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Is your plant covered?
- 50 MW or more: boilers, gas turbines and engines where the total rated thermal input is 50 MW or more (section 6). It is the fuel input that counts, not the heat output.
- The common stack rule: several plants count as one if the flue gases are discharged, or could be discharged, through a common stack. Units below 15 MW are not included in the sum, but are still covered by the requirements (sections 36 and 38).
- 2013 plant or new: if the plant was put into operation before 7 January 2014 and had a permit or a complete application before 7 January 2013, it is a 2013 plant (the ordinance's term for an existing plant). All others are new and have stricter limit values (sections 8 and 11).
- Excluded are, among others, plants where the flue gases are used directly for drying or heating materials, post-combustion of process gases, coke oven batteries and engines in vehicles and ships. If you burn waste, the rules on waste incineration apply instead (section 15).
- Diesel engines and recovery boilers: the limit values do not apply to stationary diesel engines or to the pulp industry's recovery boilers (section 39).
- The permit and BAT apply at the same time: the ordinance applies on top of the conditions in the permit (section 16), and the BAT conclusions apply in parallel with both through the Swedish Industrial Emissions Ordinance (SFS 2013:250). The strictest requirement governs.
What must be measured, and how often?
The measurement requirements are in sections 21–25 of the ordinance (SFS 2013:252). From 100 MW total rated thermal input the main rule is continuous measurement with automated measuring systems (AMS), below 100 MW periodic measurement. Limit value (begränsningsvärde) is the ordinance's word for emission limit value. The emission checks must follow CEN standards, both the measurements and the quality assurance of the measuring systems (section 26).
| Plant | What is measured | How often | Section |
|---|---|---|---|
| 100 MW or more | SO2, NOx and dust, plus the oxygen content, temperature, pressure and water vapour of the flue gas | Continuously | Sections 21 and 23 |
| 100 MW or more, gaseous fuel | CO as well | Continuously | Section 22 |
| Automated measuring systems (AMS) | Checked by parallel measurements with reference methods | At least once every year (AST). Calibration (QAL2) at least every five years according to EN 14181 | Section 27, EN 14181 |
| Below 100 MW | SO2, NOx and dust | Periodic measurement at least once every six months | Section 24 |
| Below 100 MW, gaseous fuel | CO as well | At least once every six months | Section 24 |
| Hard coal or lignite, all sizes | Total mercury | At least once every year | Section 24 |
| Few operating hours, periodic measurement | SO2, NOx, dust and CO | The measurement may wait until the plant has run 700 operating hours since the last one, but never longer than one year | Section 24, second paragraph |
| Exemptions from continuous measurement | SO2 and dust with natural gas; SO2 with oil of known sulphur content without desulphurisation, or with biomass if the value can never be exceeded; plants with fewer than 10,000 operating hours left | Periodic measurement under section 24 instead | Sections 21 and 22 |
The supervisory authority may grant an exemption from the periodic measurement of SO2 and NOx if the emissions are checked in an equivalent way according to a standard, for example by analysing the sulphur content of the fuel, according to the Swedish Environmental Protection Agency (Naturvårdsverket) (section 25). No exemption can be granted for dust, CO or mercury. Water vapour does not need to be measured continuously if the sample gas is dried before analysis (section 23). Where the measurement points are to be placed is decided in the permit or by the supervisory authority on your proposal (sections 34–35).
Measurement requirements under the BAT conclusions (BAT 4)
If the plant is covered by the BAT conclusions (EU) 2021/2326, the monitoring in BAT 4 applies too: at least the frequency stated, according to EN standards. For continuous measurement that means EN 14181 and EN 15267. According to the Swedish EPA, BAT 4 must be met, but another form of check can be accepted if it gives at least the same level of environmental protection.
