the book redesigned and reordered · architect’s intent to create a comfortable, natural space....

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Gregory Wolfe 2004 Senior Thesis Lighting / Electrical

Westwood Community Church Chanhassen, Minnesota

Worship Space Function and Orientation The function of this space is primarily to hold masses and worship activities. The stage is used as both a pulpit and a place for choirs and musical acts. The floor below is where the congregation gathers. There are two screens in front of the room upon which song lyrics will be shown during worship, as well as presentations and other forms of visual entertainment. However, the space does not solely function as a worship area. It is also used as a dining and fellowship facility. In this case, the floor is likely set with tables and used as the primary eating area, while the stage is used either for entertainment or is left alone. As a fellowship facility, the variety of functions for this space is basically limitless. Space Characteristics As seen in the picture below, there is a pulpit / stage at the front of the worship space. Permanent risers can be seen at the right and left of the picture, these risers correspond to those at the bottom and top of the floor plan above. In the center of the room are nearly 400 temporary chairs. These seats can be moved around to fit the service and can be removed for banquets, dinners and any other possible functions. You can see steel trusses at the top of the photo, hanging amongst these trusses are wood acoustic panels used to hold lamps, speakers and absorb reverberation. Finally, at the bottom left corner of the photo is the worship space’s lighting control center.

Floor plan of Worship Space

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Material Properties The floor of the worship space is a sealed concrete finish. The east and west walls of the room are painted while the north and south walls are covered with both 1” acoustical wall panels and stained Northern Red Oak solid wood. The ceiling above is gypsum wall board and the dropped wooden acoustic panels are made of Douglas Fir-Larch. The trusses shown in the above picture are steel with W14x120 bottom chords and L8x8x1/2 cross bracing. These steel trusses go up to the ceiling apex and hold the rigging equipment and roof loads. The windows along both ends of the wall will need shades to control the amount of daylight entering the space. Design Needs Because the worship space is designed for such varying functions it is important to create a lighting system flexible enough to accommodate these needs. Just as gymnasium lights would be inappropriate for a marriage ceremony, extravagant chandeliers would be inappropriate for concerts and youth activities in the worship space. Therefore, any fixtures designated for the space must be formal enough for a worship setting yet welcoming enough for many of the church’s informal activities. While the lighting design needs to be flexible for non-worship activities, it is imperative that it can create an inspiring space for worshipers. The light must be able to be quiet, subtle and capable of creating the appropriate mood for contemplation and meditation. Although it has the ability to create strong moods, the lighting design must still remain organic. The main focus of the church’s design is to harmonize with the natural beauty of the Minnesotan landscape and create a comfortable setting, so while a dramatic, impressive design could inspire worship, it would be inappropriate for the intended design of the church. Light should be inspiring, yet simple and cozy. Design Criteria (as suggested by the IES handbook) Appearance of Space and Luminaires – In addition to the appearance desires expressed in the design needs, the luminaries should not distract the congregation at all, as the focus of the room needs to be on the pulpit/stage. The lighting in the space needs to be very capable of rendering color as well, because color can be used to create a mood in accordance with the preacher’s sermon. Daylight Integration – Daylighting is integral to the design of a worship space. Though it could be used in many ways, the most effective is as accent lighting. The daylight should not be overwhelming or distracting to the congregation however, so caution must be used. Direct Glare – Direct glare should be avoided at all costs so that the congregation can focus on the preacher with ease. This can be achieved with a diffuse lighting system

