Fault Detection Cost Calculator

FDD system cost and energy savings from fault correction.

Total BAS points

Number of AHUs

Number of VAV boxes

Annual HVAC energy ($)

Annual maintenance ($)

Building Age

Tab to move between fields

First-year total cost ($)

$20,800.00

≈ 10 gaming PCs

Net annual benefit ($)

$55,260.00

≈ 5 years of state college

Simple payback (years)

0.4

Implementation cost ($)$14,800.00

Annual software ($)$1,000.00

Energy savings ($/yr)$28,000.00

Maintenance savings ($/yr)$12,000.00

Total savings ($/yr)$57,000.00

5-year ROI (%)927

Est. faults detected/yr170

How to Use This Calculator

Enter Total BAS points, Number of AHUs, and Number of VAV boxes.
Set Annual HVAC energy ($), Annual maintenance ($), and Building Age.
Adjust New (0-5 years), Mid-age (5-15 years) as needed.
Review First-year total cost ($) ($), Net annual benefit ($) ($), and Simple payback (years).
Use Implementation cost ($) ($) and Annual software ($) ($) to inform your decision.

How the result changes with Number of VAV boxes

Number of VAV boxes	First-year total cost ($)	Net annual benefit ($)	Simple payback (years)
500	$73,800.00	$163,060.00	0.5
1,750	$223,800.00	$469,310.00	0.5
3,250	$403,800.00	$836,810.00	0.5
4,500	$553,800.00	$1,143,060.00	0.5

Total BAS points: Total building automation system points. FDD software is often licensed per point.
Number of AHUs: Air handling units — primary FDD targets for simultaneous heating/cooling, economizer faults.
Number of VAV boxes: Variable air volume terminal units — common faults include stuck dampers, reheat valve failures.
Annual HVAC energy ($): Annual HVAC energy cost (heating + cooling + fans/pumps). FDD typically saves 7-20% of this.
Annual maintenance ($): Annual HVAC maintenance budget. FDD reduces reactive maintenance by 8-20%.
Building Age: Select building age category

First-year total cost ($): Implementation + software + training cost for the first year.
Net annual benefit ($): Total annual savings minus ongoing FDD costs.
Simple payback (years): Years to recover first-year investment from net annual benefits.
Implementation cost ($): One-time cost for integration, setup, and system tuning.
Annual software ($): Yearly FDD software/platform license cost.
Energy savings ($/yr): Estimated annual HVAC energy savings from detecting and correcting faults.
Maintenance savings ($/yr): Annual maintenance cost reduction from predictive vs. reactive maintenance.
Total savings ($/yr): Combined energy + maintenance + comfort complaint savings.
5-year ROI (%): Return on investment over a 5-year period.
Est. faults detected/yr: Estimated number of actionable faults detected per year.

Identify Input Parameters
4 parameters
Total BAS points = 500, Number of AHUs = 8, Number of VAV boxes = 60, Annual HVAC energy ($) = 200000 = 6 input(s) provided
Calculate First-year total cost
First-year total cost = implementationCost + annualFDDSoftwareCost + trainingCost
20800 = $20,800
Calculate Net annual benefit
Net annual benefit = totalAnnualSavings - annualOngoingCost
55260 = $55,260
Calculate Simple payback
0.4 = 0.4
Calculate Implementation cost
Implementation cost = implementationBase + totalEquipment * implementationPerUnit
14800 = $14,800
Calculate Annual software
Annual software = totalBASPoints * fddCostPerPointPerYear
1000 = $1,000