European emission standards for solid fuel stoves 

The combustion of solid fuels is always accompanied by the production of pollutants, and the general aim should be to reduce their amount to an acceptable level. One of the tools to reduce the amount of discharged pollutants is the legislative requirements for combustion equipment and fuel, which are applied when the combustion equipment is placed on the market with the participation of a notified entity, or during their operation. The article deals with the valid requirements for emissions of pollutants and the efficiency of combustion equipment, which are legally required both throughout the EU, as well as other requirements that are given in some individual countries. The European leaders in this area are represented by Germany and Austria. Since the individual limits are expressed in different units and under different conditions (O2 reference content), this post recalculates the limits in order to compare them and answer the question of how they differ and where the requirements are most stringent.

• CR – New Green Savings (www.novazelenausporam.cz);
• Germany - DINplus (http://www.dincertco.de);
• Sweden, Norway, Finland, Denmark, Iceland - Nordic Swan (www.nordic-ecolabel.org);
• France – Flamme Verte (http://www.flammeverte.org);
• England – HETAS certification (http://www.hetas.co.uk); atd.

Note: in the next part of the text, the unit m3N is given in some cases - it represents the volume in cubic meters at 101 325 Pa and 0 °C - under so-called normal conditions.

EUROPEAN EMISSION LIMITS IN GENERAL

According to the standards, appliances must comply with emission limits only at rated power (except for appliances burning wood pellets, which have different limits at reduced power). The table of emission limits is marked as tab. No. 1. The table also shows the minimum efficiency values for the given appliances.

Tab. No. 1 General emission limits, EU

In general, these emission limits are moderate compared to boiler requirements [15] and minimum efficiencies are relatively low. The problem with efficiency occurs in the case of fireplace inserts (hereinafter referred to as KV). These are intended for the enclosure, or are connected to an accumulation element through which the flue gases pass. For the correct functioning of the unit (CH + storage element) it is therefore necessary that the flue gases behind the CH have a high temperature - the CH itself then has low efficiency. However, manufacturers offer (apparently out of fear that customers would not buy their products) KVs with an efficiency of over 70%. Manufacturers are often pushed towards this trend by stricter requirements in EU countries, in which they would not succeed with products that have lower efficiencies than required by local regulations.

It should be noted that the building's need for heat is not the same throughout the heating season. For fireplace inserts with a water exchanger, a storage tank for heating water is a possible solution, which allows the fireplace insert to work at the ideal rated output. When power is modulated (to a so-called reduced power), higher emission production and lower efficiency occur. It is therefore a good idea not to oversize the stove unnecessarily and thereby achieve the greatest possible coverage of the heating season in operation at the rated output.

CZECH REPUBLIC - EMISSION LIMITS IN GENERAL

The Czech Republic adopts the limits from the above-mentioned standards. For radiant heat sources (local heaters), Act No. 201/2012 Coll. - on air protection sets out additional obligations for both manufacturers (importers) of combustion equipment and operators.

For local heaters intended for connection to a hot water central heating system (e.g. fireplace inserts or stoves with a water exchanger), the emission limits for CO and dust (TZL) apply according to Annex No. 10 of Part I and II of Act No. 201/2012 Coll. as amended by later laws. Local heaters marketed in the Czech Republic, which serve as a heat source for the hot water central heating system, must meet the requirements listed in table tab. No. 2, which are applicable in the period from January 1, 2018 to December 31, 2019. In essence, these are 1.38 times milder requirements for CO and dust than the requirements for boiler class 4 according to EN 303-5:2012 intended for hot water boiler.

Tab. No. 2 Minimum emission requirements for local heaters placed on the market, which serve as a heat source for a hot water central heating system with a nominal input of up to 300 kW, to be used from 1 January 2018 to 31 December 2019 - Annex No. 10, Part II of Act No. 201/2012 Coll.

From January 1, 2020 to December 31, 2021, requirements according to Annex No. 10, Part III of Act No. 201/2012 Coll. for stationary solid fuel combustion sources defined in Article 1 of Commission Regulation (EU) 2015/1185 implementing Directive 2009/125/EC of the European Parliament and of the Council as regards the requirements for the ecodesign of solid fuel local heaters.

According to Article 1 of the regulation, the requirements apply to the following stationary combustion sources:

• local solid fuel heaters with a nominal heat output of no more than 50 kW.

According to Article 1 of the regulation, the requirements do not apply to:

• local solid fuel heaters that are intended only for burning non-woody biomass;
• solid fuel local heaters designed for outdoor use only;
• local solid fuel heaters whose direct heat output is less than 6% of the total direct and indirect heat output at the rated heat output;
• solid fuel local heaters that are not assembled at the factory or supplied by a single manufacturer as prefabricated parts or components intended for assembly on site;
• air heaters;
• sauna stove.