| Parameter | Fuel or technique | Minimum frequency | Standard under BAT 4 |
|---|---|---|---|
| NOx, CO and SO2 | Solid biomass and peat, coal, oil, natural gas | Continuously. Below 100 MW and below 1,500 operating hours per year: at least once every six months | Generic EN standards, for SO2 also EN 14791 |
| NH3 | When SCR or SNCR is used | Continuously. With SCR at least once a year if the levels have proved stable | Generic EN standards |
| HCl | Solid biomass and peat | Continuously, or at least every six months if the levels have proved stable. Below 100 MW every six months is enough at 500–1,500 operating hours per year, and once a year below 500 | Generic EN standards |
| HF | Solid biomass and peat | Once a year | No EN standard available |
| HCl, HF and mercury (Hg) | Hard coal and lignite | Every three months, or at least once a year if the levels have proved stable. Mercury continuously from 300 MW | EN 1911 · EN 13211 · EN 14884 |
| Dust | Solid biomass and peat, coal, oil | Continuously | Generic EN standards plus EN 13284-1 and EN 13284-2 |
| Metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Tl, V, Zn) | Solid biomass and peat, coal, oil | Once a year. The list and the frequency can be adapted after an initial characterisation of the fuel | EN 14385 |
| Mercury (Hg) | Solid biomass and peat | Once a year. That is enough at a change of fuel if the levels are stable thanks to a low mercury content in the fuel | EN 13211 |
| N2O | Circulating fluidised bed boilers firing coal, biomass or peat | Once a year, with one measurement series above and one below 70 % load | EN 21258 |
The generic EN standards for continuous measurement are EN 15267-1, -2 and -3 and EN 14181. The frequency does not apply if the plant is run solely to make the measurement possible. Periodic measurements on gas turbines are made at loads above 70 %. At co-incineration of waste, the measurement requirements in the rules on waste incineration apply too.
Which limit values apply under the ordinance?
The limit values are in sections 44–73. They are given in mg/Nm3 dry gas at 6 % O2 for solid fuels and 3 % O2 for liquid fuels in boilers (section 40). The total rated thermal input, the combined input under the common stack rule, decides the value for every boiler included (sections 37 and 38). At continuous measurement, validated monthly, daily and hourly averages are compared with the value (section 41), at periodic measurement every measurement series (section 43). The value for 2013 plants comes first and the value for new plants after the slash. The permit can set stricter requirements, and the wording of the ordinance is what applies.
| Fuel and total rated thermal input | SO2 | NOx | Dust |
|---|---|---|---|
| Biomass, 50–100 MW | 200 / 200 | 300 / 250 | 30 / 20 |
| Biomass, more than 100 to 300 MW | 200 / 200 | 250 / 200 | 20 / 20 |
| Biomass, more than 300 MW | 200 / 150 | 200 / 150 | 20 / 20 |
| Peat, 50–100 MW | 300 / 300 | 300 / 250 | 30 / 20 |
| Peat, more than 100 to 300 MW | 300 / 300 (250 in a fluidised bed) | 250 / 200 | 20 / 20 |
| Peat, more than 300 MW | 200 / 150 (200 in a fluidised bed) | 200 / 150 | 20 / 20 |
| Coal and other solid fuel, 50–100 MW | 400 / 400 | 300 / 300 | 30 / 20 |
| Coal and other solid fuel, more than 100 to 300 MW | 250 / 200 | 200 / 200 | 25 / 20 |
| Coal and other solid fuel, more than 300 MW | 200 / 150 (200 in a circulating or pressurised bed) | 200 / 150 | 20 / 10 |
| Liquid fuel, 50–100 MW | 350 / 350 | 450 / 300 | 30 / 20 |
| Liquid fuel, more than 100 to 300 MW | 250 / 200 | 200 / 150 | 25 / 20 |
| Liquid fuel, more than 300 MW | 200 / 150 | 150 / 100 | 20 / 10 |
Pulverised firing of lignite has higher NOx values (sections 56 and 64). If several fuels are fired at the same time, a fuel-weighted value applies (sections 74–79). 2002 plants, with a permit before 27 November 2002, that run at most 1,500 hours per year have higher values for SO2 and NOx (sections 48 and 59). Refinery fuels and plants that are rebuilt or extended have their own rules (sections 58, 69 and 80–81). Limit values for CO exist only for gaseous fuels.
BAT-AELs for solid biomass and peat
Plants covered by the BAT conclusions (EU) 2021/2326 must also meet the BAT-AELs for their fuel. They apply as limit values during normal operation under chapter 1, section 8 of the Swedish Industrial Emissions Ordinance (SFS 2013:250), for existing plants since 17 August 2021, and it is the upper value of the range that may not be exceeded. The values are given in mg/Nm3 at 6 % O2, as the yearly average and the daily average of valid hourly averages at continuous measurement, or as the average of three measurements of at least 30 minutes at periodic measurement. Both averages must be met. New plant here means that the first permit was granted after 17 August 2017, or that the plant has since then completely replaced an earlier one on the same site. The values apply to solid biomass and peat (BAT 24–27 and BAT 7).
