Energy Simulation Parameters
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Energy Simulation Parameters
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This section pertains to simulation settings which primarily impact the energy analysis. Expand all sections to see all inputs.
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Air Velocity for Comfort Calculations
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This field sets the air velocity for ASHRAE 55 comfort calculations.
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Maximum Data Visualization Variables
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This field sets the maximum number of variables that may be produced in a single calculation. The purpose is to prevent memory overload. User may adjust this at their discretion.
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This field sets the timestep of the system calculations. This is different from the overall Simulation Timestep in General Settings. The system calculation timestep subdivides the simulation timestep. The default is four system timesteps per simulation timestep. In new projects, the default general simulation timestep is 60 minutes and the minimum system timestep is 15 minutes, a factor of four.
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This field sets the maximum number of system iterations the engine is allowed to perform. The purpose of this field is to reduce time if the iterations have difficulty converging.
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This field sets the minimum number of plant iterations the engine is allowed to perform. The purpose of this field is to allow the user to force a minimum in case the plant loops are not behaving as expected.
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This field sets the maximum number of plant iterations the engine is allowed to perform. The purpose of this field is to reduce time if the iterations have difficulty converging.
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Temperature Capacity Multiplier
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This field is used to alter the effective heat capacitance of the zone air volume. This affects the transient calculations of zone air temperature. Values greater than 1.0 have the effect of smoothing or damping the rate of change in the temperature of zone air from timestep to timestep. Note that sensible heat capacity can also be modeled using internal mass surfaces.
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Humidity Capacity Multiplier
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This field is used to alter the effective moisture capacitance of the zone air volume. This affects the transient calculations of zone air humidity ratio. Values greater than 1.0 have the effect of smoothing.
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Carbon Dioxide Capacity Multiplier
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This field is used to alter the effective carbon dioxide capacitance of the zone air volume. This affects the transient calculations of zone air carbon dioxide concentration. Values greater than 1.0 have the effect of smoothing or damping the rate of change in the carbon dioxide level of zone air from timestep to timestep.
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CBECS Benchmarking for Site Consumption
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The U.S. Energy Information Administration has taken surveys of commercial building energy consumption called the Commercial Buildings Energy Consumption Survey (CBECS). These surveys take data from different building types in different years and can be used as a benchmark for comparing individual building’s energy consumption. Select a Building Type and CBECS Survey Year in the fields in this section to compare the current model to the CBECS averages. The output comparison will appear in the Site Consumption Summary report.
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District Heating Efficiency
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This field sets the efficiency of district heating plants. An input of 0.3 means the district heating plant is 30 percent efficient. In other words, the district heating plant would consume 1/0.3 = 3.33 times the energy than the heating load.
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This field sets the COP of district cooling plants. An input COP of 3 means the district cooling plant produces 3 units of cooling for every 1 unit of raw energy consumed. In other words, the district cooling plant would consume 1/3 = 0.333 times the energy than the cooling load.
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Steam Conversion Efficiency
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This field sets the efficiency of steam generation. An input of 0.25 means the steam heating plant is 25 percent efficient. In other words, the steam heating plant would consume 1/0.25 = 4 times the energy than the heating load.
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Equivalent Emission Factors
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These fields set the equivalent greenhouse potential of nitrous oxide, methane, and carbon dioxide. Nitrous oxide defaults to a potency 298 times greater than carbon dioxide, and methane defaults to a potency 25 times greater than carbon dioxide. See the Carbon Footprint and Renewable Energy Summary.
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These fields set the efficiency of delivering energy to the site from the source. For example, electricity defaults to 3.167, meaning that 3.167 units of raw energy are consumed in the power plant and transmission lines for every 1 unit delivered to the site for use. See the source energy consumption in the Site Consumption Summary report.
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