Masterspec

THE BURNING QUESTION - CAN I USE ANY TYPE OF WOOD FIRE?

22 Oct 2019

In the middle of winter, there is nothing better than sitting in a cosy room in front of a wood fire (or wood burner) with a glass of your favourite tipple. But is that project you are planning (for next winter) allowed an open wood fire or does it have to be a particular type of high tech wood burner? The answer is "yeah...na...depends" - in other words, it's complicated!

Types of wood fires
Open Fires  Traditional type of fire, prefabricated or in-situ, with one side (or more) open and no or little air flow control.
Open Fire with glass front Similar to the open fire, usually prefabricated, but with a glass front (door) and some air flow control. May or may not be tested (to AS/NZS 4012 & AS/NZS 4013 - emissions ≤ 1.5 g/kg, efficiency ≥ 65%).
Wood burner Purpose made, prefabricated, fully enclosed with airflow control (& possibly other features). May or may not be tested (to AS/NZS 4012 & AS/NZS 4013 - emissions ≤ 1.5 g/kg, efficiency ≥ 65%).
1Wood burner, old-style 1Wood burner, old-style - may, be multi-fuel and have two air flow controls but can be banked down overnight.  May or may not be tested (to AS/NZS 4012 & AS/NZS 4013 - emissions ≤ 1.5 g/kg, efficiency ≥ 65%).
1Wood burner, low  emission (LEB) Only tested to AS/NZS 4012 & AS/NZS 4013 with emissions ≤1 g/kg, efficiency ≥ 65%.  (Note: NES2 emissions ≤ 1.5 g/kg).
1Wood burner,  ultra-low  emission (ULEB) Tested to the Canterbury Method 1 (CM1), emissions and efficiency standard ≤ 38 mg/MJ of useful energy and a thermal efficiency of ≥ 65%.

Notes
1 Environment Canterbury (ECAN) description
2 NES is National Environmental Standards for Air Quality


National Environmental Standards for Air Quality
It starts with the Ministry for the Environment's (MFE), National Environmental Standards for Air Quality (NES), which covers standards for air quality and in doing so provides performance standards for indoor wood (& other fuel) burners. It does not cover multi-fuel burners (including coal burners) or open fires as these are not recommended forms of heating because of the increased particulate matter emissions. In some regions, councils may control these specific forms of heating through rules or by-laws. However, NES does limit its scope to properties less than 2ha (4.94 acres) in size, so on properties bigger than that, subject to local council requirements, any type of burners (including coal burners) or open fires may be able to be used.

Standards
Two testing Standards form the basis of defining  the performance of wood fires nationally:

  • AS/NZS 4012: 2014 Domestic solid fuel burning appliance - Method for determination of power output and efficiency
  • AS/NZS 4013: 2014 Domestic solid fuel burning appliances - Method for determination of flue gas emission

Both of these Standards align with the NES performance requirements.
Beyond these and NES, some Local Authorities bodies such as Environment Canterbury have specific requirements. It pays to check with the Local Authority (BCA, Regional, etc.) to see what restrictions there may be for your project..

Environment Canterbury
Environment Canterbury (ECAN) seem to have the most comprehensive clean air zones and special requirements for indoor wood fires, including their test requirement Canterbury Method 1 (CM1). This test is slightly different and more stringent than AS/NZ 4013 (& NES) and defines Ultra-Low Emission Burners (ULEB) fires. ULEB fires are allowed to be specified in all situations and zones, but not all zones limit the choice of fires to ULEB. Note, heritage buildings are treated as a one-off special case regardless of property/zone.
However, the CM1 test is easier to use for new kinds of burners, whereas the NES requirements were thought to be too restrictive.
ECAN has been used as an example of a Local Authority special requirements (although quite stringent). Some other local authorities have their own requirements, and some also recognise the CM1 test.


