JACK EVANS POLICE STATION

SITE

The 3.20 acre previously developed urban brownfield site, a former home to an auto service center with associated underground petroleum storage tanks and contaminated soils, included approximately 98% of impervious surfaces. The new headquarters building provides extensive open space redevelopment by incorporating an additional 30% improvement of vegetated surface, providing surrounding areas with some relief from impervious hardscape and residually minimizing storm water runoff from the site.  Since the early 1990s, the City of Dallas has operated a Brownfield Assistance Program, promoting the redevelopment of abandoned or neglected sites, such as this one.  As a result, the City prioritized the remediation and reclamation of this brownfield site in the hopes that the project would provide an economic stimulus for nearby private development.

Four existing Live Oaks were protected and incorporated into a large planting area. These native trees shade the ground plane, funnel breezes toward the building, and provide habitat for various native wildlife such as birds and squirrels. Bald cypress trees located in a large grove at the site's southwest corner capture the southwesterly winds that prevail from spring through mid-fall to cool the building. The mulch beds below the trees catch the needle-like leaves, which reduce soil erosion and retain moisture. Native Texas redbuds located at the north side of the building bloom in the early spring with pinkish-purple clusters that provide food for butterflies and bees. The project's light-colored finishes reduce its contribution to the urban heat-island effect.

WATER CONSERVATION AND USE

The building uses approximately 21% less potable water than a comparable conventional project by utilizing low-flow fixtures and waterless urinals.  A cooling-tower water-treatment system utilizes ionization and filtration to remove chemicals and bacteria from the potable water, eliminating scaling on the tower’s tube infrastructure. With no scaling, the requirement to use potable water for cooling tower blowdowns was eliminated, saving approximately 2.3 million gallons of water per year. For irrigation, the project borrows graywater from a 60-inch stormwater main running adjacent to the project site. The system, which includes a 10,000-gallon underground water storage tank, supplies all of the project's landscape irrigation needs.

ENERGY

The building was designed to reduce energy costs by over 40%, compared with a comparable building designed in minimal compliance with ASHRAE 90.1-1999.   With the aid of energy-modeling studies, various modifications to the building envelope were incorporated that reduced potential heat gain into the building. This process led to increased energy efficiency of the mechanical system and a workable return on investment with the higher performance equipment utilized by the project.

Because of the project's north Texas climate, the building envelope is optimized to reduce heat gain. Passive design strategies include the use of high-performance glazing that reflects more than 60% of potential solar heat gain while allowing 85% light transmission. A highly reflective roof coating further reduces heat gain. Other load-reduction strategies include the building's compact shape, which minimizes the ratio of surface area to floor area; a reduction in exterior glazing; and the use of light-colored finishes to minimize heat absorption.

High-efficiency fluorescent direct/indirect lighting throughout the building minimizes the number of fixtures required, reducing the electrical and heat load. Occupancy and daylight sensors further reduce electricity consumption. The owner-installed Energy Star equipment reduces the facility's plug load.  The building earned a high U.S. Environmental Protection Agency Energy Star rating of 84.

MATERIALS AND RESOURCES

One of the most important material selections in the project surrounded the building structural system selection. Although structural steel framing was slightly less expensive and higher in recycled content than cast-in-place concrete, its transportation costs were moderately higher. Concrete was determined to be more desirable for its local availability, stability, fire resistance capabilities, and durability over a potentially longer life-cycle.

Economy and durability were also considerations for the building envelope. Brick was selected as the primary exterior finish to complement the existing neighborhood warehouses and reduce additional solar heat gain. Numerous masonry suppliers with regional manufacturing facilities were interested in the project. Their ability to deliver material to the site at minimal transportation cost was an important consideration in the selection of brick veneer over a conventional curtainwall envelope.

INDOOR ENVIRONMENT

Striving to create a comfortable and productive indoor environment, the headquarters incorporated extensive daylighting and views to the exterior for every workspace. An analysis of the owner's needs revealed that large, contiguous office areas were required for effective operation. To overcome the impact of large floor plates, a central courtyard was incorporated allowing abundant daylight to penetrate deep into interior spaces. Private offices and support spaces were grouped toward the interior, leaving open office perimeter spaces for the majority of the building occupants.  Energy efficiency, indirect lighting in all open office areas, and an underfloor air distribution system is incorporated throughout the facility.

