| Row | Surface | Moisture | Time | Sun (lux) | Refl (%) | Shade (%) | Cover (%) | Dist (m) | Angle (°) | Reduction (%) | Final GI | Risk |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | White Pebbles | Dry | Midday | 100000 | 55 | 20 | 10 | 3 | 10 | 32.4 | 1520 | Very High |
| 2 | Mulch / Soil | Wet | Afternoon | 80000 | 22 | 50 | 45 | 5 | 30 | 78.6 | 210 | Low |
| 3 | Concrete / Pavers | Dry | Morning | 65000 | 35 | 35 | 25 | 4 | 25 | 60.2 | 520 | Moderate |
Reduction% = 100 × (1 − GIfinal / GIbaseline).
- Pick the reflective surface you want to evaluate.
- Enter sunlight, then your best reflectance estimate.
- Add shade percent from trees, cloth, or structures.
- Add coverage from hedges, trellises, or screens.
- Set distance and viewing angle from seating areas.
- Press calculate and compare saved runs before exporting.
Glare sources in garden layouts
Glare in outdoor spaces usually comes from high-reflectance materials, smooth wet surfaces, and direct sightlines to bright patches. Light gravel, white pebbles, pale pavers, and water features can push perceived brightness above comfortable viewing levels, especially in midday sun. This calculator converts your surface reflectance, sunlight level, viewing angle, and distance into a consistent glare index so you can compare design options objectively.
How the inputs change results
Sunlight (lux) sets the starting illuminance. Shade percentage reduces incident light on the surface, while plant or screen coverage reduces the visible area of reflective patches from the observer position. Viewing angle influences how “head-on” the bright patch appears, and distance applies an inverse-square reduction. Moisture can lower sparkle for dusty or granular surfaces by reducing micro-facet reflections, which is why the tool includes a simple moisture factor.
Interpreting reduction and risk ratings
The output provides an estimated reduction percentage by comparing a baseline case against your mitigation settings. A higher reduction means the seating area should feel calmer and less visually fatiguing. Risk ratings (Low to Very High) help you prioritize changes: “Very High” suggests strong discomfort potential, while “Moderate” indicates improvements may be desirable for west-facing patios or areas used at peak daylight.
Design strategies the tool helps test
Use the calculator to compare replacing bright aggregate with darker mulch, adding pergola shade cloth, shifting seating farther from reflective paths, or redirecting sightlines with trellises and hedges. Small changes often compound: a 20% shade increase plus a 20% coverage increase can outperform a single large material change. Save multiple runs, then export CSV for quick option reviews.
Documenting decisions for maintenance
Gardens evolve through seasonal growth and material aging. Keeping a session history lets you revisit the assumptions behind a redesign, such as reflectance changes after staining pavers or adding groundcover. Exporting a PDF summary supports contractor notes, homeowner associations, or maintenance checklists, ensuring glare controls remain effective as surfaces settle and planting density changes.
Frequently asked questions
What is a good lux value to start with?
Use 90,000–120,000 lux for clear midday sun, 30,000–60,000 for bright overcast, and 10,000–25,000 for hazy mornings. If unsure, run several values to see how sensitive your layout is.
How do I estimate surface reflectance percent?
Use a visual comparison: white pebbles often exceed 45%, light gravel 30–40%, concrete 25–35%, mulch 15–25%, and grass near 20%. Enter a range (low and high) to bracket outcomes.
Why does distance matter so much?
Brightness at the eye drops quickly as you move away from a reflective patch. The calculator uses an inverse-square style factor, so doubling distance can cut glare intensity to roughly one quarter, improving comfort.
What does coverage percent represent?
Coverage is how much of the bright surface is blocked from view by plants, screens, or elevation changes. It is not ground cover percentage. Think of it as visible area reduction from the seating viewpoint.
Should I choose Wet or Dry?
Choose Wet after rain, irrigation, or frequent misting near hardscape. Choose Dry for most days. Wet can reduce sparkle on dusty aggregates, but glossy puddles on smooth stone may still create hotspots.
Is the glare index a measured standard?
No. It is a practical comparison score that stays consistent across your scenarios. Use it to rank options, identify major drivers, and document improvements, then validate with on-site observation at the same time of day.