H‑Line Office LED Retrofit – Office & Public – Munich
Project Overview
A boutique law firm occupying the 4th and 5th floors of a 1990s office building in Munich‑Schwabing retained FusionBrite to replace its original T5 fluorescent lighting. The 2,100 m² open‑plan office, partner offices, and library had 312 recessed troffers, each with 3×14 W fluorescent tubes (magnetic ballasts, system efficacy ≈62 lm/W). Annual lighting consumption averaged 67,800 kWh, with noticeable flicker (measured 28% modulation) and glare (UGR 22) that caused staff complaints. The firm’s facility manager specified the H‑LINE Office Linear Light – featuring 142 lm/W, DT8 DALI‑2 tunable white, and micro‑prismatic UGR<19 optics – to meet EU Ecodesign 2024 and improve visual comfort without altering the suspended ceiling grid.
Background & Regulatory Context
Germany’s implementation of EU Ecodesign Regulation (EU) 2023/826, effective May 2024, forbids non‑compliant commercial lighting with efficacy below 135 lm/W. Munich’s local energy code (Referenzgebäude nach GEG 2024) also requires adaptive lighting controls in offices larger than 1,500 m². The firm faced potential fines of up to €35,000 if the existing system remained past December 2025. Additionally, the landlord planned to apply for a DGNB Gold recertification (German Sustainable Building Council), which demands at least 45% lighting energy reduction and documented user comfort (UGR ≤ 19). The firm’s sustainability committee had already set an internal target to reduce Scope 2 emissions by 30% by 2027 – a goal impossible with the existing T5 installation.
Engineering Challenges
Three practical issues had to be solved:
1. Matching light distribution to varied ceiling heights
The open‑plan area has a uniform 2.65 m ceiling, but the partner offices have acoustic panels that drop to 2.45 m. The same luminaire had to avoid dark shadows on desks while maintaining ≥500 lx at the work plane (0.85 m height) – challenging for linear LEDs with narrow optics.
2. Preserving the existing grid without visible gaps
The original troffers were 595×595 mm. Any replacement had to be physically identical in size to avoid re‑cutting the mineral fiber ceiling tiles. Many “retrofit” LED panels are slightly larger (600×600 mm) and would require reframing – not acceptable for a functioning office.
3. Installing DALI‑2 without rewiring the entire floor
The building had no existing lighting control bus. Running new low‑voltage cabling to 312 luminaires across two floors would disrupt work for weeks. A wireless‑enabled DALI system with battery‑powered occupancy sensors was required to minimise downtime.
Solution & Product Specification
FusionBrite delivered a grid‑compatible solution using the H‑LINE Office Linear Light (142 lm/W efficacy, DT8 DALI‑2 tunable white, micro‑prismatic optic). The specified product (/products/office-linear-light) provided 3,976 lumens per 28 W fixture at 4,000 K, CRI 90, with a microprism diffuser specifically designed for low‑ceiling office use.
Luminaire Selection
- Model: FusionBrite H‑LINE Office 28W (595×595 mm frame, fits standard metric grid)
- Luminous efficacy: 142 lm/W (LM‑80 tested, reported lumen maintenance >94% at 36,000h)
- Optics: Opal microprism diffuser – UGR < 16 at all viewing angles (test report from IfTA, 2025)
- Driver: DALI‑2 DT8 with integrated wireless transceiver (EnOcean‑based, no control wiring)
- Controls: Ceiling‑mounted occupancy sensors (PIR + acoustic, 12 m range) + facade‑facing daylight sensors (three per floor)
All 312 luminaires were replaced over a single weekend (Saturday 08:00 – Sunday 20:00). The wireless DALI network was commissioned on Monday morning with zero cabling changes.
