Energy Conservation Techniques Flashcards

Which ENERGY STAR Portfolio Manager metric is commonly used to benchmark a commercial building's annual energy performance?

Answer: Energy Use Intensity (EUI) in kBtu/ft²/yr

EUI normalizes total annual energy use by floor area so buildings can be compared.

Air compressor systems often waste energy mainly through:

Answer: Leaks in distribution piping and fittings

Leaks can waste 20–30% of compressor output, so leak detection and repair is a key conservation measure.

Optimal start control in a BAS saves energy by:

Answer: Calculating the latest start time needed to reach setpoint by occupancy

Optimal start uses space and outdoor conditions to start equipment just in time, which avoids unnecessary early runtime.

Which lighting control is most suitable for perimeter offices with large windows?

Answer: Daylight harvesting with photosensors

Daylight harvesting dims electric lights in proportion to the natural light available near windows.

Lowering condenser water supply temperature (within manufacturer limits) generally:

Answer: Improves chiller efficiency but may increase cooling tower fan energy

Cooler condenser water reduces compressor lift, but the tower fans may run harder, so the total plant energy has to be optimized.

What is the primary purpose of a heat recovery wheel (enthalpy wheel) in an air handling unit?

Answer: Transfer heat and moisture between exhaust and incoming outdoor air

Enthalpy wheels recover sensible and latent energy from exhaust air to precondition outdoor air.

Simple payback for an energy conservation measure is calculated as:

Answer: Installed cost ÷ annual savings

Simple payback in years equals the project cost divided by the annual dollar savings.