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NetZero.GlobalSustainability Consultancy
Aerial view of London with Tower Bridge, the Thames and Canary Wharf
Case study · Corporate

Commercial estate energy audit, London

Whole-estate audit of a London commercial portfolio identifying significant operational savings and a phased retrofit pathway.

Location
London, UK
Service
Energy Audits

Unsplash

Identified energy savings18%
Quick-win payback< 2 yrs
Sites assessedMulti-site
12-month trajectory

Energy intensity, monthly index

The challenge

An ageing commercial estate was facing rising utility costs, inconsistent occupant comfort, and limited visibility on system performance across multiple sites.

Our approach
  • 01Site survey of fabric, HVAC, lighting and water systems
  • 02Half-hourly energy data analysis across a 12-month period
  • 03Engagement with FM and operations teams to validate findings
  • 04Costed retrofit register with payback and carbon impact
In detail
18%
Identified savingsagainst the 12-month baseline

A portfolio without a portfolio view

The portfolio's energy spend had been climbing for three consecutive years, but without a coherent view across sites it was hard to prioritise capital. We started with a top-down half-hourly data review to find the biggest signals, then went on site to validate the worst offenders.

What the data revealed

Heating and cooling controls were the largest single contributor — zones running outside occupancy hours, simultaneous heating and cooling, and BMS schedules drifting from intent. Fabric losses and inefficient lighting compounded the problem.

The single highest-value finding was simultaneous heating and cooling in three buildings — a recurring issue that quietly inflates energy spend by 8–15% without ever triggering a fault alert.

How we structured the response

We produced a prioritised register that grouped interventions into three tiers:

  • Quick-win operational changes — schedule corrections, setpoint discipline, controls tuning. Sub-12-month payback.
  • Medium-term retrofit — lighting upgrades, controls modernisation, targeted fabric work.
  • Longer-term strategic upgrades — plant replacement, heat decarbonisation, on-site generation.

The deliverable

A single board-ready document that translated technical findings into capital sequencing, payback and carbon impact — the basis for the next two years of estates investment.

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