Cooling Loads

Cooling Loads calculates room cooling loads and free-floating temperatures using the CIBSE admittance procedure.

The calculation is carried out for one design day in each of a user-selected range of months, using weather data provided in APlocate. The calculation takes into account the timing and nature of each gain, applying the appropriate radiant fraction to all sources of heating and cooling. Inter-room dynamic conduction and ventilation heat transfer is accounted for. Glazing solar transmission properties are treated using an analysis based on the Fresnel equations. At the user’s option the effects of ventilation air exchanges and external solar shading, as calculated by SunCast, may be incorporated.

 

Vista presents the Heat Gain results in tabular or graphical form in a variety of formats. Gains are broken down by heat transfer mechanism and by type (sensible or latent). Results may be displayed by room or totalled over the building, and peak loads are identified. Various measures of room temperature are displayed, together with room relative humidity. Data may be exported to other applications.

Results from Heating Loads also appear in Space Data and Apache Systems, where they can be used for equipment and air flow sizing.

For a description of the calculation methods used in Heat Gain see APcalc Methods.

 

Tick this box to include a Cooling Loads calculation when you click on Calculate.

Air exchanges specified in Space Data are divided into three categories: infiltration, auxiliary ventilation and natural ventilation. Any infiltration air exchanges are included unconditionally, but auxiliary and natural ventilation air exchanges may be switched on or off at calculation time.

Tick this box if you wish to include Space Data auxiliary ventilation air exchanges in the Heat Loss calculation.

Tick this box if you wish to include Space Data natural ventilation air exchanges in the Cooling Loads calculation.

Variation Profiles for natural ventilation are interpreted as for mechanical ventilation.

Tick this box to include the effects of external solar shading, as calculated by SunCast, in the Cooling Loads calculation.

It is important to ensure that the shading data is kept up to date with any changes to the building geometry. The shading calculations should be repeated after any such changes.

Select the months for which Heat Gain calculations are required.

The Cooling Loads calculation is carried out for one design day per month. Indicate which day of the week is to be used to set the profiles used in Heat Gain for casual gains, ventilation rates and (if appropriate) temperature boundary conditions.

Click on this button to start the Heating and Cooling Loads calculations.

Click on this button to leave the CIBSE Loads dialog and save the data.

Click on this button to leave the CIBSE Loads interface.