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Design Criteria (cont.) Modeling of Faces or Objects – Everything on the stage must be modeled well. Also, the faces of the people in the congregation must be modeled well so that people can see each other clearly. In order to do this, the lighting system must be more than simply direct downlight fixtures. Reflected Glare – Reflected glare from the floor must be avoided. It is best to use a matte floor finish to avoid this problem. System Control (high importance) – Considering the worship space can be used for a variety of services (funeral, marriage, baptism, worship, etc.) it is crucial that a highly effective control system is in place. Horizontal Illuminance- minimum of 10 footcandles on work plane Vertical Illuminance- minimum of 3 footcandles on walls Existing Design The worship space is currently lit with mostly incandescent lights. In zone 1 (outlined in blue), there are incandescent downlights recessed into the dropped acoustic panels. In zone 2 (outlined in orange), there are incandescent downlights recessed into the sloped ceiling planes on both sides of the worship space. Finally, the lights in zone 3 (outlined in green), are also incandescent downlights, this time recessed into the overhead ceiling. In addition to the incandescent downlights, there are two metal halide flood lights positioned on top of each acoustic panel. These lights are shown in green and flood light up in to the ceiling cove. There is also an intricate rigging system that lights up the stage at the front of the worship space, but this information is not included in this report. One final thing of note is that, like the open plan office, some of the downlights are equipped with an emergency backup system that is activated when the voltage drops below 80% of its capacity. The existing design has a power density of 3.02 W/ft2, which, although high, is within the 3.2 W/ft2 maximum requirement for a worship space seating area.

Existing Lighting Layout

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Critique The existing design seemed somewhat counteractive to the architect’s intent to create a comfortable, natural space. The steel trusses and wood acoustic panels in particular seem to clutter the space and create tension throughout the room. On the right, the architects original sketch of the space is shown. Notice that the emphasis in the architect’s original design was on the wood pitched roof. The trusses in this case were wood and not very prominent. Though the acoustic panels still existed in this sketch, they were used to break up the ceiling, not become the ceiling. This emphasis created a very natural outdoorsy feel to the worship space. It seemed to fully connect with the outside environment. Unfortunately, the addition of steel trusses and the magnitude of the acoustic panels seemed to disrupt this intention. As for the lighting in the space, there seems to be too much of it. The incandescent fixtures are obviously inefficient, while the light levels throughout the room feel a bit too great for a worship space. Even though it is a multi-purpose room, it seems the multi-purpose nature of the space has taken away from the fact that this space is primarily used for worship. In my redesign, I am intent on returning this space to the way it was originally intended. The structural breadth will attempt to switch the steel truss back to wood, while an acoustical breadth will attempt to remove the hanging acoustic tiles and investigate means of overcoming their loss. Finally, the lighting redesign of the space should hopefully create a versatile, comfortable and natural, yet intimate atmosphere.

Original Sketch of Worship Space

View of worship space – note trusses and panels

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Structural Breadth

Currently in the worship space, there are four steel trusses spanning a length of 120’ and a height of 35’. These trusses rest on steel columns at grid lines 7, 8, 9 and 10. These trusses are loaded with roof loads, self loads and any live, dead and snow loads on the roof of the Westwood Community Church.

The truss has a bottom chord of W14x120 with web members of (2)C15x33.8 and (2)L8x6x1/2. The top chords are both W33x118. While the truss is structurally sound, from an architectural standpoint the worship space would look much more natural with a timber truss in its place. The design process for creating a new timber truss can be broken down into 3 steps:

(1) choosing a truss style (2) choosing a wood type and (3) choosing the appropriate beam sizes

These decisions were obviously not just pulled from thin air. They required much discussion with structural AE students, research from a variety of books (listed in the references) and the use of Staad.Pro software.

Existing steel truss

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Choosing a Truss Style My decision on truss style was solely aesthetic. The current truss in the space, an expanded Howe truss, seemed very busy. The number of web members made it difficult to view the ceiling and, as a result, the truss (with the help of the acoustic panels) seemed to overtake the space. Therefore, I wanted a truss that was obviously still very functional but also had a pretty open and simple form, so that the truss structure wouldn’t overtake the ceiling cavity. The truss that best fulfilled this desire was the Fink truss (shown below). Choosing a Wood Type Douglas Fir – Larch was chosen as the wood to be used in the truss because it is readily available in the Western portion of the U.S. While it is not extremely indigenous to Minnesota, according to www.treeguide.com , there are Douglas Fir trees in the state. Douglas Fir was originally used for the hanging acoustic panels; further proof that this wood is appropriate. Because it is the strongest possible grade, Select Structural was chosen as the type of Douglas Fir used. Choosing the Appropriate Beam Sizes Truss size analysis was done using Staad.Pro and the National Design Specification Supplement. Unfortunately, Staad does not have a database for timber beams. Therefore, I needed to find the values for Modulus of Elasticity, Poisson’s Ratio and the Density.

