Energy Modeling & Simulation Tools Flashcards

In EnergyPlus, what is the function of the 'Output:Meter' object?

Answer: It reports aggregated energy consumption for specified fuel types and end uses

Output:Meter objects in EnergyPlus aggregate and report energy consumption by fuel type and end-use category (e.g., cooling electricity, heating gas) at user-specified intervals.

Which weather file format is natively used by EnergyPlus for annual energy simulations?

Answer: EPW (.epw)

EnergyPlus uses the EnergyPlus Weather (.epw) format, which contains hourly typical meteorological year data including temperature, humidity, solar radiation, and wind.

What does 'source energy' represent compared to 'site energy' in building performance analysis?

Answer: Source energy includes transmission and generation losses; site energy is what enters the building

Source energy accounts for all energy consumed upstream (power plant generation losses, transmission losses) to deliver one unit of site energy, making it a more comprehensive comparison metric.

In a building energy model, how is 'internal heat gain' from lighting typically calculated?

Answer: Wattage × lighting power density × zone floor area × schedule fraction

Lighting heat gain is computed as installed watts (LPD × area) multiplied by the hourly schedule fraction, which determines the fraction of rated power in use at each hour.

What is the primary advantage of using EnergyPlus over simplified degree-day methods for energy estimation?

Answer: EnergyPlus models dynamic system interactions, part-load equipment behavior, and hourly weather simultaneously

EnergyPlus performs full hourly simulation capturing HVAC system controls, equipment part-load curves, and thermal mass interactions that simplified degree-day methods cannot represent.

In energy modeling, what does 'load matching' refer to in the context of renewable energy systems?

Answer: Aligning renewable energy generation profiles with building consumption profiles

Load matching evaluates how well a renewable energy system's output timing aligns with building consumption to minimize grid imports and maximize self-consumption.

What is the purpose of the 'economizer' control logic in HVAC system energy modeling?

Answer: To reduce chiller energy by using cool outdoor air for free cooling when conditions allow

Economizer control opens outdoor air dampers when outdoor conditions are cooler than return air, providing free cooling and reducing mechanical refrigeration energy.