Reports & Publications - Case Studies
Library | Office | Retail | Schools | Warehouse
Library
Harmony Library
Daylight Dividends Case Study: Harmony Library 
Located in Fort Collins, Colorado, uses daylighting to illuminate its book stacks and provide a comfortable, inviting atmosphere for its patrons.
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Office
TomoTherapy, Inc.
Daylight Dividends Case Study
This case study is unique in that it involves a tenant-occupied building that the designers and building owner agreed to design to take advantage of daylighting for the TomoTherapy building as a means of improving energy efficiency and helping to ensure occupant comfort.
California State Auto Association
Daylighting Initiative: Pacific Gas and Electric Daylighting Initiative
This single-story office space uses skylights as the main source of daytime illumination. The skylights are 15’ above the floor, set into splayed wells in a 10’ ceiling, and cover approximately 3.4% of the roof area. Occupants report that the office has a spacious feel; this may be enhanced by the use of perforated venetian window blinds that preserve a view out of the building even when closed.
The daylighting features of the building reduce the need for electrical lighting during the daytime, which in turn reduces the cooling requirements. This allowed the building designers to downsize the heating, ventilation, and air-conditioning (HVAC) system. The skylights are equipped with vents that allow hot air to be discharged outside the building, and with louvers that allow sunlight to be excluded. On-site studies show that the use of daylight saves nearly one-third of the building’s total energy costs.
Sacramento Municipal Utility District
DELTA Portfolio: Sacramento Municipal Utility District Customer Service Center
This large office building was designed from the beginning to make best use of daylight. The main facades are oriented north and south to maximize energy efficiency and make daylight as predictable and manageable as possible; full height windows with vertical blinds are used on both facades, and the south-facing windows have light shelves.
Employee break rooms have full height windows that allow direct sunlight to pour in freely. These are bright, cheerful places for employees to retreat from the office routine and take a visual break.
A daylight-linked dimming control system reduces power consumption to 0.58W/ft2 from the installed load of 0.87W/ft2. Compared to a building that just meets Title 24, this 184,000 ft2 building saves $56,000 in energy costs per year: $43,000 from the lighting system and $13,000 from the HVAC system.
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Retail
Costco
Daylighting Initiative: Design tools and information from PG&E
Skylights and lighting controls are now installed as standard in Costco stores and distribution centers to improve the shopping environment and to save lighting energy costs. Lighting energy savings are projected at around 50%, or $150,000 per year across all Costco Stores.
Diffusing skylights, 8 ft. x 4 ft. each, cover approximately 4% of the roof area of the high-ceiling, warehouse-style buildings. A single photosensor is used to control all the metal halide fixtures in the store, switching them on and off in three groups to provide a stepped response to daylight that ensures a minimum of 550-650 lux (55-65 footcandles) at all times. Operating costs are minimized by integrating the photosensor with the store’s energy management system, controlled off-site.
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Schools
Daylighting in Four Schools
An Evaluation in Four Schools in the Research Triangle Area of North Carolina
Smith Middle School
Daylight Dividends Case Study
In 2001, the Smith Middle School opened its doors, embracing not only a new student body, but also an environmentally conscious attitude. Part of the Chapel Hill-Carrboro City School District in Chapel Hill, North Carolina, the Smith Middle School exemplifies good daylighting design practice. This case study documents that good daylighting design incorporated at a building's inception yields positive results in energy savings, comfort and a reasonable return on the added investment.
Marin Country Day School
Daylighting Initiative: Design tools and information from PG&E
When architects were asked to design a new multipurpose building at Marin Country Day School in Corte Madera, California, they evaluated possible design options by building a daylighting model. Modeling helped decide the scheme that clearly provided the best quality of light in the new 4,500 sq.ft. building. Their final selection included large vertical windows and a roof clerestory for even light distribution. Site orientation and ceiling color contributed to the effectiveness of the roof design, overcoming glare and heat gain problems.
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Warehouse
Costco
Daylighting Initiative: Design tools and information from PG&E
Skylights and lighting controls are now installed as standard in Costco stores and distribution centers to improve the shopping environment and to save lighting energy costs. Lighting energy savings are projected at around 50%, or $150,000 per year across all Costco Stores.
Diffusing skylights, 8 ft. x 4 ft. each, cover approximately 4% of the roof area of the high-ceiling warehouse-style buildings. A single photosensor is used to control all the metal halide fixtures in the store, switching them on and off in three groups to provide a stepped response to daylight that ensures a minimum of 550-650 lux (55-65 footcandles) at all times. Operating costs are minimized by integrating the photosensor with the store’s energy management system, controlled off-site.
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