Georgina Blach Intermediate School (Los Altos, …Los Altos, California) Daylight Human Factors Evaluation ... California Daylight Human Factors Evaluation ... caused high velocity

Georgina Blach Intermediate School (Los Altos, California)

Daylight Human Factors Evaluation

AUGUST 2004

Published by the Energy Center of Wisconsin for the United States Department of Energy

and National Association of State Energy Officials (NASEO)

455 Science Drive, Suite 200 Madison, Wisconsin 53711

608.238.4601 www.ecw.org

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PROJECT OVERVIEW The Association of State Energy Research and Technology Transfer Institutions, Inc. (ASERTTI) and the National Association of State Energy Officials (NASEO) with the Department of Energy (DOE) and the EnergySmart Schools Program conducted a joint project that encompassed applied research, field testing and technology integration. The following organizations worked collectively to conduct this research:

• Energy Center of Wisconsin • Iowa Energy Center • Lighting Research Center • Lawrence Berkeley National Laboratory • Dalhoff & Associates • Fort Collins Utilities

As part of the overall project there were eight distinct tasks outlined, each with its own set of goals, activities and deliverables. This document was created as part of Task 4: Advanced Daylighting Research.

Georgina Blach Intermediate School Los Altos, California

Daylight Human Factors Evaluation

Report submitted to:

Energy Center of Wisconsin Project J30447

Energy Smart Schools

Report submitted by:

Lighting Research Center Rensselaer Polytechnic Institute

August 2004

August 2004 - 1 - Lighting Research Center California Classroom Daylight Evaluation Rensselaer Polytechnic Institute

Table of Contents – Blach Intermediate School Los Altos, California

Evaluation Summary ……………………………………………………………………… 2 Site Conditions ……………………………………………………………………………… 4 Appendix A: Teacher/Staff Interviews …………………………………………………… 6 Appendix B: Daylighting Evaluation Survey ……………………………………………… 9 Appendix C: Survey Results …….………………………………………………………… 10 Windows ………………………………………………………………………………. 10 Blinds …………………………………………………………………………………… 11 Bright vs. Dark …………………………………………………………………………. 12 Electric Lighting ……………………………………………………………………… 13 Overall Rating ………………………………………………………………………… 14 Appendix D: Window Blind Use During Site Visit ……………………………………… 15 Appendix E: Horizontal Illuminance Measurements …………………………………… 16 Appendix F: Classroom Plans and Measurement Points ……………………………… 17 Appendix G: LRC Contact Information ..………………………………………………... 19


Evaluation Summary: Georgina Blach Intermediate School Classrooms in most of Georgina Blach school demonstrate Cool Daylighting™ principles. Some classrooms are entirely new, while most are substantially renovated. Daylight is provided by clerestory windows or roof monitor skylights (all north-facing). There are few “view” windows, but many rooms have display case windows that allow some visual connection to the exterior. Most classrooms have a sliding glass door, providing the majority of the view. Sliding doors are shaded with wide exterior overhangs and interior opaque curtains. Clerestory windows and skylights typically have perforated roller shades for use during audio/visual presentations. Glazing departs from Cool Daylighting specifications, as it is apparently not tinted. Electric lighting for each classroom is controlled by a photosensor mounted on underside of each row of light fixtures. Electric lighting is continuously-dimmed. (For more information about the site, see “Site Conditions” and Appendices.) An LRC researcher visited Blach School in March 2004. LRC is charged with evaluating human factors at this and other schools as part of NASEO contract J30447. Energy use will be monitored by other parties. This human factors study focused on acceptance of the system by the teachers and students. Extensive surveys were done to monitor student response. (See Appendix C.) Multiple teachers were interviewed on site and most also answered the survey. (See Appendix A.) Surveys showed that the luminous environment is well-accepted by students and staff alike. Appearance of upper windows was rated as comfortable. There were few complaints of either excessive or insufficient illuminance in the classrooms. A few students and staff notice the photosensor-controlled dimming, but most but do not find it distracting. Few complaints were registered about the minimal view, despite the limited number of view windows. Some teachers indicated that the blinds were difficult to access, or had drawcords that distracted students. Some indicated that the perforated blinds did not shade sufficiently for audio-visual needs. But complaints about blinds were minor and infrequent. (See Appendix A.) The only widespread complaint about lighting technology was that occupancy sensors sometimes falsely turned off lights when teachers work late or on weekends. (Occupancy sensors are not explicitly part of the Cool Daylighting curriculum, thus they do not reflect on the success of recommendations.)