Outdoor fires
Outdoor fires are mostly open wood fires. They are generally excluded from the restrictions of indoor wood fires by the manufacturer providing cooking facilities (fixed or removable - grills, hotplates, ovens, etc.). NES, ECAN and other requirements mostly exclude cooking facilities, so open fires (along with BBQs, Pizza Ovens, etc.) with cooking facilities are usually allowed in external situations regardless of property size and location. Some Local Authorities may have requirements that smoke should not cause a nuisance, and some clean air zones may be more restrictive. Their use may be curtailed in extremely high fire risk conditions.

2 Hectare Properties and Clean Air Zones
Generally, in most regions, there are three main zones/properties that define what type of indoor fires can be used:
  • Clean Air zones
  • Properties less than 2 hectares(ha) - not in a clean air zone (sometimes referred to as "urban" or "urban/rural")
  • Properties 2ha (4.94 acres) or greater  - not in a clean air zone (sometimes referred to as "rural")
The type of fire these can have may vary slightly between Local Authorities, so it pays to check. Usually, properties 2ha or greater, and not in a clean air zone, have the least restrictions on the type of fire and they are about the only places you might be able to install a completely open fire. This case is very true for regions with no special requirements and only covered by the NES requirements (outside scope of NES). Properties less than 2ha, and not in a clean air zone, come within the requirements of NES or regional special requirements. Clean Air zones are most likely defined by a Local Authority, and generally, they have more stringent special requirements.

Besides restricting types of new fires to be installed in different zones, some local authorities have rules that ban the use of certain existing fires for particular zones, either now or from a prescribed date in the future. Again it pays to check.

Wood Burners Performance Requirements (new installations)
The following tables show the requirements under, the national requirements of NES, and the particular local requirements of Environment Canterbury (used as an example of special Local Authority requirements).

NES with AS/NZ 4013 & AS/NZ 4012
Property Emissions g/kg (AS/NZ 4013) Efficiency (AS/NZ 4012)
< 2ha < 1.5g/kg (particles/dry wood burnt) ≥ 65% (thermal efficiency)
≥ 2ha no restriction (including open fires) no restriction (including open fires)


 

Environment Canterbury - Low Emission Burners (LEB)
 Property  Emissions g/kg (AS/NZ 4013)  Efficiency (AS/NZ 4012)
 < 2ha (not clean air zone)  < 1.0g/kg (particles/dry wood burnt)  ≥ 65% (thermal efficiency)
 ≥ 2ha (not clean air zone)  no restriction (including open fires)  no restriction (including open fires)
 < 2ha (clean air zones - allowed  some zones only)  < 1.0g/kg (particles/dry wood burnt)  ≥ 65% (thermal efficiency)
 ≥ 2ha (clean air zones - allowed  most zones)  < 1.0g/kg (particles/dry wood burnt)  ≥ 65% (thermal efficiency)

Note; if project in a particular clean air zone, check that LEB burners are allowed.

Environment Canterbury - Ultra Low Emission Burners (ULEB) - to CM1
Property Emissions g/kg (AS/NZ 4013) Efficiency (AS/NZ 4012)
< 2ha (all zones) ≤ 38 mg/MJ of useful energy ≥ 65% (thermal efficiency)
≥ 2ha (all zones) ≤ 38 mg/MJ of useful energy ≥ 65% (thermal efficiency)

Note; "all zones" includes clean air zones.

Wood Fire Marking and Labelling Requirements
Approved or authorised burners must have labels indicating; details of testing, authorisation requirements, and manufacturers details. NES uses the label requirements set out in AS/NZS 4012, section 8, Marking. Environment Canterbury has label requirements for fires tested to CM1.

Lists of acceptable/authorised Burners
Both NES and Environment Canterbury have authorised indoor wood (& pellet) burner lists based on manufacturer and model.

The NES list is burners that meet the National Environmental Standards and may be installed on properties less than two hectares, anywhere in New Zealand, unless more stringent regional rules apply. The NES list is available at https://www.mfe.govt.nz/woodburners.

Environment Canterbury lists are burners that have either been tested and meet Low Emission Burners LEB or Ultra-Low Emission Burners ULEB requirements; these are available at https://www.ecan.govt.nz/data/authorised-burners/.

These list may not be completely up to date so always check with the manufacturers.
 


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