Computer gains

Activity tab in model data

Check the Computers > On checkbox to model the heat emissions and fuel consumption due to computer gains and other related IT equipment in the simulation.

Units

When the Gain definition level model option is set to 2-Zone by zone in model data you can select the units to be used for internal gains here on the Activity tab. Choose from the options:

• 1-Power density where zone equipment gains are entered as a power density, i.e. as a power per zone floor area in W/m2 or W/ft2. This option is usually the most convenient method for most general purpose modelling as the data is normalised by area and so can be inherited from levels above in the model hierarchy and can be effectively loaded from Activity template.
• 2-Absolute zone power where zone equipment gains are entered as a power value in W. This option is usually used when detailed zone by zone survey or design data is available. Unless you need to enter specific known lighting equipment gains zone by zone, this option is best avoided as it increases the amount of work involved due to the inheritance mechanism not working effectively for gains that are not normalised by floor area.

Gain

Set the design level of energy consumption due to computers. 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).

The fuel is assumed to be electricity, all gains are assumed to be emitted to the space.

Schedule

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.

Radiant Fraction

This field 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 computer 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 computer 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 0.2.

If the Internal gains operate with occupancy model option is not selected you can also set the operation schedule.