Figure 1: Georgina Blach School


To support the human factors evaluation, LRC measured illuminances in the four classrooms identified for monitoring by Lawrence Berkeley National Laboratory (LBNL). The lighting system successfully maintained IES-recommended illuminances of 300-500 lux (see Appendix E). LRC did not attempt to monitor operation of dimming as this was out of the scope of this evaluation. Some teachers prefer to turn electric lights off completely during classtime, which is made possible due to the use of daylighting at the school. LRC logged operation state of the blinds on clerestory windows and drapes on sliding doors. In both cases, blinds tended to be open, which is important since photosensors are located inside the classroom space (see Appendix D). The teachers are permitted to use blinds as they wish. Maintenance staff and independent commissioning agents were also interviewed. Use of clerestory windows did interfere with the HVAC system design, which together with “eyeball” vent design, caused high velocity air output. Teachers have reported to maintenance staff some discomfort from high velocity air, although this has not been investigated in this report. Maintenance staff explained that the operation of occupancy sensors has been impacted by air flow. (Although occupancy sensors are not strictly part of the Cool Daylighting curriculum, they do impact energy savings and occupant satisfaction.) LRC has some concern that this facility may in the future experience premature lamp failures since maintenance staff do not perform the seasoning of lamps before they are dimmed1. After two years of operation, lamps can be expected to start needing normal replacement soon, therefore this issue would not previously have been problematic. Aside from HVAC issues and possible future lamp failure problems, there were few problems with the maintenance of the daylighting systems. In summary, Cool Daylighting creates a pleasant environment for teachers and students of Blach Intermediate School.

1 Anecdotal field reports from other sites indicate operational instability or premature lamp failures when new lamps are operated in a dimmed condition. Many lamp manufacturers suggest operating lamps at full power for 100 hours (“seasoning” or “burn-in”) before dimming. NEMA has established 12-hour seasoning guidelines to minimize flicker and visual instabilities, not for premature failure. Research is in progress to clarify cause of premature lamp failure when dimming. For more information see the NEMA publication “LSD 23-2002 Recommended Practice --Lamp Seasoning for Fluorescent Dimming Systems.”


Site conditions – Blach Intermediate School

General: • See plans, Appendix F • This is a suburban school, new

construction and substantial retrofit, completed 2002

• Not year-round operation • Grades 7-8 • Most of the school has Cool Daylighting;

approximately 26 classrooms Architectural: • Most classrooms have no view window,

but rather a sliding glass door and small display window

• Wide overhangs shade exterior hallways and sliding doors

• Ceilings are sloped • North-facing clerestory windows or roof

monitor skylights • Sliding doors and clerestory windows are

clear glass (according to reports from facility director)

• Sliding doors are generally not used for entry, since traditional hinged doors are adjacent.

• Clerestory windows typically have perforated shades

• Air conditioning is provided, to promote comfort and focus in the warm months.

• Desks are 29” high. • Eyeball-type HVAC vents (see Figure 2). Lighting: • Pendant direct-indirect fixtures, manufactured by Metalumen, product Horizon II

O5K-B4L44 • Two lamps in cross section, two continuous fixture rows per classroom, mounted

typically 8’-10” above finished floor. • Photosensors are mounted on the bottom of each row of fixtures, manufactured by

Easylite; photosensors were pre-set by Easylite, then controls and dimming ballasts were forwarded to fixture manufacturer for integration

• Initial set-up in the field performed by Easylite; commissioning verification performed by independent contractor, Keithly Welsh Associates (see Appendix A)

Figure 2: Sliding glass doors with curtains (R), typical pendant lights (C), and wraparound lights (L) in low-ceiling area. Eyeball-type HVAC vent shown upper L.

