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1.4 Open Office Area 1.4.1 Introduction

Figure 4.1 Exterior View Office Area

The office area is located on the first floor below the overhanging studio/classroom spaces. It has a north facing façade with punched windows. It is designed to function as a small open office area for zoo staff. Tasks to be performed in this space are: reading (typed or written documents), writing, VDT usage, and personal interaction. The walls in this area are painted drywall, the ceiling is white high reflectance ceiling tiles, and the floor is carpeted.

1.4.2 Design Concepts

The design concept for this space was to provide an extremely functional and energy efficient space. To provide this the space I utilized a low level ambient lighting system Figure 4.2 Daylight Rendering (Figure 4.3) along with individual task lighting. The fluorescent ambient lighting will also be dimmed by a photocell to utilize the available daylight (Figure 4.2). In this system a lower level of illumination is provided for movement, interaction, and facial modeling while the task lighting provides high lighting levels on the task plane. This design concept will be compared to a recessed direct fluorescent system. In this alternative lighting solution the recessed direct lighting provide higher levels over the entire space. These two systems will be analyzed for performance, and energy efficiency. Figure 4.3 Lighting Section

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1.4.3 Design Criteria

Appearance of Space: In this space its appearance is important because it will be someone’s work environment. It needs to have a comfortable and appealing appearance.

Color Appearance: Color appearance is important because someone will be spending at least 8 hours a day in this space and a better color appearance could allow someone to be more productive.

Daylight Integration: In this space daylight integration is very important because not only does it help to lower powerconsumption in this space but if it is not controlled it could make the space very uncomfortable.

Direct Glare: This is very important for this space because there will most likely be intensive VDT use in this

space as well as reading and writing. Light Distribution on Task Plane: In this space it is important to have a uniform distribution of light on the task plane. Also a 3:1

task to adjacent ratio and a 10:1 near field to far field ratio should be used. Luminance of Room Surfaces: This is important to this space because of the VDT use and the glare and reduced contrast that

can result from room surfaces that are too bright. An 8:1 uniformity ratio should be achieved on the ceiling also the ceiling should not exceed 850cd/m².

Modeling of Faces: In this space modeling of faces is important because it will be many peoples’ daily working and

interacting environment. Reflected Glare: This is important for this space again because of heavy VDT usage. Source/Task/Eye Geometry: In this space because of the use of VDTs and also because there will be reading and writing

going on daily the source/task/eye geometry is important. System Controls: In this space personal control of lighting levels is desirable because most people have different

preferences as to how much light they enjoy working under. Allowing them to partially control the light levels at their own work station provides a more comfortable and enjoyable working environment.

Horizontal Illuminance: 30 fc on the work plane Vertical Illuminance: 5 fc ANSI/ASHRAE/IESNA Standard 90.1 – 2001 Power Density: 1.1 Watts/ sq.ft.

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1.4.4 Equipment

Fixture Schedule

Fixture Type Manufacturer Lamp Ballast Watts/Fixture CCT Controls

F1 Semi-Indirect

Linear Fluorescent

Peerless 1-32W T8 Lutron Eco-10

Electronic Dimming 100% to 10%

38.78 4100

Switch / Occupancy

Sensor / Photo Cell

F2 Bi-Level

Fluorescent Task Light

Waldmann 1-18W CFL K-Tronik Electronic 21 4100 Switch

F10

Recessed Fluorescent

Prismatic Troffers

Lithonia 3-32W T8 Advance

Transformer Electronic

90 4100

Switch / Occupancy

Sensor / Photo Cell

*Cut Sheets for Fixtures, Ballasts, and Controls can be found in Appendix A-4 *All Lamps provided by Sylvania

Lighting Plan

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Alternate Lighting Plan

As can be seen in the lighting plans for each system the first system uses many more fixtures this will cause the initial cost of the first system to be substantially higher than the alternate system.

1.4.5 Analysis

Light Loss Factors

Luminaire LLD Maintenance Category

Degree of

Dirtiness Cleaning

Cycle LDD Luminaire Distribution

Room Cavity Ratio

RSDD Ballast Factor

Light Loss

Factor

F1 0.9 II Clean 12months 0.93 Semi-Indirect 3.15 0.92 0.96 0.74

F2 0.9 IV Clean 12months 0.88 Direct 3.15 0.92 1.00 0.73 F10 0.9 IV Clean 12months 0.88 Direct 3.15 0.92 0.96 0.70 The light loss factors for the fixtures in both systems are very similar however the first system has slightly better light loss factors.

