This facility is concerned with specifying data for the simulation of natural ventilation.
An aperture is an opening in a wall or ceiling through which air may flow. Examples of apertures are windows, doors, louvres and floor openings such as stair wells. Aperture profiles can be assigned to any building element.
As a rule, any building surface which has a building element with an aperture profile assigned to it will become an aperture. Internal and Null Link surfaces are the exception to this rule: pressure is assumed to be equalised within a zone and across Null Links, so there would be no flow through apertures of these types.
The flow of air through each aperture resulting from wind pressure, buoyancy (stack effect) and any user-specified air flows are calculated by Tas, together with the associated heat and moisture transfers. After a simulation, aperture air flows may be viewed in the result viewer.
Warning - Using apertures in combination with plant sizing (either heating or cooling) must be considered very carefully. For example, a core office area may be separated from the perimeter area by a tracked wall. During heating sizing hot air from the core area may move through the aperture to the perimeter thus reducing its size accordingly. The total heating size for both core and perimeter would be the same had there been no air movement but the distribution may not be as expected. In this circumstance simply closing the internal apertures during sizing calculations would be recommended. However, there may be situations where the migration of heat due to natural convection needs to be taken into account for the sizing calculation, in which case the apertures should remain open.
For details on how to apply aperture types to a building element, please read the section: Aperture Types Table.
The aperture properties specify the extent to which an aperture may open and how its degree of opening varies with time:
Name
The name of the profile. To change it, double click in this box, type in a new name and then press <Tab> or left-click in another box.
Description
The details of the profile. This can be edited by the user.
Sheltered
A flag indicating whether apertures for the given building element are in a sheltered position. By default this is unchecked, specifying that the apertures are exposed to the wind. If this option is checked it means that the apertures are sheltered from the wind. This would be appropriate, for example, in the case of apertures facing into an enclosed courtyard.
The Sheltered flag may also be
used to investigate building performance in the absence of wind effects:
in this case the flag should be checked for all aperture types.
If a Wind Pressure Coefficient File is specified (see Section: Building Summary), the Sheltered flag is ignored.
Day types
The day types, the profile is assigned to. To assign a profile to a day type, left click on the day type's name in this box so that it is highlighted. To unassign the profile, left click on the day type's name in this box so it is not highlighted.
Opening
The proportion of the aperture that is open. For more details on how to edit this parameter, please read the section: Gains Table.