December 17, 2007
The case study assessment was conducted on site between August 15, 2007 and August 25, 2007. The First Environments Early Learning Center was instrumented to provide a snapshot of a measured thermal, luminous environment and user interface performance. The instrumentation used results in a variety of cross-sectional data, each of which have provided a visual overlay of the data; utilizing the unique characteristics of these instruments: 1. HOBO Onset data logger: Exterior and interior temperature; interior relative humidity; interior illuminance and interior Carbon Dioxide content sampling. 0HQROWD +DQG KHOG OXPLQDQFH DQG ,OOXPLQDQFH PHWHUV SURYLGHG ÀHOG GDWD DVVHVVPHQW RI GD\OLJKW DQG HOHFWULF OLJKWLQJ SHUIRUPDQFH DQG glare 3. IR Photography 4. HDR Photography 7KH IROORZLQJ LVVXHV WKURXJK SRVW RFFXSDQF\ HYDOXDWLRQ VXJJHVW D PHDVXUH RI ÀQH WXQLQJ VKRXOG EH DGGUHVVHG 7KH PHFKDQLFDO V\VWHP DQG RXWVLGH DLU FRQWUROV PD\ UHTXLUH D VLJQLÀFDW EDODQFLQJ EHQHÀFLDO WR LQVXUH HFRQRPLF RSHUDWLRQV (See Thermal
.
Analysis, pg.3)
2. The data reveals an adequate amount of daylight is available to meet the current LEED metric, however there is also evidence that daylight LQJ HIĂ€FLHQF\ LV FRPSURPLVHG E\ RFFXSDQW RYHUULGH RI H[LVWLQJ FRQWURO V\VWHPV 7KLV REVHUYDWLRQ LV SULPDULO\ GXH WR WKH IDFW WKDW WKH GLPPLQJ photo sensors do not appear to be installed as per recommended practice (See photo control assessment, pg.19). 2a) A thorough evaluation of the daylighting system should be reviewed by authorized representitives of WattStopper to assure quality applica WLRQ RI WKHLU SURGXFW LQ DFFRUGDQFH ZLWK WKHLU VSHFLĂ€FDWLRQV 2b) A re-callibration of the integrated lighting system should be done to set the 50fc limit for uniform classroom illumination, and insure that each respective bank of classroom luminares (outward normal to the window wall) are responding accordingly. 2c) Daylight in the corridor can also be enhanced by: F 7KH DSSOLFDWLRQ RI ZKLWH QRQ VSHFWXUDO PLQ UHĂ HFWDQFH SDLQW VXUURXQGLQJ WKH FOHUHVWRU\ DSHUWXUH DQG 2c3) The elimination of light blocking artifacts placed on the corridor glazing which separates the corridor and classroom spaces.
CONCLUSION Fundamentally, the daylighting attributes of the FEELC are in accord with the original design intent of the architect. Consideration of the above recommendations should result in a more apparent daylight dividend with respect to electrical consumption. As for human factors, additional issues VKRXOG EH FRQVLGHUHG WKDW FDQ UHĂ€QH XVHU XQGHUVWDQGLQJ FRQWURO DQG RSWLPL]H RYHUULGLQJ RI V\VWHPV RSWLRQV 1) An in-staff workshop would be useful tool to determine the acceptable “working illuminance “. This should be conducted under a typi cal night sky, overcast and clear-sky conditions in order to determine how the staff perceives the 50fc illumination standard - With the objec tive of setting the Photo Controller to accommodate a “consensus/ operational benchmark illuminanceâ€?, and; :LWK WKDW LQIRUPDWLRQ LW LV VXJJHVWHG WKDW D XVHU¡V PDQXDO ZRXOG SURYLGH D FRPSUHKHQVLYH DQG EHQHĂ€FLDO WRRO WR H[WUDFW WKH JUHDWHVW EHQ HĂ€WV WR HQHUJ\ HIĂ€FLHQF\ LQ WKH XVH RI WKH VSDFH This Post-occupancy daylighting assessment was conducted - in the same prototypical pre-school classroom pair (N-S) as was simulated in the initial daylighting design development assessment document (see appendix B, pg 36).
