How a wave could spread
Change the assumptions and see how far a few window-film kits could reach. Every number here is a projection, not a promise and not anyone's real data.
The projection now reaches about 65 households.
- The starting kits
- One household
- One round of paying forward, dashed because it is projected
| Ring | Households |
|---|---|
| Starting households | 8 |
| Round 1 of paying forward | 12 |
| Round 2 of paying forward | 18 |
| Round 3 of paying forward | 27 |
| All households | 65 |
| Pay-forwards | 57 |
Rows are rounded to whole households, so they may not add up exactly to the total.
The whole wave
Projection- Households
- about 65
- Pay-forwards per starting kit
- about 7
- Money, all homes
- about $24,000 a year
- CO₂, all homes
- about 41 t a year
SaveWave's illustrative assumptions
- 8 households start with a kit.
- 75% of the people who get a kit pay it forward, 2 kits each.
- 3 rounds of paying forward.
- Every home saves like SaveWave's example home in York, Maine, with 8 windows: about $371 and 631 kg of CO₂ a year.
- The totals are a year's savings once every projected household has its kit. A round is a step of paying forward, not a length of time.
Model interim-artifact-2026-10 and projection-2026-10. How we project
How we project
The projection multiplies its way out from the starting kits. It uses no participant's data and stores nothing.
- The starting households each get a kit: bought themselves, or given to start the wave.
- In each round, the share of last round's households who pay forward, times the kits each of them passes on, gives the next round's households. A round can hold a fraction of a household, because these are expected values.
- Every household saves like SaveWave's example home in York, Maine, so the money and CO₂ totals are households times that home's estimate.
- Households round to whole numbers, money and CO₂ to two significant figures, and CO₂ shows in tonnes from 1,000 kg.
How many pay-forwards are enough?
An early estimate for one funder put the break-even for funding window film for its CO₂ at about 3 to 5 pay-forwards per kit in the leakiest homes, and about 10 in more efficient ones. It hasn't been tested yet; the pilot will measure how often savings lead to another gift. Under SaveWave's illustrative assumptions, each starting kit would lead to about 7.