the energy impact of daylighting and your impact on building design jon mchugh, msme heschong mahone...
TRANSCRIPT
The Energy Impact of Daylighting
and Your Impact on Building Design
Jon McHugh, MSME
Heschong Mahone GroupASHRAE/AIA Meeting April 20, 1999
What is Daylighting
Daylighting is the illumination of building interiors with:
Direct beam Sunlight
Sky Diffuse Light
Reflected light from the sun or sky
Effective Daylit Buildings Need an Integrated Design
• Orientation and Shape
• Glazing
• Mechanical System
• Lighting Controls
Need to Work Together
Correlation studies of daylighting and productivity
HMG Analysis of 108 Stores (2/3s daylit)
HMG Analysis of 21,000 elementary student test scoresOperable windows also a benefit
Daylighting Motivation - Energy Savings
FractionDaylitArea50%
FractionLighting Energy
Savings inDaylit Area
30%
PrimaryLightingEnergy
3.73 Quad10 6 GWH
MarketPenetration
16%X X X =
26,000GWH
Savings
• 30% to 70% savings in daylit zone
• 60% of commercial space directly under a roof– Single story buildings 41% of area
• 18% could be daylit over next 10 years
US Carbon EmissionsProjected Carbon Emissions by Region 1990 - 2010
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
Uni
ted
Stat
es
Oth
er N
Amer
ica
Japa
n
Wes
tern
Euro
pe
EE/F
SU
Chi
na
Oth
erAs
ia
Mid
dle
East
Afric
a
C. &
S.
Amer
ica
Ann
ual M
illio
n M
etri
c To
nnes 1990
1992
2000
2005
2010
Design Goals: Visual Quality–Provide appropriate illuminance levels
(task and ambient)–Control luminance contrast (highlight
or uniformity)–Integrate electric lighting and daylight–Provide a view–Create a pleasing environment
Design Goals: Energy Savings
• Electric lighting reduction
• Cooling load avoidance
• Passive solar heat gain
Design Goals: Cost Containment
–Use standard building elements–Use building form and orientation
to admit light and reject heat–Reduce mechanical equipment
size–Reduce connected lighting load–Simplify controls
Orientation - Solar Gain
0
1000
2000
3000
4000
5000
6000
7000
8000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
North East/West South Horiz
Source: ASHRAE 1997 Handbook of Fundamentals, SHGF
Overhangs - Sun Path Diagram
Shading 4’ below2’ overhang
Ref: Fuller Moore - Architectural Daylighting
15
Quick Estimate of Solar Altitude, at at Solar Noon
At Latitude, L, and a declination, :
at=90° - L + (degrees)
= 0, during equinoxes (3/21, 9/22)
= 23.45°, summer solstice (6/21)
= -23.45°, winter solstice (6/21)
Albuquerque L = 35°
Glazing Specifications
Solar Heat Gain Coefficient (SHGC) - how much heat gain is transmitted
SC = SHGC x 0.87
15.1tCoefficien Shading
nceTransmittaVisible
0.1SHGC
nceTransmittaVisible
Zero Energy Building
• Ultra Efficient Small Office
• R-19 Walls, R-32 Ceiling
• R-8 Glazing R-5.5 overall window
• Photocontrols on dimmable electronic fluorescent ballasts
• Direct/indirect evaporative cooling
18
Daylighting Design Constraints
• Multi-Story Design
• No Moving Parts (Passive)
• Inexpensive Components
• Make use of Direct Beam Sunlight
20
Simulation Steps
DAY3DProgram
Geometry and Surface Props
ExchangeFractions
TMYData
Irradiance PerezEfficacyModel
Electric Lighting Savings
Illuminance
BuildingDescription BLAST Energ
y Results
21
Parametric Runs
a) Chiller no daylighting
b) Evap cooling no daylighting
c) Chiller w/ daylighting
d) Evap w/ daylighting
e) “c” w/o daylighting controls
f) “c” w/o clerestory
Annual Energy End Uses
0
10
20
30
40
50
60
( a ) ( b ) ( c ) ( d ) ( e ) ( f )
kB
tu/S
F
BoilerChillerHW PumpFansPlugLights
23
Skylighting Guidelines
Skylighting design manual
Can be downloaded from www.energydesignresources.com
Funded by public interest energy research grant
24
SkyCalc - Skylighting Design Software
MS Excel application (spreadsheet)
Simple inputsType of building
Type of skylights
Number of skylights
Lighting control type
25
Outputs
Total Energy Cost Savings from Skylightsfor Lighting, Cooling and Heating
Design
-$2,000
$0
$2,000
$4,000
$6,000
$8,000
$10,000
0.0% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% 14.0%
Skylight to Floor Ratio (SFR)
Ann
ual C
ost
Savi
ngs
($/y
r)
26
Components of Energy Savings
-400,000
-300,000
-200,000
-100,000
0
100,000
200,000
0% 2% 4% 6% 8% 10% 12%
Skylight to Floor Ratio
kWh/
yr
Lighting
Cooling
Heating
Total Energy
Efficacy of Light Sources
0
20
40
60
80
100
120
140In
can
d
EE
Ma
g
Ele
ctro
nic
Met
alH
alid
e
HP
S
Su
nli
gh
t
Cle
ar
Sky
Ove
rcas
tS
ky
Lu
men
s/W
att
28
Cost-effectiveness of skylights
Optimum Sizing of Skylights for Cost Savings
$-
$1.00
$2.00
$3.00
$4.00
$5.00
$6.00
$7.00
1 2 3 4 5 6 7 8 9
Cos
t Sav
ings
per
SF
of G
lazi
ng A
rea
Daytona
Albuquerque
Albany
Nashville
Madison
Seattle