Activity tab in model data
Check the Process > On checkbox to include any process gains in the simulation. Process gains model the heat emissions and fuel consumption due to any manufacturing or industrial process which is part of the business activity.
Set the design level of energy consumption due to process activity. The actual heat gain to the space may be reduced through the Fraction lost data (below).
Depending on the Equipment gain units model option setting, the gains data is entered either as Absolute zone power in W or as Power density (in W/m2 or W/ft2).
Tip: You can enter negative process gains for modelling the cooling effect from refrigeration units such as those found in supermarkets where the refrigerator doors may open and cause cool air to enter the zone.
Select the schedule that governs the timing of gains in the zone. The level of gains are multiplied by the time-varying factor in this schedule to give the gain for each timestep in the simulation.
The fuel can be selected from a drop down list. Note that these fuels are currently mapped to a shorter list in the results as follows:
|
Fuel in Model Data
|
Mapped to Fuel in Output |
|
1-Electricity from grid |
Electricity |
|
2-Natural gas |
Gas |
This field is a decimal number between 0.0 and 1.0 and is used to characterise the amount of 'lost' heat being given off by the process equipment in a zone. The number specified in this field will be multiplied by the total energy consumed by equipment to give the amount of heat which is 'lost' and does not impact the zone energy balances. This might correspond to electrical energy converted to mechanical work or heat that is vented to the atmosphere.
This field is a decimal number between 0.0 and 1.0 and is used to characterize the amount of latent heat given off by process equipment in a zone. The number specified in this field will be multiplied by the total energy consumed to give the amount of latent energy produced by the process equipment. This latent energy affects the moisture balance within the zone.
This is a decimal number between 0.0 and 1.0 and is used to characterise the amount of long-wave radiant heat being given off by process equipment in a zone. The radiant fraction will be multiplied by the total energy consumed by electric equipment and (1-Fraction lost) to give the amount of long wavelength radiation gain from process equipment in a zone. A value of zero means that the heat gain is entirely convective in which case all the heat is transferred to the air node in simulations. A value of 1 means that the gain is entirely radiative in which case all the heat is distributed to the inside surfaces. a typical value is somewhere between 0.1 and 0.5.
If the Internal gains operate with occupancy model option is not selected you can also set the operation schedule.
This numeric input field, available only when the fuel is selected as 2-Natural gas, specifies carbon dioxide generation rate with units of m3/s-W or (ft3/min)/(Btu/hr). The default value of 0.0 assumes the equipment is fully vented to outdoors.
In the absence of better information, a value of 3.45E-8 m3/s-W can be used which assumes the equipment is not vented to outdoors. This value is converted from natural gas CO2 emission rate at 11.7 lbs CO2 per therm, the CO2 emission rate provided by U.S. Energy Information Administration. The maximum value for this input field is 3.45E-7 m3/s-W.
The fuel input to the equipment ultimately appears as heat that contributes to zone loads. In the simulation this heat is divided into four different fractions. Three of these are given by the input fields Latent fraction, Radiant fraction and Fraction lost. The convected fraction, defined as the fraction of the heat from electric equipment convected to the zone air, is calculated by the program as:
Fconvected = 1.0 – (Latent fraction + Radiant fraction + Fraction lost)
You will get an error message if Fraction Latent + Fraction Radiant + Fraction Lost exceeds 1.0.