CES cheat sheet

Energy use intensity (EUI) = annual site energy use (kBtu or kWh) ÷ conditioned floor area; compare like-for-like building types only.

Degree days drive weather-normalized baselines: heating degree days use base 18.3 °C (65 °F); cooling degree days use the same base, summing daily mean temperature deviations.

Load factor = average load ÷ peak load over a period; a low load factor signals demand-charge reduction potential through peak shaving.

Power factor = kW ÷ kVA; correction capacitors reduce reactive kVA, cutting kVA demand charges but not kWh consumption.

Energy savings measure screening order: no-cost operational changes first, then controls/tuning, then capital retrofits; verify each with measurement and verification.

Simple payback (years) = installed cost ÷ annual savings; it ignores time value of money, so pair it with life-cycle cost or IRR for capital decisions.

IPMVP options: A (retrofit isolation, key parameters measured), B (retrofit isolation, all parameters measured), C (whole facility utility meter), D (calibrated simulation).

Motor and fan affinity laws: flow scales linearly with speed, pressure with the square, power with the cube - a 20% speed reduction cuts power about 49%.

Commissioning (Cx) phases: pre-design, design, construction, acceptance, and post-acceptance/warranty; each phase ends with a documented deliverable.

Functional performance test (FPT) proves a system meets design intent under modes of operation; it differs from a static installation check.

Retro-commissioning applies Cx to existing buildings without major capital work; typical savings of 5–15% come from tuning and fault correction.

Monitoring-based commissioning (MBCx) uses trend data and fault detection diagnostics to persist savings after the initial Cx effort.

Energy performance contract (EPC) guarantees savings; measurement and verification per IPMVP underpins the guarantee and the shared-savings split.

Energy service company (ESCO) models: guaranteed savings, shared savings, and chauffage/outsourcing; the client's balance-sheet treatment differs by model.

Sequence of operations is the reference document for Cx testing; a missing or vague sequence is itself a common Cx finding.

ASHRAE Guideline 0 covers the Cx process and ASHRAE Guideline 1.1 covers HVAC&R commissioning; both define owner's project requirements (OPR) as the anchor.

Triple bottom line evaluates projects on economic, environmental, and social performance rather than financial return alone.

Greenhouse gas accounting scopes: Scope 1 direct fuel combustion, Scope 2 purchased electricity/heat, Scope 3 value-chain emissions.

Life-cycle assessment stages: goal and scope, inventory analysis, impact assessment, and interpretation (ISO 14040/14044).

Embodied carbon is the upfront and cradle-to-grave carbon in materials; operational carbon is energy use in service - whole-life carbon sums both.

Renewable energy credit (REC) markets: one REC represents 1 MWh of renewable generation; bundled vs unbundled determines the claim.

Demand-side vs supply-side sustainability measures: efficiency and load shifting reduce demand; on-site renewables and storage shift supply.

Circular economy hierarchy: refuse, reduce, reuse, repair, remanufacture, recycle, recover - disposal is the last resort.

Electricity tariff components: energy charge (per kWh), demand charge (per kW of billed demand), and fixed customer charge; each responds to different measures.

Billed demand is often the maximum 15- or 30-minute interval kW in the billing month, sometimes ratcheted to a prior-year peak.

Time-of-use rates price energy by period (on-peak, mid-peak, off-peak); load shifting moves consumption to lower-cost periods.

Real-time or hourly pricing exposes customers to wholesale prices; hedging and demand response manage the price risk.

Demand response programs pay for verified load curtailment during grid events; baseline methods (e.g., 10-of-10 or high-5-of-10) determine the credited reduction.

Utility bill audit checks: meter multiplier, rate schedule appropriateness, power factor penalty, ratchet clause, and tax or rider application.

Net metering credits on-site generation against consumption; the compensation rate and true-up rules vary by jurisdiction and program.