CEM Facilities and Site Selection 5 — Questions and Answers
Question 1: A CEM is analyzing two candidate sites for a data center. Site A is in a cool northern climate; Site B is in a warm southern climate. Assuming similar electricity rates, which site offers a structural energy efficiency advantage and why?
- Site B, because warmer air improves server processor efficiency
- Site A, because the cooler climate enables more hours of economizer (free cooling) operation, reducing mechanical cooling energy (Correct answer)
- Site B, because higher ambient temperatures increase the delta-T across cooling towers
- Site A, because northern utilities have fewer peak demand events
Correct answer: Site A, because the cooler climate enables more hours of economizer (free cooling) operation, reducing mechanical cooling energy
Cooler climates provide more annual hours when outdoor air or water-side economizers can cool the data center without mechanical refrigeration, directly reducing PUE and energy cost.
Question 2: What does a Power Usage Effectiveness (PUE) ratio of 1.0 indicate for a data center facility?
- The facility is powered entirely by renewable energy
- All facility power is used exclusively by IT equipment with zero overhead energy loss (Correct answer)
- The facility meets ASHRAE Tier 1 redundancy standards
- The cooling system operates at maximum efficiency
Correct answer: All facility power is used exclusively by IT equipment with zero overhead energy loss
PUE = Total Facility Energy / IT Equipment Energy; a PUE of 1.0 means 100% of energy goes to IT loads with no cooling, lighting, or UPS losses — a theoretical ideal.
Question 3: During site selection due diligence, a CEM discovers that a candidate site is located in an area with high seismic activity. What energy infrastructure concern is most relevant?
- Solar panels are less efficient in seismically active regions
- Utility gas and electrical service interruptions following seismic events may require costly on-site backup energy systems (Correct answer)
- Seismic activity increases ground-source heat pump drilling costs only marginally
- ASHRAE 90.1 exempts seismic zones from envelope requirements
Correct answer: Utility gas and electrical service interruptions following seismic events may require costly on-site backup energy systems
Seismic events can sever utility gas and electric service; facilities in high-seismic zones often must invest in substantial on-site backup generation and fuel storage for resilience.
Question 4: A facility is being planned adjacent to a river. Beyond flood risk, which energy-related opportunity should a CEM evaluate at this site?
- Use of river water as a heat sink or source for water-source HVAC systems (Correct answer)
- Installation of tidal energy generators in the river
- Use of river water as direct process steam
- Diversion of river flow to generate hydroelectric power on-site
Correct answer: Use of river water as a heat sink or source for water-source HVAC systems
River water at relatively stable temperatures can serve as a heat sink for cooling systems or a heat source for heat pumps, significantly reducing HVAC energy consumption.
Question 5: Which metric best quantifies the financial impact of energy price volatility risk when comparing two candidate facility sites with different fuel mixes?
- Peak demand charge per site
- Coefficient of variation of historical energy prices for each dominant fuel type (Correct answer)
- Current spot price of natural gas
- Annual carbon emission intensity of each site's grid
Correct answer: Coefficient of variation of historical energy prices for each dominant fuel type
The coefficient of variation (standard deviation / mean) of historical fuel prices measures price volatility relative to average cost, allowing direct comparison of financial risk across fuel types.
Question 6: A facility planning team is considering a site in a state with a carbon cap-and-trade program. How should a CEM incorporate this into the site's life-cycle cost analysis?
- Ignore carbon costs since they apply to utilities, not end users
- Include projected carbon allowance costs or credit revenues as an annual operating line item over the analysis period (Correct answer)
- Only include carbon costs if the facility expects to exceed 25,000 metric tons CO₂e/year
- Apply a one-time carbon offset purchase at project inception
Correct answer: Include projected carbon allowance costs or credit revenues as an annual operating line item over the analysis period
Cap-and-trade compliance costs or revenues affect operating budgets annually; including them in the LCCA as projected line items ensures the true long-term cost of the site is captured.
Question 7: When evaluating a site for a process manufacturing facility, which utility reliability metric is most critical to quantify for energy cost risk management?
- Average monthly electricity bill variance
- System Average Interruption Duration Index (SAIDI) for the serving utility (Correct answer)
- Peak solar irradiance at the site
- Number of rate schedule tiers offered by the utility
Correct answer: System Average Interruption Duration Index (SAIDI) for the serving utility
SAIDI measures the average total duration of interruptions per customer per year; high SAIDI values signal unreliable power that can cause costly process shutdowns and necessitate expensive backup generation.
CEM Facilities and Site Selection 5
A CEM is analyzing two candidate sites for a data center.
Site A is in a cool northern climate; Site B is in a warm southern climate.
Assuming similar electricity rates, which site offers a structural energy efficiency advantage and why?