| Parameter and averaging period | 50–100 MW | 100–300 MW | 300 MW and more |
|---|---|---|---|
| NOx, yearly | 70–225 (new 70–150) | 50–180 (new 50–140) | 40–150 (new 40–140) |
| NOx, daily | 120–275 (new 120–200) | 100–220 (new 100–200) | 95–165 (new 65–150) |
| SO2, yearly | 15–100 (new 15–70) | < 10–70 (new < 10–50) | < 10–50 (new < 10–35) |
| SO2, daily | 30–215 (new 30–175) | < 20–175 (new < 20–85) | < 20–85 (new < 20–70) |
| HCl, yearly | 1–15 (new 1–7) | 1–9 (new 1–5) | 1–5 |
| HCl, daily | 1–35 (new 1–12) | 1–12 | 1–12 |
| HF, sampling period | < 1.5 (new < 1) | < 1 | < 1 |
| Dust, yearly | 2–15 (new 2–5) | 2–12 (new 2–5) | 2–10 (new 2–5) |
| Dust, daily | 2–22 (new 2–10) | 2–18 (new 2–10) | 2–16 (new 2–10) |
| Mercury, sampling period | < 1–5 µg/Nm3 | < 1–5 µg/Nm3 | < 1–5 µg/Nm3 |
| NH3 with SCR or SNCR, yearly or sampling period | < 3–10 (15 at varying load) | < 3–10 (15 at varying load) | < 3–10 (15 at varying load) |
The size classes mean at least the lower and below the higher value; the ordinance's classes run up to and including 100 and 300 MW. The yearly values do not apply to plants that run below 1,500 hours per year, and below 500 hours the daily values are only indicative. Higher upper values apply for NOx with fuels containing at least 2,000 mg/kg potassium or 300 mg/kg sodium (200–310 depending on the class), for SO2 in existing plants from 100 MW with at least 0.1 % sulphur in the fuel (100–215) and for HCl with at least 0.1 % chlorine or co-firing with sulphur-rich fuels (15 for new, 25 for existing, with no daily value). Plants in operation by 7 January 2014 have slightly higher upper NOx values from 300 MW (160 yearly, 200 daily).
Natural gas, gas engines and gas turbines
Gaseous fuels have their own values in the ordinance (sections 49, 54, 60, 62, 66, 67, 70 and 73): boilers at 3 % O2, gas turbines and gas engines at 15 % O2. CO has a limit value only for gaseous fuels. The value in mg/Nm3 for 2013 plants comes first and the value for new plants after the slash.
| Plant | NOx | CO |
|---|---|---|
| Boiler, natural gas | 100 / 100 | 100 / 100 |
| Boiler, gas other than natural gas | 200 / 100 | – / 100 |
| Gas engine (Otto cycle) | 100 / 75 | 100 / 100 |
| Gas turbine, natural gas | 50 / 50. In single cycle with an ISO efficiency above 35 %, instead 50 × the efficiency / 35. For 2013 plants 75 in CHP with a total ISO efficiency above 75 % and in combined cycle with an electrical efficiency above 55 % | 100 / 100 |
| Gas turbine, light or medium distillate | 90 / 50 | 100 / 100 |
| Gas turbine, gas other than natural gas | 120 / 50 | – / 100 |
The values for gas turbines apply at loads above 70 % and not to gas turbines and gas engines for emergency use that run at most 500 operating hours per year. Gas turbines in 2002 plants that run at most 1,500 hours per year may emit 150 (natural gas) or 200 mg/Nm3 NOx (section 61). SO2: 35 mg/Nm3 for gases except LPG (5), coke oven gas and blast furnace gas; dust 5 mg/Nm3, not for gas turbines and gas engines. BAT-AELs for NOx with natural gas (BAT 41–43) as yearly averages: boilers 50–100 (new 10–60), gas engines 20–100 (new 20–75), open-cycle gas turbines 15–50 (new 15–35) and combined-cycle gas turbines 10–50 (new 10–30), with daily values and exceptions in Tables 24 and 25.
