How much does HVAC design cost for a commercial building in Australia?

For a standard commercial fitout (200-500 sqm), expect $3,000-$8,000 for mechanical design. Mid-size projects (500-2,000 sqm) range from $8,000-$25,000. Multi-storey developments (2,000+ sqm) can be $25,000-$80,000+ depending on system complexity. These are engineering design fees only, not installation costs.

What's included in HVAC design fees?

Heating and cooling load calculations, equipment selection, ductwork layout drawings, ventilation calculations per AS 1668.2, Section J energy compliance documentation, specifications for tendering, and coordination with other building services. Most engineers provide a fixed-fee proposal based on project scope.

Why do I need to pay for HVAC design separately from installation?

The design documentation is what your certifier needs to issue a construction certificate. It's also what contractors price from. Without engineering drawings, contractors are guessing - which leads to over-sizing (wasting money), under-sizing (uncomfortable spaces), or non-compliance (failed CC applications). Design fees are typically 5-10% of the installation cost but prevent much larger problems.

Can I get a free HVAC design from the contractor?

Some contractors offer "free design" bundled with installation. This works for simple split systems but creates problems on commercial projects. The contractor's design prioritises their preferred equipment and may not optimise for energy efficiency or lifecycle cost. It also can't be independently tendered to other contractors, so you lose competitive pricing.

How Much Does HVAC Design Cost for a Commercial Building?

Section 1

The Short Answer

HVAC design fees in Australia range from $3,000 for a simple commercial fitout to $80,000+ for a multi-storey development. Most projects fall in the $5,000–$25,000 range. These are engineering design fees for the drawings, calculations, and documentation you need for certification and construction. They do not include the cost of equipment or installation. Most engineers quote a fixed fee based on project scope, so you know the cost upfront before committing.

Section 2

Typical Fee Ranges by Project Type

1

Small Commercial Fitout (under 500 sqm)

Office, retail, or cafe fitout. $3,000–$8,000. Includes load calculations, equipment selection, duct layout, Section J input, and specification. Turnaround: 2–3 weeks.

2

Medium Commercial (500–2,000 sqm)

Multi-tenancy office, large retail, restaurant, gym. $8,000–$25,000. More complex systems (VRF, central plant, kitchen exhaust). Includes full documentation set for CC. Turnaround: 3–6 weeks.

3

Multi-Storey Development (2,000+ sqm)

Mixed-use, residential towers, large commercial. $25,000–$80,000+. Central plant design, riser coordination, BMS specification, staged documentation across DA, CC, and construction. Turnaround: 2–6 months depending on project program.

4

Specialist Systems (any size)

Car park ventilation, smoke exhaust, kitchen exhaust, clean rooms, data centres. Add $2,000–$15,000 depending on complexity. These are often quoted separately because they require specific calculations and compliance documentation.

Section 3

What Drives the Cost Up or Down

Building size and number of floors - more area means more design work
System complexity - split systems are simpler than central plant or VRF
Number of zones and control requirements - more zones, more coordination
New build or refurbishment - existing buildings have more constraints
Specialist requirements - kitchen exhaust, car park ventilation, smoke exhaust
Documentation scope - DA-level vs full CC documentation vs construction-phase support
How quickly you need it - rush jobs cost more
Multi-discipline packages - adding hydraulic, electrical, fire reduces per-discipline cost

Section 4

What You Get for the Fee

Heating and cooling load calculations for every zone
Equipment selection and scheduling (make, model, capacity)
Ductwork layout drawings (plan and section)
Mechanical ventilation calculations per AS 1668.2
Section J energy efficiency compliance documentation
Specification for tendering and construction
Coordination with hydraulic, electrical, and fire services
Response to contractor queries during construction (most engineers include a set number of hours)

Section 5

Design Fee vs Installation Cost

Engineering design fees are typically 5–10% of the mechanical installation cost. On a $150,000 HVAC installation, expect $8,000–$15,000 in design fees.

This investment produces the documentation for certification, competitive tendering (which typically saves 10–20% on installation by getting 3+ quotes), and a system that is correctly sized for the space.

Skipping the design phase does not save money. It shifts the design risk to the contractor, who builds it into their price. You also lose the ability to tender competitively, which almost always costs more than the engineering fee would have.

Section 6

Who Needs to Know What

Section 7

References

National Construction Code 2022, Section J — Energy Efficiency
AS 1668.2:2012, The use of ventilation and airconditioning in buildings — Mechanical ventilation in buildings
Consult Australia, Fee guidelines for consulting engineers
AIRAH, Industry benchmarks for HVAC design