If the Advanced Shading Model is used, the user also needs to provide information how the system is controlled. DAYSIM supports the following modes:
- Manual control (control keyword = ManualControl): This control applies to a standard, manually controlled mechanical shading systems such as venetian blinds that are ubiquitous in office buildings across the globe. To model such a system a set of CONTROL SENSOR POINTS has to be identified. These sensors should be near positions where the occupants in charge of controlling the shading system are usually located such as work stations, help desks and the like. The shading device is then operated according to the Lighswitch Model. The control points are defined by the sensor_file_info keyword.
- Automated Control:Shading devices such as mechanical blinds or dynamic glazing that provide dynamic solar control can also be automatically controlled. The following control strategies are supported.
- Idealized (control keyword = IdealizedAutomatedControl): In this model the shading group is fully opened when there is not glare at any of the CONTROL SENSOR POINTS and fully closed otherwise. This unrealistic control yields the upper bound of usable (non glare generating) daylight possible for a given space.
- With an occupancy sensor (control keyword = AutomatedGlareControlWithOccupancy): Two automated control modes support occupancy sensors along with start and end calendar dates of the cooling period for the controlled zone. When in cooling mode, the shading device is fully lowered when the occupant is absent. Otherwise, the shading system is fully opened or (in the case of switchable glazing) in its clearest state.
- Thermal control (control keyword = AutomatedThermalControl or AutomatedThermalControlWithOccupancy or AutomatedGlareControl or AutomatedGlareControlWithOccupancy): The shading system is controlled in a way that excessive interior daylighting levels are avoided. In this control mode it is assumed that the reference sensor for the system is either an internal or and external illuminance sensor. If internal, the sensor would typically face the nearest facade and be ceiling mounted or on the window or curtain wall frame. When the illuminance at the control sensor rises beyond a user specified threshold, the system automatically readjusts the shading system to the next lower setting. (For a venetian blind system this would mean that the slat angle is further closed or the blinds are further lowered. For an electrochromic glazing system this would mean that the glazing is further tinted.) On the other hand, once the illuminance threshold falls below a second user specified illuminance threshold the system switches to the next higher state.
- Glare control (control keyword = AutomatedGlareControlWithOccupancy or AutomatedGlareControl): In combination with the thermal control, it is also possible to further adjust the dynamic shading/ glazing system to avoid glare form direct sunlight. In order to do so, the system requires a second, exterior illuminance sensor. This would typically be a facade mounted sensor facing perpendicular to the facade plane. The control is timed and gets as inputs upper and lower solar altitude and azimuth levels. When the facade illuminance is above a user defined threshold level and the sun is located within the azimuth altitude range, the system is fully closed to avoid glare form direct sunlight. The system is only opened once the sun leaves the azimuth/altitude range.
- External shading schedule (control keyword = AnnualShadingSchedule): Daysim uses an external shading file that detemrines the status of the dynamic shading systems at every hour in the year. The external shading profile should be a comma seperate file with a three line header and the format: month, day, hour, shading fraction [0,1] in each line. See sample file: BlindsAlwaysClosed.csv.
shading -n [followed by n shading group definitions]
m control_keyword <shading_group_opened.rad> [followed by m lines]
<shading_group_1_state1.rad> <shading_group_1_state1.dc> <shading_group_1_state1.ill>
with n = 1 or 2 = number of shading groups
m = number of states in shading group
control_keyword = ManualControl IdealizedAutomatedControl
This systems consists of a single shading group made of manually controlled venetian blinds that are modeled in three states, full opened, partially closed and full closed.
BlindsPartiallyClosed.rad BlindsPartiallyClosed.dc BlindsPartiallyClosed.ill
BlindsFullyClosed.rad BlindsFullyClosed.dc BlindsFullyClosed.ill
This systems consists of a single shading group made of an automated electrochromic glazing with Thermal, Glare and Occupancy Control. If no user is present the EC glazing is in tinted state from June 1 (06 01) to August 15 (08 15). During occupancy the system is switching to tinted state when the illuminance at any control point rises above 2500lux and (once tinted) the system switches back when the illuminance falls below 300lux. When the illuminance at an outside facade sensor rises above 10000lux and the sun's azimuth and altitude is between -45 and 45 and as well as 30 to 60 degrees, respectively, then the EC glazing is fully tinted.
10000 -45 45 30 60
06 01 08 15 EC_ClearState.rad
300 2500 EC_TintedState.rad EC_TintedState.dc EC_TintedState.ill
In case there are several shading groups in the same façade, Daysim assumes that for an automated system the signal at the control illuminance sensor for one group is not influenced by the setting of the independent control group. For example, if a venetian blind is combined with an electrochromic blind system and the EC glazing is automatically control via an internal illuminance sensor, Daysim assumes that the venetian blinds do not block the view of the illuminance sensor when lowered. If they do, this would in reality lower the signal at the EC control point and switch the EC glazing into a clear state. Daysim will not reproduce this because the illuminances for different shading groups are assessed independently form each other.