Energy & carbon
Commercial Energy Audits
Building-level energy audits with investment-grade financial appraisal — every measure carries capex, NPV, payback and carbon savings, so recommendations are decision-ready.
What it is
Detailed, building-level energy audits that identify cost-effective energy and carbon reduction measures across fabric, services and controls.
Every measure is presented with an investment-grade financial appraisal — capex, annual saving, simple payback, 15-year NPV and carbon impact — so recommendations are decision-ready rather than generic.
Audits are designed to be usable both as a technical work-list for facilities teams and as a board-grade business case for capital approval.
When you need it
- You want to reduce energy cost and carbon across a building or estate and need to know where to spend first.
- You need ESOS-grade audits that meet Lead Assessor expectations for evidence and rigour.
- You are building a business case for capital spend on energy measures and need defensible payback and NPV figures.
- You're planning major plant replacement (heating, cooling, lighting) and want a properly appraised options assessment.
- You operate a multi-site estate and need a consistent audit approach to compare and prioritise across assets.
Our approach
- 1
Consumption and tariff review
Analyse 12+ months of energy consumption and tariff data by meter and fuel to baseline performance and identify anomalies.
- 2
Site survey
On-site survey covering building fabric, HVAC, controls, lighting, small power and any process loads — including BMS interrogation where available.
- 3
Identification of measures
Identify a full slate of measures across fabric (insulation, glazing), services (heat pumps, LED, VSDs, solar PV) and controls (BMS, sub-metering, remote monitoring).
- 4
Investment-grade financial appraisal
Appraise each measure using HM Treasury Green Book methodology — 3.5% discount rate, HMT energy price escalation, 15-year horizon — to produce defensible NPV and payback.
- 5
Carbon savings quantification
Quantify carbon savings using current DEFRA GHG conversion factors, so reported tCO2e align with your wider SECR, GHG Protocol and investor reporting.
- 6
Prioritisation and reporting
Rank measures by payback, NPV and carbon impact and produce a report written for both technical teams and board-level decision-makers.
What you receive
Prioritised schedule of measures
A ranked schedule of energy and carbon reduction measures, ready to feed straight into a capital plan.
Capital cost and annual saving
Indicative capex, annual energy saving (kWh) and annual cost saving (£) for every measure.
Payback and 15-year NPV
Simple payback plus 15-year NPV under HM Treasury Green Book assumptions, so finance teams can compare measures on a like-for-like basis.
Carbon savings
Annual and lifetime carbon savings (tCO2e) using current DEFRA factors — usable in SECR, GHG Protocol and investor reporting.
Decision-ready report
A single report written for both technical teams and board-level decision-makers — no separate "exec summary" needed.
Why NZC Consultants
- Accredited ESOS Lead Assessor
- Sterling Accreditation registered
- Energy Institute member
- Independent — no software resale, no kit sales
Frequently asked questions
Reference library
Related official guidance
Reference links to the standards, regulations and governing bodies that underpin this service.
ESOS
ESOS — guidance for participants
Environment Agency
Lead Assessor guidance on undertaking and notifying ESOS energy audits, including significant energy consumption and de minimis rules.
View official guidanceESOS
ESOS — overview and qualification
GOV.UK
Statutory overview of ESOS qualification criteria, compliance routes (ISO 50001, DECs, EPCs, audits) and reporting obligations.
View official guidanceESOS
MESOS portal — notification system
Environment Agency
Online notification system used by ESOS Lead Assessors and responsible undertakings to submit compliance and action plan reports.
View official guidanceESOS
ESOS Phase 4 updates
Environment Agency / DESNZ
Latest updates on Phase 4 qualification dates, audit requirements and action plan reporting for the 2027 compliance cycle.
View official guidanceBuilding Performance
CIBSE — technical knowledge portal
Chartered Institution of Building Services Engineers
Technical guides, TMs and application manuals covering building services design, energy and HVAC performance.
View official guidanceBuilding Performance
NABERS UK
BRE / NABERS UK
Operational energy rating scheme for UK offices, providing a measured performance benchmark complementary to EPCs.
View official guidanceBuilding Performance
CIBSE TM54 — evaluating operational energy use at design stage
CIBSE
Methodology for predicting in-use energy performance of new and refurbished buildings beyond Part L compliance modelling.
View official guidanceBuilding Performance
TM44 Air Conditioning Inspections
CIBSE / GOV.UK
Statutory inspection regime for air conditioning systems above 12 kW in England, Wales and Northern Ireland.
View official guidanceBuilding Performance
Building Regulations — Approved Document Part L
MHCLG
Conservation of fuel and power requirements applied to new build, refurbishment and material changes of use.
View official guidanceBuilding Performance
BSI — relevant British Standards
British Standards Institution
BS EN 16247 (energy audits), BS EN ISO 50001 (energy management) and related standards underpinning UK compliance regimes.
View official guidance
Speak to an NZC Consultants assessor
Tell us about your building or estate and we'll scope an audit package that fits — we'll respond within one working day.