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Executive Summary Energy Consumption
i 2-3
Thermal Assessment HOBO Data Assessment Infrared Assessment Psychrometric Assessment
4-10
Daylight Assessment HOBO Data Assessment Photometric Assessment Control System Assessment
11-23
HDR Assessment
24-25
Appendix AHOBO Onset Supporting Data
26-36
Appendix BDesign Development Analysis
37-50
7KH DYHUDJH UHFRUGHG WHPSHUDWXUHV Ă€JXUH IRU WKH SHULRG EHtween August 2006 and June 2007 provide an external reference to compare gas consumption and electric consumption. The temperaWXUHV REVHUYHG GXULQJ WKHVH WLPHV LQIRUP Ă€JXUHV E\ SURYLGLQJ insight into what the outdoor conditions were which explain the heating and cooling load demands on the building. However, the recorded temperatures do not explain the peculiar spikes and dips found in either of the graphs. The utility bills for the FEELC were reviewed for the period beginning July 2006 - June 2007. The average natural gas consumed over typical thirty day periods for the course of one year illustrate a trend toward a consumption of approximately 5 therms per GD\ $V VHHQ LQ Ă€JXUH WKH JDV FRQVXPSWLRQ ULVHV IURP WKH IDOO of 2006 through the winter. This rise is in direct correlation with the expected increased demand of gas to heat the building through the respective heating season. Likewise, the diminishing consumption of heating fuel as we move through spring correlates with the buildings requirment for less heating energy. One point of interest is the dip in Btu consumption near the end of January. Because this time is near the peak of the heating system, the decrease in Btu’s consumed is peculiar. This drop could be related to either a varying holiday occupant load or an issue related to routine maintenance/ balancing of the performance of the HVAC system in FEELC. Figure 3 illustrates the average amount of electical consumption (KWhrs) for thirty day periods over the course of this same period. As seen in the graph, there is a large spike in February. One H[SODQDWLRQ IRU WKLV PD\ FRUUHODWH ZLWK WKH Ă XFWXDWLRQ RI HOHFWULFity experienced with the HVAC system only one month prior. The additional reductions in electric demands recorded in October and March correspond with periods in which the exterior temperature was bwetween 50-60 degrees farenheit and possibly indicate the use of “free coolingâ€?.
ENERGY CONSUMPTION
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The following graphs relate the recorded interior temperature and relative humidity readings as taken with HOBO Onset Data Loggers at the window wall within a cross section of the typical classrooms. 7KH GDWD IRU WKH 1RUWK &ODVVURRP UHYHDOV WKDW WKH LQWHULRU WHPSHUDWXUH ÀJXUH DV ZHOO DV WKH UHODWLYH KXPLGLW\ ÀJXUH DUH GLUHFWO\ DIIHFWHG E\ WKH exterior thermal conditions. The interior temperature ranges between 75 and 90 degrees farenheit and the relative humidity ranges from 34%-70%. Although north facing glazing is normally not as great a concern for direct solar heat gain, here the north classroom is affected to a greater magnitude of solar temperature DFURVV WKH JOD]LQJ DUHD %\ FRPSDULVRQ WKH 6RXWK &ODVVURRP ÀJXUHV is less auspicious. Overall, the data reveals that the humidity is not too far off of the 40%-60% desired range. The moisture content in each of the typical classroom environments is slightly too humid in the morning and slightly under in the late afternoon. Shifts in temperature variation from north to south account for the positive impact of solar control on the south elevations. The interior readings within the corridor also prove a correlation with exterior conditions although not to the extent shown from within the classroom spaces. In the case of relative humidity, we can also see that the outdoor temperature, which has a range of 80-100 degrees, has a direct effect on the corridor. In this case the data shows that the corridor has a higher than desired relative humidity for approximately one half of the typical day.
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Data from the South classroom again reveals a direct interior to exterior relationship. However, here the interior temperature range is between 70 and 78 degrees farenheit, which is far more controlled than that of the north classroom, reinforcing the fact that the shading devices in this space are indeed effective. The relative humidity ranges from 45%-70%,which is not too far off the desired range of 40-60%. Being that the relative humidity is slightly high for the majority of the time within each of the spaces, it may be concluded that the HVAC units are bringing in too humid of air without dehumidifying it before releasing the air into each of the spaces. A simple adjustment to the mechanical system would therefore assist in further energy savings.
Thermal Assessment 8
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Figures 1 and 2 are infrared images which were recorded with a Fluke IR DigitĂĽl imaging system. Given a consistent average temperature and Emissivity settings, the color translation of the images provide a relative measurement of the thermal qualities within each space as well as a comparison of one space to another.
Thermal Assessment 10
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11
The North Classroom Psychrometric Chart is a measure of the physical properties of the air within the space. The blue box represents the desired conditions for winter comfort and the red box is representative of summer comfort. The scatter plots are from data taken over the course of one week. Ideally the plots would land between summer and winter comfort and around 50% Rh. The graph therefore communicates a space a little cool and too humid.
Thermal Assessment
12
Like the North Classroom, the Corridor Psychrometric Chart also depicts a space that is not warm enough and too humid.
13
Not unlike the North Classroom or Corridor, the South Classroom Psychrometric Chart also provides us with data that supports the fact that the South Classroom is cooler and too humid. The plots jumping to the top of the chart are from tainted data and are not relevant to this discussion.
Thermal Assessment 14
Daylight Assessment 15
The graph below illustrates the light intensity of the North Classroom over a typical day as recorded by the HOBO Onset data loggers. The green line represents the 50 footcandle metric; the IESNA desired quantity of light at a given workspace. From this graph we can conclude that there is more than enough light available during periods of occupancy to provide a daylit space. However it should be noted that this data accounts for the combined effect of both daylight and the application of electric lighting system.
