BREEAM Ene 02 KNX Sub-Metering: Lighting, HVAC and Transport Zones for Energy Credits
BREEAM Ene 02 credits reward buildings that implement sub-metering across all major energy end-uses. A KNX-based sub-metering architecture with ARISTO BewO logging provides both the real-time monitoring capability and the 15-minute interval data records that BREEAM assessors require for credits 3 through 5.
BREEAM UK NC 2018 Ene 02 credit requirements
BREEAM UK New Construction 2018 issue 1.0 Ene 02 awards up to 5 credits based on the percentage of total energy consumption that is sub-metered by end-use category. Each credit level has minimum requirements for which systems must be separately metered and what fraction of total consumption they represent.
| Credits | Minimum metered % | Required systems metered |
|---|---|---|
| 1 credit | ≥ 40% of total consumption | At least 3 major systems (e.g. HVAC, lighting, DHW) |
| 2 credits | ≥ 60% of total consumption | HVAC, lighting, and transport (lifts/escalators) |
| 3 credits | ≥ 80% of total consumption | Above plus small power and DHW; 15-min logging required |
| 4 credits | ≥ 90% of total consumption | Sub-system metering (e.g. chiller vs AHU fans separated) |
| 5 credits | ≥ 95% of total consumption | Full sub-metering with automated M&T reporting |
Assessed at design stage: Ene 02 is assessed at both design stage (credits awarded for committed metering design) and post-construction stage (credits confirmed by commissioning evidence). The metering design must be documented in the M&T strategy report submitted to the BREEAM assessor at design stage.
Mandatory sub-metering zones: system-by-system guide
The following metering zones cover the five major end-use categories required for BREEAM Ene 02 credits. Each zone requires a dedicated MID-certified meter connected via Modbus TCP to the KNX gateway.
Ene 02 sub-metering zones and meter allocation
Zone 1 — Lighting (distribution boards per floor/zone):
Meter: ABB B24 or Eastron SDM630 per distribution board
Location: Incoming supply to each DB dedicated to lighting
Coverage: All luminaire circuits (not emergency lighting —
BREEAM assessors accept emergency lighting exclusion)
KNX GAs: 6/1/0 (kW), 6/1/1 (kWh), 6/1/2 (cos-phi)
Zone 2 — HVAC plant:
Meters: Separate meters for chiller, AHU, boilers, pumps
(combined for credit 1–2, separated for credit 4–5)
Location: Incoming supply to plant room MCCs
KNX GAs: 6/0/0 to 6/0/9 (multiple meters within zone)
Zone 3 — Domestic Hot Water (DHW):
Meter: ABB B24 on immersion heater or heat pump DHW circuit
Location: Dedicated MCB for DHW plant
KNX GAs: 6/3/0 (kW), 6/3/1 (kWh)
Zone 4 — Transport (lifts and escalators):
Meter: Carlo Gavazzi EM270 or ABB B24 per lift machine room
Location: Dedicated MCB for each lift machine room
Note: Must be separate from HVAC — assessors check
KNX GAs: 6/2/0 (kW), 6/2/1 (kWh)
Zone 5 — Small power (office equipment, IT, catering):
Meter: Eastron SDM630 CT per distribution board
Location: Outgoing circuits to small power sockets per floor
KNX GAs: 6/4/0 (kW), 6/4/1 (kWh)
Server room (additional for credit 4–5):
Meter: Dedicated meter for IT room UPS input
Purpose: IT power separated from general small power
KNX GAs: 6/5/0 (kW), 6/5/1 (kWh)15-minute interval logging requirement for credits 3–5
BREEAM Ene 02 credits 3 through 5 require that the sub-metering system records energy data at 15-minute intervals (or shorter) and retains the data for at least 12 months. ARISTO BewO meets this requirement through its logging module with configurable averaging intervals.
ARISTO BewO 15-minute logging configuration
BewO trend channel per KNX energy GA:
Channel type: Energy (kWh accumulation)
Logging interval: 15 minutes
Averaging: Pulse count over interval (for kWh counters)
Average of sampled values (for kW power)
Retention: 36 months (3 years, exceeds BREEAM 12-month min)
Storage: BewO server internal SSD or NAS share
Data export for assessor:
BewO Reports module → Energy trend → CSV export
Date range: full 12-month post-occupancy period
Format: ISO 8601 timestamp, zone name, kWh value per interval
Frequency: 15-minute data = 35,040 rows per meter per year
Gap analysis (credit scoring):
BREEAM assessor calculates:
Metered consumption / total building consumption × 100%
If metered zones = HVAC + lighting + transport:
Typically covers 85–92% of total → credits 3–4 achievable
If server room and catering added → 95%+ → credit 5
Evidence package for assessor:
1. Meter calibration certificates (MID Class B)
2. Screenshot of BewO real-time dashboard (each zone)
3. CSV export of 15-minute data (at least 3 months)
4. M&T strategy report naming all meters and KNX GAsGap analysis: percentage of consumption sub-metered
The BREEAM assessor calculates the gap analysis — the percentage of total building energy consumption that flows through sub-meters. Identifying which loads are excluded from sub-metering is important for predicting credit scores at design stage.
Typical commercial office breakdown
- HVAC: 45–55% of total consumption
- Lighting: 20–30% (varies by daylight design)
- Small power (IT/office): 15–25%
- Transport (lifts): 3–5%
- DHW: 2–4%
- Other (catering, external): 2–5%
Credit prediction at design stage
- Meter HVAC + lighting only: ~75% → 2 credits
- Add transport + DHW: ~82% → 3 credits
- Add small power: ~95% → 4 credits
- Add server room + catering: ~97% → 5 credits
- Rule: always add one extra meter as contingency
Commissioning evidence package
The post-construction BREEAM assessment requires physical commissioning evidence demonstrating that all sub-meters are installed, operational, and logging data. The evidence package must be assembled during the commissioning visit.
Commissioning evidence checklist for Ene 02
Document 1: Meter calibration certificates — MID certificate number for each meter — Issued by notified body (e.g. KEMA, Bureau Veritas) — Date of calibration (within 10 years for Class B) Document 2: Meter installation photographs — Photo of each meter showing DIN rail position and serial number — Photo of CT clamps on cables (SDM630 MCT installations) — Photo of Modbus wiring terminations Document 3: ARISTO BewO dashboard screenshots — Date and time visible in screenshot — Real-time kW reading for each zone (non-zero during occupied hours) — Historical trend chart showing minimum 48 hours of data Document 4: KNX Group Monitor export — ETS6 Group Monitor CSV export showing energy GA values — Timestamps and values confirming 15-minute poll cycle Document 5: M&T strategy report (if not provided at design stage) — List all meters with serial numbers, locations, and KNX GAs — Diagram of metering hierarchy (M0 to M10) — Statement that data is retained for 36 months — Contact details for FM team responsible for M&T monitoring
Need a BREEAM Ene 02 sub-metering system with KNX?
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