# Filter 12: Clear-sky GHI reduction

**Status:** Not started.

**Data key:** `clearSkyGhiReductionIndex`. Calculation:
[filter-calculations.md](../filter-calculations.md) §12.

## Findings

**10. Clear-sky reduction averages ratios rather than energy totals.** This is
a valid but specific definition. It gives each retained time row equal weight,
rather than weighting rows by available clear-sky energy. The label and
documentation should retain this distinction.

Cross-filter findings that affect this filter, in
[00-cross-filter.md](00-cross-filter.md): 11 (inconsistent aggregation) and
16 (the app's NSRDB source link no longer resolves).

## Decisions

None yet.

## Tasks

Not started; follow the per-filter review checklist in
[pipeline-plan.md](../pipeline-plan.md) §5.