Miscellaneous gains

Activity tab in model data

Gain

Set the design level of energy consumption due to miscellaneous equipment per unit floor area. The actual heat gain to the space may be reduced through the Fraction lost data (below).

 

The Gain, entered in Watts/m2 (or Watts/ft2), is typically used to represent the maximum fuel consumption of miscellaneous equipment in a zone that is then multiplied by a schedule fraction (below). This is slightly more flexible in that the design level could be a 'diversity factor' applied to a schedule of real numbers. Note that while the schedule value can vary from hour to hour, the design level field is constant.

Fuel

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

3-Oil

Oil

4-Coal

Solid

5-LPG

Gas

6-Biogas

Gas

7-Anthracite

Solid

8-Smokeless fuel (including coke)

Solid

9-Dual fuel appliances (mineral + wood)

Other

10-Biomass

Other

11-Waste heat

Other

Fraction lost

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 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.

Latent fraction

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 miscellaneous 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 miscellaneous equipment. This latent energy affects the moisture balance within the zone.

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 miscellaneous 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 miscellaneous 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.

Calculation

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.