A commercial building energy audit report should do more than describe a building and list possible energy-saving ideas. It should connect energy data with the way the building is occupied, controlled and operated, then turn the findings into practical priorities.

The best reports distinguish between unavoidable consumption and genuine waste. They explain which improvements are worth pursuing, where further investigation is needed and what should happen next.

“The value of an energy audit report lies in the quality of the diagnosis, not the number of pages.”

What is a building energy audit report?

A building energy audit report is the written output of an investigation into how a commercial building uses energy.

It will normally draw on several sources of evidence, including:

electricity and gas consumption;
half-hourly energy data, where available;
utility bills and meter information;
building operating hours;
occupancy patterns;
heating, cooling and ventilation systems;
lighting and controls;
plant schedules and Building Management System settings;
conversations with facilities, estates or operational staff;
observations made during the site visit.

The report should bring this information together into a clear explanation of the building’s current energy performance.

It should not simply repeat the information supplied to the auditor. It should interpret it.

Executive summary

Most commercial building energy audit reports begin with an executive summary.

This should give decision-makers a concise overview of:

the main findings;
the most significant sources of waste;
the strongest energy-saving opportunities;
any urgent operational or control issues;
the recommended priorities;
the potential costs and savings, where these can be estimated reliably.

The executive summary is particularly important for senior managers, trustees, finance teams or board members who may not read the full technical report.

It should be possible to understand the building’s main energy issues and recommended next steps without working through every detailed section.

Building and operational overview

A report should explain what kind of building has been audited and how it is used.

This may include:

the building type;
approximate floor area;
age and construction;
operating hours;
occupancy levels;
seasonal patterns;
areas with different uses;
landlord and tenant responsibilities;
specialist environmental or operational requirements.

This context matters because the same level of energy use may be reasonable in one building and excessive in another.

A museum with environmental controls, a theatre with evening performances and an office with conventional weekday hours will have very different energy profiles.

Energy-consumption analysis

One of the most important sections should explain how much energy the building is using and how that consumption changes over time.

The report may review:

annual electricity use;
annual gas or other fuel use;
monthly consumption patterns;
seasonal peaks;
changes from one year to another;
energy use per square metre;
comparisons with available benchmarks;
unusual increases or inconsistencies;
the effect of occupancy or operating changes.

The aim is not merely to reproduce utility bills in a chart. The analysis should identify meaningful patterns and explain what they may indicate.

Half-hourly data and load profiles

Where half-hourly electricity data is available, the report should examine the building’s load profile.

This can reveal:

when consumption rises in the morning;
when it falls after normal operating hours;
whether equipment starts too early;
whether plant continues running after the building closes;
what happens overnight;
whether weekends resemble weekdays;
whether consumption is stable or erratic;
whether the building has a high baseload.

Half-hourly data is valuable, but it does not explain the cause of every pattern on its own. A rise in electricity use may be caused by heating pumps, cooling, ventilation, lighting, process equipment or a combination of systems.

Overnight and out-of-hours energy use

A good report should pay particular attention to what happens when the building is closed or lightly occupied.

Some overnight demand may be essential. Fire alarms, security systems, servers, refrigeration and specialist equipment may need to operate continuously.

The report should distinguish this necessary baseload from avoidable consumption. Common findings include:

heating running overnight;
pumps operating continuously;
fans and ventilation systems left on;
cooling operating in empty areas;
hot-water systems maintaining unnecessary temperatures;
local heaters or air-conditioning units left running;
weekday schedules copied into weekends;
controls left in override;
large numbers of smaller electrical loads remaining active.

Out-of-hours consumption is often important because it can continue for more hours each week than the building is fully occupied.

Heating, cooling, ventilation and lighting

A commercial building energy audit report should examine the major systems that drive consumption and explain how their operation affects the overall energy profile.

Heating systems

The report may assess:

boiler or heat-pump performance;
heating schedules;
start and stop times;
temperature settings;
weather compensation;
zoning;
simultaneous heating and cooling;
local heaters;
control overrides;
frost-protection settings.

Poor schedules, unsuitable set points or ineffective control can cause substantial waste even where the main plant is relatively efficient.

Cooling and ventilation

The report may examine:

air-handling unit schedules;
extract and supply fans;
cooling set points;
local split systems;
ventilation rates;
heat recovery;
occupancy controls;
areas with different operating needs.

Lighting

The lighting section should consider both the efficiency of the fittings and the way lighting is controlled.

It may cover LED replacement, occupancy sensors, daylight controls, external lighting, display lighting, over-lit areas and lighting left on outside occupied hours.

Building Management System and controls

Controls are often one of the most important parts of a commercial energy audit.

A building may have efficient equipment but still use excessive energy because the controls do not reflect how the building is occupied.

The report should consider:

time schedules;
temperature set points;
optimum start and stop;
holiday settings;
weekend operation;
overrides;
sensor locations and accuracy;
manual controls;
competing systems;
responsibilities for checking and changing settings.

A schedule displayed on a BMS does not guarantee that the plant is operating correctly. Sensors may be inaccurate, overrides may be active and equipment may behave differently from what the screen suggests.

