The Idaho Central Credit Union (ICCU) Headquarters, in Eastern Idaho, is an excellent example of an energy efficient and well daylit office building. Top executives at ICCU and LCA Architects agreed early in programming phases to include daylight in a substantial manner in the new building to create a pleasant, healthy and professional environment. The owner-designer team exhibited the willingness to challenge conventional design assumptions and investigate design principles and technologies that would prove to benefit the entire project.
The design team mined energy savings by considering not only technological improvements but design improvements as well. The team employed integrated design principles that allowed successful implementation of alternative thermal comfort strategies, increased controllability of systems, and proper building orientation combined with strategic shading elements and daylight harvesting. Energy reduction measures were thoughtfully considered from the earliest design stages and the details were well executed in the final product, including careful furniture and position design for good daylight penetration and commissioning of lighting and air delivery systems.
Idaho Power was an important partner in this project in that they provided incentives for efficiency measures that were identified during the integrated design process like daylight photo controls, occupancy sensors, and high performance windows.
The building’s modeled Energy Use Index (EUI) is 67.2 kBTU / FT²•YR* as compared to an average office building in Idaho at 89.3 kBTU / FT²•YR.** The reduction in energy use offsets approximately 331 tons of CO2 per year and is equivalent to removing 64 cars from the road per year. ***
The ICCU Headquarters is located in Chubbuck, Idaho and is a major employer in the economy of Eastern Idaho. With a total of 68,000 square feet, made up of four floors, this building significantly increased the visual presence of ICCU as well as provided much needed room for corporate growth. The building employs a raised floor system that expedited data and power runs during construction, provides employees with optimum electrical outlet and supply air placement, and is easy to reconfigure. ICCU has a healthy high performance building that was completed on budget and provides a solid foundation for continued growth.
Strategies & Features
- Minimize energy use
- Reducing the use of interior lighting 10% below minimum density code requirements
- Healthier and cleaner zones to reduce illness and loss of work hours of employees
Visual Comfort and Quality
- Utilize natural daylight as primary light source
- Maximized north and south exposure
- Narrow office bays (<30') through much of building
- Glare and heat gain mitigation on south façade with substantial fixed overhangs
- Light redirecting ‘shelves’ at south façade to direct daylight to ceiling
- Partitions designed to provide necessary privacy while taking better advantage of daylight
- Supplement daylight with energy efficient, cost effective lighting design
- Reduced first cost of installed electric lighting by 10% due to ample daylight and use of direct/indirect fixtures
- Incorporated simple proven daylight harvesting techniques with central touch screen controls for ease of maintenance
- Installed lighting power density is 10% below code and daylight harvesting saves up to 50% energy additionally on an annual basis.
- Create a pleasant and professional interior office environment
- Open office floor plates and low office partitions to improve access to daylight and views
- Improve visual comfort through use of daylight and direct/indirect pendant electric lighting
- Create visual interest and balance daylight contribution with well-designed electric lighting
- Promote use of stairways for healthy vertical circulation by designing them with windows and high quality finishes
Thermal Comfort and Air Quality
- Reduce first cost and lifecycle cost of cooling systems while providing improved indoor air quality
- Underfloor air distribution and displacement ventilation to reduce indoor air contaminants and promote a healthy workplace
- Underfloor distribution promotes thermal comfort by delivering air closer to people and at temperatures closer to comfort zone
- Low VOC marmoleum and carpet tile throughout
Energy & Financial Analysis
Lighting: 361,300 kWh (Baseline), 168,720 kWh (53% better)
Ventilation: 232,300 kWh (Baseline), 108,260 kWh (53% better)
Space Cooling: 140,100 kWh (Baseline), 80,008 kWh (23% better)
Pumps: 13,400 kWh (Baseline), 8,140 kWh (39% better)
Heating: 2,465 MBTU (Baseline), 1,492 MBTU (39% better)
Energy Use Guide: 102.9 kBtu / ft²• yr (Code Baseline), 89.3 kBtu / ft²• yr (Typical Idaho)**, 67.2 kBtu / ft²• yr (As Designed)
Carbon Offset: 331 tons of CO2 / year (energy savings) ***
Project Budget: $12,000,000
Cost per Square Foot: $178
Energy Cost: $129,563 (Baseline), $87,786 annually (32% savings)
Operating Energy: $41,777 in modeled annual Savings as compared to base (ASHRAE 90.1)
Utility Incentive: $100,000 from Idaho Power
Load Reduction Measures
Under Floor Air Distribution. The building is equipped with a raised floor system with plenum space for ventilation supply air, thus delivering air closer to the occupants with less fan power and minimizing the air change requirement. Vents and outlets can easily be placed at each individual’s workstation, providing excellent access to fresh air and individual temperature control. The raised floor system allows the building to use outside air for more hours on an annual basis because the air is delivered at cooler temperatures during the heating season and warmer temperatures during the cooling season due to the close proximity to people.
