By Craig DiLouie
HGA Architects, Engineers, and Planners practices what it preaches. The firm, which often incorporates sustainable design principles in its services to clients, recently earned a LEED-CI Silver rating for its new offices in Milwaukee.
The Marine Terminal Building was built in 1921 and used as an off-loading facility for cargo ships from the Great Lakes docking in the Milwaukee River. HGA designed the renovation, which enabled the building to be converted to a mixed-use development, including condominiums, with HGA's regional offices at the street level.
In open offices, T5HO fixtures provide about 25 footcandles of ambient illumination. Total connected load for ambient and task fixtures is 0.81 watts per square foot, although most task lights are rarely used because ample daylight is provided via the southern exposure. PHOTO:Jill Cody
The 30,000-square-foot renovated office space includes open-plan workstations, partially enclosed offices for principals and project managers, open teaming spaces, conference rooms, and support spaces including a library, archives, and social spaces for about 125 employees.
Bricked-up windows were reopened, allowing river views, and glazed with a small-paned sash as required by historic preservation bylaws. On the street side, a band of enclosed support spaces forms a dense layer in the plan, along which is a major circulation spine that features a series of teaming spaces as well as exhibits that conceal library materials, printers, copiers, and entrances to lavatories and support spaces.
HGA's Jill Cody, IALD, LC, LEED-AP, and Jay Oleson, PE, LEED-AP, describe the lighting challenge as creating a lighting system that would express the architecture, provide a quality, illuminated environment for users, and minimize energy consumption.
"The lighting palette was limited to a few elements, selected to avoid visual clutter and push architectural forms to the forefront," says Cody. "Major design components include lines of indirect light, accent lighting for displays, revealed light sources for wayfinding, and uplighting of columns."
Simplicity was the key to achieving energy-efficient lighting without sacrifice. The lighting interacts with the architecture to provide interest and drama and emphasizes quality, functional lighting for users of the space. The lean power requirements were achieved by using highly efficient light sources and light fixtures, placing light only where it is needed, and maximizing use of daylight.
|Ceramic metal halide lamps, using minimal energy,
dramatically uplight columns. Like most display
lighting, these fixtures are programmed to turn off
during daylight hours. PHOTO: Jill Cody
"The desire to create drama with lighting can counteract the goal of reducing lighting loads," Cody explains. "These needs were balanced by limiting displays and associated lighting to certain areas. Other spaces, such as the library shelves, integrate lighting nearby to reduce inefficiency associated with high ceilings. The emphasis on efficiency didn't affect lighting quality but it did force us to be very selective and make some deliberate choices about what we lighted."
The resulting connected lighting load is 1.15 watts per square foot, a 26-percent reduction from the requirements of ASHRAE/IESNA Standard 90.1-1999 and a greater than 14-percent reduction from Standard 90.1-2004. Due to an integrated lighting control system incorporating automatic shutoff, occupancy sensors, and daylight harvesting switching control, the actual operating load during daylight hours is 0.9 watts per square foot or lower - a 46-percent reduction below Standard 90.1-1999.
The lighting not only satisfied the occupants and helped the project achieve its LEED-CI goals, but also earned the firm a 2005 GE Edison Award for Sustainable Design.
Daylight and Views
Cody and Oleson had to work with windows that limited daylight penetration to 20 to 25 feet into open-office areas that were 65 feet deep but afforded views to 90.2 percent of regularly occupied spaces.
"This is not to say that the space does not receive adequate daylight," explains Oleson. "On most days, clear or overcast, we are automatically turning off more than 5,000 watts of lighting, and on clear days we are turning off another nearly 2,000 watts, due to the availability of daylight."
Cody and Oleson faced a challenge with glare and solar gain due to the large riverside elevation facing due southwest. They mitigated these potential problems through the use of balconies and motorized shades.
