If you love real flame heat but don’t love smoky winter inversions, Ultra-Low Emission Burners (ULEBs) are the sweet spot: proper woodfire vibes, Clean Air Zone-compliant, and future-proof for Canterbury’s tight rules.
What exactly is a ULEB?
In plain English: a ULEB is a Ultra Low Emission Burner (Wood) that’s been independently tested under “real-life” conditions and proven to produce ultra-low particulate emissions while still being efficient. In Canterbury, that testing uses the Canterbury Method (CM1) with a pass mark of ≤ 38 mg of particulates per megajoule of useful heat and ≥ 65% efficiency. Only models that pass and are authorised by Environment Canterbury (ECan) count as ULEBs. Environment Canterbury
Heads-up: “Clean Air approved” nationally ≠ ULEB in Christchurch. National rules use a different test (g/kg), and regions like Canterbury can set stricter standards. Always check the ECan Authorised Burners list. Ministry for the Environment+1
Canterbury vs the rest of NZ (why Christchurch is stricter)
NZ national baseline (NESAQ) for urban properties under 2 ha: ≤ 1.5 g/kg particulate and ≥ 65% efficiency (AS/NZS 4013 & 4012) Building Performance+1
Canterbury Clean Air Zones (Christchurch, Timaru, etc.) layer stricter, local rules on top. In many urban areas, new installs must be ULEB models (not just “clean air”). ECan publishes the zone-by-zone rules and they do change—so check before you quote. Environment Canterbury
Translation: If you’re in Christchurch’s Clean Air Zones, ULEB = the safe choice for new installs.
Why ULEBs matter (beyond ticking the consent box)
Cleaner air in winter: ULEBs are engineered to slash PM emissions during the dirtiest phases (start-up/low burn). That’s the whole point of CM1. Ministry for the Environment
Future-proofing: Rules tighten over time; ULEB authorisation gives you headroom. ECan also confirms authorised ULEBs can be installed into any home without a resource consent (you still need building consent). Environment Canterbury
Real heat, real ambience: You still get the wood-burner experience—just with modern combustion design.
How ULEBs hit those numbers (the tech, minus the fluff)
Optimised airflow paths (pre-heated secondary/tertiary air) to burn smoke before it leaves the firebox.
High-temp fireboxes & baffles to keep gases hot long enough to combust.
Chimney/flue systems that maintain stable draft across start-up and low-burn conditions (the tricky parts CM1 tests).
Many models are also tested to the national standards for safety/efficiency in addition to CM1—check the spec sheet. Example: Masport publishes CM1 results (e.g., 31 mg/MJ on Hurunui) alongside AS/NZS figures. CLICK HERE FOR ULEB FIRE OPTIONS
Installing in Canterbury: the rules in one place
Confirm your zone (Christchurch, Timaru, Ashburton, etc.) and property size (< 2 ha vs > 2 ha). ECan’s Clean Air Zone pages lay out exactly what’s allowed. Environment Canterbury
Pick an ECan-authorised ULEB (don’t assume; look it up on the ECan Authorised Burners database). Environment Canterbury
Consent: Building consent is typically required. Resource consent isn’t for authorised ULEBs (that’s one perk of ULEB status). Environment Canterbury
Secondary emission devices: In some cases, an approved electrostatic precipitator (e.g., OekoTube) can bring a standard NES-compliant burner down to ULEB-equivalent discharges—but it must be an approved device fitted to an eligible burner. Great for edge cases/retrofits. Environment Canterbury
NZ-wide angle: what if you’re not in Canterbury?
The national authorised wood-burners list (Ministry for the Environment) is valid anywhere in NZ unless your regional council has stricter rules (like Canterbury). Use it for regions that stick to NESAQ. Ministry for the Environment
Running a ULEB like a pro (this is where owners win or lose)
Burn dry wood. Most manuals specify < 25% moisture—that alone can make or break emissions and glass cleanliness. CLICK HERE FOR INFO
Right-sized loads & air settings: Don’t baby it; get to operating temp promptly, then settle to a clean, steady burn.
Annual service & flue sweep: Keeps draft strong and emissions low.
Store wood properly: Off the ground, covered top, open sides, 12+ months seasoning for most hardwoods.
Quick buyer’s checklist (Canterbury focus)
Zone-legal? Confirm ULEB status on ECan’s database before you fall in love with a brochure. Environment Canterbury
Specs you can trust: Look for CM1 results (mg/MJ) and the AS/NZS efficiency figure (≥ 65%). Environment Canterbury
Installer & consent: Use an experienced local installer who knows Clean Air Zone paperwork. SEE OUR INSTALLATION PHOTOS
Flue system: Stick with the tested flue kit or an equivalent the manufacturer specifies—draft stability matters.
Fuel reality: Plan your wood supply now; “Good Wood” quality is not optional for clean burns.
FAQs we hear all the time
“Is a ULEB actually cleaner than a standard ‘Clean Air’ burner?”
Yes—different test, stricter threshold. ULEB ≤ 38 mg/MJ under CM1 vs national ≤ 1.5 g/kg under AS/NZS; CM1 also includes start-up/real-world conditions. Christchurch requires ULEBs for many urban installs. Environment Canterbury+1
“Do ULEBs need resource consent in Christchurch?”
No—authorised ULEBs may be installed in any home without resource consent (building consent still applies). Environment Canterbury
“Can I upgrade an existing burner to comply?”
Sometimes. Approved secondary emission reduction devices (e.g., electrostatic precipitators) can reduce particulate to ULEB-equivalent levels on certain eligible burners—must be an approved device on an eligible model. Environment Canterbury
Bottom line
If you’re in Christchurch/Canterbury urban areas, ULEB is the go-to: compliant today, kinder to winter air, and still proper, toasty wood heat. For other regions, ULEBs keep you ahead of tightening standards—and they just burn cleaner. Classic heat, modern conscience. Win-win.