Cooling. The under floor plenum is pressurized to deliver cool air through floor diffusers. Since the air is delivered closer to the users, it can be delivered at a higher temperature requiring less cooling energy. This system also improves indoor air quality because it takes advantage of stratification and a ceiling return plenum to remove stale air without mixing it with the supply air, thus, leading to fewer employee sick days. Due to the less extreme supply air temperature the chiller could be downsized, reducing first costs and operation costs.
Heating. Again, less extreme supply air temperatures reduce the size of heating equipment and save both energy and first cost.
Envelope. Spectrally selective high performance glazing was used throughout. The glass is effective at keeping the heat outside in the summer and inside during the winter while allowing a large amount of visible light to penetrate the building for further electric lighting savings and increased user satisfaction. The exterior overhangs minimize glare and heat gain and are also
an aesthetic asset to ICCU.
Design for Daylight. The building incorporated daylighting by maximizing north and south exposures since they are easier to control for sun penetration and kept perimeter to core depths as small as possible. Much of the open plan office area is less than 30 feet from the window wall. The open floor plate allows daylight to penetrate deeper into the space while low partitions further promote daylight penetration and view potential. The interior partitions are carefully designed to provide the necessary privacy with taller segments (55”) perpendicular to the window wall while keeping partitions parallel with the window wall lower (38”). Further, the upper most segments of many of the partitions are translucent and all are light in color to increase the perception of lightness. External solar shading and internal lightshelves are supplemented with louver blinds to minimize glare from low angle sun penetration during winter sunny conditions.
ICCU owners and their design team are pleased with the Headquarters project and cite the daylight strategies as an important feature that added to the project. LCA Architects considers the daylight design a huge success story for the client and building occupants. This success story started off by simply positioning the building to maximize north and south exposures in order to harvest daylight and use it as the primary lighting source for the building. Users are pleased with the abundant daylight and their ability to control against the occasional glare from direct sun during clear winter days. The low office partitions have been well received and any concerns for privacy are far outweighed by access to daylight and view. The external shading devices are considered an aesthetic asset and also happen to mimic the corporate logo on the façade during sunny days, an unexpected plus.
Steve Christensen at LCA Architects indicated that although the daylighting design is considered a success, he had some concern over the design and operation of the emergency lighting system. Because of certain assumptions about fire code, the small number of fixtures designated for egress lighting do not turn off even though there is ample daylight. More than the sacrificed energy savings, in a well daylit space where almost all the electric lighting is off, the few emergency lights at full power are visually awkward. An alternative is to design the emergency lights such that they only come on during a power outage or an alarm signal.
Lighting. Direct/indirect pendant electric lighting was designed to carefully consider the daylight available and installed lighting was modestly reduced. Further, a small number of photosensors per floor were configured in a closed loop system and located between windows and electric light fixtures to read illumination levels on desks and control the electric light component to meet a prescribed light level. The system was designed and commissioned so as to minimize user overrides. Designed and installed properly, and combined with robust and careful architectural daylighting, the visual environment has been well received by users and saves substantial electric lighting energy and, therefore, cooling energy.
Also related to electric lighting, Geoff Johnson at Eidam and Associates suggested that they might have been even more aggressive in reducing the installed lighting by reducing electric lighting design criteria a bit further as well as accounting for the low office partitions and light color finishes. These small integration issues would combine for even more first cost and operating cost savings.
Up-Front Capital Savings. Open floor plans, good envelope design, and load reductions in heating, cooling and ventilating allowed designers to downsize the mechanical systems, reducing equipment and installation costs. These savings were reinvested into the under floor air distribution system, lighting control system, and external shading which combined to further improve building performance.
Increased Profitability for Owners. Recipients of the 2007 Idaho BetterBricks Award, Chris Hyer and Kent Oram of ICCU have been acknowledged for their commitment to sustainable business practice. The ICCU Headquarters has proven that ‘building green’ increases profitability for owners right away, and suggests that higher profitability will be enjoyed by the owners over the life of the building due to energy cost reductions, improved employee satisfaction and lower turnover.
In an owner occupied building, employee satisfaction and performance is paramount. For a 30-year outlook, over 90% of office business costs are in labor, while less then 2% are for capital outlay and 6-9% are for energy and other operating expenses.
ICCU has chosen wisely by investing in a building that will serve to create a high performance environment for their employees while minimizing operating expenses. Their investment paid back handsomely when they were presented with Idaho Power’s maximum energy efficiency incentive payout of $100,000.
Idaho Power, Intermountain Gas
Eidam & Associates
Contact & Resources
* Energy Model for LEED certification performed by design team
** Based upon USEPA© Target Finder for Idaho
*** Based upon USEPA© @ 5.2 tons of CO2/car•year