As someone who works with commercial HVAC systems every day, I can tell you that most buildings waste energy in ways that can be corrected — often without major investment. You don’t need to replace everything at once. But to do this, you need to understand how your system currently operates and where adjustments, upgrades or better controls can reduce unnecessary energy use.
In this guide, I’ll walk you through specific changes you can make to your existing system to help you cut energy costs, improve control, and keep your system running more effectively over the long term.
1. Assess your current HVAC setup
Before making any changes, you need to understand what you’re working with. Many commercial buildings have HVAC systems that have been extended or altered over time. Without a clear picture of what’s installed and how it operates, it’s difficult to identify where energy is being wasted.
Start by listing the main components of your system. This may include boilers, chillers, air handling units (AHUs), ventilation fans, radiators, fan coil units, or heat pumps. If you’re unsure, check the building logbook or speak to your maintenance contractor. Each component should be checked for age, condition, and whether it still suits how the building is used today.
Next, look at how your system is zoned. Are there areas being heated or cooled that don’t need to be? Many older systems were set up with little flexibility, so identifying zones that can be controlled separately is often a good starting point.
Review how your system runs throughout the day and week. Is it on when the building is empty? Are there temperature complaints in certain areas? These signs can point to inefficient operation or poor control settings. If you don’t already monitor your HVAC energy use separately from your total energy bill, consider installing basic sub-metering or using your building management system (if available) to track usage.
2. Reduce unnecessary heating and cooling loads
One of the most effective ways to improve energy efficiency is to reduce how much heating and cooling your system needs to deliver in the first place. The less energy your building loses or gains through external factors, the less your HVAC system has to work.
Start by looking at the building envelope. This includes insulation, windows, doors, and any other areas where heat can be lost or gained. Poor insulation and air leaks increase the load on your system, especially during temperature extremes. If parts of the building are regularly overheating or losing heat quickly, there may be opportunities to improve insulation or reduce draughts.
You should also review how much heat is being generated inside the building. Lighting, IT equipment, and refrigeration units all contribute to internal heat gains. Switching to energy-efficient lighting and ensuring that equipment is turned off when not in use can help reduce cooling demand.
Consider natural ventilation where it makes sense. If the outside temperature is lower than the inside, you can use controlled ventilation to reduce indoor temperatures without running mechanical cooling. However, this must be balanced against security, noise, and air quality requirements.
Zoning is another key factor. If your current system heats or cools the entire building at the same level, you’re likely wasting energy. Divide the building into areas based on usage patterns. Meeting rooms, storage spaces, and unoccupied zones do not need the same conditions as occupied office areas. Installing separate controls or adjusting existing ones can help you better match HVAC output to actual need.
3. Optimise system controls
Once you’ve reduced unnecessary demand, the next step is to ensure your system only operates when and where it’s needed. Many buildings use more energy than necessary simply because HVAC controls are poorly set, ignored, or overridden.
Start with time controls. Check if your system is running outside of occupancy hours. Heating or cooling an empty building leads to avoidable energy use. Use programmable timers to align operation with actual working hours. For more accuracy, consider adding motion sensors in low-use areas, such as meeting rooms or corridors, so the system only runs when people are present.
Next, review your temperature settings. Many systems are set higher in winter or lower in summer than required. Aim for reasonable temperature bands instead of precise fixed values. It’s also important to maintain a “dead band” — a gap between heating and cooling set points to avoid both systems running at the same time. A difference of 4 to 5°C is usually effective.
Demand-controlled ventilation (DCV) can be a good option for areas where occupancy varies. These systems use sensors (such as CO₂ or motion sensors) to adjust airflow based on actual use. By reducing ventilation rates when rooms are empty or lightly used, you can cut fan energy and reduce heating and cooling loads at the same time.
Don’t forget to check your control devices themselves. Thermostats should be installed in appropriate locations — not near heat sources, direct sunlight, or draughts. If you’re using thermostatic radiator valves (TRVs), make sure they’re working properly and set to appropriate levels.
Many systems are capable of better performance, but are held back by poor control settings. Taking time to set controls correctly — and reviewing them regularly — is one of the simplest ways to reduce your HVAC energy use.
4. Maintain Your System Regularly
No matter how efficient your system is on paper, poor maintenance will reduce its performance and increase energy use over time. Dust, blockages, leaks, and worn parts all affect how well your HVAC system operates.
Regular servicing is essential. Boilers should be checked annually by a qualified engineer. Gas boilers require inspection at least once a year; oil-fired systems may need more frequent attention. Poorly maintained boilers can waste up to 10% more energy compared to those in good working order.
Filters in ventilation and cooling systems should also be inspected regularly. Blocked or dirty filters restrict airflow, which forces fans to work harder and reduces system efficiency. Many systems benefit from installing pressure gauges to indicate when filters need replacing.
Ductwork, fans, and coils should be kept clean. Dust and debris can significantly reduce the performance of air handling units. If your system includes refrigerant-based cooling, check that insulation on pipework is intact and that refrigerant levels are correct. Leaks or degraded insulation can lead to higher energy use to achieve the same cooling effect.
