(big image 42k .jpg) (bigger image 63k .jpg) The City of Fort Collins' new office building was built with energy efficiency and employee comfort in mind.

Fort Collins builds efficiency into new city office building

When Fort Collins, Colo., built a new office building for 155 city employees, it incorporated efficiency as part of the design process.

In fact, the city developed five goals for the design:

• Meet the City of Fort Collins Facility Services Green Building Criteria.
  
  
• Reduce energy costs to 25 percent below the Fort Collins Energy Code requirements.
  
  
• Use daylighting in designated areas to increase worker comfort and productivity while reducing electrical lighting energy consumption.
  
  
• Provide uniform comfort throughout the building and visually connect the building to outdoors while controlling glare and solar heat gain.
  
  
• Reduce the environmental impact of the building by decreasing consumption and incorporating sustainable materials and components.
  

To ensure these goals were met, the city formed a design team. Members include the Neenan Company, the design-build team leader; OZ Architecture, the architect; Architectural Energy Corp., a daylighting and energy consultant; and Swanson Rink, Inc., mechanical and electrical engineers.

This collaborative process was not new to the city. Fort Collins has a history of using design teams to plan for efficiency in new buildings. For example, Fort Collins Utilities has provided design assistance for area schools, the city's own Harmony Library, and a local manufacturing plant.

With its goals set, the city kept efficiency in mind throughout the design and construction of the 71,500-square-foot, $8.8 million facility. It also encouraged an integrated design process with the design team working collaboratively to achieve desired results.

During design, AEC evaluated the design using DOE-2 energy modeling software. To determine how the daylighting measures would perform, the city used physical and computer models. The results led to improvements.

The final design included 10-foot ceilings with both windows and a band of daylighting glazing above them. The glazing allows light to pass through while minimizing solar heat gain and glare. A double light shelf on the east, south, and west project light onto the ceiling, providing daylighting further into the building's interior. A lighting control panel schedules lighting for hours when the building is occupied. The lighting system also features switches to override the automatic controls when needed during off-hours. A photosensor controls lighting fixtures near windows based on daylight availability.

Thanks to this system, about 25 percent of the building's ambient lighting needs are met by daylighting. The system reduced the lighting requirements from 0.98 watts per square foot to 0.73 W/SF.

Throughout the construction process, the builders and the city kept sustainable concepts in mind as an important part of the process. This focus carried over to the commissioning of the heating, ventilation, and air conditioning system, lighting, and control systems.

The HVAC system features highly efficient VAV DX rooftop units and variable speed drives. The glazing and efficient lighting allowed the cooling system to be downsized from 90 to 75 tons. An energy management control system provides automatic data collection to ensure efficient operation of equipment and to learn more about how the building operates.

Thermostats in work spaces allow occupants to increase or decrease space setpoints in their zone. The system automatically turns off during unoccupied hours and on during the workday.

The result is a comfortable workspace and that demonstrates to utility customers the benefits of energy efficiency.