CSHQA 2B Office Building
200 W Broad St.
Boise, ID 83702
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Building Description
The CSHQA office building is a state-of-the-art adaptive reuse of a 1950’s railway warehouse as an architecture and engineering design studio. The more than 18,000 square foot, single-story structure went through long periods of vacancy for several decades and would be best described as so nondescript that most locals had to be reminded that it was there. CSHQA had been looking for a building in the downtown district to relocate and after evaluating the structural integrity of the building they felt it would make a good home for the business, with some improvements.
Public spaces including the exterior patio, entry, lobby, conference rooms, restrooms, and break room are grouped to the east side of the building. Auxiliary spaces including print room, mechanical and telecom rooms, and restrooms with showers and lockers are grouped on the west wall, which is a shared property line with another building. The central, open design studio for 70-80 staff extends from north to south walls.
Building Envelope
The original building was constructed with CMU and brick exterior walls on a raised concrete slab. The roof was framed with rough sawn lumber and timber beams. Fenestration had not been replaced since the building was originally constructed. The old rail car loading doors were constructed of corrugated sheet metal on wood frame and were still in place. The gaps around these doors were as much as three inches in some places. The walls were uninsulated and the roof assembly was insulated with R19 foil faced batt. There were no interior finishes other than paint splatters left behind by a previous tenant.
CSHQA upgraded the envelope to exceed ASHRAE 90.1 2007 baseline. The R19 batt from the roof assembly was removed and reinstalled at the exterior walls by adding a wood frame wall inboard of the CMU. The resulting wall assembly was increased to R22.5. The roof was reinsulated with R30 continuous board insulation. The new roof membrane is TPI with an ENERGY STAR initial solar reflectance rating of 0.87. The existing window and door openings were infilled with new storefront NFRC labeled as U-0.37 and SHGC-0.6.
Daylighting
The central, open design studio for 70-80 staff extends from north to south walls. The midpoint between the walls is over 60 feet from an exterior wall so skylights were seen as an absolute necessity. The daylighting concept was modelled to optimize the distribution of natural light while minimizing penetrations in the roof.
Ventilation, Heating, and Cooling
The primary HVAC system is a water source heat pump system arranged in a traditional boiler/tower configuration with a twist. The city of Boise is fortunate to be located in an area known for volcanic activity. Geothermal hot water wells located in the foothills outside of town supply a municipal distribution system with 170 degree hot water. The water source system at CSHQA uses the district geothermal in place of a boiler for heat addition to the source loop. The CSHQA building makes use of this resource to generate domestic hot water and provide some space heating as well as supply the source loop.
Ventilation as well as supplemental heating and cooling is provided by a roof-mounted water source heat pump. This unit operates most of the time in 100% outside air mode on a DCV control strategy. During mild seasons this unit will provide space conditioning mostly in economizer mode.
Radiant Heating and Cooling
The CSHQA office building is the first commercial building in Idaho to use radiant slab heating and cooling. The slab system is supplied with hot or cold water by a series of water to water heat pumps. Operation has been on a seasonal basis to offset baseline heating and cooling loads with the supplemental air system meeting peak demands. The slab control strategy is predictive rather than reactive due to the thermal inertia of the floor mass. The slab is “charged” during the night on a schedule that allows the thermal inertia to meet the peak load later in the day.
Lighting
High efficiency, high frequency, electronic, dimmable ballast fluorescent fixtures are spaced throughout the design studio for consistency and even lighting. All other fixtures are LED in conference rooms, the break room, exit signs, accent lighting, and restrooms. Daylight harvesting and lighting systems are centrally monitored, then dimmed or turned off with local daylight and occupancy sensors and a central lighting control panel.
Building Control Systems
The CSHQA building HVAC is controlled by a direct digital control system. The operator is a staff engineer who can modify the software as needed to facilitate low or no cost improvements to energy efficiency. Most buildings this size would not have the resources available to assign skilled staff to ongoing energy efficiency measures and maintenance. CSHQA has the resources and has made the commitment to this effort.
Communications:
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Testimonial:
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Please note: Narrative information in this profile has been provided by 2nd and Broad, LLC or a representative of this facility. Other building information was verified and submitted to EPA at the time of application. Building energy performance, operating characteristics, and ownership/management may be subject to change over time.
Building Owner:*
2nd and Broad, LLC
Property Manager:*
N/A
Year(s) Labeled (Rating):
2015 (96)
Facility Type: Office
Total Floorspace: 18962 sf
Year Constructed: 2013
Contract Type: None
Technologies Used:
| Stage 2-Lighting |
| Stage 3-Load Reductions |
| Stage 4-Fan Systems |
| Stage 5-Heating and Cooling Plant |