These values were found in the following manner: E (modulus of elasticity) = 1600 ksi This value was found from p.44 of the NDS Supplement. Poisson’s Ratio = .292

This value is for deformation along the radial axis as caused by stress along the longitudinal axis. The value was found from Table 4-2 in the Wood Handbook.

Density = 1.97 x 10-5 kips/in3

Specific Gravity was found on page 2-37 of the Timber Construction Manual. For 12% moisture content, G = .49.

Density for G=.49 was found on table 3-7b of the Wood Handbook. Density = 549 kg/m3 = 1.97 x 10-5 kips/in3

Fink Truss

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With those values in the truss and the structure built, the next step was to calculate necessary loads on the truss members. The loads considered for the truss were: live load, load of the shingles and decking, snow load and the dead self-weight of the truss. Wind loads were not considered for this design because they would be minimal compared to the live and dead loads. As a result, the truss will be sized extra large, just to make sure. Live Load = 40 psf = .96 kips/linear foot

This value was taken from the Westwood Community Church specifications. This value is significantly higher than is specified by BOCA. More than likely, this load calculation is high in order to cover the snow load.

Shingle Load = 3psf = .072 kips/linear foot Assumption Decking Load = 3.5 psf = .084 kips/linear foot Assumption Truss Self-Weight = 7.68 psf = .0768 kips/linear foot

W=.064L where L = 120’. Taken from pg. 168 of Principles of Timber Design My intention in sizing a truss was not to find a truss that would just barely fulfill the load requirements. The entire purpose for switching to a timber truss was to select a truss that looked good in the space. Therefore, I placed various truss sizes in AutoCAD to see which sizes looked best. Then, knowing which size I wanted, I took this data into Staad to see if the truss was structurally feasible. Members of size 8x20 were chosen for all chords and web members. However, the likelihood of finding enough 20” deep Douglas Fir members is not very great. Thus, the wood type was switched to an 8-3/4” x 19-1/2” Glued Laminated Douglas Fir Larch timber. While this will reduce the aesthetic nature of the wood, the truss is high enough in the space that occupants will likely not notice the difference. Grade L2 was chosen for this timber because it matched the 1.6x106 psi modulus of elasticity value of the original members. These 8-3/4” x 19-1/2” members were placed on the Staad truss and the analysis was run. Three goals needed to be met in order for the truss to pass:

(1) Maximum nodal deflection needed to be less than L/360. (2) Compression stress had to be less than that of the timber. (3) Tension stress had to be less than that of the timber.

Deflection: Length of the truss = 120’ = 1440” Length / 360 = 4” A maximum deflection of 1.14” is found at node 8. Goal (1) is met.

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Compression Stress: Stress = P/A Area of timber = 8.75” x 19.5” = 170.63 in2

A maximum compression force of 130.5 kips is found at beams 10 and 13.

Compression Stress = (130.5 x 1000) / 170.63 in2 = 765 psi

According to Table 5B of the NDS, the maximum allowable stress is 1600 psi. Thus, Goal (2) is met.

Tension Stress: Stress = P/A Area of timber = 170.63 in2

A maximum tension force of 104 kips is found at beams 7, 8 and 9. Tension Stress = (104 x 1000) / 170.63 in2 = 606 psi

According to Table 5B of the NDS, the maximum allowable stress is 1250 psi. Thus, Goal (3) is met. Conclusion

A wood truss of Douglas Fir Larch Glu-Lam will replace the steel trusses at column lines 7, 8, 9 and 10. All members in these trusses will be 8-3/4” x 19-1/2”.

