How this calculator works
This page estimates the business value of improving indoor air quality (IAQ) in a workplace by translating changes in
CO and total volatile organic compounds (TVOC) into an estimated productivity uplift, then adding the
value of recovered work time from fewer sick days. Finally, it subtracts any added annual operating cost (energy,
filter replacements, maintenance) and compares the net benefit to your capital cost to compute simple payback and ROI.
The model is intentionally simple: it is designed for early-stage budgeting, comparing scenarios, and communicating assumptions.
It is not a substitute for an industrial hygiene assessment, medical guidance, or a detailed energy model. In practice, teams often use
this kind of estimate to decide whether to proceed to the next step: commissioning, measurement campaigns, or a full mechanical design.
The calculator treats improvements conservatively: if your target pollutant level is higher than your current level, that component is
counted as no gain. This prevents the model from producing negative productivity values when you are exploring “what if” cases.
It also means you can use the tool safely for scenario planning without worrying that a single input mistake will flip the sign of the result.
Use measured or well-supported estimates whenever possible. If you are unsure, run two scenarios (conservative and aggressive)
to bracket the likely outcome. The most common source of confusion is mixing time periods (monthly vs. annual) or mixing measurement
contexts (peak readings vs. occupied-hour averages). The notes below help you choose values that are consistent and defensible.
- Employees affected: the number of people who experience the improved air (not total headcount if only one floor is upgraded). If you have multiple zones, consider running the calculator once per zone and summing the results.
- Average hourly value per employee ($): an all-in value proxy (wages + overhead + contribution margin). If you only have salary, convert to hourly and consider adding overhead. For knowledge work, some teams use revenue per employee as a proxy; for operations, they may use fully loaded labor cost.
- Work hours per employee per year: typical full-time values are ~1,800 2,000 hours/year. If you have shift work, use the average hours actually worked in the space affected by the upgrade.
- Current / target CO (ppm): use time-weighted averages from sensors during occupied hours. Outdoor CO is often ~400 450 ppm; targets below outdoor levels are not realistic. Targets far below ~700 800 ppm may be difficult in dense spaces without significant outdoor air or reduced occupancy.
- Current / target TVOC ( g/m ): use consistent measurement methods; TVOC is a broad indicator and varies by sensor type and calibration. If you are using low-cost sensors, focus on relative change (before vs. after) rather than absolute precision.
- Baseline sick days per employee and expected sick day reduction (%): enter your current annual average and the improvement you believe is plausible after the IAQ change. If you have HR absence data, use a multi-year average to reduce noise from unusual seasons.
- Added annual operating cost ($): incremental cost of the upgrade (energy, filters, service contracts), not total HVAC spend. If you are unsure, start with a conservative estimate; operating cost is often the main factor that turns a “good” project into a “great” one when optimized.
- Project capital cost ($) and analysis horizon (years): used for payback and total net value over time. If your organization uses depreciation schedules or lease terms, align the horizon with those planning cycles.
Measurement tip: if you have CO sensors, prefer an occupied-hour average (for example, 9am 5pm) over a daily maximum. A maximum is useful for diagnosing ventilation issues, but it can overstate typical exposure. For TVOC, document the sensor model and placement; readings near printers, cleaning closets, or new furniture can be higher than the general office.
The calculator converts pollutant reductions into a productivity fraction. It only counts improvements (if targets are worse than current,
the gain is treated as zero). The coefficients are planning-level approximations intended to make the model easy to understand and audit.
If you have internal research or a consultant-provided factor, you can still use this page by adjusting targets and comparing relative outcomes.
1) Productivity uplift fraction
Interpretation: a 100 ppm CO reduction contributes about 0.5% uplift (0.00005 100 = 0.005). A 50 g/m TVOC reduction contributes about 0.3% uplift (0.00006 50 = 0.003).
These are simplified, population-level relationships intended for planning.
2) Annual productivity value
3) Recovered sick time value
The model assumes an 8-hour workday for converting days to hours.
4) Net annual benefit
Example (worked scenario)
Suppose a workplace improves ventilation and source control for 200 employees. Each employee is valued at $60/hour and works
1,900 hours/year. CO improves from 1,050 ppm to 800 ppm (a 250 ppm reduction), and TVOC improves from
250 g/m to 170 g/m (an 80 g/m reduction). Baseline sick days are 4.5 per employee and you expect a
10% reduction. Added operating cost is $25,000/year, capital cost is $300,000, and you evaluate over 7 years.
- Productivity fraction: 0.00005 250 + 0.00006 80 = 0.0125 + 0.0048 = 0.0173 (1.73%).
- Productivity value: 200 1,900 $60 0.0173 $394,000/year (approximate; the calculator will format precisely).
- Recovered sick time: 200 4.5 0.10 8 = 720 hours 720 $60 = $43,200/year.
- Net annual benefit: productivity + recovered operating cost $412,200/year in this example.
- Simple payback: $300,000 / $412,200 0.73 years (about 9 months).
Your results will differ based on your inputs. Use the example to understand the direction and scale of each component, then run your own baseline and two variants.
Scenario comparison (quick sensitivity)
The table below illustrates how outcomes can change when only the target air quality changes. Use it as a planning aid, then rely on the
calculator results for your exact inputs. In general, the biggest drivers are (a) how many people are affected, (b) how many hours they spend in the space, and (c) whether your current CO is meaningfully above your target.
The results panel reports three value components and three decision metrics. Read them in order. First, productivity uplift value is the estimated annual value of improved performance during working hours. Second, recovered sick time value is the estimated annual value of fewer sick days, converted to hours using an 8-hour day. Third, net annual benefit after costs subtracts the added operating cost you entered.
The payback and ROI are intentionally simple. Simple payback is capital cost divided by net annual benefit. Annual ROI is net annual benefit divided by capital cost. Total net value over the analysis horizon multiplies net annual benefit by years and subtracts capital cost. These metrics are useful for quick comparisons, but they do not discount future cash flows. If your finance team requires discounted metrics, you can export the annual net benefit and apply your discount rate in a separate model.
Sanity-check guidance: if you double employees, the productivity and recovered values should roughly double. If you set targets equal to current values, productivity uplift should go to zero and only sick-day recovery (if any) remains. If operating cost exceeds the combined value, the net annual benefit will be zero and the page will explain that the inputs do not yield a positive benefit.
After you run a baseline scenario, use this checklist to turn the estimate into an actionable plan. These steps also help you defend the assumptions when presenting to leadership, finance, or a health and safety committee.
If you want to extend the analysis, consider adding a retention or turnover component outside the calculator. For example, if improved air quality reduces voluntary turnover by even a fraction of a percent, the avoided replacement cost can be meaningful. Similarly, fewer complaints and fewer hot/cold calls can reduce facilities workload, which may show up as avoided overtime or fewer service tickets.
