# IEA Solar Heating & Cooling Programme Task 31: Daylighting ...

Document source : www.iea-shc.org

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low
mid
high
Solar incidence angle
[°]
70
80
90
membership functions [-]
1
Figure 3: Fuzzy logic variable "theta" (incidence angle of the direct solar radiation on
the window)

The rule base, providing the blind position as a fuzzy variable, is given by the table
below.

Ehdiff low
High
Evdir low
mid
high
very
high
low mid high very
high
theta=low open
half
closed
closed closed half
closed
half
closed
closed closed
theta=mid open
half
open
half
closed
half
closed
half
closed
half
closed
half
closed
half
closed
theta=high
open open open open half
closed
half
closed
half
closed
half
closed

B. "User not present" strategy

The window, equipped with its blind, is considered as a "heat source" controllable by the
blind position. A simple thermal model for the window + blind system has been used in
the controller, giving the heat power per unit area of window by the following formula:

Ps = Gv
· g · + Gv · g · g · (1-) ­ U'' · (Ti-Te)

where
= blind position (01, 0=closed, 1=open)
[W/m2]
g = transmission coefficient of window glazing

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Summary :