The 6-foot-deep balconies of the condo units on the floor above the office level provide significant shading of these windows. In the gaps between the balconies, sections of horizontally mounted louver panels were installed to make the shading continuous along the entire length of the building. Cody and Oleson point out that this system provides at least 2 hours of beneficial shading per day from March 15 through October 1.
"During times when the balconies are not adequate to block direct sunlight from workstation areas, a motorized shade takes over," says Oleson. "Based on detailed sun angle and building orientation calculations, a time-of-day program was developed to automatically lower the shades progressively throughout the day to block direct sunlight. The shade fabric is a 5-percent open weave, preserving some view even when the shades are closed. They automatically open at sunset, resetting the system daily."
Cody adds, "The most important feature of the office is really the feeling of the space and the relationship to the outdoors and the river. In the end, the architecture and the lighting serve as a clean backdrop for our work and our views."
|In the lobby, limiting display lighting to certain
areas creates efficiency and emphasis. PHOTO: Jill Cody
In the entry lobby, the back wall is washed with T5HO lamps to separate it from the ceiling plane, while graphics are highlighted with adjustable accent light fixtures and visitors are oriented by glass-trimmed downlights over the reception desk.
In the main circulation corridor, columns are accented with grazing light from 20-watt ceramic metal halide lamps.
Open-office areas receive ambient illumination from single-lamp T5HO indirect light fixtures and task illumination from furniture-mounted task lighting.
In collaborative team areas, working drawings, renderings, and other project materials are pinned onto walls lighted with discreet multihead fixtures lamped with 39-watt ceramic metal halide lamps.
Lighting for the freestanding library alcoves was placed on the structure itself, increasing efficiency.
Cody points out that these highly efficient sources and design decisions worked within the visual strategy. "The metal halide uplights lighting the columns create a rhythm of light that punctuates the main circulation corridor along the length of the office. In the open-office areas, the rectangular profile of the indirect fixtures echos the clean lines of the dropped ceiling elements. In the collaborative team spaces, the display lighting served two functions - lighting the wall while also indirectly lighting adjacent workspace. Mounting the lighting directly on the structure of the library alcoves keeps the ceiling free of clutter, as the other side of the alcoves faces the main circulation corridor."
In addition, the indirect and decorative fixtures used were manufactured within 100 miles of the project, low-mercury lamps were used wherever possible, the number of lamp types was limited to support maintenance, and all equipment was acquired within budget.
Lighting controls are used extensively in HGA's Great Lakes offices, including automatic shutoff, occupancy sensors in individual spaces, and individual control for occupants. All workstations have individually controlled task lighting.
The controls have a significant impact on energy consumption, resulting in an estimated 22-percent reduction in lighting operating load. The controls are still being commissioned.
"We have been surprised by the amount of time the commissioning has taken," says Oleson. "There have been several hurdles in this process, from a contractor who was very hands-off on the controls and relied on the vendor to provide all the support to incorrectly wired relays and software glitches."
He adds: "One of the lessons we've learned is to better document the intended functionality of the lighting controls. A detailed sequence of operations similar to what the HVAC industry has been doing for years has now become part of the documentation for our projects. This gives us a benchmark to measure whether the system is functioning per the original design intent. Now that lighting controls systems are getting much more sophisticated in an effort to save energy, both contractors and designers are trying to find a good way to communicate this information so we're all on the same page."
Photocell input to the lighting control system regulates light fixtures near windows for increased energy savings. PHOTO: John Korom
"The new office space is a hit with employees, from the availability of daylight and views to the collaboration spaces," says Cody, who credits a team effort for the result. Laughing, she adds that designing for co-workers added another dimension to the challenge of the project.
"Ambient light levels are lower than the previous office, but because task lighting is incorporated into the furniture system, employees have more control over their individual light levels than before," says Oleson. "Daylight is also much more evenly and widely distributed than in our previous office. The excellent quality of the light, from the high color rendering to the importance placed on visual comfort, has received a very positive response."
Craig DiLouie, a journalist, analyst, and consultant, is principal at ZING Communications Inc. (www.zinginc.com).