Building fabric and operational practices

Building fabric

The audit report may identify opportunities related to:

roof, wall or floor insulation;
windows and glazing;
doors and draughts;
air leakage;
damaged seals;
thermal bridging;
areas of poor comfort.

In historic buildings, changes may need to respect conservation requirements, moisture behaviour and the significance of the fabric.

Operational practices

Not all energy waste is caused by inefficient equipment. The report should also consider:

unclear responsibility for controls;
contractors changing settings;
temporary overrides becoming permanent;
equipment added without reviewing the load;
poor communication between facilities and occupants;
no routine review of energy data;
responsibility gaps between landlords and tenants.

Identified energy-saving opportunities

The recommendations section should set out the opportunities identified during the audit and explain why each recommendation has been made.

These may include:

correcting time schedules;
reducing unnecessary overnight operation;
adjusting heating or cooling set points;
repairing or replacing failed sensors;
improving zoning;
installing occupancy controls;
improving staff procedures;
carrying out maintenance;
upgrading lighting;
improving insulation;
investigating plant replacement;
reviewing solar PV or other generation;
introducing regular energy monitoring.

Generic recommendations such as “improve staff awareness” or “consider renewable energy” are unlikely to be useful unless they are linked to an identified issue.

Estimated costs, savings and payback

Where sufficient information is available, the report should estimate:

implementation cost;
annual energy saving;
annual financial saving;
carbon reduction;
simple payback period;
expected lifespan;
level of confidence in the estimate.

Not every measure can be calculated precisely during a building energy audit. Some recommendations may require contractor quotations, detailed design, temporary monitoring or further investigation.

A good report should be open about this rather than presenting uncertain estimates as guaranteed savings.

Prioritised action plan

A report should help the organisation decide what to do first.

Immediate actions

Correct schedules, reset overrides, change set points, switch off unnecessary equipment, repair simple control faults and clarify responsibility.

Short-term actions

Install additional controls, replace failed sensors, improve zoning, introduce monitoring or carry out targeted maintenance.

Medium- or long-term measures

Replace major plant, improve fabric, undertake larger controls projects, install solar PV or consider heat pumps and other capital measures.

The report should indicate which actions are likely to deliver the strongest benefits and which depend on other work being completed first.

Further investigation and monitoring

Some energy problems cannot be fully diagnosed from existing information and a single site visit.

The report may recommend:

temporary electricity sub-metering;
temperature or humidity monitoring;
logging plant operation;
checking sensor accuracy;
reviewing control trends;
obtaining contractor quotations;
carrying out a specialist survey;
monitoring the effect of control changes.

Recognising where more evidence is needed is often better than making a weak recommendation based on assumptions.

What makes an energy audit report genuinely useful?

A useful commercial building energy audit report should be:

specific to the building;
based on evidence;
clear about assumptions;
technically credible;
understandable to non-specialists;
practical for facilities and operational teams;
useful to financial decision-makers;
realistic about costs and constraints;
prioritised;
focused on action.

The report should also recognise that energy management does not end when the document is delivered. Schedules change, equipment fails, staff move roles, contractors alter settings and new systems are added.

Case study

Turning audit findings into practical action

At Stourbridge Glass Museum, analysis found that the museum was using almost as much electricity while closed as it did while open.

The building already had efficient air-source heat pumps, but control problems, unsuitable settings and the use of direct-electric heaters were affecting performance.

The importance of the audit was not simply that these issues appeared in a report. It was that the evidence helped the organisation understand what was happening and identify practical actions.

Read the Stourbridge Glass Museum energy audit case study

Historic estate

Energy management at Blenheim Palace

OES has also supported energy management work at Blenheim Palace, where the combination of a historic estate, complex buildings and operational requirements made context particularly important.

Read the Blenheim Palace energy management case study

Questions to ask before commissioning an audit

Will the audit include a site visit?
Will energy data be analysed rather than simply reproduced?
Will the auditor investigate out-of-hours use?
Will plant, controls and schedules be reviewed?
Will the report explain the likely causes of waste?
Will recommendations be specific to the building?
Will actions be prioritised?
Will estimated costs and savings show their assumptions?
Will the report identify where further investigation is needed?
Will the findings be clear enough for technical and non-technical readers?

The answers will help distinguish a practical building investigation from a generic report-writing exercise.

A report should lead to better decisions

The purpose of a commercial building energy audit report is not to create a record that sits on a shelf.

It is to help the organisation understand the building, reduce avoidable waste and make better decisions about controls, maintenance, operational changes and future investment.

The most valuable report is not necessarily the longest. It is the one that gives the clearest explanation of what is happening and what should happen next.

Need clearer evidence from your building?

Start with a practical building energy audit

Oxford Energy Services provides fixed-fee building energy audits for organisations that need clearer evidence, practical recommendations and a prioritised plan.

The audit reviews energy use, available half-hourly data, plant, controls, schedules and building operation to identify where energy may be wasted and which actions are worth pursuing.

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