Mechanical Overrun Calculator

Mechanical overruns stem from equipment and commodity swings. This calculator sizes risk.

Mechanical budget

Lead time months

Refrigerant transition cost

Copper escalation %

Labor escalation %

Overrun risk

$667,400

Copper exposure

$84,000

Lead time risk

$420,000

How the math works

Overrun = copper share × esc + lead time risk + labor exposure + refrigerant transition.

Issue purchase orders on mechanical equipment as soon as bid is accepted. Equipment ordered at bid time locks price; equipment ordered at install time typically carries 8-15% escalation plus missed lead-time risk. This single discipline moves mechanical overrun rates from 15% to 5%.

How to Use

Enter mechanical budget.
Enter equipment lead time months.
Enter refrigerant transition cost.
Enter copper price escalation %.
Enter labor escalation %.
Read overrun risk.

Frequently Asked Questions

Lead times?

Standard HVAC equipment: 8-16 weeks. Custom large commercial: 20-40 weeks. Chillers, VRF systems: 26-52 weeks. Long lead times compound price risk (quotes valid 30-90 days typical). Pre-order long-lead items 12-18 months out.

Refrigerant transition?

R-410a phasing out 2023-2025 in favor of R-454b and R-32. Transition equipment can cost 10-20% more. Refrigerant itself 30-80% more expensive post-transition. Budget accordingly for any project commissioning 2025+.

Copper?

Copper 60-80% of AC coil cost. Copper prices 2020-2024 swung 40-60% in 12-month windows. Quote copper-heavy equipment within 30 days of price lock. Long-dated quotes add 5-10% escalation.

How often should I rerun this?

Rerun this calculator whenever inputs change materially — new rent roll data, rate moves, loan balance updates, or quarterly operating data. For active deals, monthly refresh is typical. For stabilized assets under monitoring, quarterly is fine. Treat the output as a decision tool, not a one-time answer — market conditions evolve and so should your analysis.