Energy Conservation Techniques Flashcards

A steam trap stuck open on a 100 psig line causes energy loss mainly by:

Answer: Allowing live steam to pass into the condensate system

Failed-open traps pass live steam, wasting the energy used to generate it.

What is the typical energy-saving effect of lowering boiler excess air from 50% to 15% on a gas-fired boiler?

Answer: Reduced stack heat loss and higher combustion efficiency

Less excess air means less air to heat and send up the stack, which raises combustion efficiency.

Which instrument is most appropriate for finding missing insulation and air leaks in a building envelope?

Answer: Infrared thermal imaging camera

Infrared cameras show temperature differences on surfaces that reveal insulation voids and air infiltration.

Variable frequency drives on chilled water pumps save the most energy in which type of system?

Answer: Variable-flow system with two-way control valves

Two-way valves let flow vary with load, so the VFD can slow the pump and cut power.

An energy audit level that includes detailed analysis of capital-intensive measures with investment-grade savings estimates is typically called:

Answer: Detailed analysis of capital-intensive modifications (ASHRAE Level 3)

ASHRAE Level 3 audits give investment-grade analysis for major capital projects.

Which measure reduces energy used for domestic hot water in an office building with minimal capital cost?

Answer: Lowering the water heater setpoint to about 120°F where codes allow

A lower setpoint reduces standby losses and heating energy, and 120°F is generally enough for handwashing.

Supply air temperature reset in a VAV system during mild weather saves energy mainly by:

Answer: Reducing reheat energy at terminal units

Raising supply air temperature when loads are light reduces both overcooling and the reheat needed to correct it.