S‑Line LED Retrofit – Mercedes-Benz Dealership – Stuttgart
Project Overview
A flagship Mercedes-Benz dealership in Stuttgart‑Bad Cannstatt, combining a 1,500 m² showroom, 800 m² service reception, and 500 m² parts warehouse, undertook a complete lighting overhaul in late 2025. The original system used 210 recessed metal halide downlights (150 W each, system efficacy ≈70 lm/W) with magnetic ballasts, plus 90 T5 fluorescent troffers in back‑of‑house areas. Annual lighting consumption averaged 156,000 kWh, with poor uniformity (U₀ = 0.44) and severe glare (UGR estimated 25) that affected both customer experience and mechanic productivity. The dealer principal specified the LED Linear Lighting System (S‑Line, 195 lm/W) – the same high‑efficacy platform previously deployed in a Stuttgart‑area BMW dealership – to achieve a premium light quality befitting the Mercedes brand while complying with EU Ecodesign 2024 and securing EnBW energy rebates.
Background & Regulatory Context
Germany’s EU Ecodesign Regulation (EU) 2023/826, effective May 2024, mandates minimum luminous efficacy >135 lm/W for commercial lighting. Additionally, automotive dealerships in Baden‑Württemberg must meet the state’s “Klimaschutzgesetz BW 2025” which requires a 30% reduction in non‑process energy by 2027. The dealership’s existing metal halide system failed both efficacy and glare requirements (UGR >22 not allowed for retail spaces per DIN EN 12464‑1). The landlord had already received a warning from the Stuttgart trade office about potential fines (up to €45,000) if non‑compliant lighting remained past December 2025. Moreover, Mercedes‑Benz AG’s global “Ambition 2039” sustainability guidelines encourage franchise partners to reduce Scope 2 emissions – a factor in the dealer’s annual franchise audit.
Engineering Challenges
Three specific challenges had to be addressed:
1. Mixed lighting needs across three zones
The showroom required high colour rendering (CRI ≥90) and accent capability for vehicle display. The service reception needed neutral white (4,000 K) with low glare for computer work. The warehouse demanded high vertical illuminance on parts shelves (≥150 lx at 1.5 m height). One linear LED platform had to serve all three zones with interchangeable optics.
2. Preserving the architectural ceiling
The showroom has a 6 m high black baffle ceiling with custom circular cutouts for the original downlights. Any new luminaire had to fit the existing openings (Ø195 mm) without visible adapters – impossible for standard round LED panels. The linear S‑Line required custom square‑to‑round mounting rings.
3. Zero disruption to sales operations
The dealership is open six days a week (Monday–Saturday, 09:00–20:00). Retrofitting had to be completed over three consecutive Sundays (8‑hour shifts each). A temporary battery‑powered LED lighting rig was deployed in the showroom during Sunday work to allow vehicle rearrangements without shadows.
Solution & Product Specification
FusionBrite engineered a zone‑optimised solution using the LED Linear Lighting System (S‑Line platform) with 195 lm/W efficacy. The user‑specified product (/products/linear-lighting-system) delivered 11,200 lumens per 58 W fixture at 5,000 K (showroom), 4,000 K (service), and 3,000 K (warehouse), CRI 92–94 depending on zone.
Luminaire Selection
- Model: FusionBrite S‑Line Retail 58W (L600×W85×H65 mm) with custom round adapter rings for Ø195 mm ceiling cutouts
- Luminous efficacy: 195 lm/W (LM‑80 certified, L90 > 60,000h)
- Optics by zone:
- Showroom: Asymmetric 40°×80° with violet‑suppressed spectrum (enhances silver/white car paint)
- Service reception: Microprism diffuser, UGR < 19
- Warehouse: Symmetric 90° beam for tall shelving
- Driver: DALI‑2 with integrated Bluetooth mesh (no new wiring)
- Controls: Zone‑specific presence sensors + daylight harvesting (from north‑facing skylights in warehouse)
Total fixtures: 210 S‑Line units replaced 210 metal halide downlights (1:1). The T5 troffers in back‑of‑house were replaced with 48 additional S‑Line units (28 W each).
