America’s public buildings at the turn of the last century were awash in daylight – large skylights illuminated assembly spaces, stair cases, conservatories, and libraries. The motivations for this approach were both pragmatic – free lighting to public spaces during business hours – and decorative, as brilliant light “diffusers” became celebrated touchstones of architectural and artistic expression in many civic and academic buildings. Unfortunately, with the advent of inexpensive and safe artificial lighting, the preference of designers and users of public spaces shifted toward the convenience and predictability afforded by first gas, and then electric lighting, and away from maintenance-intensive and leaky skylights. Existing skylights were frequently covered or removed, often dramatically altering these grand public spaces by abandoning previously focal diffusers or finish work to relative darkness and obscurity.
The past decades have seen a steady resurgence in the appreciation for daylight in public spaces. This resurgence has been motivated and helped by several convergent forces: historic preservation interests, energy efficiency considerations, an appreciation for the benefits of natural lighting on worker well-being and productivity, and finally improved building enclosure and mechanical engineering technology that makes for more reliable, efficient and user friendly skylights.
This paper will survey daylighting design practices and approaches in American public architecture prior to the Great Depression, and the decline of both utilitarian and decorative skylights. Drawing on their own experience recreating several lost or diminished skylights, the authors present techniques and best practices for the rehabilitation and restoration of historic skylights and diffusers.