Air Handling Unit Cost

Why there is no simple price per m³/s

Airflow duty is where an AHU specification starts, and it is a poor predictor of cost on its own. Units built for the same nominal airflow routinely differ several-fold in price, and the reasons are worth understanding before you compare quotations.

Construction specification is the biggest single multiplier. A standard office AHU, a corrosion-resistant unit for a swimming pool hall, and a hygienic unit for a food or pharmaceutical application are genuinely different machines — different casing materials and treatments, different coil protection, different fixings, different internal finishes and drainage detailing. See pool AHUs for the clearest example of why this matters.

Heat recovery is the next. Whether the unit has recovery at all, and whether it uses a plate heat exchanger, a thermal wheel or a run-around coil, changes both cost and physical size. Recovery efficiency is a headline figure worth comparing directly between bidders, because on a system that runs continuously the difference compounds every hour of operation.

Standard product versus bespoke matters too. Manufacturers offer standard ranges at competitive prices; a unit built to fit a specific plant-room opening, or to hit an unusual duty, costs more and takes longer. On a replacement into an existing plant room, physical constraints frequently force the bespoke route — see air handling units.

Beyond the unit itself, fan and motor specification, filtration grade (higher grades cost more to buy and more to run, because finer filters mean higher pressure drop), attenuation where noise is a concern, and the controls package all move the total.

The cost that is not the unit: getting it in

On replacement projects, installation regularly exceeds the price of the equipment, and the reason is almost always access.

Air handling units are large. Getting one into a plant room can require craneage, removal of louvres or roof sections, temporary structural work, or — quite commonly — splitting the unit into sections for transport and rebuilding it in place. Some plant rooms were built around their AHU, with no route large enough to remove it intact, and in those cases the existing unit may have to be cut up and removed in pieces.

The other installation lines: ductwork modifications where the new unit's connections differ; electrical supply and controls wiring; pipework for heating and cooling coils; structural support and anti-vibration mounting; commissioning and balancing, which on a ducted system is a substantial exercise in its own right and should be a priced deliverable with measured records; and builder's work and making good.

This is why an AHU quotation should always be read as a package. A low equipment price with installation excluded tells you very little.

Replace or refurbish?

Full replacement is not always the right answer, and refurbishment is frequently overlooked. Where the casing is structurally sound and the access problem is severe, replacing components in situ can deliver most of the benefit at a fraction of the disruption.

Refurbishment typically covers fan replacement — often the single highest-value item, since swapping an old belt-driven fan for a modern direct-drive EC fan can substantially cut energy use — plus coil replacement, filter section upgrades, damper and actuator renewal, controls replacement, and casing repairs with new insulation and panel seals.

Refurbishment makes most sense where the casing is sound, where access makes replacement very expensive, where the existing duty is still correct, and where the building can only tolerate short shutdowns. Replacement wins where the casing is corroded, where the duty has changed because the building's use has changed, where you want modern heat recovery that the old unit cannot accommodate, or where the unit is simply beyond economic repair.

A useful intermediate step: an upgrade to the controls and fans only is often the highest return per pound spent on an older AHU, because it addresses the running cost — which over the unit's life is the dominant number — without the capital and disruption of a full replacement.

Running cost: fans, filters and recovery

An AHU's lifetime cost is dominated by the energy its fans consume, and fan power rises sharply with resistance in the system. That makes three things unusually important.

Filter selection and maintenance. Filters are the largest single resistance in most systems, and a loaded filter costs energy every hour until it is changed. There is a genuine trade-off between filtration grade and running cost, and it should be a considered decision rather than an inherited default.

Fan type. Modern direct-drive EC fans avoid belt losses and modulate efficiently, which matters because ventilation systems, like cooling systems, spend most of their life below design duty.

Heat recovery efficiency. On a system moving large volumes of tempered air continuously, the difference between a mediocre and a good recovery efficiency is a large annual number. It is worth comparing this figure carefully rather than accepting that recovery is simply "included".

Then there is ductwork hygiene under TR19, which carries both indoor-air-quality and fire-safety dimensions and is a recurring cost — see SFG20 and maintenance and PPM.

Frequently asked questions

How much does an air handling unit cost?

The range is very wide — from around £15,000 for a modest standard unit to £400,000 or more for a large or specialist one. Airflow duty is only the starting point; construction specification, heat-recovery type and efficiency, filtration grade, controls, and whether the unit is standard or bespoke all move the price substantially, often several-fold for the same nominal airflow.

Why is installing an AHU more expensive than buying one?

Because access usually dominates. AHUs are large, and getting one into a plant room can require craneage, louvre or roof removal, temporary structural work, or splitting the unit into sections and rebuilding it in place. Add ductwork modifications, electrical and pipework connections, structural support, commissioning and balancing, and installation frequently exceeds the equipment cost.

Should I replace or refurbish my air handling unit?

Refurbish where the casing is structurally sound, access makes replacement very expensive, the duty is still correct and the building can only tolerate short shutdowns. Replace where the casing is corroded, the building's use has changed the required duty, or you want modern heat recovery the old unit cannot accommodate. Upgrading fans and controls alone is often the best return on an older unit.

What is the biggest running cost on an AHU?

Fan energy, and it rises sharply with system resistance. That makes filter selection and change frequency, fan type — modern direct-drive EC fans avoid belt losses and modulate well — and heat-recovery efficiency the three levers that matter most. Over the unit's life these normally exceed the purchase price considerably.

Do pool or food-industry AHUs cost more?

Substantially, because they are different machines. A pool hall AHU needs corrosion-resistant casing, coils, fasteners and drainage to survive warm chlorinated air, and hygienic units for food or pharmaceutical use have their own construction and finish requirements. This specification is the line most often trimmed when a project is over budget, and the consequence arrives years later.

See air handling units for capacity, construction and ductwork, pool AHUs for the specialist case, and the main cost guide for other systems. Or request a quote.