Article 08: From 38 to 73 Per Cent Energy Savings: How Major UK Landlords Have Cut Office Energy in a Decade

A series mining the PhD thesis "London and UK Office Buildings: Investigating Energy Use and Landlord-Tenant Influences" (Azhari, 2025).

Key takeaway. Leading UK commercial landlords have reported portfolio energy reductions of 38 to 73 per cent over a decade, well above the sector average. The repeatable moves behind the headline are surprisingly few and surprisingly mundane.

Chart

Reported portfolio energy reductions, decade to 2021

Three major UK landlords report cuts of 38 to 73 per cent, all above the sector averages from the Better Buildings Partnership.

A decade of cuts, anonymised

Three of the seven major UK property organisations interviewed for the thesis reported portfolio energy reductions of 38 per cent, 42 per cent and 73 per cent across landlord-controlled and tenant-controlled areas over roughly the decade prior to the COVID-19 pandemic. Even the smallest of these comfortably beats the sector-wide reductions of 30 per cent in absolute terms and 26 per cent in intensity reported by the Better Buildings Partnership for its broader membership.

The headline numbers are self-reported and have not been independently audited or normalised to a common boundary. They are a directional signal rather than a controlled comparison. What makes them interesting is what the interviews say sits underneath them. Strip the rhetoric and you find a short, repeatable list of moves.

Lever 1: replace what is at end of life with something more efficient

The largest single contribution across the interviewed organisations came not from heroic refurbishment but from the discipline of always replacing end-of-life kit with the most efficient available option. Chillers, boilers, lighting, refrigeration, lifts, fans and motors all reach end of useful life on a predictable schedule. Replacing each with current-generation equipment delivers compounding gains over a decade. As one interviewee put it:

"As part of lifecycle replacements of highly intensive equipment, we have replaced it with more energy-efficient systems."

The discipline is not glamorous. It does not generate press releases. It does require capital planning, a lifecycle register and a procurement standard that defaults to efficient equipment rather than to cheapest like-for-like.

Lever 2: control what you already have

The second lever is operational tuning. Buildings rarely run at the efficiency their design implies. Set-points drift. Schedules misfire. Plant fights itself, with heating and cooling running simultaneously on adjacent floors. BMS analytics and the willingness to act on what they reveal can recover much of this drift without any capital spend. A landlord interviewee captured the value:

"We have done a lot to optimise the control of these systems by analysing the energy data and making informed decisions."

This is where the BMS investment of the previous decade starts to pay off in operational terms, and where the gap between landlords with mature data infrastructure and those without becomes visible.

Lever 3: see what is happening

The third lever is sub-metering and energy management systems. Most of the interviewed organisations were early adopters of half-hourly metering across base-building and (where lease structures allowed) tenant spaces. Granular data enables granular control: identifying which floors run lights overnight, which AHUs run at weekends, which tenants have left equipment on across holidays.

"We started putting in smart meters in the building so we are more able to understand the running of equipment and ensure efficiency."

The benefit is not the meter. It is the analytics layer on top of it and the operational discipline to read the dashboards. Without that discipline, sub-metering is just an expensive way to collect data that no one looks at.

Lever 4: align the people

The fourth lever is stakeholder engagement. The most-quoted line across the interviews was about goal alignment:

"Successful energy management is not only about having the data and recommendations but ensuring that everyone is working towards the same goal."

In practice this means in-house energy and sustainability teams (rather than outsourced FM), regular communication with tenants, internal training for asset managers, and visible executive sponsorship. None of these are technical interventions. All of them multiply the effect of the technical ones.

What did not move the dial

It is as instructive to note what did not feature heavily in the interviews. Fabric upgrades (insulation, double-glazing, façade improvements) were mentioned but were rarely the dominant lever. BREEAM and GRESB certification efforts drove reporting discipline but were not themselves the source of large operational savings.

Heat decarbonisation (replacing gas boilers with heat pumps) was emerging at the time of the interviews but had not yet been delivered at scale. The interviewed organisations were planning it. Most had not yet harvested the savings. This is the area where the next decade of effort will sit, and where the policy and lease conditions discussed in Articles 6 and 7 will determine whether the planning translates into delivery.

Internal carbon pricing appeared in the REITs in the sample but not in the private or public sector organisations. REIT structure encourages public reporting and explicit decarbonisation pathways. Privately held funds and public-sector estates do not face the same pressure and have not yet adopted comparable mechanisms.

The 2026 National Buildings Database (DESNZ), which the author contributed to, sharpens the public-sector point. Around 10 per cent of office premises and 19 per cent of office floorspace nationally are public-sector occupied. The disproportionate floorspace share reflects the size of central and local government offices. For a national decarbonisation programme, the public-sector estate is therefore a much larger target than its premise count alone would suggest, and the policy mechanisms available to government on its own estate (Display Energy Certificates, direct procurement standards, Greening Government Commitments) are correspondingly important.

What a smaller landlord can take from this

The 38 to 73 per cent numbers reflect what large landlords with REIT-level resources and dedicated sustainability teams can do. A smaller landlord cannot replicate the full programme, but the four levers above are scale-independent in their principles.

