Energy Efficiency and Sustainability Flashcards
7 cards from real CDCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Energy Efficiency and Sustainability flashcards as text
A data centre uses a wet cooling tower for heat rejection. What environmental resource does this approach consume that a dry cooler does not?
Answer: Water through evaporation
Wet cooling towers reject heat through evaporative cooling, which consumes significant quantities of water—a concern captured by the Water Usage Effectiveness (WUE) metric.
What is the recommended server inlet temperature range published by ASHRAE for Class A1 data centre environments?
Answer: 18–27°C (64.4–80.6°F)
ASHRAE A1 class specifies an allowable inlet temperature range of 15–32°C, though the recommended range for optimal efficiency without risking equipment is 18–27°C.
Which renewable energy procurement model allows a data centre operator to claim renewable energy credits without physically receiving green electricity at the facility?
Answer: Renewable Energy Certificate (REC) purchase
RECs (Renewable Energy Certificates) represent the environmental attributes of one MWh of renewable generation and can be purchased separately from the physical electricity supply.
What is 'IT equipment utilization' in the context of data centre energy efficiency, and why does it matter?
Answer: The percentage of provisioned IT capacity actively processing workloads; low utilization wastes energy on idle servers
Most servers consume 60–70% of peak power even when idle, so low utilization means significant energy is wasted on servers that are provisioned but not doing productive work.
A facility-wide energy audit reveals that legacy UPS systems operate at 85% efficiency. What technology should the operator consider to improve this?
Answer: Modular UPS with high-efficiency (eco) mode
Modern modular UPS systems with eco (high-efficiency) mode can achieve efficiencies of 97–99%, dramatically reducing conversion losses compared to legacy double-conversion UPS at 85%.
Which of the following best describes a 'carbon-neutral' data centre operation?
Answer: A facility that offsets its net greenhouse gas emissions through renewable energy and carbon credits
Carbon neutrality means that a data centre's net greenhouse gas emissions are balanced by equivalent reductions or offsets, such as renewable energy purchases and verified carbon credits.
What is the significance of a 'partial PUE' (pPUE) measurement in large, multi-tenant or campus data centres?
Answer: It calculates PUE for a specific zone or module rather than the entire facility, enabling granular efficiency analysis
Partial PUE (pPUE) isolates the efficiency of a specific data hall, pod, or module within a larger campus, allowing operators to pinpoint inefficiencies at a more granular level than facility-wide PUE.