AEE Certified Energy Auditor flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

ASHRAE Level 2 Audit

An energy survey and analysis that adds an end-use breakdown, a bin or hourly model, and cost and payback estimates for each recommended measure beyond the Level 1 walk-through.

Energy Use Index (EUI)

Annual site energy consumption divided by conditioned floor area, expressed in kBtu/ft²-yr or kWh/m²-yr, used to benchmark a building against peers of the same type.

Baseline Period

The consecutive 12-month interval of utility and operating data used as the reference against which savings are measured; it should reflect normal weather, occupancy, and operations.

Load Factor

Average electrical demand over a period divided by the peak demand in that same period; a low value suggests demand-charge exposure or oversized equipment.

Degree-Day Normalization

Adjusting energy use for weather by regressing consumption against heating or cooling degree days so a baseline year and a post-retrofit year can be compared fairly.

Four-Parameter Regression Model

A regression of energy use on both heating and cooling degree days plus an intercept, used when a building has meaningful weather-driven heating and cooling loads.

Interval Data

Utility or sub-meter records at 15-minute or hourly resolution that reveal load shapes, peak demand, and after-hours operation, which monthly bills cannot show.

Power Factor

The ratio of real power in kW to apparent power in kVA; values below about 0.90 can trigger utility penalties and reduce available transformer capacity.

Therm

A unit of natural gas energy equal to 100,000 Btu, roughly 29.3 kWh; gas utility bills are commonly priced in dollars per therm.

Simple Payback

Installed project cost divided by first-year energy savings; a screening metric that ignores the time value of money and all savings accruing after payback.

Net Present Value

The sum of all future cash flows discounted to today at the organization's discount rate, minus the initial cost; a positive result means the project adds value.

Capital Recovery Factor

A factor converting an initial capital cost into an equivalent uniform annual payment over n years at interest rate i, used to annualize costs for comparison.

Lumen Method

A calculation giving the number of luminaires needed: target illuminance times area, divided by lumens per luminaire times coefficient of utilization times light loss factor.

Lighting Power Density

Connected lighting watts divided by floor area, expressed in W/ft², compared against code allowances to judge whether a lighting system is a retrofit candidate.

Lamp Lumen Depreciation

The fraction of initial lamp output remaining at the end of rated life or at the maintenance interval, and one component of the light loss factor.

Energy Efficiency Ratio

Cooling output in Btu/h divided by electrical input in watts at rated conditions; convert to COP by multiplying by 0.293, or to kW/ton as 12 divided by EER.

Fan Affinity Laws

For a fixed fan or pump, flow varies with speed, pressure with speed squared, and power with speed cubed, so modest speed reductions yield large power savings.

Cooling Tower Approach

The difference between leaving condenser-water temperature and entering air wet-bulb temperature; a rising approach signals fouling or degraded fill and raises chiller energy.

Uniform Energy Factor

The standardized efficiency rating for residential water heaters under the test procedure; higher values mean less energy wasted during standby, cycling, and draws.

Legionella Storage Temperature

Guidance to store hot water at or above 140 degrees Fahrenheit to limit Legionella growth, then temper it to no more than 120 degrees Fahrenheit at the fixture to prevent scalding.

Drain Water Heat Recovery

A heat exchanger installed on shower drains that preheats incoming cold water using waste greywater heat, typically recovering 40-60% of the heat.

Compressed Air Specific Power

Compressor input power divided by delivered flow, typically 18-22 kW per 100 cfm at 100 psig; lower values indicate a more efficient system or trim compressor.

Motor Slip Method

Estimating motor load from measured shaft speed: load fraction equals synchronous speed minus measured speed, divided by synchronous minus rated full-load speed.

VFD Affinity Savings

Because fan and pump power varies with the cube of speed, a variable frequency drive on a variable-torque load can cut power roughly in half at 80% speed.

U-Factor

The overall heat transfer coefficient of an assembly in Btu/(h-ft²-°F); it is the reciprocal of R-value, and a lower U-factor means better insulation.

Solar Heat Gain Coefficient

The fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed then re-radiated inward; lower values reduce cooling load.

BACnet

An open data communication protocol for building automation and control networks that lets controllers, sensors, and workstations from different vendors interoperate on one system.

Optimal Start

A control routine that calculates when to begin pre-conditioning based on indoor and outdoor temperature and building mass, so setpoint is met exactly at occupancy.

Betz Limit

The theoretical maximum fraction of a wind stream's kinetic energy that any turbine can extract, equal to 16/27 or approximately 59.3 percent.

Round-Trip Efficiency

The fraction of electrical energy put into a storage system that is returned on discharge, accounting for charging and discharging losses; lithium-ion typically reaches 85-95%.

Anti-Idling

A policy or technology that shuts the engine down or powers accessories without it, eliminating roughly 0.5-1.0 gallon of fuel burned per idle hour.

Well-to-Wheel Emissions

Total greenhouse gas emissions from fuel production, processing, and delivery plus vehicle tailpipe combustion, used to compare alternative fuels fairly with conventional fuels.