 |
DETERMINE VISUAL FUNCTIONS AND TASKS |
MATERIAL PROPERTIES
The tables below shows the typical reflectances and characteristics of common materials, and recommended reflectance guidelines for different types of surfaces in an interior space.
1. Reflecting materials [1]
Material |
% Reflectance |
Characteristics |
|---|---|---|
| Reflecting | ||
| Specular | Provide directional control of light and brightness at specific viewing angles. Effective as efficient reflectors and for special decorative lighting effects. | |
| Mirrored and optical coated glass | 80-99 |
|
| Metallized and optical coated plastic | 75-97 |
|
| Processed anodized and optical coated aluminum | 75-95 |
|
| Polished aluminum | 60-70 |
|
| Chromium | 60-65 |
|
| Stainless steel | 55-65 |
|
| Black structural glass | 5 |
|
| Spread | General diffuse reflection with a high specular surface reflection of from 5 to 10 per cent of the light. |
|
| Processed aluminum (diffuse) | 70-80 |
|
| Etched aluminum | 70-85 |
|
| Satin chromium | 50-55 |
|
| Brushed aluminum | 55-58 |
|
| Aluminum paint | 60-70 |
|
| Diffuse | Diffuse reflection results in uniform surface brightness at all viewing angles. Materials of this type are good reflectingbackgrounds for coves and |
|
| White plaster | 90-92 |
|
| White paint* | 75-90 |
|
| Porcelain enamel* | 65-90 |
|
| White terra-cotta* | 65-80 |
|
| White structural glass | 75-80 |
|
| Limestone |
35-65 |
2. Transmitting materials [2]
Material |
% Transmittance |
Characteristics |
|---|---|---|
| Transmitting | ||
| Glass | ||
| Clear and optical coated | 80-99 |
Low absorption; no diffusion; high concentrated transmission. Used as protective cover plates for concealed light sources. |
| Configurated, obscure, etched, ground, sandblasted, and frosted | 70-85 |
Low absorption; high transmission; poor diffusion. Used only when backed by good diffusing glass or when light sources are placed at edges of panel to light the background. |
| Opalescent and alabaster | 55-80 |
Lower transmission than above glasses; fair diffusion. Used for favorable appearance when indirectly lighted. |
| Flashed (cased) opal | 30-65 |
Low absorption; excellent diffusion. Used for panels of uniform brightness with good efficiency. |
| Solid opal glass | 15-40 |
Higher absorption than flashed opal glass; excellent diffusion. Used in place of flashed opal where a white appearance is required. |
| Plastics | ||
| Clear prismatic lens | 70-92 |
Absorption; no diffusion; high concentrated transmission. Used as shielding for fluorescent luminaires, outdoor signs and luminaires. |
| White | 30-70 |
High absorption; excellent diffusion. Used to diffuse lamp images and provide even appearance in fluorescent luminaires. |
| Colors | 0-90 |
Available in any color for special color rendering lighting requirements or aesthetic reasons. |
| Marble (impregnated) | 05-30 |
High absorption; excellent diffusion; used for panels of low brightness. Seldom used in producing general illumination because of the low efficiency. |
| Alabaster | 20-50 |
High absorption; good diffusion. Used for favorable appearance when directly lighted. |
3. Surface Reflectance Guidelines for Work Environments [3]
Surface |
Suggested Reflectance |
Complying Material |
|---|---|---|
| Work surfaces | 20 to 40% | Light woods, Medium and light laminates |
| Window treatments image preserving | Match wall reflectances | Medium value mesh shade, Medium value frit pattern, Light-to-medium opaque frit pattern |
| Floors | 20% or greater | Medium-to-light carpet, Medium-to-light wood, Medium tile |
| Ceilings | 85% or greater | Premium white tile, Ultra-white tile, White paint |
| Partitions or Walls | 40% or greater | Light fabric, Medium-to-light paint/ laminates/ wall covering, Very light wood, Very light stone |
References