End-of-life replacement discipline is essentially free. It requires a procurement standard and a register, not a balance sheet. Operational tuning depends on data. The BMS in a small building may not be sophisticated, but most controllers can be reviewed annually for set-point drift, schedule errors and plant conflicts. Sub-metering and analytics are scale-dependent. A small single-let building may not justify a dedicated EMS platform but can use spreadsheet-based monthly tracking of meter reads, which catches most drift. Stakeholder engagement is the easiest to underdo. Tenants who never hear from their landlord about energy will treat it as someone else problem. Tenants who do, sometimes change behaviour.

The numbers under the numbers

Caveats apply to the headline range. The 38, 42 and 73 per cent figures are self-reported by landlords, not independently audited. Portfolios change shape over a decade through acquisition, divestment and refurbishment, so like-for-like comparison is approximate. The sample is concentrated in large landlords with dedicated sustainability teams. SMEs, single-asset owners and public-sector landlords are under-represented.

The decadal cuts predate the 2022 energy price shock, the broader push to electrify heat and the more recent focus on embodied carbon. The four common levers are descriptive, not causal. The article does not attempt to attribute kWh saved to each intervention; the interview data does not support that level of decomposition.

The headline still matters because it bounds what is achievable. If three of the seven largest UK property organisations cut a third to three-quarters of their portfolio energy in a decade using mostly mundane operational moves, the rest of the sector has both an existence proof and a target.

The next article moves from what private actors have done to what public policy could do. Article 9 looks at NABERS in Australia, NABERS-UK in Britain, and what an operational rating scheme would have to look like to bite on the office sector at the scale the climate target requires.

Limitations

Headline reduction figures are self-reported by landlords and have not been independently audited or normalised to a common boundary. Portfolios change shape over a decade through acquisition, divestment and refurbishment, so like-for-like comparison across the decade is approximate. The sample is concentrated in large landlords with dedicated sustainability teams. SMEs, single-asset owners and public-sector landlords are under-represented. Decadal cuts predate the 2022 energy price shock, the broader push to electrify heat and the more recent focus on embodied carbon. The four common levers are descriptive, not causal. The piece does not attempt to attribute kWh saved to each intervention.

References

• Azhari, R. (2025) London and UK Office Buildings Investigating energy use and landlord/tenant influences. Doctoral thesis (Ph.D), UCL (University College London). URL: https://discovery.ucl.ac.uk/id/eprint/10204821/

• Bunn, R., Mavrogianni, A., Azhari, R., and Burman, E. (2022). Delivering Net Zero Carbon in the Workplace. British Council for Offices. Available at: https://www.bco.org.uk/Research/Publications/Delivering_Net_Zero_Carbon_in_the_Workplace.aspx

• Better Buildings Partnership (2019, 2020, 2023). Real Estate Environmental Benchmark and Climate Commitment reports. Available at: https://www.betterbuildingspartnership.co.uk/our-priorities/measuring-reporting/real-estate-environmental-benchmark

• Hoyt, T., Arens, E., and Zhang, H. (2015). Extending air temperature setpoints: simulated energy savings and design considerations.

• Roussac, A. C. (2013). Strategies for energy reduction in commercial buildings.

• BEIS (2016). Building Energy Efficiency Survey: offices final report. Available at: https://www.gov.uk/government/publications/building-energy-efficiency-survey-bees

• Evans, S., Fennell, P., Humphrey, D., Liddiard, R., Oraiopoulos, A., Palmer, J., Ruyssevelt, P., Shamsi, H., Amrith, S., and Steadman, P. (2026). National Buildings Database Phase 2. Department for Energy Security and Net Zero. Available at: https://www.gov.uk/government/publications/national-buildings-database-phase-2-understanding-great-britains-buildings

Read next

• Article 6: The Split-Incentive Problem.

• Article 9: NABERS for Britain.

About this series

This article is part of a fifteen-piece series adapting the 2025 PhD thesis "London and UK Office Buildings: Investigating Energy Use and Landlord-Tenant Influences" (Azhari, 2025) for a mixed academic and industry readership. The empirical findings draw on the 3DStock model of 6,038 office Self-Contained Units in Greater London with metered energy data for 2017, supplied by BEIS under a data-sharing agreement, alongside the Better Buildings Partnership Real Estate Environmental Benchmark. The qualitative findings draw on semi-structured interviews with seven major UK property organisations, conducted during the 2021 lockdown. Interviewees and their organisations are anonymised by role and organisation type. Please cite the original thesis for academic use.

Author. Rayan Azhari completed his PhD at the UCL Bartlett School of Environment, Energy and Resources in 2025, supervised by Paul Ruyssevelt and Kathryn Janda. The research was supported by the EPSRC Centre for Doctoral Training in Energy Demand (LoLo) and UK Research and Innovation through the Centre for Research into Energy Demand Solutions.

Other articles in the series. Article 1 The 30/85/89 Problem; Article 2 Why EPCs Do Not Tell You How Much Energy a Building Uses; Article 3 Eighteen Per Cent; Article 4 Mapping the Stock; Article 5 Height, Age and the Fuel Question; Article 6 The Split-Incentive Problem; Article 7 Green Leases and Service Charges; Article 8 From 38 to 73 Per Cent Energy Savings; Article 9 NABERS for Britain; Article 10 Time to Retire ECG-19; Article 11 Can London Speak for England and Wales; Article 12 The Hybrid-Work Footprint; Article 13 Why I Used Linear Regression Over Random Forest; Article 14 Vertical Postcodes; Article 15 What Is a Building?