Check valves, pumps, and control systems. A faulty valve or a pump running continuously can waste a significant amount of energy without any visible symptoms. Small issues like this often go unnoticed until energy costs increase or comfort problems appear.
Maintenance should not be treated as a one-off task. Set up a maintenance schedule that includes routine inspections and corrective action. Doing so helps to avoid breakdowns, extend equipment life, and keep your energy use under control.
5. Upgrade components where it makes sense
Once you’ve optimised controls and ensured regular maintenance, the next step is to look at component upgrades. These don’t have to involve a full system replacement. In many cases, upgrading individual parts can result in meaningful energy savings without major disruption.
Start with boilers. If your system still relies on a non-condensing boiler, switching to a modern condensing model can improve efficiency significantly. Condensing boilers recover heat from exhaust gases, which would otherwise be wasted. This allows them to operate at higher efficiency, especially in systems with lower return water temperatures.
Motors and pumps are another area worth reviewing. Older systems may still use standard AC motors, which tend to run at a fixed speed. Replacing them with high-efficiency motors (class IE3 or better) and adding variable speed drives (VSDs) allows the system to match output to actual demand. This can reduce energy use substantially, particularly in ventilation and chilled water systems.
If your system uses fans or belt-driven equipment, check whether direct drive alternatives are available. These tend to be more efficient and require less maintenance. Electronically commutated (EC) motors are also a useful upgrade for fan coil units and smaller HVAC components, offering lower energy use and better control.
Heat recovery is another upgrade to consider. Many systems allow heat from exhaust air to be captured and reused to warm incoming fresh air. This reduces the heating load without additional fuel use. If you already have an air handling unit, check whether a heat recovery section can be added.
Lastly, review your control system. If your current controls are outdated or inflexible, upgrading to a basic building management system (BMS) can give you better oversight and control over time schedules, temperatures, and equipment status. Even small systems can benefit from smarter controls.
These types of upgrades can often be done during planned maintenance or minor refurbishments, and in many cases, the savings will cover the cost within a few years.
6. Consider whole-system upgrades in major renovations
If you’re planning a major renovation or fitting out a new building, this is the best time to address HVAC energy efficiency at a broader level. Starting from scratch gives you the flexibility to choose systems that match the building’s actual needs and reduce long-term operating costs.
In these cases, it’s important to think beyond individual components. A well-designed system should integrate heating, cooling, and ventilation in a way that matches the building layout, usage patterns, and future occupancy. For example, rather than installing standalone heating and cooling units, you might choose a centralised system with zone controls, or a mixed-mode setup that combines natural and mechanical ventilation.
Make sure to allow for zoning at the design stage. Different parts of the building will have different occupancy patterns and temperature requirements. Meeting rooms, server rooms, and open-plan offices should not be treated the same. Zoning allows you to control conditions more precisely and avoid wasting energy in unused areas.
Modern heat pumps, especially those with variable refrigerant flow (VRF) or ground source systems, are also worth considering. They provide both heating and cooling from a single unit and can be designed to recover heat between zones. If your building has consistent heating and hot water needs, a combined heat and power (CHP) system might also be a suitable option — provided the building runs year-round and the heat load is stable.
Don’t overlook system flexibility. The system you install should allow for future changes in occupancy or use. This might include modular components that can be added later, or a controls platform that supports new zones without replacing core hardware.
Although upfront costs are higher during a full renovation, the opportunity to improve performance and reduce energy costs long-term is also much greater. A well-designed system will deliver consistent savings and help the building meet future energy and carbon targets.
7. Track results and keep improving
Once you’ve made changes to your HVAC system, it’s important to measure the results and make further adjustments where needed. Energy efficiency isn’t something you fix once — it needs to be monitored and managed over time.
Start by comparing energy usage before and after each change. If you have sub-metering in place, check the energy consumption of your HVAC equipment directly. If not, use your overall energy bills, but keep in mind that seasonal variations will affect the data. Try to compare similar periods under similar weather conditions.
Log any adjustments you make to temperature settings, time schedules, or zoning. Over time, this helps you understand what’s working and what still needs attention. If you’re using a building management system (BMS), review the data regularly to spot trends, such as unnecessary out-of-hours operation or unexpected spikes in usage.
You should also check whether the changes are affecting comfort. Speak to the people using the building. If certain areas feel too hot, too cold, or poorly ventilated, it might be a sign that your system needs further adjustment. The goal is to reduce energy use while maintaining acceptable conditions throughout the building.
Make time to review your HVAC performance at least once or twice a year. Include it as part of your regular building checks. Doing this helps ensure that your system remains efficient, and that small problems don’t develop into larger issues.
If you’re unsure where to begin or would like expert support in reviewing your HVAC system, we’re here to help. Our team can assess your current setup, identify areas of improvement, and recommend practical steps to reduce energy use without compromising comfort. Get in touch with us to schedule a consultation and take the first step towards a more efficient system.