Key dates
The dates come from the ordinance's definitions and transitional provisions, from the BAT decision and from the regulations on the annual environmental report. The measurement intervals are in the table of measurement requirements.
| Date | What applies |
|---|---|
| 7 January 2013 and 7 January 2014 | The line between a 2013 plant (permit or complete application before 7 January 2013 and in operation before 7 January 2014) and a new plant (section 8). |
| 1 January 2016 | The ordinance's requirements apply in full to 2013 plants (transitional provisions). |
| 17 August 2017 | The BAT conclusions were published. A plant granted its first permit after this date is new under the BAT conclusions. Decision (EU) 2021/2326 of 30 December 2021 re-adopted the same conclusions. |
| 17 August 2021 | The BAT-AELs apply as limit values for existing plants (chapter 1, section 8 of the Swedish Industrial Emissions Ordinance). |
| 31 March | The annual environmental report for the previous year, with the information in annex 2 to NFS 2016:8 and the results of the annual check of the measuring systems (section 5 c). |
| 1 October 2026 | Last day to respond to the Swedish government's memorandum on improved implementation of the Industrial Emissions Directive (municipalities 1 November). The proposals have not been decided. |
The measurement year at a large combustion plant
Establish what applies
Add up the total rated thermal input under the common stack rule, determine whether each boiler is a 2013 plant or new, and which fuels are fired. Check too whether the plant is covered by the BAT conclusions, so that the monitoring programme covers BAT 4. If the position of the measurement points is not set in the permit, you propose a position to the supervisory authority (section 34).
Continuous measurement and QAL3
From 100 MW the permanently installed measuring systems measure all the time. The plant's emission data system converts the concentrations to mg/Nm3 dry gas at the reference oxygen content and validates them. Between our visits you run the ongoing control according to EN 14181 (QAL3), with zero and span checks. The measuring systems must have a measurement uncertainty of at most 10 % for CO, 20 % for SO2 and NOx and 30 % for dust, as a 95 % confidence interval at the daily limit value (section 29).
AST every year
Automated measuring systems must be checked at least once every year by parallel measurements with reference methods (section 27). According to EN 14181 this is done as an AST: a functional test of the measuring system and at least five parallel measurements, normally in one day. You must inform the supervisory authority of the result (section 28).
QAL2 at least every five years
The ordinance sets no interval of its own, but the quality assurance must follow CEN standards (section 26), and EN 14181 requires a QAL2 when the measuring system is new, then at least every five years and after major changes to the plant or the measuring system. We measure in parallel at least 15 times over at least three days and calculate the calibration function. Read more about QAL2 and AST.
Periodic measurements
Below 100 MW we measure SO2, NOx and dust, and CO with gaseous fuel, at least every six months. Under BAT 4, for solid biomass and peat, mercury, HF and metals are added once a year, and HCl if it is not measured continuously. Coordinate them with an AST or a QAL2 if you can.
Report
The measurement results must be recorded, processed and presented so that the supervisory authority can check that the requirements are met (section 33). In the annual environmental report, submitted by 31 March, you report emissions, fuels and operating hours according to annex 2 to NFS 2016:8 and the results of the annual check of the measuring systems. The emissions are stated as averages before validation (section 94).
How the measured values are compared with the limit values
At continuous measurement the hourly, daily and monthly averages are validated for measurement uncertainty before they are compared with the limit value: the value is multiplied by 0.90 for CO, 0.80 for SO2 and NOx and 0.70 for dust (section 30). The factors correspond to the largest measurement uncertainty the measuring systems may have (section 29). The requirement is met for a calendar year if no validated monthly average exceeds the limit value, no validated daily average exceeds 110 % of it and at least 95 % of the validated hourly averages lie below 200 % of it (section 41). Periods of breakdown, exemption and start-up and shut-down are not counted (section 42). If more than three hourly averages in one day are invalid because of faults or maintenance, the whole day is invalid, and after more than ten such days the measuring system must be improved (sections 31 and 32).
At periodic measurement every measurement series must show that the limit value has not been exceeded (section 43), and the ordinance specifies no deduction for measurement uncertainty there. Against the BAT-AELs, according to the Swedish EPA, no standard deduction is made at all: the yearly and daily averages are formed from the valid hourly averages, and both must be met. In supervision, the measurement uncertainty is handled in the same way as for conditions in the permit.
The common stack rule: what counts as one plant?
Two or more plants count as a single plant if the flue gases are discharged through a common stack, or if they were granted their first permits on 30 June 1987 or later and are installed so that it would be technically and economically possible to discharge the flue gases through a common stack (section 36). The assessment concerns what would have been possible, not the solution that was chosen. Units below 15 MW are not included in the sum, but are covered by the limit values when the sum reaches 50 MW (section 38). The Swedish EPA's example: boilers of 20, 30, 10 and 2 MW add up to 50 MW, and all four are covered. If the sum does not reach 50 MW, the rules on medium combustion plants apply instead to boilers of 1–50 MW. The BAT conclusions have the same aggregation rule, but there units below 15 MW are left out entirely. A part of the plant that runs below 1,500 hours per year may be assessed separately if its emissions are measured separately.
