Bathroom Lighting (C) Daniel Friedman Guide to Recommended Lighting Levels for Indoor Areas
Tables & Rules of Thumb for Interior Lighting
     


InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

This article series details guidelines for selecting and installing interior lighting to meet the requirements for different building areas. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Also see LIGHTING, INTERIOR GUIDE our home page for information about all lighting topics relating to building interior

Green links show where you are. © Copyright 2015 InspectApedia.com, All Rights Reserved.

Guide to Recommended Lighting Levels Indoors

Bath light, poorly placed (C) D FriedmanMany factors affect the illumination needed for a specific task. An often overlooked factor is the age of the occupants. At 60 years old, we need two to three times the light we needed at age 20, and also more shielding and diffusers since older eyes are more sensitive to glare.

[Click to enlarge any image]

The other main factors in determining lighting requirements are how detailed the work is and the level of contrast and reflectance of the work surface.

Table 5-21 shows the recommended lighting along with common strategies for each type of room. For task lighting, the low numbers in each range represent the light needed for simple tasks with high contrast (reading large black type on white paper).

The high number is for tasks with more detail or lower contrast (reading the newspaper). For very detailed, low-contrast work or for older persons, light levels of 100 footcandles are often needed.

Table 5-21: Suggested Lighting Strategies and Lighting Levels by Room Type (C) J Wiley, S Bliss

Interior Lighting Rules of Thumb

Task lighting (C) D FriedmanThe illumination level on a surface depends on many factors, including the colors of the room and furnishings and the type of lamp and fixture. High ceilings, dark colors, and diffusers on fixtures all reduce light levels. The commonly used black baffles in recessed lights reduce output by up to 40%.

Tightly focused spots produce much higher light levels than wide floods.

Rules about Distance from Light Source

The distance from the light source is also critical. Doubling the distance to a lamp reduces the lighting level by a factor of four. So moving the light closer to the task is often the simplest way to provide a big boost in lighting levels.

Rule of Thumb for Brightly-Lit Space Needs

As a starting point for design in kitchens, baths, home offices, and other brightly lit spaces, provide at least 2 watts of incandescent light or 3/4-watt of fluorescent light per square foot of floor area. In larger spaces, using multiple fixtures will provide more even lighting and reduce glare.

Also, since lighting needs change throughout the day with changes in daylight and usage, it is good to provide flexibility by separately switching groups of lights and adding dimmers. Increase these minimums by 50 to 100% for:

  • Valences or other indirect lighting schemes
  • Rooms with dark surfaces
  • Lighting placed in cathedral ceilings or other high ceilings
  • Recessed lighting with diffusers, black baffles, or other light-blocking trim

-- Adapted with permission from Best Practices Guide to Residential Construction.

Resources: Manufacturers, Industry Associations, & Sources of Indoor Wall Materials, Flooring, Carpeting, Lighting, Sound Control Materials

Industry & Trade Associations for Lighting and Other

-- Adapted with permission from Best Practices Guide to Residential Construction.

More Reading

Green link shows where you are in this article series.

...




Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

HTML Comment Box is loading comments...

Technical Reviewers & References

Publisher's Google+ Page by Daniel Friedman

Click to Show or Hide Citations & References