This tab is displayed for all building space templates (room, void, RA plenum and SA plenum). It specifies air flows into the space.
This tab specifies room air exchanges (infiltration, natural ventilation and auxiliary ventilation).
All air exchanges represent air flow entering the space. The source of the air may be the external environment (optionally with a temperature offset), an adjacent space or a supply at a temperature specified by an absolute profile.
Air exchanges are of three types: Infiltration, Natural Ventilation and Auxiliary Ventilation. Infiltration air exchanges are included unconditionally in ApacheSim, ASHRAE Loads and CIBSE Loads. Natural and Auxiliary Ventilation air exchanges may be switched on and off at calculation or simulation time.
Auxiliary Ventilation air exchanges are intended to be used in the context of the ApSys methodology to specify minimum levels of either mechanical or natural ventilation for fresh air purposes. This type of ventilation can alternatively be specified using the ‘System outside air supply’ settings on the System tab. If this convention is followed ventilation will be correctly handled in simulations for building regulation compliance.
Air Exchange Parameters
Type
The type of air exchange (Infiltration, Natural Ventilation or Auxiliary Ventilation).
Reference
A name attached to the air exchange.
Variation Profile
The profile governing the time variation of the air exchange.
Units
The units of an air exchange can be selected from the drop-down list.
Max Flow
The maximum flow rate, expressed in the specified units.
Adjacent Condition
This sets the adjacency (source) condition for the current air exchange type. The options are:
· External Air – air at outside temperature.
· External Air + Offset Temperature – air at outside temperature plus a temperature offset.
· Temperature From Profile – a fixed temperature defined by a temperature profile.
Temperature Offset
The offset temperature to be used in conjunction with the outside air temperature for the associated adjacent condition. This setting is only displayed if the adjacent condition is set to External Air + Offset Temperature.
Temperature Profile
An absolute profile specifying the temperature of the supply air. This setting is only displayed if the adjacent condition is set to Temperature From Profile. A pull-down menu enables the required absolute profile for the ventilation air temperature to be selected.
Adding an Air Exchange
To add an air exchange click the Add/Edit button and the following window will appear:
To add an air exchange to a template, for that air exchange click on the cell in the column Add To Template. A green tick will appear and click OK. The window will close and the air exchange will appear in the Air Exchanges tab list.
More than one air exchange can be added at a time by selecting the appropriate cells to display a green tick. The Select All and Deselect All buttons can be used to make this process easier.