Figure 3: Typical pendant lights, white-board light (C), and clerestory windows (R)


• There are two fixture types used in most classrooms, not controlled by photosensors: • Dedicated white-board asymmetric wall-washer • Wraparound fixture, mounted in low ceiling area near doorway


Appendix A: Teacher/Staff Interviews, Blach Intermediate School

LRC interviewed ten teachers and noted anecdotal comments from a few other staff members. All teachers thought electric lighting dimmed appropriately, in terms of response to weather and time of day (if they noticed at all). The elements of Cool Daylighting are well-liked. There were no widespread complaints about visibility of the white board or veiling reflections. Some teachers reported that they change the lighting conditions to see white board better, such as using dedicated light, turning off lights or closing blinds. There were no complaints about the clerestory window being too bright. A few teachers reported having problems accessing upper window shade controls, causing them to leave the blinds in one position (“I never touch the blinds” or “always open”). Teachers at Blach school use overhead projectors and televisions frequently. A few teachers (3/10) said the environment is not dark enough for such audio/visual presentations. Most are satisfied with the amount of view in their room (8/10) and tended not to be concerned with visual distraction to students from the sliding door. There were many complaints about occupancy sensors (7/9), although this is not a feature of Cool Daylighting. Principal:

• Most teachers are very pleased with the lighting and daylighting of the school • The principal is not entirely satisfied with the control of upper blinds • Art teacher and music teacher are dissatisfied with lighting. However, it should be

noted that they have unusual needs and atypical classrooms: • Art teacher — not dark enough for slides, not bright enough for art production • Music teacher — not bright enough to see music

• Air conditioning is important to student focus, to extend learning season Additional comments from teachers:

• “I like automatic dimming… no-fuss” • “It has worked flawlessly.” • “It's working out fine.... This is wonderful!” • “My lighting is fine. In winter and on dark days, I use electric lights. Otherwise, all

daylight. Kind of a silly bottom-up shade.” • “On dark days it’s a little too dark, but it may be just my age” (50’s) • One teacher reported that the white board light glares in her eyes and gives her a

headache, so she never uses it. • “I really like the idea that these lights automatically turn off” (in response to

daylight) • One teacher said that the window box must be covered a few times a year to

darken the space for movies.


• One teacher mentioned she dislikes the fluorescent wrap fixtures in low ceiling area (magnetic ballasts, buzz, too bright/glaring)

• One science teacher appreciates undercabinet light fixtures to assist in microscope slide production

• In the computer lab, blinds are left closed due to extensive use of LCD projector, and half of electric lighting is routinely switched off.

Maintenance Personnel:

• The lighting control system works satisfactorily; after the work of KWA (see below), no need for further adjustment to the system.

• At first the teachers objected to light levels because they were accustomed to higher light levels. But they quickly became accustomed to the current conditions.

• There have been no complaints of premature lamp failure. • There is no plan for seasoning of lamps when spot-relamping. • HVAC vents are high velocity, which causes problems with occupancy sensors. • Having windows high up makes cleaning more difficult/dangerous.

Independent Commissioning Agent (Holly Robinson Townes, P.E., Keithly Welsh Associates (KWA) of Seattle, Washington)

• Initial set-up and calibration performed by controls manufacturer, Easylite • KWA verified that the building systems were working as intended

(“commissioning”) • Target illuminance established by the architect was 35-50 fc (375-540 lux) • At first, some classrooms were being overlighted or their systems had lost

calibration, but they have been adjusted as a result of KWA’s verifications. All control boards in all fixtures had to be replaced due to an error in the control board logic revealed by KWA’s verifications.

• At Blach School, the use and placement of clerestory windows did interact/conflict with the HVAC system. The placement of windows resulted in a change to the HVAC specification, which together with the eyeball-type vent specification (Figure 2), caused vents to produce high-velocity air flow. This causes thermal discomfort to occupants, and interferes with functioning of lighting occupancy sensors. This conflict was never fully resolved at Blach. Also, some air conditioning units were placed in the vicinity of clerestory windows, undermining their use for “natural” ventilation due to noise distraction. Ms. Townes often sees conflict between HVAC and lighting.

• Ms. Townes is concerned about the need for lamp seasoning with dimming systems. Blach school intends to spot-relamp, yet staff have no plans for lamp seasoning. (Note: This may lead to lamp operational instability or premature lamp failure when dimming, as discussed on page 3.)

(Continued below)


• In Ms. Townes’ experience, it is critical to have the following information included in the project specifications in order to make a successful daylighting project, to form a clear design intent and instructions for the contractor: • Clear criteria for lighting levels • Intended sequence of operation • Requirement for contractor testing, calibration and training

• Ms. Townes also points out the need for better information from daylighting control equipment manufacturers: • Need very thorough and clear calibration procedures and lighting sensor

placement procedures. • At Blach School they had none, so KWA arranged for manufacturer to

develop them (except for the photocell which was integral to fixture). • On other jobs, the manufacturer is expecting the electrical contractor to

calibrate and install the system yet instructions for calibration and parameters of installation of the photosensor are either not there, not complete or not clear. Electrical contractors are struggling with this, and without clear instructions equipment is not installed or set-up correctly.