Daylight Assessment 16
Like the North Classroom, we can see that the South Classroom also has more than enough light to create the potential for a daylit space. The distinguished drop in light intensity in the middle of the day portrays a period of time in which the electric lights were turned off by occupants in correlation with nap time.
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7KH JUDSK EHORZ LOOXVWUDWHV WKH 1RUWK &ODVVURRP ,OOXPLQDQFH DV PHDVXUHG E\ SKRWRPHWHUV ZLWKLQ WKH ÀHOG VHJUHJDWLQJ WKH FRQWULEXWLRQ RI GD\light from electric light. While we know there is enough light potential for the space to be adequately daylit, the date indicates that the amount of daylight dips under the desired 50 footcandles about 8’-0� away from the window wall and continues to fall. This diminishing of light distribution can be explained in two ways. First, the north classroom does not employ a light shelf which assists in the distribution of light. Also, the GD\OLJKW GHVLJQHG WR LQÀOWUDWH WKH FODVVURRP IURP WKH LQWHULRU FRUULGRU SURYLGHG E\ WKH FOHUHVWRU\ LV EHLQJ EORFNHG E\ D VHULHV RI DUW SURMHFWV DQG papers on the glazing between the classroom and corridor. The green horizontal line represents the uniform illumination contribution estimated from on site observations of the electric lighting system.
Daylight Assessment 18
Similar to the North Classroom, the South Classroom also has enough light to create a more than adequare daylit space. However, the daylight drops below the desired 50 footcandles about 11’-0” into the space. Because of the light shelf, the daylight is able to penetrate further into the space. While the South Classroom’s daylight levels dip down as you near the corridor, the overall illuminance level in the room is still higher than the North Classroom. Like the North Classroom, careful consideration for removing “light absorbers” hung on the glazing between the corridor and classroom would help create a more uniform distribution of light to the space.
19
0.10
Series1
Average Daylight Factor
LEED
0.09
External Constant Fc: 8361
0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01
Feet from Window Wall
North Classroom As Found
Daylight Assessment 20
Blinds Down_Zero % Lights
26
23
21
19
14
12
9
6
3
0
0.00
0.10
Series1 LEED
Average Daylight Factor
0.09
External Constant Fc: 9290
0.08 0.07 0.06 0.05 0.04 0.03 0.02
26
23
21
19
14
12
9
6
3
0.00
0
0.01
Feet from Window Wall
South Classroom As Found Blinds Up_100 % Lights 21
Closed Blinds
Open Blinds
Zero % Lights Zero % Lights Photometric readings were taken in a series of cross-sectional placements through each classroom outward from the window to the corridor wall. The following assessment was done to facilitate greater understanding of the contribution of devices such as interior shading blinds and on-off photometric control in order to assess their impact upon the effective distribution of daylight in their respective spaces. Results are compared to an external sky luminance reference reading and translated into a percentage of exterior light recorded at various points with in the respective rooms (i.e. a daylight factor). The data has been translated into the isocontour color representations shown. The scale represents the amount of illuminance with blues being the darkest spaces and reds being the brightest.
Daylight Assessment 22
Closed Blinds
Open Blinds
100 % Lights
100 % Lights
Each graph represents a varied condition of lighting system integration and window opening as may be determined by the user. According to the data recorded, the desired metric of a daylight factor of 2 across 75% of the space is currently being met in each condition.
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The red circle in the photograph pinpoints the location of the light sensor (Typ. classroom) within the classroom space. Although the lab was not able to disaggregate the electric load to verify the results of dimming the lights because of the sensor, the lab was able to conclude that 50% dimming of electric lights would create an intermediate condition . %DVHG RQ WKHVH ÀQGLQJV WKH ODE recommends an assessment of the actual circuitry as well as the placement of the sensor. In addition, dual curcuits would provide the greatest energy savings and balance of illumination. The following pages give an in depth look of appropriate circuitry and installation.
Control Systems Assessment 24
25
LS-190C Placement
Better performance from moving back from the window Let window act as an aperture Do not want to mount directly above direct/indirects
Control Systems Assessment 26
LS 190C Mounting Detail
27
7KH ZLQGRZ WR Ă RRU UDWLR SURYLGHV adequate brightness as has been proved by the former analysis. High Dynamic Range (HDR) images record contrast ratios as candellas per meter2 and allow for representation through a color scale as shown in the false color images that follow. In context of the broad concerns contained within this report, the amount of glare within the typical classroom space is negligible. The openess of the window wall as well as physical light conrols and orientation are the greatest contributors to the current environment, however the ease of use of the interior blind sytem may inhibit the inherent advantages. Evidence of this may be seen in the comparison of conditions, VSHFLĂ€FDOO\ WKRVH RI WKH QRUWK DQG south classrooms as found.
HDR Assessment 28
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Appendix A 30
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Appendix B 41
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