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Case Studies: Flannery Construction

GENERAL INFORMATION

Project name: Flannery Construction

Location: St. Paul, MN

Web site: www.flanneryconstruction.com

Architect: Roark Kramer Kosowski/DESIGN

Builder: Flannery Construction

Building size: 14,000 sf

Building use(s): Office, conference room, garage/workshop

Date of completion: November 2005

Ratings and awards:

  • 2007 Sustainable St. Paul Award - City of St. Paul
  • Best Office Building - Precast Concrete Institute; Chicago, IL
  • Sustainable Design Award - Precast Concrete Institute; Chicago, IL

OVERVIEW

Flannery Construction incorporated solar thermal space heating and domestic hot water into their new facility to match up with their goals and to apply for LEED certification. The building itself was designed with energy efficiency strategies, and provides a mix of office spaces, conference room, and a workshop in the garage area. The solar thermal array is mounted on the rooftop and one of the most visible systems in the Twin Cities as it sits just off of I-94 by Snelling Avenue. Currently this is the largest solar thermal installation in Minnesota. The collectors were flown in by crane as three separate arrays, preassembled in the factory by Solar Mining Co. This reduced some of the labor costs for connecting individual panels.

BUILDING PERFORMANCE

Effective energy use solutions:

  • Energy-efficient heating and cooling systems were employed
  • Well insulated building shell
  • In-floor radiant heating
  • Gathered activity spaces-open seating plan in the office
  • Perimeter of office lighting is on motion sensors
  • Lighting systems use Super T-8's
  • Computers and office equipment energy star rated
  • Rooftop has an ENERGY STAR rated white roof of Duro-last

Orientation: East west axis

Daylighting strategies:

  • Every office workstation has access to daylight and views
  • Restrooms have Solatubes for natural light, balanced with motion and light level sensors
  • As the site is just above I-94, the windows were angled to prevent sound penetration from highway

Shading of structure:

  • Sunshades on east west windows
  • Structural design of wall window system provides shading

Envelope:

  • Wall thickness: 9.5 inches
  • Insulation R-values:
    • o Wall: R-value 14.71, precast concrete panels with insulation sandwiched between concrete layers, no thermal breaks at corners
    • o Roof: R-value 31, fire resistant acoustic material adds to R-value
  • Windows:
    • o High efficiency, low-E, high sound transmittal coefficient (highway noise)
    • o Southside windows are transparent with shade to prevent direct daylight

Climate control systems:

  • Air handling systems: capturing climate control temperatures to preheat/precool incoming air
  • Heat exchange control system

Backup heating/power: Infloor radiant heating: Weil Mclain Ultra 310 Boiler with PhD reheating system internal combustion unit using natural gas: efficiency rating 95.6%

Total building energy use:

  • 1st year: 5170 ccfs natural gas; electricity: 145, 280 kWhrs
  • Overall building performance at 37% better than code standard

RENEWABLE ENERGY SYSTEM INFORMATION

Solar system description and size:

  • Three solar thermal collector arrays are mounted on the rooftop to provide domestic hot water and primary garage space heating in a pressurized system with solar electric panels powering the pumps.
  • One array of 10 panels 10' x 4' (400 sf), two arrays of eight panels 10' x 4' (320 each= 640) total 1040 sf of collector area
  • Collectors supplied by Solar Mining Co. are mounted at a 60 degree angle.
  • One panel 3'x 3', 1 150 watt pv panel per array for master pump, four panels at 10 watts act as sub-array pv for powering pumps
  • 350 gallon storage tank by Design Tanks with site built heat exchangers
  • The garage space heating has a 45-70° Farenheit fluctuation before backup heating start or shuts the system down.

Solar system cost: approximately $70,000

Financial incentives/donations:

  • Xcel provided $485 incentive for solar thermal
  • Xcel incentives were $5,500 for energy efficiency strategies

Payback:

  • Payback of comprehensive project: 7-8 years
  • Payback of solar thermal system: 12-15 years

Date installation was completed: November 2005

System Designers: Innovative Power Systems (IPS) and Solar Mining Co.

Engineer: Gausman & Moore

Installer: Solar Mining Co. (sub contractor), IPS (General Contractor)

Estimated amount of energy delivered by system: approximately 2,000 therms per year

Percent of building's total energy use provided by solar: 6%

TOOLS UTILIZED

Modeling software: Energy modeling with engineering with Gausman & Moore

MOTIVATION FOR INSTALLATION

Flannery Construction's goal was to build its new headquarters in the most energy efficient manner possible with no more than a 5-7% increase in upfront costs and a cost savings pay-off within 7 years.

Flannery's healthy environment is greatly appreciated by employees, who all have access to daylight views from their workstations, and benefit from a controlled indoor climate through the building's in-floor radiant heat.

Flannery Construction has a commitment to using low-toxic finishes, sealants, carpet, and cleaning products. The company offers yoga to the employees two times a week and a place to shower and change afterwards. These steps were taken According to owner Gerry Flannery, "Employee health and well-being is directly correlated with productivity and retention."

LESSONS LEARNED

This innovative construction company evaluated its own work flow before designing the office to minimize waste and to maximize efficiency, and was able to appropriate some great ideas from the many offices they have built for clients over the years.

Solar thermal panels work well in this climate.

Flannery recommended use of solar thermal in facilities that use a large amount of hot water (showers, swimming pools, etc), as well as incorporating a way to harness cooling energy from solar panels.

OTHER INFORMATION

Other Sustainable Features:

  • 50% of overall electricity purchased from Wind power
  • Sustainable materials, low-toxic finishes, and cleaners used
  • Recycled, reused, and reclaimed building materials used

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