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CDC Daylighting 


March 07, 2010 


• Daysim is used to analyze daylighting availability 
over a year course and glare condition. 




Daylighting availability is measured in Daylight 
Autonomy (DA) and Useful Daylighting llluminace (UDI) 

DA is the percentage of the occupied times of the year when the 
minimum illuminance requirement is met by daylight alone. 

U D 1 100-2000 is the percentage of the occupied times of the year when 
illuminance at a point is between 100 and 2000 lux (10 to 200 fc). 

Glare is caused by high illumiance level and high 

U D I >2000 is the percentage of the occupied times of the year when 
illuminance at a point is greater than 2000 lux (200 fc). 

Maximum Daylight Autonomy (DAmax) is the percentage of the 
occupied times of the year when illuminance at a point is more 
than 10 times the minimum illuminance requirement. 

Baseline Analysis 

Daylighting simulation shows that: 

- The 4' overhand cannot block direct sunlight (from the 
south) in winter months in the atrium and the 
multipurpose room. 

- Direct sunlight penetrates in the training room and the 
director's office during the whole year. 

- The current window openings do not bring enough 
daylight into the classrooms. 

- The current window openings do not bring enough 
daylight into the multipurpose room. (The west-facing 
windows have been removed.) 


Baseline - Daylight Autonomy at 

30 fc 

Red indicates 100% Daylight 

Blue-jndicates 0% Daylight 


Need more daylight in 
The multipurpose room and 
the back of the classrooms. 

Baseline - Areas with less than 10 

fc (UDIioo) 

Baseline - Glare Conditions > 300 

fc (DA max) 

Recommendations: Classrooms 

To increase daylight levels in the back of the 
room, Solatubes (skylights) can be used. 
(Increasing the size of north facing windows is not 
sufficient to increase daylight penetration.) 

One sky opening positioned 8' from the back was 
simulated in our model. We recommend installing 
2-3 solatubes for each classroom, depending the 
size and the photometric profile of the chosen 

Recommendations: East-facing 


Since it is difficult to shade the direct sunlight into 
the east-facing rooms (one of the classrooms, 
director's office, and training room), we 
recommend using tinted windows to control the 
glare condition in the morning. 

Our simulation shows that tinted glass with 40% 
visible light transmittance can decrease glare and 
let enough daylight enter the rooms. 

Recommendations: Training room 

The training room has two south-facing windows 
and one east-facing window. Our analysis shows 
that the overhand does not block the direct 
sunlight in the winter mornings. Due to the ceiling 
height , light shelf is not a good solution. 

Considering that projectors might be be used for 
training purpose, Roller blinds going bottom up 
are recommended for darken the space. We also 
recommend using tinted glass on both south and 
east sides, so that the windows will look the 
same from inside. 

Recommendations: Multipurpose 


To increase the daylighting uniformity, we 
recommend increasing the north-facing window 
height from 3'-5" to 6' tall. The south-facing 
windows should keep the original size. 

One of the following two measures need to be 
taken to block direct sunlight from entering the 
space through the south windows. 

- Install In-the-window lightshelves . 

- Hang translucent fabric baffles on south. 

Baffles can block direct light and spread diffuse 
light into the space. 

Multipurpose Room - South Baffles 

Recommendations: Atrium 

We recommend hanging fabric baffles to block direct 
light entering the atrium from the south windows. 

Our simulation shows that the ceiling structure that 
James proposed during the design meeting does not 
effectively block the direct sunlight. Additional baffles 
are needed to control glare. 

The baffles (size and height) need to be designed 
after ceiling structure is finalized. 

We also recommend increasing north windows from 
2'-8" to 4' tall to increase the daylight uniformity. 

An alternative solution is the in-the-window 

This ceiling 
structure does not 
effectively block 

direct s 




The following measures have been incorporated in 
the new model and the daylighting results are 

- Sulatubes (skylights) in the two north-facing 

- Tinted (40% VLT) glass for all of the east-facing 
windows and the south-facing windows in the 
training room. 

- Translucent fabric baffles in the multipurpose 
room and the atrium. 

- Increased north-facing glazing area in the 
multipurpose room the and atrium. 

Updated Model with 

Day I ight_Autono my Ji 

Davlioht Autonomy at 30 fc 

More light at the 
back of the 
Closer to 100% Daylight 

Updated Model with 
Recommendations Areas with less 

Daylight (UDI 100) 

Solatube (Skylight) 
provides enough 
daylight to the bac 
of the room 

Updated Model with 

Updated Model with 
Useful Daylight Illuminances (10-