Few operating hours, standby operation and breakdowns
2002 plants that run at most 1,500 hours per year, counted as a rolling average over five years, may emit more SO2 and NOx: with solid fuels 800 mg/Nm3 SO2 and 450 mg/Nm3 NOx (sections 48 and 59). Gas turbines and gas engines for emergency use that run at most 500 operating hours per year are exempt from their limit values (sections 60, 62, 66 and 67). Operating hours are counted without start-up and shut-down periods (section 13). In the BAT conclusions the yearly values do not apply below 1,500 hours per year, and below 500 hours the daily values are indicative. In the BAT conclusions, according to the Swedish EPA, the operating hours refer to the individual year, and they are reported in the annual environmental report.
If the flue gas cleaning equipment malfunctions or breaks down, the plant may not run without working cleaning for more than 120 hours in total in twelve months, and you must inform the supervisory authority within 48 hours (section 18). If normal operation cannot be resumed within 24 hours, operation must be reduced or stopped, or continue with low-polluting fuels (section 19). After a sudden interruption of the gas supply the supervisory authority can grant an exemption for at most ten days, and at a shortage of low-sulphur fuel for at most six months (sections 82 and 83). Measured values from such periods are not included in the averages (section 42).
What do the measurements cost?
The price depends on how many measuring systems and parameters are to be checked, whether it is a QAL2 with at least three measurement days or an AST, how many periodic parameters BAT 4 adds, the conditions at the measurement site and the travel distance. Several boilers on the same stack are often measured on the same visit, and periodic samples of mercury, HF and metals are coordinated with the AST or QAL2. Request a quote – we reply within two working days. Approximate prices for the most common measurements are in the price guide.
Frequently asked questions about large combustion plants
How often must a large combustion plant be measured?
From 100 MW total rated thermal input continuously for SO2, NOx and dust, with an annual check of the measuring systems by parallel reference measurements (sections 21 and 27). Below 100 MW periodically at least once every six months (section 24), but BAT 4 can require more, see the next question.
Our plant is 80 MW. Do we need continuous measuring systems?
Not under the ordinance, which requires periodic measurement every six months below 100 MW. If the plant is covered by the BAT conclusions, BAT 4 specifies continuous measurement of NOx, SO2, CO and dust, and for solid biomass and peat also HCl, in all sizes. If the plant runs below 1,500 hours per year, measurement every six months is enough. The permit can also require continuous measurement.
How often must QAL2 and AST be done, and who may do them?
An AST every year, since the ordinance requires an annual check by parallel measurements (section 27). A QAL2 when the measuring system is new, then at least every five years according to EN 14181 and after major changes. According to the standard, the reference measurements must be made by a laboratory accredited for the task according to ISO/IEC 17025. METLAB is accredited by Swedac for QAL2 and AST.
May the measurement uncertainty be deducted from the measured value?
Against the ordinance's limit values a standard deduction is made at continuous measurement: the averages are multiplied by 0.90 for CO, 0.80 for SO2 and NOx and 0.70 for dust (section 30). Periodic measurements are not validated. Against the BAT-AELs, according to the Swedish EPA, no deduction is made.
What happens if a limit value is exceeded?
The ordinance's requirements are assessed per calendar year (section 41): a validated daily average above 110 % of the value, a monthly average above the value or more than 5 % of the hours above 200 % means that the requirement is not met. If a BAT-AEL is not met, you must inform the supervisory authority immediately and take the measures needed (chapter 1, section 9 of the Swedish Industrial Emissions Ordinance). The supervisory authority can order measures under chapter 26, section 9 of the Swedish Environmental Code.
Do we have to measure mercury, HCl and HF when we fire wood chips?
The ordinance requires mercury measurement only with hard coal and lignite. For solid biomass and peat, BAT 4 specifies mercury, HF and metals once a year and HCl continuously, with periodic measurement at least every six months if the levels have proved stable.
Are new rules on the way?
Proposals exist. The EU's revised Industrial Emissions Directive (EU) 2024/1785 was to be transposed by 1 July 2026, and the Swedish government has a memorandum on improved implementation of the directive out for consultation, with responses due by 1 October 2026. The ordinance's measurement rules have not yet been changed (October 2026), and the BAT conclusions from 2017 apply until new ones are adopted.