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					     CNN Center

    John Hester
Turner Properties, Inc.
CNN Center

         • Built in 1975
         • 1,583,000 square feet on
           18 floors
         • Five structures joined by
           a common atrium
         • Multiple building uses
            – hotel, five cable
               networks, retail &
               food court,
               computer/data center,
               & office space
         • Building operated 7 days
           a week, 24 hours a day
                    CNN Center
            Pre-1994 Cooling Equipment

• Main plant - three 1200 ton centrifugal chillers
  – with 0.9 kw/ton efficiency, R-500 refrigerant, installed in
    1975
• Secondary plant - two 300 ton centrifugal chillers
  – cool the CNN Tower, 0.65 kW/ton efficiency, R-11
    refrigerant, installed in 1986
• Five cooling towers installed in 1975
• Constant volume air distribution system
  – older areas (circa 1975) multi-zone units
  – newer areas (circa 1983) use VAV boxes
              CNN Center
  Original Building Envelope & Lighting


• R-10 walls, with R-5 to R-10 roof
• Mostly double-glazed, bronze tinted
  windows with aluminum frames
• Primarily 40 Watt fluorescent light fixtures
  with T-12 lamps and electronic ballasts
• Some incandescent down-light fixtures
• Motion detectors added in 1993
                 CNN Center
                Project Scenario


• HVAC systems being maintained and
  upgraded over time
• Expansion of facility decided on in late 1995
  – addition of two new networks and a new studio
  – two of the original 1200 ton chillers replaced in
    1994 with 1500 ton chillers
  – need to replace third chiller & upgrade capacity
              CNN Center
            Project Challenges

• Wanted operational flexibility
• Wanted to capitalize on real-time pricing
  benefits
• Needed emergency cooling & electrical
  generation
• Building must be kept operational 24
  hours a day throughout all retrofit work
• Need to serve new network loads
             CNN Center
            System Solutions

• Three new chillers, two electrical & one
  gas-engine driven
• One new cooling tower added
• Back-up electrical generator added
• Chilled water piping balancing
• Air handler units converted & upgraded
  to direct digital controls
• Lighting load reductions made
                   CNN Center
                 New Chiller Plant

• Two York 1500 ton electrical centrifugal chillers
  – added in 1994, 0.6 kW/ton efficiency, R-22 refrigerant
• One York/Caterpillar 1800 ton gas-engine-
  driven chiller
  – added in 1996, 2.03 COP, R-134a refrigerant
• New cooling tower added for redundancy
• Secondary chiller plant
  – now used as backup for CNN studios & data center
  – emergency electrical generators installed
               CNN Center
               Chiller Piping


• Constant volume primary piping system
  – small plant piped to more critical studio &
    network loads
  – dedicated chilled water pumps for each chiller
• Unbalanced chiller loads discovered
  – flow test and analysis revealed piping wasn’t
    large enough for north part of building
  – increased pipe sizes saved having to run
    backup plant to meet loads
                CNN Center
        Other HVAC Improvements

• Air handler units being upgraded
  – variable air volume diffusers
  – variable speed drive controls
• Pneumatic controls being replaced with
  direct digital controls
• Hotel hot water
  – future ability to preheat through plate heat
    exchanger with the gas-driven chiller’s jacket
  – new shell & tube heat exchanger for
    instantaneous hot water from building steam
              CNN Center
         Lighting Improvements


• T-12 lighting fixtures de-lamped from 4 to 2
  lamps per fixture
• Electronic ballasts added
• Incandescent down-lights replaced with
  fluorescent PL fixtures
• Motion sensors previously installed in
  offices
                    CNN Center
      Real Time Pricing & Utility Competition

• RTP rates are two-part tariffs
  – first part is standard bill based on the Customer
    Baseline Load (CBL)
  – second part charges the prevailing real-time price for
    energy use above the CBL
  – refund at real-time prices if under the CBL
  – CBL charges are usually higher than real-time prices
• Gas chiller allows for a lower CBL
• Competition led to cost savings on both electric
  and gas operation
                                                     CNN Center
                                 Electric Energy Use Comparison

                       220,000



                       200,000



                       180,000
Energy Use Intensity
 (BTU/square foot)




                                    ne w e le ctr ic chille r s adde d


                       160,000



                       140,000

                                                                          gas e ngine chille r adde d

                       120,000



                       100,000
                                  1993             1994              1995            1996            1997     *1 998

                                                                             Year
                                                     Actual Ener gy Use                Baseline Energ y Use
                      CNN Center
                Integrated Economics
                               Annual      Annual Rebates Payback
                               Energy      O& M       &     Period
                               Savings     Savings Grants (years)
    Two Electrical Chillers    $225,000           0          4.5
   Gas-Engine-Driven Chiller   $210,000   ($40,000) $50,000  3.2
      Piping Rebalancing        $45,000           0          3.5
  AHU’s & Controls Upgrades    $150,000     $10,000          3.7
  Hot Water Heat Exchangers     $50,000           0          0.5
             Total             $680,000   ($30,000) $50,000  3.6

• Cooling tower & lighting measure savings unknown
• Lower payback measures help reduce overall payback
              CNN Center
             Project Results

• Operational flexibility provided by the
  gas chiller
• Reliable backup systems provided
• Higher efficiencies of new chillers
  provides substantial savings
• Loads being met thoughout existing
  building and expansion
• Energy and utility bill savings

				
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posted:2/27/2010
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