Appendix B: Daylighting Evaluation Survey


Window Comfort Reports: StudentsStudents: Blach Intermediate School

0%

20%

40%

60%

80%

100%

Too Dark Dark Comfortable Bright Too Bright

Low er Window s(sunny) n=237Low er Window s(cloudy) n=203Upper Window s(sunny) n=213Upper Window s(cloudy) n=186Sliding Door(sunny) n=204Sliding Door(cloudy) n=175

Window Comfort ReportsTeachers: Blach Intermediate School

0%

20%

40%

60%

80%

100%

Too Dark Comfortable Too Bright

Low er Window s(sunny) n=18Low er Window s(cloudy) n=18Upper Window s(sunny) n=16Upper Window s(cloudy) n=16Sliding Door(sunny) n=14Sliding Door(cloudy) n=14

Appendix C: Survey Results Approximately 240 students and 18 teachers filled out the survey about windows, blinds, and the lighting system. Overall, the students and staff at Blach School find the classrooms visually comfortable and equivalent or better in quality to those in other schools. Windows: When students and staff look at both the upper clerestory and lower view windows, they find them comfortable to look at. Staff approve of window comfort even more than students. Weather conditions do shift opinion slightly, but overall, the staff and students find the windows comfortable.

Figure 5: Survey, Window Comfort Reports


"Blinds Block ____ of the Light"Teachers: Blach Intermediate School

0%

20%

40%

60%

80%

All Most Half A Little None

Blinds atClerestoryn=14Curtains atDoor n=16

Other Blinds n=10

"Blinds Block ____ of the Light"Students: Blach Intermediate School

0%

20%

40%

60%

80%

All Most Half A Little None

Blinds atClerestory n=207

Curtains at Doorn=204

Other Blinds n=174

Blinds: Teachers indicated that blinds block little of the light, but student surveys indicated that blinds are used to a greater extent than reported by teachers (Figure 5). Use of blinds is important at Blach School because they impact electric light energy savings. (See Appendix D.)

Figure 5: Survey, Blinds block light


"How frequently is it (too dark)/(too much light) in this classroom?"

Teachers: Blach Intermediate School

0%6%

11%28%

56% 33%

60%

7%0%

20%

40%

60%

80%

Never Sometimes Often Always

Too Dark n=18

Too much light n=15

"How frequently is it (too dark)/(too much light) in this classroom?"

Students: Blach Intermediate School

33%

4%

68%

9%

54%

7%5%21%

0%

20%

40%

60%

80%

Never Sometimes Often Always

Too Dark n=240

Too much light n=229

Bright vs. Dark Most students and staff thought the classroom was “Never” too dark (Figure 6). Of those who commented that it was “Sometimes” or “Often” too dark, most (56-75%) explained this was simply due to weather conditions, rather than type of activity, blind settings, or electric lighting control. Students and staff were also asked whether there was too much light. Once again, most thought there was “Never” too much light. Of those who offered explanation for responding “Sometimes” or “Often,” most (50-71%) cited weather as the reason there was too much light in the room, as opposed to audio/visual needs.

Figure 6: Survey, Too Dark and Too Much Light


Other lighting questionsTeachers: Blach Intermediate School

11%0% 0%

89%100% 100%

0%10%20%30%40%50%60%70%80%90%

100%

Notice DIMMING? Is dimmingDISTRACTING?

Lightinguncomf ortably

bright?

No

Yes

n=18 n=18n=15

Other lighting questionsStudents: Blach Intermediate School

23% 16% 16%

78% 84% 84%

0%10%20%30%40%50%60%70%80%90%

100%

Notice DIM M ING? Is dimmingDISTRACTING?

Lightinguncomfortably

bright?

No

Yes

n=240 n=238n=238

Electric Lighting: As shown in Figure 7 below, the majority of the students and staff do not notice the lights automatically dimming, and few reported that they found the dimming distracting. Students and staff did not find the electric lighting uncomfortably bright.

Figure 7: Survey, Lighting Controls


"Compared to classrooms at other schools, the lighting is ___?"

Teachers: Blach Intermediate School n=15

20%7%

73%

0%

20%

40%

60%

80%

Better About the same Worse

"Compared to classrooms at other schools, the lighting is ___?"

