Façade Based Ventilation
The F-Series e-stack ventilation units are designed for rooms
which have access to the exterior and with a floor to ceiling
height of at least 3.5m in part of the room. It is ideally suited
to classrooms which have an external wall and where a sloping roof
has been designed so that high level windows can be introduced at
the rear of the classroom, thereby allowing additional natural
daylight into the space. An F-Series e-stack ventilation unit
is located directly under one of the high level opening windows.
The F-Series controller is used to control the window (or variable
control damper) above the F-Series unit as well as one other high
level window.
In winter the system uses a mixing ventilation strategy. Fresh
air is brought in through the window or damper immediately above
the F-Series unit, where it is then mixed with hot interior air
before being released into the room. Hot polluted air is exhausted
from the room through the other window controlled by the F-Series
controller. By using this e-stack strategy, the heat gains which
arise in the room are used for heating the incoming air
during the occupied time rather than a radiator which is required
in conventional upflow displacement ventilation mode to
preheat incoming air at low-level. The heat gains within heavily
occupied spaces (e.g. school classrooms) are often sufficiently
high that additional heating is not needed until the external
temperature falls to somewhere in the range 5-10°C, depending on
the U- value for the room.
Once the external temperature has increased such that air can be
brought in at low level directly onto occupants without
pre-heating, the ventilation strategy for the system changes to
upflow displacement ventilation. Windows or low level vents are
opened, as well as the high level windows or dampers so as to
maximize air flow and to minimize build up of heat in the
space.