Natural Interior Daylight Brings Light and Joy to Berkeley West Library

Overview

This five-page case report from the Eneref Institute, a nonprofit advocacy research group, profiles the West Branch of the Berkeley Public Library in Berkeley, California, completed at the end of 2013. The report's stated aim is to examine whether library use rose after the new skylit building replaced its predecessor. It is built around interviews with branch manager Sarah Denton, branch librarian Amanda Myers, architect Gerard Lee of Harley Ellis Devereaux, and Neal DeSnoo of the city's energy program office.

Key Findings

• The 9,500-square-foot, 24-foot-tall library was designed to meet Berkeley's 2009 Climate Action Plan, which calls for new city buildings to reach zero net energy on the way to an 80% emissions cut by 2050. It came in well under its $7.5 million budget.
• Nearly 30 VELUX skylights supply most of the interior daylight. They are tilted 20 degrees toward north to limit glare, use a Cardinal LoE3 glass that passes visible light while rejecting most infrared, and carry built-in sensor-driven shades. Installation took two days.
• Fifteen skylights open to vent hot air and bring in fresh air, supporting a natural-ventilation scheme that replaces a rooftop air handler; the remaining fourteen are fixed.
• Most windows face north, and south-facing openings sit behind deep trellises so light arrives indirect. Book stacks get conventional electric task lighting aimed at the spines.
• Rooftop photovoltaic and solar thermal systems produce about 17.4 kBtu per square foot per year, which the report says matches the building's total load, making it net zero.
• Staff report that both visitor counts and time spent in the building have increased compared with the old branch, where floor-to-ceiling windows had ended up blocked by shelving. No numeric usage figures are given.
• The report cites Heschong Mahone Group's classroom daylighting research and a Group14 Engineering study on venting skylights as supporting evidence.

Why It Matters for Daylighting

Berkeley West is a compact demonstration of the design moves that make toplighting work in any single-story building: many small apertures spread evenly across the roof rather than a few large ones, orientation and tilt chosen to tame glare, glazing that separates visible light from heat, and daylight modeling done early enough to place skylights around rooftop solar. Those same principles apply to a distribution center or a manufacturing floor, where prismatic skylights achieve the diffuse, even illumination this project reached with tilted glass units and shades.

The venting skylights are also worth noting for warehouse owners. Hot air collects at the roof deck, and skylights that open let it out where it gathers, cutting cooling load and improving air quality in the process. The staff testimony on how people use a daylit space, lingering rather than grabbing and going, is the kind of occupant benefit that rarely appears on an energy model but matters to any building that serves the public.

About the Source

The Eneref Institute is a nonprofit that publishes advocacy-oriented case reports promoting natural interior daylight and other sustainable building practices; its founding director, Seth Warren Rose, is quoted in the report. No author is named. The report is undated but describes the library as completed at the end of 2013 and appeared in 2014; the library copy is five pages with photographs credited to Mark Luthringer. The report page and downloadable PDF are on Eneref's website.