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HVAC BOQ Estimator Calculator

Reference: Order-of-magnitude estimate

📋 HVAC

Free HVAC BOQ estimator. Order-of-magnitude bill of quantities and cost for chillers, AHUs, ductwork and piping from built-up area, cooling load in TR, system type and duct type.

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Order-of-magnitude estimate

Design criteria, governing codes and assumptions.

ℹ About This Calculator

A quick air-conditioning budget is often needed before any HVAC design exists. This estimator produces an order-of-magnitude bill of quantities and cost for the plant, air side and water side from the built-up area, the cooling load in TR, the chosen system type and the ductwork type, using typical per-TR and per-square-metre allowances so you can frame a budget and compare system options early.

The allowances reflect typical systems, but real cost depends on the specification, redundancy, controls, local rates and the detailed design. VRF, central chilled water, packaged and split systems have very different cost profiles. Use the estimate for early budgeting and option comparison, not tender, and replace it with a measured BOQ from drawings and current pricing before committing.

Concept HVAC BOQ Method

Order-of-magnitude estimate

Step 1 - Apply a per-TR allowance to the cooling load for the plant (chiller/DX, pumps, cooling tower).
Step 2 - Apply per-m² allowances for ductwork, diffusers and insulation to the served area.
Step 3 - Add chilled-water and refrigerant piping allowances scaled to load and system type.
Step 4 - Adjust for the system type (VRF, chilled water, packaged, split) and duct type.
Step 5 - Sum into a headline value and a per-TR and per-m² benchmark.

Worked Example

A 4,000 m² office with a 250 TR block load on central chilled water, applying a per-TR plant allowance plus per-m² ductwork and piping allowances, gives a headline HVAC budget and a per-TR and per-m² benchmark for the project cost plan.

HVAC Budgeting Notes

System type dominates cost

The single biggest driver is the system choice — central chilled water with AHUs, VRF, packaged rooftop or splits — because each carries a different plant, distribution and controls scope. Compare options at the headline level before committing to one.

Air side vs water side

Ductwork, diffusers and insulation scale with the served area, while chillers, pumps and piping scale with the cooling load. Splitting the estimate this way makes it easier to sense-check.

From estimate to BOQ

As the design firms up, replace the allowances with measured duct and pipe quantities and scheduled plant priced at current rates.

Frequently Asked Questions

How is HVAC cost estimated at concept stage? +

From the cooling load in TR and the served area, applying typical per-TR plant allowances and per-m² air-side and piping allowances, adjusted for the system type. It gives a ballpark before detailed design.

What is a typical HVAC cost per TR? +

It varies widely with system type, redundancy and specification, so use it only as a benchmark. Central chilled water, VRF and packaged systems each sit in different ranges.

Which system type is cheapest? +

It depends on size and use — VRF and splits often suit smaller or distributed loads, central chilled water suits large or campus loads. The estimator lets you compare the headline numbers.

Does this replace a measured BOQ? +

No. A measured bill of quantities is taken off the drawings at current rates. This tool is only for the early ballpark.

Should I use connected or design cooling load? +

Use the design (block) cooling load in TR for the plant, and the served floor area for the air-side allowances.