Utilisation Factor Table
Table rows explaining utilisation factor assumptions for room lighting estimates.
UF 0.80
UF 0.70
UF 0.60
UF 0.50
Table PDFUtilisation Factor Table
Download the table with the page URL and retrieval date for offline lighting checks.
| UF band | Room or fitting condition | Effect on lumen target | Boundary |
|---|---|---|---|
| 0.80 | Efficient optical distribution in a bright, simple room with supporting surface records. | Lower lumen allowance for the same target lux. | Use only when photometry, surfaces and assessed plane support it. |
| 0.70 | Common preliminary estimate for ordinary interiors and early calculator checks. | Balanced early estimate for room calculations. | Not a substitute for luminaire photometric data or room-index method. |
| 0.60 | Darker finishes, less efficient distribution, obstructions or higher ceiling effects. | Raises required lumens by about 17% versus UF 0.70. | Check whether reflectance, layout, mounting height or fitting optics caused the change. |
| 0.50 | Difficult geometry, dark surfaces, blocked light paths or poor delivery to the task plane. | Raises required lumens by about 40% versus UF 0.70. | May indicate the fitting type, aiming or layout needs review before more lumens are added. |
| Photometric method | Room index, reflectance, luminaire data and target-plane calculation method. | Replaces generic UF assumptions in formal calculations. | Use the applicable method and data when a project record needs more than an estimate. |