Lotte World Tower Reflectivity Study

Solar Reflectivity

Solar Reflectivity Examples

The Death Ray

Solar Control technologies

• IGU’s – Coatings – Films

• Shading devices

– Louvers – Brise soleil – Solar screens

• Finishes – Natural stone – Metal Panels – Composites

Modeling tools

CDC’s Reflectivity modeling Old technology

Building Orientation • What if the Vdara was still in Las Vegas but rotated 90 degrees?

Building Location • What if the Vdara was in Sao Paulo, Brazil?

Glare issues • Sustainability impact

– Micro-climates modified • Neighboring buildings affected • Glare onto highways • Discomfort for pedestrians

• LEED

Glare limits • Lack of criteria in the industry • Measurement is subjective

– Age – Eye color – Eye ware – Scars – Contrast

Glare Comparison

Cloudy Sky (2,000 cd/m2)

Moon Surface (2,500 cd/m2)

Clear Sky (8,000 cd/m2)

Vdara (9,000 cd/m2)

Compact Fluorescent light (11,000 cd/m2)

Walt Disney Concert Hall

(18,000 cd/m2)

60 Watt Light Bulb (120,000 cd/m2)

Candle light (200,000 cd/m2)

Sunset (600,000 cd/m2)

Sun at noon (1,600,000,000 cd/m2)

Lotte World Tower

Seoul, Korea 123 Stories 555 Meters

Unique Features

Figures

Optics • Light rays traveling in a

medium – Scope of this study

• Reflection laws

• Reflection types

– Specular – Diffuse

Glare Notes • Vertical fins influence

– High incident angle – Low/normal incident angle

• Metal frame effect

Glare Notes • Effect at building corners

Boundary Conditions

• Model Simplification – Results (simplified)

• Only reflections from the Tower are analyzed

• Only primary specular reflection

– Diffuse reflection – Secondary reflection

(rebound)

Comparison

Shadows

Magnitude of the Study • Each simulation traces 500,000 rays. • 198 total simulations for Lotte World Tower

• If 1 ray = 1 Coca Cola bottle (250 ml) – Case study = 99,000,000 Coca Cola bottles – 10 Olympic size pools

How is it done?

Ray injection (December 21st at 16:00 hrs)

How is it done?

Reflected rays (December 21st at 16:00 hrs)

How is it done?

Reflected ray “curtain” (June 21st at 11:00 hrs)

Sun Tracking

• December 21st

Sun Tracking

• All year (at noon)

Observations • Reflectivity path on

Road/bridge • Maximum intensity

– buildings across from the lake

• Buildings at northwest of Tower; reflectivity intensity and presence varies during April to August

• The tower, reflects onto itself from April to August

Reflectivity Control

• Distant reflections – Sunrise and sunset, low solar angles

• Glass reflectance coefficient – >16% – <16%

• Reflectivity close to Tower’s shaft – Shading devices

• Buildings west of the Tower – Skylight

• Shading devices

Thank you

Presented by:

Vicente Montes CDC

CurtainWall Design Consulting, Inc.