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Acoustic Breadth

Introduction In order to clear up the ceiling space and create a more open atmosphere, the acoustic panels will be removed from the worship space. There are ten of these panels in full, nine over the seating area and one over the stage. The nine panels over the seating area measure 15’1 x 15’1, or 227.5 ft2. The panel over the stage measures 590 ft2. Obviously by eliminating this much surface area of absorbing material, the reverberation time will be impacted. As a result, the intention of this breadth is to see by just how much this time is affected and, as a result, what type of supplemental systems may need to be needed to regain a quality acoustic environment. Reverberation Time For a worship space, a longer reverberation time (over 2s) is often preferred. Music performances need the longer time for tone enhancement, while a greater reverberance helps the congregation avoid the feeling of “singing alone”. (Architectural Acoustics, 119)

Sound Absorption Data

Part of Room Material

Surface Area

α at 125 Hz

α at 250 Hz

α at 500 Hz

α at 1000 Hz

α at 2000 Hz

α at 4000 Hz

Pitched Roof Plywood 8632 0.28 0.22 0.17 0.09 0.1 0.11

Walls/Ceiling Gypsum board 1/2 in thick 11202 0.29 0.1 0.05 0.04 0.07 0.09

Floor Concrete 11760 0.01 0.01 0.02 0.02 0.02 0.02Truss Plywood 223.723 0.28 0.22 0.17 0.09 0.1 0.11

Windows Glass, Ordinary Window 2344.7 0.35 0.25 0.18 0.12 0.07 0.04

Pulpit Wall Wood, 1/4" paneling 3975.9 0.42 0.21 0.1 0.08 0.06 0.06

Audience Congregation 4687 0.57 0.61 0.75 0.86 0.91 0.86Acoustic Board

1" acoustic wall panels 1440 0.4 0.9 0.8 0.5 0.4 0.3

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Reverberation Chart

Part of Room

Surface Area * α at 125 Hz at 250 Hz at 500 Hz at 1000 Hz at 2000 Hz at 4000 Hz

Pitched Roof 2416.96 1899.04 1467.44 776.88 863.20 949.52Walls/Ceiling 3248.58 1120.20 560.10 448.08 784.14 1008.18Floor 117.60 117.60 235.20 235.20 235.20 235.20Truss 62.64 49.22 38.03 20.14 22.37 24.61Windows 820.65 586.18 422.05 281.36 164.13 93.79Pulpit Wall 1669.88 834.94 397.59 318.07 238.55 238.55Audience 2671.59 2859.07 3515.25 4030.82 4265.17 4030.82Acoustic Board 576.00 1296.00 1152.00 720.00 576.00 432.00 Total = 11583.90 8762.24 7787.66 6830.55 7148.77 7012.67

Volume of Worship Space = 427736 ft^3

Reverberation Time = 1.85 2.44 2.75 3.13 2.99 3.05

The reverberation time for all frequency levels (aside from 125 Hz, which is often ignored) is over 2s. Reverberation times of 3.5 and greater tend to create too much noise, so it seems that the reverberation time without the hanging acoustic panels is pretty much perfect. Vocal Reinforcement Although the reverberation time is perfect for singing and music, loudspeakers are still needed to reinforce the speech coming from the stage. In the original design, one central cluster and two side fill speakers were placed on top of the acoustic panel over the stage. In addition, ten delay speakers were placed on the original steel trusses in the space. However, the new design removed both the acoustic panels and the steel truss. Therefore, a new design is necessary.

Existing Vocal Reinforcement Plan

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Vocal Reinforcement Redesign The new loudspeaker system will still rely on the same theme as the original layout. Because the central cluster of speakers is most effective at helping the audience correlate the sound with the source, the central cluster and side fill speakers will be maintained. In addition, the delay speakers will continue to be used to supplement the sound over the side and back seating areas. However, because the hanging acoustic panel over the stage has been removed, there is no longer a surface on which to mount the central cluster and side fill speakers. Because of this, these speakers will be moved back behind the pulpit and placed on top of the rigging beam behind the stage. Cutouts in the wall will allow for the speakers to project into the worship space.

There are three concerns with the new central cluster placement:

(1) Will speakers located behind the pulpit create feedback? (2) Is the central cluster capable of covering the entire central seating section? (3) Can the side fill speakers effectively fill the side seating areas?

Section of Speaker Placement – Leaders show where the central cluster and side fill speakers will be moved

Rigging beam

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Will speakers located behind the pulpit create feedback? Using the new design, the central cluster is positioned at its new location behind the pulpit at a level of 29’ above the pulpit ground. By aiming this cluster at the mid point of the central seating area (50’-5” from the speaker) and assuming a standard pitch spread of 30 degrees, it can be seen that the entire spread of the speaker waves will safely miss the stage area. For reference, the person standing on the stage is 6’ tall.