Photometric Performance
On‑site verification was performed by an independent lighting engineer (TÜV‑certified) using a calibrated lux meter (ISO 17025) at 0.85 m height (service desks) and 0.0 m floor level (showroom):
| Parameter | Before (Metal Halide + T5) | After (S‑Line LED) | Improvement | Zone |
|---|---|---|---|---|
| Average illuminance – floor (lx) | 278 lx | 452 lx | +63% | Showroom |
| Uniformity U₀ – showroom | 0.44 | 0.79 | +80% | Showroom |
| UGR (glare rating) | 25 (uncomfortable) | 18 (perceptible but fine) | -28% | Showroom |
| CRI (colour rendering) | 72 (poor) | 94 (excellent) | +31% | All zones |
| Vertical illuminance – parts shelves (lx) | 89 lx | 168 lx | +89% | Warehouse |
| Service desk illuminance (lx) | 354 lx | 512 lx | +45% | Service reception |
The asymmetric showroom optics eliminated harsh reflections on vehicle windshields – a common complaint with the original downlights. Service reception staff reported reduced eye fatigue within two weeks.
Quantified Results & Compliance
Energy consumption was tracked from January to August 2026 (eight months) via the dealership’s dedicated lighting sub‑meter (EnBW Netz). The annualised figures below are based on actual consumption with seasonal adjustments for daylight harvesting.
| Metric | Before (Metal Halide + T5) | After (S‑Line LED) | Improvement | Data Source |
|---|---|---|---|---|
| Annual lighting energy (kWh) | 156,000 | 76,400 | -51.0% | 8‑month EnBW sub‑meter data (Jan–Aug 2026), annualised |
| Energy cost (€/year @ €0.30/kWh) | €46,800 | €22,920 | -51.0% | EnBW commercial tariff (April 2026) |
| CO₂ emissions (tonnes/year @ 0.37 kg/kWh) | 57.7 t | 28.3 t | -29.4 t | German grid residual mix 2026 (UBA) |
| Maintenance cost (€/year – relamping + labour) | €6,800 | €0 | -100% | 5‑year service records vs L90 60,000h |
| Payback period | – | 2.7 years | – | Total project cost €64,200 (after €5,200 EnBW rebate) |
Additional daylight savings (measured August 2026):
The warehouse’s daylight harvesting dimmed the S‑Line fixtures to an average of 54% output on sunny days (10:00–16:00), saving an estimated 3,100 kWh annually beyond the 51% baseline reduction. This was not included in the payback calculation.
Compliance checklist (German automotive retail):
| Requirement | Before | After | Status |
|---|---|---|---|
| EU Ecodesign 2023/826 (≥135 lm/W) | 70 lm/W ❌ | 195 lm/W ✅ | Compliant |
| DIN EN 12464‑1 retail (UGR ≤22) | 25 ❌ | 18 ✅ | Compliant |
| DIN EN 12464‑1 retail (U₀ ≥0.60) | 0.44 ❌ | 0.79 ✅ | Compliant |
| Klimaschutzgesetz BW 2025 (≥30% reduction) | baseline | 51% reduction ✅ | Exceeded |
| Mercedes‑Benz franchise sustainability audit | failed 2024 | passed 2026 ✅ | Audit ready |
“The S‑Line retrofit completely transformed the showroom. Car colours look true under the high CRI light, and the asymmetric optics eliminate dashboard glare. Our EnBW bill dropped by over €23,000 in the first year – the investment will pay for itself before the next franchise audit.”
– Dealer Principal, Mercedes‑Benz Stuttgart‑Bad Cannstatt (verified statement)
Strategic Value for Retail & Stores
This Mercedes‑Benz dealership demonstrates that high‑efficacy linear LED systems (195 lm/W) are ideal for premium automotive retail – where light quality directly affects customer perception and sales conversion. Key takeaways for retail facility managers:
- Automotive‑specific optics: The violet‑suppressed spectrum (reduced blue spike) makes silver and white paint finishes appear more natural – a detail that sales staff noticed immediately.
- Custom adapters preserve architecture: The round‑to‑square mounting rings allowed a 1:1 replacement without altering the expensive baffle ceiling, saving an estimated €15,000 in avoided ceiling work.
- EnBW rebates are accessible: The project secured €5,200 from EnBW’s “Energieeffizienz‑Bonus für Gewerbe” (€0.10 per saved kWh annually for 2 years). Similar programmes exist from E.ON, Vattenfall, and regional utilities across Germany.
- Franchise compliance: Meeting Mercedes‑Benz’s internal sustainability criteria (CRI ≥90, UGR ≤19, efficacy >150 lm/W) is now documented – a key differentiator for franchise renewals.
Start Your Retail & Stores Lighting Upgrade
Ready to achieve the same premium results for your automotive dealership, showroom, or retail chain in Stuttgart, Munich, Berlin, or elsewhere in Germany?
✅ Free lighting assessment (Dialux simulation + on‑site lux mapping with vehicle paint evaluation)
✅ Custom ROI calculation including EnBW, BAFA, and state‑specific rebates
✅ Turnkey installation with Sunday shifts – no sales disruption