What s New for Data Centers in Title Jeff Stein, PE Taylor Engineering

Transcription

1 What s New for Data Centers in Title Jeff Stein, PE Taylor Engineering SVLG Workshop November 14, 2013

2 About Jeff Stein Principal, Taylor Engineering now Professional Experience Eley Associates, ACCO Engineered Systems, LBNL, Education Cornell University, BS, 1990 UC Berkeley, MS, 1997 Data Center Design/Commissioning Apple, Brocade, Cisco, ebay, Kaiser, Oracle, Symantec, etc. Research Data center environmental conditions, chiller plant optimization, etc. Energy Codes Title , -2005, -2008, ASHRAE

3 New Title 24 Computer Room Definition a room whose primary function is to house electronic equipment and that has a design equipment power density exceeding 20 watts/ft 2 of conditioned floor area. 3

4 Lighting Envelope Ventilation Computer Rooms Now Covered by All of Title 24, including Mandatory equipment efficiencies for packaged units, chillers, towers, etc. Unlike 90.1, Title 24 does not have separate efficiency category for CRAC units Variable flow and variable speed requirements for chilled water systems New exemption: computer rooms exempt from normal economizer requirements 4

5 New Prescriptive Requirements for Computer Rooms 1. Economizers 2. Reheat 3. Humidification 4. Power Consumption of Fans 5. Fan Control 6. Containment 5

6 Economizers Must have an integrated air or water economizer Air economizer can be air-air heat exchanger if it can meet 100% of load at 55/50 DB/WB. Water economizer must meet 100% of load at 40/35 DB/WB Exceptions: Individual rooms under 5 tons in a building without economizers 50 tons of equipment added to an existing computer room 20 tons of equipment added to new computer room in an existing building If you have a lead system with economizer then you can have a backup system without an economizer 6

7 Reheat No reheat 7

8 Humidification Non-adiabatic humidification (e.g. steam, infrared) is prohibited. Only adiabatic humidification (e.g. direct evaporative, ultrasonic) is permitted. 8

9 Power Consumption of Fans The total fan power at design conditions of each fan system shall not exceed 27 W/kBtuh of net sensible cooling capacity. Can be met by a system with 20ºF ΔT, 2.5 total pressure, 55% fan efficiency and 90% motor/drive efficiency. It can also be met at 3 total pressure and 65% fan efficiency Calculation can account for redundancy. A CRAC unit may be designed for 30 W/kBtuh but will operate at 20 W/kBtuh at peak load because it will not be running at full speed 9

10 Power Consumption of Fans Survey of Recent Projects 10

11 Fan Control Variable speed fans required on: DX units over 5 tons CHW units of any size Must vary fan speed as a function of actual load 11

12 Containment Computer rooms with air-cooled computers in racks and with a design load exceeding 175 kw/room shall include air barriers such that there is no significant air path for computer discharge air to recirculate back to computer inlets without passing through a cooling system. Exceptions: Expansions of existing computer rooms Computer racks with a design load less than 1 kw/rack Equivalent energy performance based on CFD or other analysis 12

13 Performance Approach Modeling Rules Proposed Design is compared to a Baseline Design: If total computer room load > 250 tons then all computer rooms have CHW CRAH units Otherwise all computer rooms have DX CRAC units Baseline building will have separate systems for computer rooms and other spaces User enters peak load in W/ft2. Both models use part-load schedule that varies monthly: 100%, 75%, 50%, 25%, 100%, 75%, etc. 13

14 CRAH Baseline Design supply/return temp: 60ºF / 80ºF CFM sized 110% of the calculated load Fan power: 0.49 W/cfm (e.g. 60% fan efficiency, 2.5 TSP) Airside economizer - differential drybulb control No humidification or reheat CHW plant follows normal Title 24 rules for efficiency of chillers, towers, pumps, staging, etc. Supply Air Temperature and Fan Control Fan volume shall be linearly reset from 100% air flow at 100% cooling load to minimum air flow at 50% cooling load and below. Supply air temperature setpoint shall be linearly reset from 60 o F at 50% cooling load and above to 80 o F at 0% cooling load. 14

15 CRAC Baseline Air-cooled DX Design supply/return temp: 60ºF / 80ºF Fan Control: Constant speed if total cooling capacity for the room < 5 tons, otherwise variable speed Fan power: 0.39 W/cfm for constant speed, 0.49 W/cfm for variable speed Airside economizer (regardless of system size) No humidification or reheat CFM and cooling capacity sized 120% of the calculated load Supply Air Temperature and Fan Control (for variable speed) Fan volume shall be linearly reset from 100% air flow at 100% cooling load to minimum air flow at 50% cooling load and below. Supply air temperature setpoint shall be linearly reset from 60 o F at 50% cooling load and above to 80 o F at 0% cooling load. 15

16 Contact Info Jeff Stein, PE, Principal Taylor Engineering, LLC 1080 Marina Village Parkway Alameda CA