PG&E and Altera Data Center Energy Efficiency Project

PG&E and Altera: A History of Energy Efficiency After hours cooling project Chiller VFD retrofit CDA compressor replaced with VFD CDA compressor Data Center Efficiency Project

PG&E and Altera: A History of Energy Efficiency Chiller VFD Retrofit Project Cost: $139k ROI: 3.8 years PG&E Rebate: $31k Annual Savings: $29k Project Cost: $110k ROI: 3 years PG&E Rebate: $15k Annual Savings: $32k Project Cost: $78k ROI: 1.1 years PG&E Rebate: $36k Annual Savings: $39k After Hours Cooling Project VFD CDA Compressor Retrofit

Altera Data Center Energy Efficiency Project Objectives Keep servers between 68° and 77° F (ASHRAE) Reduce energy use Accommodate server growth Increase server and data center reliability

Data Center Layout

Data Center Before Improvements Portable AC unit

Two Interests Meet Altera had a temporary cooling unit in place to serve a ‘hot spot’ and was looking at ways to handle planned load increases. In PG&E’s territory, improving data center energy efficiency by 15% would save 100 GWh of electricity – the equivalent of powering 15,000 homes for a year or taking almost 8,000 cars off the road.

Why is Airflow a Problem in Data Centers? Wasted energy Wasted money Less capacity Less reliability

Why Do These Problems Exist? In a typical data center… Only 40% of AC air is used to cool servers Robert 'Dr. Bob' Sullivan, Ph.D. Uptime Institute HVAC systems are 2.6 times what is actually needed Robert 'Dr. Bob' Sullivan, Ph.D. Uptime Institute Not a big concern when power density was low but it continues to grow (about 150w/sqft) The culprit: allowing hot and cold air to mix

First Step: Assess Current Situation Data loggers placed in the inlet and discharge air streams of each cooling unit. Four loggers placed in each cold aisle. Current transformers installed on the electrical distribution circuits feeding the two roof-top condensing units. Total rack kW load was recorded to establish baseline.

Findings Temperature across cooling units ranged from 12° to 18°F. Temperature variance of up to 14° degrees from one server to another. Approximately 45 kW could be saved in theory if air flow was ideal

Second Step: Implement Ideas from Meeting with PG&E ALL servers must be in hot/cold aisles (HACA) Blanking plates between servers Strip curtains at ends of aisles Remove perforated tiles from hot aisles Partitions above racks

Third Step: Altera Adopts Changes APC in-row coolers installed Temporary cooling unit removed Blanking plates added Installed strip curtains to separate the computing racks from the telecom area Shutting off CRAC unit

Addition of APC IRCs’

Simple changes, big benefits

Simple Changes, big benefit

Final Measurement and Review Even after Altera made all of these changes, excess cooling capacity still existed. PG&E recommended shutting down a second CRAC unit, thus putting all primary cooling on chilled water units.

Altera’s New and Improved Data Center Temporary mobile cooling unit gone Two CRAC units shut off Server temperature variance a mere 2° F Net electricity reduction of 44.9 kW Annual energy savings of MWh Overall energy savings: 25%

Moral of the Story? Improving airflow is a safe and sensible strategy to simultaneously make data centers greener, more reliable, higher capacity, and more economical to operate. To achieve results such as Altera’s, it takes teamwork between IT, Facilities, HVAC experts, and PG&E.