Is the central cluster capable of covering the entire central seating section? As the cluster is aimed in the drawing above, the central cluster does cover the entire central seating section.

Beam spread of the Central Cluster

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Can the side fill speakers effectively fill the side seating areas? As seen in the picture below, when a speaker is aimed at the front row of side seats 45’ away from the back of the stage, a horizontal beam spread of 40 degrees covers the entire seating section. However, some of the sound is likely to be bounced back off the wall above the side seating section. In addition, a side fill speaker is not likely to be powerful enough to throw full coherent sound on the side seating areas without some supplemental speakers.

Beam spread of the Side Fill Speaker

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Sound Reinforcement for the Side and Back Seating Areas To supplement the side fill speakers, small fill speakers will be recessed into the slanted ceiling surfaces above the side seating areas. These speakers will be on delay and will have 4” round white baffles so that they blend in with the gypsum surface of the ceiling. Specifications for these baffles can be found in the appendix. No sound from the stage reaches the back seating area. Therefore, the three loudspeakers originally placed on the truss will remain attached to the truss. Circuiting

There will be four circuits for the new vocal reinforcement plan. One circuit will be composed of the seven recessed speakers above the left seating area, while a second circuit will cover the seven speakers over the right seating area. A third circuit will connect the central cluster with the two side fill speakers (all three components behind the stage). Finally, the fourth circuit will connect the three speakers on the truss in above the back seating area.

New Vocal Reinforcement Plan

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Conclusions

By removing the acoustic panels, the clutter in the ceiling area above the space is significantly reduced. As a result of this deletion, the reverberation time ranges from 2.5 – 3 seconds, a preferable range for a worship space reliant on music production. However, by removing the acoustic panels, changes needed to be made to the vocal reinforcement system. The room’s central cluster was moved behind the stage and placed on the rigging beam, where it successfully covers the entire central seating area and acts as an initial source for the side seating areas. To create a full sound over the side seating areas, 8” recessed speakers with baffles were placed in the ceiling over the seats. Finally, to get sound over the back seating area, three speakers were hung on the truss just in front of the seats. This new revised system creates a much less visible layout in the worship space. Even though there are still speakers hung from the back truss, the new layout goes far to create a more organic, less engineered worship space.

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Lighting the Worship Space

The original design for the worship space used the hanging acoustic panels to hold luminaries and the sloped ceilings to recess downlights. Thanks to the structural and acoustic redesign, the acoustic panels no longer exist and the sloped ceilings are occupied with recessed speakers. As a result, the design for the space needs to be drastically altered.

Re-Design

The lighting re-design of the worship space involves constructing two coves and five different types of lamps in the space.

A. Hang 14 Metal Halide pendants over the central seating area of the worship space. The pendants should drop 13’-3” from the ceiling to a height of 38’ above the ground.

B. Place 23 wallwashers just

below the bottom of the ceiling pitch. Do this for both the left and right sides of the space.

C and D.

Build cove surfaces along the top and bottom portion of the sloped roof. Along the top of the roof (C), place 15 4’x7” T8 lamps. Along the bottom portion of the roof (D), place 14 4’x2” T5 lamps. Both of these lamps should be positioned to wash the ceiling surface. Repeat for the ceiling above both seating areas.

E. Place 12 compact fluorescent downlights down each hallway outside of the worship space.

Re-Design Lighting Layout for the Worship Space

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Controls There are 18 lighting circuits created in the re-design of the worship space. Details of circuitry can be found in the five accompanying figures. With the exception of the four CFL hallway circuits, all other circuits will be placed on an existing dimming panel. This dimming panel (dimmer #1 in the existing panel schedule) also controls the stage lighting in the worship space. By placing all of these circuits on the dimming panel, it becomes very simple to create lighting moods for specific functions. Circuits W1, W1, W15 and W17 will be on battery pack back-up.

Circuits in the center of the worship space.