An extensive indoor air quality management plan was used during construction and prior to building occupancy. Air handling equipment operated during construction was equipped with pre-filters and HEPA filters. The particulate filters prevented contamination of the operating system and the service zones, allowing the work areas to be ventilated with outside makeup air. The filters were replaced at the end of construction at which point the building began using high performance MERV-7 pre-filters and MERV-13 HEPA filters. Adhesives, sealants, paints, and carpeting were selected for their low emissions of volatile organic compounds (VOCs).  Building management software monitors carbon dioxide levels and controls fresh-air intake accordingly, and heat-recovery ventilation further reduces energy demand.

Because this facility was planned to replace an 80-year-old facility, durability was an essential consideration. Police operations require great flexibility, placing a premium on adaptability. The project's large open-plan areas allow for manageable future modifications.

BY THE NUMBERS

A brief overview of the pursued LEED NC credits utilized in the building is listed in the following table:

Sustainable Sites 6
Water Efficiency 1
Energy and Atmosphere 9
Materials and Resources 4
Indoor Environmental Quality 7
Innovation in Design 4
Total 35

BY THE DETAILS

A detailed breakdown of the individual credits achieved with the LEED Silver Certification of the building is listed below:

SUSTAINABLE SITES

  • SSp 1    Erosion & Sedimentation Control
  • SS c1    Site Selection
  • SS c3    Brownfield Redevelopment
  • SS c4.1    Alternative Transportation, Public Transportation Access
  • SS c4.2    Alternative Transportation, Bicycle Storage & Changing Rooms
  • SS c4.4    Alternative Transportation, Parking Capacity
  • SSc 5.1    Reduced Site Disturbance, Protect or Restore Open Space
  • SS c5.2    Reduced Site Disturbance, Development Footprint
  • SSc6.1    Stormwater Management, Rate and Quantity
  • SS c7.1     Landscape & Exterior Design to Reduce Heat Islands, Non-Roof
  • SS c7.2    Landscape & Exterior Design to Reduce Heat Islands, Roof

WATER EFFICIENCY

  • WEc3.1    Water Use Reduction, 20% Reduction

ENERGY AND ATMOSPHERE

  • EAp1    Fundamental Building Systems Commissioning
  • EAp2    Minimum Energy Performance
  • EAp3    CFC Reduction in HVAC&R Equipment
  • EAc1.1    Optimize Energy Performance, 45% New
  • EAc3    Additional Commissioning
  • EAc5    Measurement and Verification

MATERIALS AND RESOURCES

  • MRp1    Storage & Collection of Recyclables
  • MRc2.1     Construction Waste Management, Divert 50%
  • MRc2.2    Construction Waste Management, Divert 75%
  • MRc5.1    Local/Regional Materials, 20% Manufactured Locally
  • MRc5.2    Local/Regional Materials, of 20% Above, 50% Harvested Locally

INDOOR ENVIRONMENTAL QUALITY

  • EQp1    Minimum IAQ Performance
  • EQp2     Environmental Tobacco Smoke (ETS) Control
  • EQc 3.1    Construction IAQ Management Plan, During Construction
  • EQc 3.2    Construction IAQ Management Plan, Before Occupancy
  • EQc 4.1    Low-Emitting Materials, Adhesives & Sealants
  • EQc 4.2    Low-Emitting Materials, Paints
  • EQc 4.3    Low-Emitting Materials, Carpet
  • EQc7.1    Thermal Comfort, Comply with ASHRAE 55-1992
  • EQc8.2    Daylight & Views, Views for 90% of Spaces

INNOVATION AND DESIGN PROCESS

  • IDc1.1     Innovation in Design "Process Water Savings"
  • IDc1.2     Innovation in Design "Green Education"
  • IDc1.3     Innovation in Design "Organic Landscaping"
  • IDc2    LEED® Accredited Professional
  • PROJECT TEAM

Owner: City of Dallas
Architect: PSA-Dewberry
Interior: Corgan Associates
Structural: Charles Gojer and Associates
Mechanical: Blum Consulting Engineers
Electrical: Campos Engineering
Civil: Halff Associates
Landscaping: Caye Cook & Associates
Energy: ENSAR/RMI Built Environment
Commissioning: AIR Engineering and Testing
Contractor: Centex Corporation
Contractor: 3D/I
Photographer: Mark Trew Photography