About CEMS Terminology Logo


Terminology in Continuous emissions monitoring systems and software can be complicated.
Commonly used phrases can be referenced below but contact G2 Data Systems if more help is required.


Term Definition
Analogue Signal Signals which continuously vary in amplitude and frequency and are subject to interference (noise).
A to D Converter Analogue to Digital Converter
Converts an analogue signal into a digital signal.
AMS Automated Measuring System
AST Annual Surveillance Test
Part of the QAL process, this is a manual test every 12 months to ensure that the specific analyser is still reading measurements accurately. Required for BS EN 14181 to determine whether the Continuous Emissions Monitoring System is operating within specification and that the calibration process remains operational.
BAT Best Available Technique
The approach used by the operator to ensure that the environment is protected in a cost effective way.
British Standards Institute (BSI) BSI is appointed by the UK Government as the national standards body (NSB), holds the Royal Charter, and represents UK interests at the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC) and the European Standards Organizations (CEN, CENELEC and ETSI). BSI is the UK's first national standards body to be created.
Calibration Calibration is the process require to check the accuracy of measuring equipment and can also include the adjustment of the instrument back in line with the required guidelines.
CE marked Relates to the CE symbol which shows that the product conforms with the EU environmental protection directives.
CEN The European Committee for Standardisation (CEN).
CEMS Continuous Emission Monitoring System
CEMS continuously collect, record, analyse process and report emissions data to ensure that emissions and other measurements are in line with relevant regulations.
COP Conference of the Parties
The yearly gathering of world leaders for the Climate Change Conference known as the Conference of the Parties (COP) is used to define Global environmental targets and policies. As of 2021, there have been 26 conferences and hence the abbreviated name includes this number (E.g. COP26).
CUSUM Chart Stands for Cumulative SUM (CUSUM) and is used to detect sudden changes in the process.
DAHS Data Acquisition and Handling System
DAHS continuously collect, record, analyse, process and report any measurement data and processes it in line with relevant regulations.
DAS DATA Acquisition System
DAS continuously collect, record and report data to the end user.
Data Mirroring A technique of replicating data to another location in real-time.
Defra Deparment for Environment, Food and Rural Affairs.
Digital Signal Digital signals consist of pulses that can be only two states: 0 (OFF) or 1 (ON).
Dual Redundancy A technique which allows for a copy of a primary system to operate independently. If the primary system stops, the operation continues on the secondary system (copy) until the primary system is back on-line.
EmiDAS G2 Data Systems MCERTS Continuous Emissions Monitoring and Data Aquisition and Handling System.
Emissions Release of substances primarily into the air.
ELV Emission Limit Value
The level of an emission which cannot be exceeded during a specified time period.
EN 14181 Outlines the quality assurance levels that are required to ensure that a Continuous Emission Monitoring System (CEM) is able to meet the uncertainty requirements on measured values. This includes QAL1, QAL2, AST, QAL3.
EN 17255 Stationary source emissions - Data acquisition and handling systems
• Part 1 specifies the requirements for the handling and reporting of data. • Part 2 specifies the requirements on data acquisition and handling systems. • Part 3 will specify the requirements for the performance test of data acquisition and handling systems. • Part 4 will specify the requirements for the installation and on-going quality assurance and quality control of data acquisition and handling systems.
EP Regulations (EPR) Environmental Permitting (England and Wales) Regulations 2010
E-PRTR European Pollutant Release and Transfer Register
EWMA Exponentially Weighted Moving Average
A method of smoothing data incorporating a weighting which will give more weight to the most recent readings in the series.
FLD First Level Data
FTIR Fourier-transform infrared (FTIR)
IED Industrial Emissions Directive (IED 2010\75\EU)
Merges the IPPC, IED, WID, LCPD and titanium dioxide directives into a single directive
IPPC Integrated Pollution Prevention and Control Directive
Includes the regulating of air, land and water, noise, vibration, energy efficiency, waste minimisation, environmental accidents and site protection.
LCPD Large Combustion Plant Directive
Provides legislation to limit emissions from combustion plants with a thermal capacity of 50 MW or greater. For example large power stations, steelworks and petroleum refineries.
LAPPC Local Air Pollution Prevention and Control
Covers regulations under Part B of the EP Regulations.
LA Local Authority
General terms referring to county and borough councils in England and Wales.
LA-IPPC Local Authority Integrated Pollution Prevention & Control
Covers local authority regulations under Part A(2) from the EP Regulations guidelines document.
LTA Long Term Average
MCERTS Monitoring Certification Scheme
A certification provided by SIRA on behalf of the Environment Agency which shows that the certified hardware and software meets the government's environmental requirements for quality.
NDIR sensor Non-Dispersive Infrared Sensors
OPC Open Platform Communications
Part A1 Regulated by the Environment agency, ´Part A1´ refers to Part A (1) of the EP Regulations.
Part A2 Regulated by the Local Authority IPPC, ´Part A2´ refers to Part A (2) of the EP Regulations.
Part B Regulated by the Local Authority PPC, ´Part B´ refers to Part B of the EP Regulations.
PG Process Guidance (PG) Notes are used to help provide guidance on the local authority's emissions to air regulations for specified industries. For example PG 1-12 for Wood-fired Boilers.
QAL Quality Assurance Levels
Generic term for the three Quality Assurance Levels required under BS EN 14181 - QAL1, QAL2, QAL3.
QAL1 Quality Assurance Level 1
Required for BS EN 14181 to show that the Continuous Emissions Monitoring System meets the performance requirements and uncertainty allowances prior to installation.
QAL2 Quality Assurance Level 2
Required for BS EN 14181 to show that the Continuous Emissions Monitoring System meets the performance requirements and uncertainty allowances once installed.
QAL3 Quality Assurance Level 3
Required for BS EN 14181 where zero and span readings are taken to show that the Coninuous Emissions Monitoring System is achieving the correct quality levels during normal operations.
RoHS Restriction of Hazardous Substances Directive
The directive covering the restrictions of the use of specified hazardous substances in electrical and electronic equipment.
SEPA Scottish Environmental Protection Agency
Scotland's government agency responsible for the regulation and enforcement of rules relating to the Scottish environment, pollution, regulation and environmental enterprises.
Shewhart A control chart that indicates that a CEMS is stable and under control (or not). Often used for EN 14181.
SIRA UK based organisation which has been endorsed by the government to assess whether a product meets set standards. This includes the running the MCERTS scheme for the Environment Agency.
SRM Standard Reference Methods
Refers to a set of measures (methods) which define the characteristics of air quality.
SSTA Standardised Short Term Average
STA Short Term Average
TUV Technical Inspection Association
German approvals organisation that validates the safety of products to ensure that humans and the environment are protected against various hazards.
TDL Gas Analysers Tuneable Diode Laser (TDL) Gas Analysers
UEA The UK Environment Agency
Responsible for environmental matters relating to waste, water and air.
US EPA United States Environmental Protection Agency
Federal US Government agency responsible for the protection of human health and the environment.
UV CEMS / UV Gas Analysers Ultraviolet spectroscopy (UV VIS) CEMS Analysers
VSTA Validated Short Term Average
WID Waste Incineration Directive
Directive to minimise the effects of pollution on air, land and water when incinerating waste.