Students: Blach Intermediate School n=235

40%

17%

43%

0%

20%

40%

60%

80%

Better About the same Worse

Overall Rating Overall, the majority of the students and staff found the lighting in their classrooms “About the same” or “Better” than other schools. Teachers were more enthusiastic about the overall lighting conditions than the students.

Figure 8: Survey, Compared to Other Classrooms


Use of Blinds and Curtains Blach Intermediate School

69%

31%

71%

29%

0% 20% 40% 60% 80% 100%

Open

Closed

Clerestory Windows

Clerestory Windows

Sliding Glass Door Curtains

Sliding Glass Door Curtains

Appendix D: Window Blind Use During Site Visit Each classroom has north-facing upper clerestory windows with perforated roller shades. Shades pull up to close rather than pull down (Figure 9). Most classrooms have a sliding glass door to use for view, shaded by exterior walkway and interior curtains (Figure 10). On a cloudy day in March, LRC surveyed the state of the various shades at the school.

Some sliding doors were used for posting of information about an annual school field trip. The principal of the school indicated that these postings are temporary, allowing improved daylight collection. As shown in Figure 11 below, most blinds were open when LRC visited Blach School. This is important because the photosensor for the electric lighting is located on each light fixture. Use of moveable shades, therefore, impacts lighting energy savings. Figure 11: Status of Blinds and Curtains on day of visit

Figure 9: Upper clerestory window with one perforated shade closed

Figure 10: Sliding glass door with curtain


Appendix E: Horizontal Illuminance Measurements

In order to examine the degree to which the photosensors maintained constant illuminance, horizontal illuminances were measured over the course of one Saturday in early April 2004. Weather was variable and darker than normal. Electric lights were allowed to operate normally as controlled by photosensor. Measurements were taken at a desk height of 29”.

It should be noted that some teachers prefer to leave electric lighting entirely off during class, so their illuminances will be lower by choice. These measurements showed that the classrooms meet the IES recommended horizontal illuminances of 300-500 lux. As shown in Table 1, the dimming system succeeded in maintaining illuminances, with most points varying less than 50% from nighttime illuminances. See Appendix F for location of measurement points.

weather Time A B C* dark 9pm 552 590 826

overcast 8 496 463 813

variable/overcast 10 482 441 830variable/overcast noon 477 390 880

sunny 2 476 490 935

Rm

B3

- His

tory

sunny 4 453 463 851

*Point C in Room B3 lighted by non-dimming fluorescent wrap fixture.

dark 9pm 567 654 707

overcast 8 481 578 532

variable/overcast 10 563 700 567variable/overcast noon 655 737 555

sunny 2 655 625 564

Rm

C4

- Sci

ence

sunny 4 562 555 570

dark 9pm 453 430 558

overcast 8 699 680 553variable/overcast 10 673 826 675variable/overcast noon 713 938 722

sunny 2 681 616 629

Rm

G1

- Spa

nish

sunny 4 664 604 541

dark 9pm 485 460 505

overcast 8 661 574 477variable/overcast 10 655 572 497variable/overcast noon 737 716 593

sunny 2 605 486 392Rm

F2

- Mat

h

sunny 4 722 585 501

Table 1: Classroom illuminances over one day


Appendix F: Classroom Plans, and Measurement Points (See Appendix E for results of illuminance measurements.)

Classroom C4 (originally called “F2”)

Classroom B3 (originally called “C3”)


Classroom G1 (originally called “2-1”)

Classroom F2 (originally called “2-10”)


Appendix G: LRC Contact Information The following parties can be contacted for more information as follows: Lighting Research Center Rensselaer Polytechnic Institute 21 Union St. Troy, NY 12180 (518) 687-7100 Project Manager, Site Evaluator, Report Author: Jennifer Brons Associate Director, Daylighting Expert: Russell Leslie Human Factors Methodology Development: Peter Boyce, PhD Yukio Akashi, PhD Publication Editing: Michael Sharp Drawings: Seth Wiley Researchers from LRC wish to express their appreciation to the following individuals for their assistance in the evaluation at Blach Intermediate School:

• Kurt Weaver, Director of Facilities • Bob Stone, Maintenance and Operations • Arthur Harris, Principal

Documents

Georgina Blach Intermediate School (Los Altos, …Los Altos, California) Daylight Human Factors Evaluation ... California Daylight Human Factors Evaluation ... caused high velocity