Circuits in upper sloped seating section Circuits in lower sloped seating section

Circuits in upper hallway Circuits in lower hallway

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Lighting Summary According to the design needs, the goals of redesigning the worship space was to create a system flexible to the many possible functions for the space and to create a system that would show off the organic nature of the space, without being overbearing. The new re-designed system is more than capable of handling the space’s flexibility. With the pendants on 100%, over 30 footcandles are placed on the floor, more than enough for any dining, lecture, or small convention. With these pendants dimmed, the light levels from the other fixtures will still be effective enough for a presentation or church service to take place. The cove lights on both sloped ceilings are to be turned on when people are seated in those areas, but they can be dimmed or turned off otherwise. Finally, all fixtures are either high enough or hidden so that any athletic activities can take place in the space without worrying about breaking a lamp.

.

With the acoustic panels removed and the steel trusses switched to timber, it is clear that the space become much more organic and open that it was originally. The new lighting system is designed to continue this trend, as most light is used simply to wash surfaces in the space. With the exception of the pendants, all light is indirect and are fixtures are nearly invisible. By taking the fixtures out of the lighting, the occupant isn’t confronted with how the space is lit, but rather with how the space looks.

Lightscape model of the redesigned Worship Space (seating not included)

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Light Fixtures The pendants are the only noticeable fixtures in the room so great care was made to ensure they would not be very intrusive. For starters, they were painted brown to match the ceiling. Also they are hung high enough so that while they can be seen by people in the room, they will not interfere with someone looking up at the truss. In fact, the light from the fixtures tend to show off the truss by creating warm spots on the wood surface. The 46 ceiling wash fixtures are purely decorative. They were placed in the worship space to show off the natural wood texture of the ceiling. With the pendants off during worship services, the ceiling wash fixtures create a powerful effect, pulling worshippers’ sight up to the massive ceiling in a symbolic gesture. The coves at the top and bottom of the sloped ceiling are also used to show off the simple materials used in the space. Although the fixtures are hidden from sight in coves, the lights subliminally lead guests to peripheral seating spaces. Fortunately, the wash from the coves is not strong enough to pick up the recessed speakers in the ceiling, even though they do place enough light for reading in the seating area. Finally, narrow direct downlights were placed in the hallways on both sides of the space so that there is no danger of light spilling over into the worship space itself.

View upon entering from the door at the back of the worship space. Note cove wash on sloped ceiling and warm spots on the truss (caused by metal halide pendants).

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View from the stage looking back into the space.

Approximately 20 footcandles on side seating areas.

“Watching the Pulpit” during a worship service. The rigging lights aren’t included in this rendering, thus the lack of light on the stage. The purpose of this model is to show how the character of the space changes when the pendants are dimmed to 5%.

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Illuminance Values (cont.)

Lamp Schedule Fixture Type

Lamp Type

CCT CRI Number of Lamps

Distribution Type

Input Power

Ballast Type

A 12” MH 3200 70 1 Direct 100 W Magnetic B 5”x5” T4 2950 100 1 Direct 150 W C 4’x7” T8 3500 82 2 Direct 40 W Electronic D 4’x2” T5 3500 85 2 Direct 121 W Electronic E 8” CFL 3500 82 2 Direct 52 W Electronic Power Density Fixture Type Quantity Number of Lamps Watts / Lamp Total Power A (Pendant) 14 1 100 1400 W B (Ceiling Wash) 46 1 150 6900 W C (Cove) 30 2 40 2400 W D (T5) 28 2 54 3024 W E (Downlight) 24 2 26 1248 W Total Power = 14972 W Total Area = 12959 ft2

Power Density = 1.155 W/ft2

Conclusions In the worship space redesign, the focus is on the light and the space itself, not the fixtures. With the exception of the hanging pendants (which are painted to match the ceiling), all fixtures in the worship space are essentially hidden from view. The light in the space can be used for multiple functions to create many different moods, from rowdy lectures to quiet worship services. Finally, from a power standpoint, the re-design is nearly one-half the power density used in the original design. See Appendix for Light Loss Factors, Ballast Information, Dimensioned Power Plan and Cut Sheets

Between 20 and 35 footcandles on the floot with the pendants on 100%.

Between 15 and 20 footcandles on Back Seating Area

the book redesigned and reordered · architect’s intent to create a comfortable, natural space....

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