of the building.
• Each sub meter has a pulsed output to enable connection to a BMS for the monitoring of water consumption.

BREEAM WAT 03 offers two credits in total both based around major water leak detection & water leak prevention.

For the first credit –

A leak detection system which is capable of detecting a major water leak on the mains water supply within the building and between the building and the utilities water meter.

The leak detection system must have the following features:

• Audible when activated
• Activated when the flow of water passing through the water meter/data logger is at a flow rate above a pre-set maximum for a pre-set period of time.
• Able to identify different flow and therefore leakage rates, e.g. continuous, high and/or low level, over set time periods.

The leak detection system must have the following features:

• Programmable to suit the owner/occupiers’ water consumption criteria
• Where applicable, designed to avoid false alarms caused by normal operation of large water consuming plant such as chillers.

Please note – Where it can be demonstrated that it is not physically possible for a meter to be installed on the pipework, the requirement for leak detection between the building and the utilities meter can be considered not applicable, and the credit awarded based on the leak detection within the building.

So long as the compliant system alerts the appropriate person to the leak so they are able to respond immediately, the assessor can judge if the aim of the issue is being met by a reliable, robust and fail-safe means of notification.

For the second credit – One of the following types of flow control device is fitted to each WC area/facility to ensure water is supplied only when needed

1. A time controller i.e. an automatic time switch device to switch off the water supply after a predetermined interval
2. A volume controller i.e. an automatic control device to turn off the water supply once the maximum pre- set volume is reached.
3. A presence detector and controller i.e. an automatic device detecting occupancy or movement in an area to switch water on and turn it off when the presence is removed.
4. A central control unit i.e. a dedicated computer- based control unit for an overall managed water control system, utilising some or all of the types of control elements listed above.

Please note – The criteria are applicable to the cold water supply only and include cold taps, WCs and urinals. Any solution implemented to achieve compliance with this Issue should effectively mitigate the risk of hot-water scalding in showers, in the event that the cold water supply is shut off.

A shut-off on the cold water supply to the whole WC facility provides a simple and effective way of reducing potential water loss. Taps which contain built in shut-off valves will not prevent any water leaks from the supply to the tap and so do not fulfil this intent.