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Anthony Dominguez, Jan Kleissl, UC San Diego Jeff Luvall NASA MSFCJeff Luvall, NASA MSFC
Presentation OverviewProject motivationDEMROES project backgroundResearch to dateFuture field studiesConclusion
Project MotivationThe thermal properties of building materials directly effect the conditions inside of buildingsH f i i d i d i i b ildi Heat transfer is not a primary design driver in building designRooftop modifications lower heat transfer which Rooftop modifications lower heat transfer, which lowers energy consumption and costsThe ‘living environmental laboratory’ attitude at The living environmental laboratory attitude at UCSD makes it the perfect place to test the success of these modifications.
E iEquationsTR 4εσ
( ) RRRR
TR
ldlusdnet +−−=
=
1 α
εσRnet = net down‐welling radiation
H = Sensible heat flux
H fl i b ildi ( )
( )wcH sp
ldlusdnet
Θ= ''ρ
q = Heat flux into building
TTMCcH roofairHp −−≈ )(ρ
( )d
TTkq ceilingroof −=&
dy
Types of Rooftop ModificationsHigh albedo (α) coatingsPhotovoltaic (PV) arrays
DEMROES Project BackgroundDEMROES is a wireless network of real time meteorological stations installed across the UCSD campuscampus
DEMROES station overviewDEMROES‐ station overview**
**
* Ai d h idi* Ai d h idi
*
* Air temperature and humidity* wind speed and direction* rain* Solar radiation (mean and variance)
* Air temperature and humidity* wind speed and direction* rain* Solar radiation (mean and variance)CMRR Station Solar radiation (mean and variance)* Solar panel temperature, power output* Roof surface temperaturefuture: particulate matter
Solar radiation (mean and variance)* Solar panel temperature, power output* Roof surface temperaturefuture: particulate matter 7
Albedo = 0.114
DEMROES‐ other sensors
Zytemp TN9 IR SensorFLIR Thermovision A320
Results: Rooftop PropertiesBuilding Albedo Roof ImageCenter for Magnetic Recording Research
(C )
0.114
(CMRR)
Biomedical Sciences Building
0.187Sciences Building
(BMSB)
Powell Structures 0 218Powell Structures Laboratory (PoSL)
0.218
Engineering 0.354g gBuilding Unit 2
(EBU2)
Results: Typical Sunny Day CurvesResults: Typical Sunny Day Curves
60
70
C]
06-Jun-2008
CMRRBMSBEBU2
12
1406-Jun-2008
CMRRBMSBEBU2
20
30
40
50
f Tem
pera
ture
[o C EBU2PoSL
4
6
8
10
ind
Spe
ed [m
/s] EBU2
PoSL
00:00 04:00 08:00 12:00 16:00 20:00 00:000
10
20
time
Roo
f
00:00 04:00 08:00 12:00 16:00 20:00 00:000
2
4
time
Wi
60
70
o C]
23-Jul-2008
CMRRBMSBEBU2 8
1023-Jul-2008
CMRRBMSBEBU2
30
40
50
of T
empe
ratu
re [o
PoSL
4
6
Win
d S
peed
[m/s
]
PoSL
00:00 04:00 08:00 12:00 16:00 20:00 00:0010
20
time
Roo
00:00 04:00 08:00 12:00 16:00 20:00 00:000
2
time
W
Results: Curve Characteristics
Research to Date – DEMROES data .45
albedo vs. amplitute of surface temperature
06-Jun-200822-Jun-200823 Jul 2008
30
EBU2
ofto
p
23-Jul-200830-Sep-200807-Oct-200811-Oct-200814-Oct-2008
PoSL
.30
albe
do o
f roo
CMRR
.15
BMSB
15 20 25 30 35 40 45 50 55
CMRR
maximum temperature minus temp at 6 am
Research to Date – DEMROES data
.45
Time past solar noon of peak roof temperature
23-Jul-200811-Oct-200814 O 2008
EBU2
oofto
p
14-Oct-2008
PoSL
.30
albe
do o
f ro
CMRR
.15
BMSBPoSL
-20 -10 0 10 20 30 40CMRR
minutes past solar noon
Future Analysis – Thermal camera imagery
200
015
050
10
50100
150
200
250
300
ConclusionsHigher albedo rooftops have less heat transferred into the buildings and lower energy costs.Th h PV h hi h lb d h i i Though PV arrays have higher albedo, their spacing from the rooftop results in shading that could also lower energy costs possibly more than high albedo lower energy costs, possibly more than high albedo coatings.Data from field campaigns as well as the continuous p gdata from DEMROES and satellite IR data provided by NASA will better quantify the benefits of rooftop modificationsmodifications.
ReferencesAkbari H, Gartland L, Konopacki S. Measured Energy Savings of Light‐Colored Roofs: Reults from Three California Demonstration Sites 1998California Demonstration Sites. 1998Akbari H, Rainer L. Measured Energy Savings from the Application of Reflective Roofs in 3 AT&T Application of Reflective Roofs in 3 AT&T Regeneration Buildings. Stull, RB. An Introduction to Boundary Layer y yMeteorology. Kluwer Academic Publishers. 1988