Grow Lighting
49 Barrina T8 LED fixtures across two circuits. All 5000K white full spectrum, V-shaped reflector, aluminum housing.
”Grow” Circuit — 34× 2FT Fixtures (816W)
Direct, close-range light over hydro and shelf positions.
| Location | Count | Watts |
|---|---|---|
| Hydro top row | 7 | 168W |
| Hydro bottom row | 7 | 168W |
| East wall shelves (seedlings) | 5 | 120W |
| West wall shelves | 15 | 360W |
Specs: Barrina 2FT T8 LED, 24W, 96 LEDs, CRI 80, 12” on center.
”Main” Circuit — 15× 4FT Fixtures (630W)
Ambient overhead light from west wall rafters. 36” on center between rafter studs.
Specs: Barrina 4FT T8 LED, 42W, 192 LEDs, CRI 98.
⚠️ 2 fixtures currently dead. Replacements ordered.
Automation
Both circuits controlled via Lutron switches → Home Assistant → ESP32 HTTP API.
| Parameter | Value |
|---|---|
| gl_auto_mode | ON |
| gl_lux_threshold | 3,000 lux |
| gl_dli_target | 14 mol/m²/d |
| gl_sunrise_hour | 7 AM |
| gl_sunset_hour | 7 PM |
The automation works by accident — the 3,000 lux threshold happens to correlate with the tree shadow clearing the lux sensor position. It’s effectively open-loop until the sensor is replaced.
DLI Contribution
Estimated 8–12 mol/m²/d from grow lights alone. Combined with corrected natural light (12–17 mol), total plant DLI is likely 20–29 mol — excellent for all planned crops.
Cost
1.93 — a meaningful portion of the daily budget but necessary for adequate DLI.
Estimated DLI (Glazing Model)
Until a proper indoor PAR sensor is installed, we estimate indoor light from the Tempest outdoor lux sensor and a physics-based glazing transmission model. The model uses measured transmission percentages at each sun angle — from 6.9% on the east face (tree shadow) to 23.5% on the southwest face.
Left: daily natural DLI with a 14 mol target line. Right: real-time estimated PPFD inside the greenhouse (green) overlaid with outdoor lux (yellow line). The ratio between them is the glazing’s effective transmission.
Effective transmission varies throughout the day as the sun moves across the hexagonal structure — peaking when the southwest face catches afternoon sun, lowest when the east tree blocks morning light.