- Evaporative cooling
- A heat-rejection method that uses the cooling effect of evaporating water to chill circulating water or air, cutting electricity use relative to mechanical chillers. Its cost is high water consumption, since the evaporated water is lost from the local system as vapor. It underlies the core water-versus-power cooling tradeoff.
- GHG Protocol scopes
- The greenhouse gas accounting framework dividing emissions by degree of control: Scope 1 is direct emissions from owned or controlled sources (e.g., on-site generators, refrigerants); Scope 2 is indirect emissions from purchased energy, mainly grid electricity; Scope 3 is all other value-chain emissions, such as embodied carbon in hardware and construction.
- Location-based versus market-based Scope 2
- Two GHG Protocol methods for accounting purchased-electricity emissions. Location-based uses the average carbon intensity of the physical grid; market-based reflects contractual instruments such as renewable energy certificates and power purchase agreements. The Protocol requires disclosing both; the gap between them reveals how much a clean-power claim rests on contracts versus physical electrons.
- Prior appropriation doctrine
- The water-rights system common in the western United States, in which rights are decoupled from land ownership and prioritized by the date they were established: 'first in time, first in right.' In a shortage, senior right holders take their full allocation before junior holders receive anything, and rights can be bought, sold, and transferred.
- Reclaimed (gray) water
- Treated municipal wastewater that is not fit for drinking but is adequate for uses such as data center cooling. Using it removes a facility from competition for potable supply, easing permitting and politics, but it requires dedicated 'purple-pipe' distribution infrastructure to deliver.
- TCFD and CDP
- Two pillars of climate disclosure. The Task Force on Climate-related Financial Disclosures, convened by the Financial Stability Board, set recommendations for reporting climate financial risk across governance, strategy, risk management, and metrics. CDP runs a global questionnaire-based disclosure and scoring system, on climate and water, backed by investors and corporate purchasers, turning disclosure into a financing and procurement necessity.
- Water Usage Effectiveness (WUE)
- A metric defined as the annual water consumed by a facility divided by the energy delivered to its IT equipment, in liters per kilowatt-hour. Lower is better. Standard (site) WUE counts only on-site water; source WUE adds the water consumed upstream at power plants to generate the facility's electricity, and can be much higher.
- Water withdrawal versus consumption
- Withdrawal is the total water a facility draws from a source; consumption is the portion that does not return to that source, mostly lost to evaporation in cooling. Consumption is the figure that actually depletes local supply and drives community and regulatory concern.