Portable Classrooms - Indoor Environment
Shingle Creek Elementary School, Orlando, Florida
The FL PERC, located at Shingle Creek Elementary School in Orlando,
Florida was sited in September 2003. The entire Shingle Creek Elementary
School campus is composed of relocatable classrooms. The Fl PERC was
built by Resun Leasing and South East Modular. Dimensionally, it is a
24�-0� x 36�-0� classroom with a bathroom totaling 864 sq. feet. The
control classroom was intended to be built by the same manufacturer
(South East Modular) but due to scheduling conflicts, it was built by
United Modular. The base construction from each manufacturer is nearly
identical. Each classroom was occupied during testing. The PERC was
located sixteen feet south of the control unit. FSEC monitored energy
performance in both classrooms. All data was downloaded daily to FSEC
via modem.
Results
Overall Results
Data collected from November 1, 2003 through May 12, 2004 showed that
the modified classroom achieved overall energy savings of 65%.
Construction efficiency related differences between the two FL
classrooms are listed in the table below.
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Side-by-Side Study of FL PERC
Specifications of Standard and Energy Efficient Construction |
| Characteristic |
Standard Relocatable |
PERC |
| Floor Insulation |
R-14 unfaced |
R-14 unfaced
Formaldehyde Free |
| Wall Insulation |
R-11 faced |
R-14 unfaced
Formaldehyde Free insulation w/ Dens Glas with polyisocyanurate foam insulation board |
| Exterior Door |
HM pressed steel
knock down CECO with solid core R=2.44 |
HM pressed steel
knock down CECO with polystyrene core R=14.8 |
| Ceiling Insulation |
R-19 faced |
R-30 Icynene spray
foam insulation @ roof deck |
| Roof |
Standard dark
roof; 0.45 mm black EPDM over Densdeck |
Reflective roof;
0.45 mm white EPDM over 5/8" Densdeck |
| Windows |
1/8� non-tempered
bronze tint glass (U-1.03, SHGC=0.84, Vt=0.77) |
Low-E Argon gas
filled vinyl framed by Ellison with Solarban 60 glass (U=0.28, SHGC=0.39,
Vt=0.71) |
| Lights |
1,420 Total
Installed Wattage |
984 Total
Installed Wattage |
| Outdoor Light |
60 Watt
incandescent Manually controlled |
15 Watt CPL.,
photosensor controlled |
| Skylights |
None |
(7) 21� diameter
Solatube Skylights |
| Interior Floor Finish |
26 oz. Rolled
carpeting |
Non-permeable
backing, Interface �Sabi� carpet tile, low VOC glue |
| Heating System |
Bard Electric
Resistance Heat 10kW heat strip, 35900 BTU heat |
Bard Qtec Heat
Pump HSPF 7.5 |
| Cooling System |
Bard Central Air
Conditioning 3.5 ton with ERV 43000 BTU cool SEER 10 |
Bard Qtec Central
Heat Pump With ERV SEER 12 |
| Ventilation System |
Fixed CFM during
occupancy |
CO2 control for
ventilation with 3-step fan speed and energy recovery ventilator |
| Bathroom Exhaust Fan |
Broan, 4 sonne,
100 CFM |
Panasonic
Whisperlite Fane, 1.3 sonne, 190 CFM |
| Duct Leakage* |
CFM25 total
return=318
CFM25 total supply=485
CFM25 out return=253
CFM25 out supply=426 |
CFM25 total
return=325
CFM25 total supply=420
CFM25 out return=216
CFM25 out supply=274 |
| Building Leakage* |
ACH50 = 2673
ACH50=4850 (ACT removed) |
ACH50 = 1107
ACH50-1139 (ACT removed) |
| Smoke test |
Infiltration air
handler unit on 2.60 ach
Infiltration air unit off 0.27 ach |
Infiltration air
handler unit on � 0.66 ach
Infiltration air handler unit off � 0.05 ach |
| *Leakage Testing performed � December 9, 2003 |
Detailed Results
The graph below shows the predicted annual energy savings potential
for typical modular classrooms in various climates. The 46% energy
savings predicted for the FL PERC was substantially surpassed with
actual savings measured at 65%.
The timing of the savings are shown in the average daily load
profiles shown in the plot below.
Lessons Learned
- Use R14 insulation in lieu of R15 because R15 is only manufactured
in 14� widths and 96� lengths, as opposed to R14 which comes in rolls
and 16� widths, which is more suitable for 16� on center construction,
i.e. wall cavity)
- Providing timely and easily understandable information to teachers
and maintenance staff is a must.
- Use of the Solatube which included a tube that is standard with
the skylight well required no extra fabrication for the skylight well
area.
- In hot, cooling dominated climates such as Florida, measures that
reduce lighting and its internal heat generation show greatest promise
to reduce building energy needs.
- Daylighting is particularly attractive in this location although
solar control glass is important to reduce the space cooling
liability. Similarly, light colored surfaces and solar control glazing
looks more important than insulation.
- Heating system type is not as critical as cooling efficiency.
- Floor insulation is counterproductive.
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