Local heaters must meet the following emission limit values, which relate to dry flue gas, a temperature of 273 K, a pressure of 101.3 kPa and a reference oxygen content of 13%:

1. TZL emission limit values:
   
   1. for heaters with an open combustion chamber, it must not exceed 50 mg.m−3N when measured by method A, or 6 g/kg (dry matter) when measured by method B;
   2. for heaters with a closed combustion chamber using solid fuels other than pressed wood in the form of pellets and from stoves must not exceed 40 mg.m−3N when measured by method A, or 5 g/kg (dry matter) when measured by method B, or 2.4 g /kg (dry matter) in the case of biomass or 5.0 g/kg in the case of solid fossil fuels when measured by method C;
   3. for heaters with a closed combustion chamber using compressed wood in the form of pellets, it must not exceed 20 mg.m−3N when measured by method A, or 2.5 g/kg (dry matter) when measured by method B3, or 1.2 g/kg (dry matter) when measured by method C.
2. Emission limit values for gaseous organic compounds (TOC):
   
   1. TOC emissions from local solid fuel heaters with an open combustion chamber, from local solid fuel heaters with a closed combustion chamber using solid fuels other than pressed wood in the form of pellets and from stoves must not exceed 120 mgC.m−3N;
   2. TOC emissions from local solid fuel heaters with a closed combustion chamber using pressed wood in the form of pellets must not exceed 60 mgC.m−3N.
3. Carbon monoxide (CO) emission limit values:
   
   1. for heaters with an open combustion chamber, it must not exceed 2,000 mg.m−3N;
   2. for heaters with a closed combustion chamber using solid fuels other than pressed wood in the form of pellets and from stoves must not exceed 1,500 mg.m−3N;
   3. for heaters with a closed combustion chamber using pressed wood in the form of pellets, it must not exceed 300 mg.m−3N.
4. Emission limit values for nitrogen oxides (NOx):
   
   1. for solid fuel heaters with an open combustion chamber, for solid fuel heaters with a closed combustion chamber and from stoves using biomass must not exceed 200 mg.m−3N, expressed as NO2;
   2. for heaters with an open combustion chamber, from solid fuel heaters with a closed combustion chamber and from stoves using fossil solid fuels must not exceed 300 mg.m−3N, expressed as NO2.

NOTE: The requirements also apply to local heaters without a heat exchanger. These emission limit values are valid in the EU only from January 1, 2022, unlike Act No. 201/2012 Coll., which applies two years earlier. In addition, the Ecodesign Regulation [1] introduces requirements for the seasonal energy efficiency of heating from 1 January 2022:

• the seasonal heating energy efficiency of local solid fuel heaters with an open combustion chamber must not be lower than 30%;
• the seasonal heating energy efficiency of local solid fuel heaters with a closed combustion chamber using solid fuels other than pressed wood in the form of pellets must not be lower than 65%;
• the seasonal heating energy efficiency of local solid fuel heaters with a closed combustion chamber using pressed wood in the form of pellets must not be lower than 79%;
• the seasonal energy efficiency of heating stoves must not be lower than 65%.

GERMANY - EMISSION LIMITS IN GENERAL

In Germany, the 1st BImSchV decree is valid, which adjusts (tightens) the limits for the concentration of pollutants released into the air during the operation of local solid fuel appliances.

For devices put into operation after 1 January 2015 applies the emission limits and minimum efficiencies listed in tab. No. 3 – so-called Stufe 2 (BIMSchV 2). These limits must be met by the device at nominal power.

Tab. No. 3 Requirements according to 1. BImSchV Stufe 2 for devices placed on the market 

The operator must prove compliance with the limits for devices put into operation before 25 November 2009. This can be proven either by presenting a certificate from the device manufacturer or by measurements carried out by a chimney sweep. If the equipment does not meet the emission limits, it must be taken out of service or equipped with additional equipment enabling the emission limits to be met (on the date specified in the decree, depending on the age of the appliance). Regular measurement of local appliances is not carried out by the operator (it is carried out only for hot water boilers).

AUSTRIA - EMISSION LIMITS IN GENERAL

In Austria, emission limits are regulated by agreement 15a B-VG [14], the required values are listed in tab. No. 4 (manual fuel supply) and tab. No. 5 (automatic fuel supply). These values must be met by each combustion device (all sizes) when tested at rated output. In the case of combustion devices with a nominal output of more than 8 kW, the limits must be met not only at nominal output, but also for CO, OGC and efficiency at reduced output (50% Pjm for manually operated ones, 30% Pjm for automatically operated ones). The minimum efficiencies even for combustion equipment with a nominal output of less than 8 kW are listed in tab. No. 6.

Tab. No. 4 Requirements according to 15a B-VG, emission limits – manual fuel delivery

Tab. No. 5 Requirements according to 15a B-VG, emission limits – automatic fuel supply

Tab. No. 6 Minimum efficiency requirements according to 15a B-VG

COMPARISON OF LIMITS

In order to be able to compare the emission limits valid in different countries, it is important to have these values expressed in the same units (concentration mg/m3N or emission factor mg/MJ) and also related to the same comparative conditions – reference oxygen content, dry flue gas under normal conditions. In Austria, the limits are given as an emission factor related to the energy contained in the fuel, in contrast to the Czech Republic and Germany, where the limits are given as concentrations related to the volume of dry flue gas. The comparison of the limits must therefore be carried out by conversion through the calorific value of the fuel and the amount of fumes produced by burning 1 kg of fuel.

A comparison of the limits shows a large fragmentation of the limits within the EU, which should be unified on 1/1/2022, when the EU Commission Regulation 2015/1185 on ecodesign for local heaters comes into force. Today, emissions of pollutants are monitored most comprehensively by Austria. The European standard has the least strict requirements.

For better clarity, tab. No. 7 shows a comparison of the minimum requirements for a fireplace insert with heat with a water exchanger with a nominal output of 8 kW for piece wood when it is put on the market and also during regular inspections (required by Act No. 201/2012 - on air protection and Austrian decree 15a B-VG).

Tab. No. 7 Comparison of today's and future requirements for emissions and efficiency for a specific installation of a fireplace insert with a water exchanger with a total output of 8 kW (power input 10 kW) - manual application with piece of wood

Source: https://vytapeni.tzb-info.cz