Commercial heating, ventilation and air conditioning (HVAC) systems are essential for maintaining comfortable, healthy working environments. However, they can also become significant sources of unnecessary energy consumption…
Heating may operate long after employees have left. Ventilation fans might run at full capacity in partially occupied buildings. Poorly configured controls can cause heating and cooling systems to work against one another.
For energy managers, these problems create an opportunity to improve building performance without necessarily investing in entirely new equipment.
The Carbon Trust identifies better controls, effective maintenance and reducing unnecessary demand as important opportunities for cutting HVAC energy consumption.
However, lower energy use should never come at the expense of adequate ventilation or appropriate workplace temperatures.
The challenge is finding the right balance between efficiency, comfort and operational requirements.
Before replacing an HVAC system, make sure the existing one is operating when, where and how it should.
At a Glance: Where HVAC Efficiency Can Be Improved
| Area to optimise | Common problem | What to review |
|---|---|---|
| Operating schedules | Systems run when buildings are empty | Occupancy patterns, start times and shutdown periods |
| Temperature controls | Overheating, overcooling or conflicting settings | Setpoints, deadbands and zone controls |
| Ventilation | Fans operate unnecessarily or airflow is poorly balanced | Fresh-air requirements, demand control and fan speed |
| Heat recovery | Recoverable heat is lost through exhaust air | Heat exchangers, bypass controls and maintenance |
| Maintenance | Faults and dirty components reduce performance | Filters, sensors, valves, dampers and servicing |
| Performance monitoring | Energy waste goes unnoticed | Metering, BMS trends, comfort complaints and faults |
Understand Where Energy Is Being Wasted
The first step in HVAC optimisation is establishing how the existing system operates.
An energy manager may know the building’s total gas and electricity consumption without understanding how much energy is used by heating, ventilation and cooling.
Building management system (BMS) records, energy meters, maintenance histories and occupancy information can help identify potential inefficiencies.
For example, heating demand during unoccupied periods may indicate that schedules need reviewing.
Persistent differences between floors could suggest problems with zoning, controls or heat distribution.
The Carbon Trust recommends identifying existing systems and assessing actual building needs before selecting energy-saving measures.
The objective should be to establish a reliable baseline and prioritise changes that address genuine operational problems.
Match Operating Schedules to Occupancy
One of the simplest opportunities is reviewing when HVAC equipment operates.
Many commercial buildings have changed their working patterns, but their heating and ventilation schedules may not have been updated accordingly.
An office operating at reduced occupancy on certain days may still follow the same programme established when every desk was occupied.
Similarly, heating and ventilation may start earlier than necessary or continue running after the building has closed.
The Carbon Trust identifies time controls as an important means of reducing unnecessary consumption.
Energy managers should compare programmed schedules against actual occupancy and building requirements.
However, shutdown periods must take account of factors such as frost protection, humidity control and any operational or ventilation requirements that continue outside normal working hours.
Optimisation means removing unnecessary operation, not indiscriminately switching systems off.
Review Heating and Cooling Setpoints
Temperature controls can have a substantial influence on energy use.
Poorly selected setpoints may cause systems to provide more heating or cooling than necessary.
In some buildings, heating and cooling equipment may even operate simultaneously because of conflicting settings or poorly coordinated controls.
Energy managers should review temperature targets, control deadbands and the way different systems interact.
A deadband is the range between heating and cooling activation thresholds. Appropriate separation can help prevent unnecessary switching between the two.
However, there is no single temperature setting suitable for every workplace.
The Health and Safety Executive (HSE) explains that thermal comfort depends on air temperature, radiant temperature, humidity, air movement, clothing and activity levels.
Setpoints should therefore reflect building use and occupant requirements rather than arbitrary energy-saving targets.
Make Better Use of Zoning
Large commercial buildings rarely have identical heating and ventilation requirements throughout.
Meeting rooms, reception areas, offices and storage spaces may operate at different times and experience varying levels of occupancy.
Treating the whole building as a single zone can result in unnecessary energy use.
Zoning allows systems to respond more closely to the needs of individual areas.
The UK Government’s Energy Technology List (ETL) highlights how heating and ventilation zone controls can reduce energy consumption by matching operation to activity and occupancy.
However, zoning requires appropriate design and reliable controls.
An excessive number of poorly configured zones can introduce complexity, while inappropriate settings may create uncomfortable conditions.
Energy managers should assess whether existing zoning reflects how the building is actually used.
Optimise Ventilation Without Reducing Air Quality
Ventilation is particularly important because reducing airflow may appear to offer energy savings.
However, employers must provide adequate fresh air in enclosed workplaces.
The HSE makes clear that ventilation is necessary to remove stale air and maintain suitable indoor conditions.
Energy managers should therefore begin by establishing the ventilation requirements of different spaces.
Some areas may need consistent ventilation because of occupancy or operational activities.
