Commercial solar window film
Window Film Savings Calculator
Evaluate annual operating savings, simple payback and net present value using your building’s assumptions. Include the winter heating effect and compare less favourable outcomes before relying on a forecast.
Hypothetical examples, not a quote or savings guarantee. Every starting value, including CAD amounts, is invented to demonstrate the calculation. These are not Clear Guard prices, Ontario averages, measured results or recommended assumptions. Replace them with evidence from your building and proposed installation.
1. Set your assumptions
Example buttons load invented inputs so you can explore different outcomes.
2. Review the outcome
Annual operating costs decrease in this scenario, but discounted savings do not recover the initial expenditure within the study period.
Gross cooling benefit: $1,080/year. Undiscounted ending balance: $0. Discounted recovery: not reached within the study period.
3. Test the cooling assumption
Compare half, the entered reduction and 1.5 times that reduction, capped at 100%. Other inputs stay fixed. These are stress tests, not confidence intervals.
| Reduction | Annual net (CAD) | NPV (CAD) |
|---|---|---|
| 10% | $260 | -$5,992 |
| 20% | $800 | -$1,823 |
| 30% | $1,340 | $2,347 |
4. Follow the cash flows
Initial expenditure occurs at year zero; savings arrive at each year end. Amounts are CAD in today’s money. Totals use unrounded values.
View annual cash-flow table
| Year | Net flow | Discounted flow | Cumulative | Discounted cumulative |
|---|---|---|---|---|
| 0 | -$8,000 | -$8,000 | -$8,000 | -$8,000 |
| 1 | $800 | $762 | -$7,200 | -$7,238 |
| 2 | $800 | $726 | -$6,400 | -$6,512 |
| 3 | $800 | $691 | -$5,600 | -$5,821 |
| 4 | $800 | $658 | -$4,800 | -$5,163 |
| 5 | $800 | $627 | -$4,000 | -$4,536 |
| 6 | $800 | $597 | -$3,200 | -$3,939 |
| 7 | $800 | $569 | -$2,400 | -$3,371 |
| 8 | $800 | $541 | -$1,600 | -$2,829 |
| 9 | $800 | $516 | -$800 | -$2,314 |
| 10 | $800 | $491 | $0 | -$1,823 |
How the savings model works
Gross cooling benefit = avoided kWh × marginal electricity charge
Annual net savings = gross benefit − added heating cost − maintenance
Simple payback = initial expenditure ÷ positive annual net savings
NPV = −initial expenditure + sum of [annual net savings ÷ (1 + real discount rate)year]
Use cooling electricity, not a film specification
This tool calculates cash flows; it does not simulate your building. The reduction input needs a project-specific energy assessment. Total solar energy rejected (TSER), infrared rejection and solar heat gain coefficient (SHGC) are not percentages of your electricity bill.
If an assessment supplies thermal cooling-load kWh, convert them to electrical kWh using appropriate system performance before entry. Coefficient of performance (COP) relates useful cooling to electrical input in consistent units. Already-electrical consumption must not be divided by COP again. Fans, pumps, part-load operation and controls may need a more detailed system model.
Include the heating season and actual avoidable charges
Reducing useful winter solar heat may increase heating needs. Price any added heating separately using the actual gas or electrical system and marginal charges. Do not subtract gas consumption directly from electrical kWh. This calculator accepts a heating penalty; it does not assume that solar film improves insulation or creates heating savings.
Use electricity charges that would actually decrease. Fixed account fees generally remain; demand-charge savings require a separate peak/tariff analysis. Time-varying rates need an appropriate weighted rate or interval analysis.
Read payback and net present value together
Zero or negative annual savings cannot fund a positive initial expenditure. A positive annual saving can still produce a negative NPV. Simple payback assumes steady savings; discounted recovery is shown at the first year end that covers the initial expenditure. With no initial cost, the tool says so without treating the project as attractive.
Cash flows stay constant in today’s CAD. The study period must fit your holding period and supported service-life assumption. No warranty duration is implied. Lighting changes, demand-charge savings, rebates, financing, tax effects, removal, replacement, residual value and performance degradation are excluded. Use a fuller lifecycle model when these affect the decision.
Test a lower cooling benefit, higher heating penalty, shorter study period and different discount rate. Keep comfort and appearance objectives separate from energy savings. The calculator does not submit or save the values you enter; its download creates a local CSV file.
Primary sources and further reading
These sources support the physical principles and definitions. They do not substantiate the hypothetical numerical inputs.
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