Case study · 6 min read
Lotte World Tower: 555 m of LUNOX Sputter Film
In 2017, the LUNOX sputter team specified and supplied the architectural window film for the world's 6th tallest building. 555 meters. 123 stories. South-facing curtain wall on a building that's its own micro-climate. Here's what the project demanded — and what the project taught us.
The project
Lotte World Tower stands at 555 meters in Songpa-gu, Seoul. Completed in April 2017, it was at the time the 5th tallest building in the world (currently 6th). The facade is a unisex curtain wall of optically-graded glass — the kind of glazing area where a wrong window-film choice plays out as a 30-year HVAC liability.
The film specification was issued through the general contractor in 2016. The brief listed three priorities, in order:
- Heat rejection without exterior color shift. The architectural exterior is the building. Any film that visibly tinted the glass was disqualified at the spec stage.
- Surface-level IR rejection, not absorptive. A 555 m building stores enormous thermal mass. Absorptive film would heat the glass itself, which transmits to the mullions, which transmits to the structural frame. Sputter was the only candidate that reflects rather than absorbs.
- Color-stable over the building's lifecycle. Replacing film on a 555 m building is functionally impossible. Whatever went up had to look the same in 2017 as it does in 2047.
Why LUNOX sputter won the spec
Three factors mattered in the final selection:
- Surface heat reflection. LUNOX Sputter Max series rejects up to 83.4% of infrared at the glass face. The glass itself stays cooler, which means the curtain wall mullions stay cooler, which means HVAC load on the south and west elevations stays predictable.
- Color neutrality interior + exterior. The interior view from a 555 m height is the building's product. Sputter coatings can be specified to look color-neutral from inside; LUNOX's stack does this without compromising IR rejection.
- 10-year color stability warranty. Sputter doesn't fade — the metal layers don't oxidize when properly encapsulated. LUNOX warrants the color spec for 10 years, with field-data tracking decades beyond that.
What the project taught us
Sputter pays for itself on tall glass
The HVAC energy savings on south and west elevations of a tall building over even 10 years dwarf the film installation cost. We've seen post-occupancy data on similar tall-glass projects showing 25–35% cooling-load reduction on treated elevations vs untreated control areas. Over a 30-year building lifecycle, that's a 7-figure HVAC cost differential.
The installer is half the spec
Sputter on a 555 m building required boom-lift installation at 100+ meter elevations. The installation crew matters as much as the film: LUNOX certifies installer partners for sputter projects globally, and we travel the QC team to the site for the first 10–15% of installation to lock in the technique.
The architectural review board notices
The Lotte spec required submitting cured-film samples at the as-installed VLT and reflectance for architectural review. Films that look good on a sample card but look wrong on a 4-meter glazing unit got rejected at this stage. LUNOX provides as-installed mockups on commercial projects for exactly this reason.
Other Korean landmarks where LUNOX is installed
- Incheon International Airport — Terminal 1 + Terminal 2 passenger glazing.
- Uljin Nuclear Power Plant — Control room and perimeter glazing (security + sputter combo).
- 30+ Tier-1 office buildings across Seoul (typically retrofit projects for energy-code compliance).
Spec'ing LUNOX sputter for your project
Architectural sputter film is a 6-week-out spec decision, not a 6-month one. Submit project details via Inquiry for as-installed mockups, thermal-stress documentation per glazing type, and installer certification list for your country.
Request architectural specification See the architectural lineup