Others may be suitable for demand-controlled ventilation, where airflow adjusts in response to relevant occupancy or air-quality information.
The ETL identifies occupancy and air-condition sensors as potential components of ventilation control strategies.
But demand control must maintain appropriate minimum airflow and respond effectively to changing conditions.
The goal is to eliminate unnecessary ventilation, not reduce necessary fresh air.
Consider Fan Speeds and Variable Controls
Ventilation fans can consume substantial electricity, particularly where they operate for extended periods.
Systems that run at a constant speed may use more energy than necessary when demand is lower.
Variable-speed drives and suitable controls can allow fans to respond to changing airflow requirements.
However, the potential benefit depends on the existing equipment, system design and operating conditions.
Simply reducing fan speed without understanding the ventilation requirements could compromise air quality or system performance.
Energy managers should work with competent specialists to establish whether speed control is appropriate.
The assessment should consider the complete ventilation system, including ductwork, pressure requirements and control arrangements.
A properly optimised system should provide the required airflow without unnecessary fan energy.
Check Heat Recovery Performance
Heat recovery ventilation can reduce the energy required to condition incoming outdoor air.
By transferring heat from outgoing air to incoming air, suitable systems can reduce heating demand during colder periods.
However, heat recovery equipment must be correctly maintained and controlled.
Fouled heat exchangers, faulty bypass arrangements or inappropriate operating settings can reduce the expected benefits.
The ETL includes heat recovery ventilation technologies and provides information about relevant energy-efficiency criteria.
Energy managers should establish whether existing heat recovery systems are operating as intended.
They should also consider whether bypass controls are functioning correctly when heat recovery is not beneficial.
The objective should be to recover useful energy when appropriate, without creating unnecessary fan energy or operational problems.
Make Maintenance Part of Energy Management
HVAC maintenance is often assessed according to equipment reliability and statutory requirements.
But it also influences energy performance.
Dirty filters, poorly maintained heat exchangers, faulty dampers and inaccurate sensors can cause systems to operate inefficiently.
The Carbon Trust identifies maintenance as a practical opportunity to improve HVAC efficiency.
Energy managers should therefore work with facilities teams and maintenance contractors to identify defects that may be increasing energy consumption.
A sensor providing inaccurate temperature information, for example, may cause equipment to operate unnecessarily.
Similarly, a control valve that fails to close properly may allow heating or cooling to continue when it is no longer required.
Maintenance reports should highlight potential energy consequences rather than record only whether equipment remains operational.
Review Building Management System Settings
A BMS can provide valuable opportunities to coordinate heating, ventilation and cooling.
However, its effectiveness depends on configuration, accurate information and regular oversight.
Systems may retain temporary overrides long after the circumstances that justified them have changed.
Schedules can become inconsistent, alarms may be ignored and control sequences may no longer reflect building requirements.
Energy managers should review BMS settings alongside relevant maintenance and operational colleagues.
This may include examining time programmes, overrides, setpoints, sensor readings and equipment status.
Trend data can also help reveal unusual patterns.
For example, repeated heating demand during warm weather may indicate a control problem requiring investigation.
A BMS should provide a basis for active management rather than simply automate inefficient settings.
Use Occupant Feedback to Identify Problems
Energy consumption data does not tell the whole story.
Employees may identify uncomfortable conditions that reveal weaknesses in HVAC operation.
Repeated complaints about overheating, cold areas or draughts can indicate inappropriate controls, poor distribution or equipment faults.
The HSE recommends assessing thermal comfort through a combination of environmental factors and worker feedback.
Energy managers should therefore compare energy data with information about actual building conditions.
If occupants regularly use portable heaters or open windows while heating is operating, the building may have an underlying control or distribution problem.
Addressing the cause could improve both comfort and efficiency.
The objective should be to make the building work better for the people using it, rather than simply reduce meter readings.
Consider Seasonal Recommissioning
HVAC systems operate under different conditions throughout the year.
A building may perform well during winter but struggle with overheating or poorly coordinated controls during warmer periods.
Seasonal recommissioning involves reviewing how systems perform as operating conditions change.
This can include checking control sequences, sensors, heating and cooling transitions, ventilation settings and relevant safety functions.
The process should also consider changes in occupancy or building use.
A room that has been converted into a high-occupancy meeting space may require different ventilation arrangements from those originally specified.
Recommissioning can help identify problems that have developed gradually or remained unnoticed.
It may also reveal opportunities for improvement without substantial equipment replacement.
Measure Savings Against Actual Conditions
Energy managers should avoid relying solely on estimated savings.
Where changes are introduced, performance should be reviewed against an appropriate baseline.
However, heating and cooling demand depends on factors including weather, occupancy and building operating hours.
A mild winter may reduce heating energy independently of any improvement to HVAC controls.
Conversely, a particularly cold period could increase consumption even when the system has become more efficient.