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Power Density

Room Fixture Watts/Fixture # Total Office Area F1 38.78 20 775.6

F2 21 8 168 Total Watts 943.6 Watts/sq.ft. 0.93

Alternate Power Density

Room Fixture Watts/Fixture # Total Office Area F10 90 10 900

Total Watts 900 Watts/sq.ft. 0.89

As can be seen in these two tables the primary system has slightly higher power density than the alternate system. However, both systems are below the ANSI/ASHRAE/IESNA criteria.

Renderings

Figure 4.4 Office Rendering

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Figure 4.5 Alternate Office Rendering

Figure 4.4, and 4.5 show the overall appearance of both systems. In the primary lighting solution the task ambient system makes the room feel large and open by throwing light onto the ceiling. The task lighting also helps to give the room a more private yet relaxed feel. This is accomplished by introducing higher light levels on the task plane that contrast the lower surround light levels. The recessed direct alternate lighting solution makes the room feel smaller by keeping the ceiling fairly dark and provides a hazy feel due to the even brightness over the entire floor area.

Calculation Grids

Figure 4.6 Calculation Grid on the Floor Level

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Figure 4.7 Alternate Calculation Grid on the Floor Level

Figure 4.8 Calculation Grid on the Work Plane

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Figure 4.9 Calculation Grid on the Work Plane

Figure 4.10 Pseudo-color of Room Luminance Levels

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Figure 4.11 Alternate Pseudo-color of Room Luminance Levels

The calculation grids for the floor area (Figure 4.6 and 4.7) show that there are substantially lower lighting levels in the primary task ambient lighting system. However, the work plane calculation grids (Figure 4.8 and 4.9) have very similar light levels. The luminance maps of the room (Figure 4.10, 4.11) show that both lighting solutions meet the design criteria for light distribution on the task plane. The 3:1 task to adjacent and 10:1 near field to far field ratios have been met easily by the alternate lighting solution and are also met by the primary lighting solution because the occupant has control over the bi-level task light. The ceiling of the task ambient space does not quite meet the 8:1 uniformity ratio recommended by IES but with enhanced glare free computer monitors this should not be a problem.

1.4.6 Daylignting Control Methods

The task ambient system will be analyzed with 2 different control scenarios. The first will be that both the front and back row are dimming and the second is that only the front row is dimming. The alternate direct system will be analyzed using only switching to dim the lighting levels.

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Task Ambient Dimming

Ambient Dimming

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20Distance Into Space (ft)

Illum

inan

ce (f

c)

Daylight

Ambient 100%

Ambient Back Row +Daylight

Ambient Dimmed +Daylight

Ambient Dimmed FrontRow + Back row andDaylight

Direct Switching Options

Daylight Switching Options

0

10

20

30

40

50

60

0 5 10 15 20

Distance into space

Illum

inan

ce (f

c)

Front 3 Lamps Back 3LampsFront 1 Lamp Back 1LampFront 1 Lamp Back 2LampsFront 1 Lamp Back 3LampsFront 2 Lamps Back 1LampFront 2 Lamps Back 2LampsFront 2 Lamps Back 3LampsFront 3 Lamps Back 1Lamp

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Direct Switching Levels

Direct Switched Levels

0

10

20

30

40

50

60

0 5 10 15 20

Distance Into Space (ft)

Illum

inan

ce (f

c)

Daylight Levels

Direct Switched 2 LampFront 2 Lamp Back

Daylight + Direct Switched

Desired Light Levels

Dimming Results

Ambient Direct Switched Ambient Front Only BF (Max) 0.96 W/Ballast 30 BF (Max) 0.96BF (Min) 0.1 Total W 600 BF (Min) 0.1Max Watts 38.78 W Saved 300

Max Watts 38.78

Min Watts 14 % Saved 33.33%

Min Watts 14

W/BF 28.81395 W/BF 28.81395BF*%Dim 0.8448 BF*%Dim 0.5088Dim W 24.34203 Dim W 14.66054Total W 486.8406 Total W 434.7449W Saved 288.7594 W Saved 340.8551% Saved 37.23% % Saved 43.95%

These results show that all systems analyzed save a substantial amount of energy. It also shows that the best performing system was the Task Ambient system with only the front row of fixtures dimmed.

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1.4.7 Conclusion The comparison between the task ambient system and the direct recessed system showed that the direct system would be a less expensive system to implement and slightly more energy efficient to operate at full output. However, both systems are extremely energy efficient and the task ambient system provides slightly more energy savings due to daylight integration. The value of the task ambient system can be seen in its performance and individual control. It produces a more friendly work environment and provides higher light levels on the task plane. The bi-level task lighting also provides each individual with control over his/her work environment. All of these aspects together provide for a more efficient work environment. With a better work environment employees will be able to be more productive. Increased productivity will more than out weigh the added cost of the task ambient system.