IEA Solar Heating & Cooling Programme Task 31: Daylighting ...
Document source : www.iea-shc.org
2. REQUIREMENTS CONCERNING CONTROL ALGORITHMS
2.1 Integration
Daylighting considerations are not independent from thermal and air quality
considerations. On the contrary, all these aspects are tightly interacting together. For
instance, controlling the daylighting quantity also controls the passive solar gains, and the
user's requirements may depend on the season perceived by the user (in summer, some
people cut more daylighting because they feel cooler with a darker ambience).
Therefore, a daylighting control which does not include thermal and air quality
considerations (and of course artificial lighting considerations) will not allow a complete
optimization of user's comfort and energy saving. The best solution is to integrate the
control of all relevant building services (heating, cooling, ventilation, artificial lighting,
daylighting) into one single controller. Such an integration allows to go one step further
than simple daylight responsive control systems for artificial lighting.
2.2 Priority of user preferences
In general, the users should be given the absolute priority when they want to get another
setting than the one provided by the automatic control. A control system which
obstinately resets the user wishes after some seconds is highly irritating and must be
absolutely avoided. Therefore, when a user has overrided the automatic control system,
the system should both adapts its characteristics to new setpoints (adaptivity to user
preferences, see section 2.4) and wait for a reasonable time before getting back the hand
(i.e. typically one or two hours), except if one of the situations below occurs:
1
the room is no more occupied;
2
security reasons apply, for instance rolling up external blinds when the wind
velocity is too high and would possibly damage them, or closing the windows in
case of rain if the window opening is controlled by the system.
Nevertheless, user preferences need to be taken into account in a different way for spaces
with a lot of people (conference rooms, open space offices, public spaces with a lot of
circulation, etc) and for spaces used by a small number of persons (for instance office
rooms with maximum 2 or 3 persons, or dwellings). In the first case, the adaptivity to
user preferences should be somehow limited to avoid too much disturbances for all the
other persons. On the contrary, "private" spaces, shared by a limited number of persons,
may use fully user-adaptive control systems.
2.3 User disturbances
A control system should not cause a too high level of disturbances for the user. For
instance, if the blind movements are rather noisy, the system should avoid to move them
too often. The issue is especially critical with devices that need to be changed by steps
Summary :
For instance, controlling the daylighting quantity also controls the passive solar gains, and the user's requirements may depend on the season perceived by the user (in summer, some people cut more daylighting because they feel cooler with a darker ambience). Therefore, when a user has overrided the automatic control system, the system should both adapts its characteristics to new setpoints (adaptivity to user preferences, see section 2.4) and wait for a reasonable time before getting back the hand (i.e.
Tags :
control,user,system,daylighting,preferences,spaces,instance,considerations,too,persons,artificial,all,lighting
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