Meaningful comparisons should therefore consider relevant external and operational factors.
Metering, BMS trends and maintenance information can help establish whether changes are delivering the intended results.
Comfort and ventilation performance should also be monitored.
An apparent reduction in energy consumption is not a success if it results from inadequate heating or fresh-air provision.
Prioritise Improvements Before Major Replacement
Not every HVAC problem requires a new heating or ventilation system.
Improved operating schedules, repaired controls, appropriate maintenance and recommissioning may deliver worthwhile benefits from existing equipment.
However, optimisation also has limits. Ageing or unsuitable plant may continue to perform poorly despite operational improvements.
Energy managers should therefore distinguish between problems that can be corrected through better management and those requiring investment.
The ETL provides information on independently assessed energy-efficient equipment that may support future replacement decisions.
A phased approach can help organisations address low-cost opportunities first while developing a longer-term plan for more substantial upgrades.
The important principle is to understand existing performance before committing significant capital expenditure.
Questions to Ask HVAC Optimisation Providers
Before engaging an HVAC specialist, energy managers should consider:
- How will current heating and ventilation performance be assessed?
- What data is required to establish an accurate baseline?
- Can operating schedules be aligned with actual occupancy?
- How will heating and cooling setpoints be reviewed?
- Are simultaneous heating and cooling problems being investigated?
- Could improved zoning reduce unnecessary energy use?
- How will adequate ventilation be maintained?
- Is demand-controlled ventilation appropriate for the building?
- Can fan speeds be optimised safely?
- Is existing heat recovery equipment operating effectively?
- Which maintenance issues may be increasing consumption?
- Can BMS settings and overrides be reviewed?
- What seasonal recommissioning is recommended?
- How will comfort and indoor air quality be assessed?
- How will energy savings be measured and verified?
Frequently Asked Questions
What is HVAC optimisation?
HVAC optimisation involves improving the operation of heating, ventilation and air conditioning systems to reduce unnecessary energy use while maintaining suitable building conditions.
How can businesses reduce HVAC energy costs?
Potential measures include better operating schedules, suitable temperature settings, zoning, demand-controlled ventilation, maintenance and improved building management system configuration.
Can ventilation be reduced to save energy?
Ventilation can sometimes be adjusted according to occupancy and demand, but adequate fresh air must always be maintained. The appropriate approach depends on the building and its operating requirements.
What is demand-controlled ventilation?
Demand-controlled ventilation adjusts airflow in response to relevant indicators, such as occupancy or indoor air conditions, helping avoid unnecessary ventilation where suitable.
Can existing HVAC systems be made more efficient?
Yes. Improvements to controls, maintenance, commissioning and system operation can often deliver benefits without replacing major equipment.
How should HVAC energy savings be measured?
Savings should be evaluated against a suitable baseline while considering factors such as weather, occupancy, operating hours and building conditions.
Product & Services Guide
The Energy Management Summit brings together senior energy, sustainability, estates and facilities decision-makers with relevant solution providers through pre-arranged one-to-one meetings, offering an opportunity to explore HVAC optimisation, building controls, heating and ventilation technology and wider energy efficiency solutions.
Make Existing Systems Work Harder
Improving HVAC efficiency does not always require replacing major building services equipment.
Often, the greatest opportunities come from understanding how existing systems operate and making targeted changes that eliminate unnecessary energy consumption.
A practical optimisation framework is: measure → adjust → maintain → verify → improve
Measure how the building and its HVAC systems currently perform.
Adjust operating schedules, controls and ventilation appropriately.
Maintain equipment to preserve efficiency and reliability.
Verify the effect on energy consumption and occupant conditions.
Then use the findings to identify further improvements.
The strongest HVAC optimisation strategy is not simply the one that produces the lowest energy reading.
It’s the one that removes wasted energy while maintaining the comfort, air quality and reliability the building needs.
The Energy Management Summit brings together senior energy, sustainability, estates and facilities decision-makers with relevant solution providers through pre-arranged one-to-one meetings, offering an opportunity to explore HVAC optimisation, building controls, heating and ventilation technology and wider energy efficiency solutions.
Related Reading
This is the second article in our November Heating & Ventilation series.
Our first article, Commercial Heating & Ventilation Systems: What Energy Managers Should Compare, explored how buyers should assess heating technologies, ventilation requirements, heat recovery, controls, installation and whole-life cost.
This follow-up focuses on improving existing systems through practical operational changes, better maintenance, smarter controls and ongoing measurement.
Sources
- Carbon Trust – Heating, Ventilation and Air Conditioning Guide
- Energy Technology List – Heating, Ventilation and Air Conditioning Equipment
- HSE – Ventilation in the Workplace
- HSE – Balancing Ventilation with Workplace Temperature
- HSE – Thermal Comfort
- HSE – Managing Workplace Temperatures
- Energy Technology List – Energy-Efficient Products
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