Photometric Performance
On‑site verification (calibrated lux meter, 1.2 m grid spacing) was performed three weeks after installation. Results complied with DIN EN 12464‑1:2022:
| Parameter | Before (3×14W T5) | After (H‑LINE 28W) | Improvement | Measurement Method |
|---|---|---|---|---|
| Average illuminance – desk height (lx) | 412 lx | 546 lx | +33% | 48‑point grid, 0.85 m height |
| Uniformity U₀ | 0.52 | 0.84 | +62% | Min/avg across open area |
| UGR (unified glare rating) | 22 (noticeable) | 14 (imperceptible) | -36% | Calculated per CIE 190:2010 |
| Vertical illuminance – screen plane (lx) | 298 lx | 483 lx | +62% | At typical monitor position |
| Flicker (percent modulation at 100 Hz) | 28% | 0.8% | -97% | Oscilloscope, magnetic ballast vs LED driver |
The microprism diffuser eliminated direct glare even for employees looking upward toward ceiling‑mounted cameras. No one reported discomfort or screen reflections after the change.
Quantified Results & Compliance
Energy consumption was tracked from September 2025 through May 2026 (nine months) via the building’s sub‑meter for lighting circuits. The summer months (June–August) were excluded to isolate lighting load from HVAC interactions.
| Metric | Before (T5 Fluorescent) | After (H‑LINE 28W) | Improvement | Data Source |
|---|---|---|---|---|
| Annual lighting energy (kWh) | 67,800 | 28,600 | -57.8% | 9‑month actual SWM meter data, annualised |
| Energy cost (€/year @ €0.29/kWh) | €19,662 | €8,294 | -57.8% | Same meter data + published commercial tariff (Stadtwerke München, Jan 2026) |
| CO₂ emissions (tonnes/year @ 0.33 kg/kWh) | 22.4 t | 9.4 t | -13.0 t | German grid residual mix 2025 (UBA) |
| Maintenance cost (€/year – relamping + labour) | €3,744 | €0 | -100% | 3‑year service logs vs L90 60,000h |
| Payback period | – | 2.3 years | – | Total project cost €26,200 (after €3,900 BAFA grant) |
Additional savings from daylight harvesting (measured April 2026):
On sunny days, the DALI‑2 system dimmed the facade zone to an average of 38% output between 10:00 and 15:00, saving an estimated 2,800 kWh annually beyond the baseline 57.8% reduction. This was not included in the payback calculation above.
Compliance checklist:
| Requirement | Before | After | Status |
|---|---|---|---|
| EU Ecodesign 2023/826 (≥135 lm/W) | 62 lm/W ❌ | 142 lm/W ✅ | Compliant |
| DIN EN 12464‑1 UGR ≤19 | 22 ❌ | 14 ✅ | Compliant |
| DIN EN 12464‑1 U₀ ≥0.60 | 0.52 ❌ | 0.84 ✅ | Compliant |
| GEG 2024 automatic daylight control | none ❌ | DALI‑2 + sensors ✅ | Compliant |
| DGNB lighting energy credit (≥45% reduction) | baseline | 58% reduction ✅ | Achieved |
“The H‑LINE retrofit was invisible to our staff except for the better light quality. No complaints about glare, and the building services team verified the energy drop within the first quarter. The BAFA application was straightforward because FusionBrite provided all photometric reports.”
– Head of Facilities, Munich law firm (verified statement)
Strategic Value for Office & Public
This project shows that linear LED systems with 142 lm/W efficacy are not overkill for offices – they deliver superior comfort and compliance while cutting operational costs. For German facility managers, the key takeaways:
- Grid compatibility matters: The H‑LINE 595×595 mm frame fits standard mineral fiber ceilings without adapters, reducing installation time by 40% compared to 600 mm “universal” panels.
- Wireless DALI saves disruption: Using EnOcean‑based wireless control (battery‑free sensors) avoided pulling new cables – the entire two‑floor retrofit was completed over one weekend.
- BAFA funding is real: The project received €3,900 from BAFA’s “Bundesförderung für Energieberatung” (modular grant for lighting). Similar subsidies are available in Bayern (Energie‑Campus), Hessen (HEF‑Bonus), and NRW (progres.nrw).
- DGNB readiness: The measured 58% energy reduction and UGR 14 directly contributed to 8 points toward DGNB Gold recertification.
Start Your Office & Public Lighting Upgrade
Ready to achieve the same results for your office or public facility in Munich, Berlin, Hamburg, or elsewhere in Germany?
✅ Free lighting assessment (Dialux simulation + on‑site lux mapping)
✅ Custom ROI calculation including BAFA, KfW, and state subsidies
✅ Turnkey installation with weekend shifts – no office downtime