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Passive First:•Passive Solar Heating
•Passive Cooling
Greek and Roman
solar buildings
featured vast, un-
glazed south-facing
apertures.
Introduction to Passive Strategies
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Maximize Gain,
Minimize Loss(per Socrates!)
1950s solar home—Howard Sloan
Your Solar Home, LOF, 1947
Alabama, Clyde Pearson
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The Idaho solar home by Ted Prichard
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Conventional
Energy provided by
utility
Conserving
Energy saved by
exceeding code
Active & Passive
Energy provided
free from environment
Passive buildings require user control and choice.
Passive Goals
Heating Season Cooling Season
1. Optimize solar
gain
2. Minimize skin
heat loss
1. Minimize solar
gain
2. Minimize skin
and internal
gains
Can a single design do both?
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Passive Heating
vs.
Passive Cooling…
Cat vs. …
Passive Strategies
Cooling Heating
Direct Loss Direct Gain
Indirect Loss Indirect Gain
Isolated Loss Isolated Gain
Avoiding Gain Avoiding Loss
Lowering Internal
Gain
No conserving
parallel
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Vs. Man
Requires apertures with switches.
Reverse diurnal operation to provide heating.
Lose heat
directly via
night radiation
Day - Night
Closed - Open
Night - Day
Open - Closed
DIR
EC
T L
OS
S
Direct loss—courtyards
Machu Picchu
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Requires Thermal Mass
DIR
EC
T G
AIN
More glass means bigger heating load,
…but more “free” energy
Solar GainSouth vs.
Horizontal
unshaded
More gain in winter
More gain in summer
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East and West,
NW and NE, +
North vs.
Horizontal
SW and SE
vs. South
In between
Balcolm House, Los Alamos, NM
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Retrofits
Formal vs. Low-Tech
Sun and thermal mass
Phase change materials
can replace thermal mass
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Lose heat to a ‘middleman.’
Requires connection to mass with switches.
Reverse diurnal operation to provide heating.
Sky Therm Mass Wall
IND
IRE
CT
LO
SS
Indirect Gain & Loss:
Roof Pond or Sky Therm
The Sky Therm
inventor.
Harold Hay
Atascadero House (Cal Poly)
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Movable insulation
Open nights to cool
Open days to heat
Hint: Ceilings
Northern Sky Therm (>36ºNL)
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IND
IRE
CT
GA
IN:
Tro
mb
e W
all
Can also provide a bit of indirect loss
Kelbaugh House, Princeton, NJ
Thermo-circulation
vents
Night (movable) insulation
Days open to heat
Nights open to cool
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Selective glazing—view not required
Street barrier, Berkeley, CA
Hybrid system:
Trombe wall for heating/cooling
Windows for light and view, Girl Scout House, NJ
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Retrofit
INDIRECT GAIN:
Water Wall
Some indirect loss is possible.
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Baer House, NM
Combo insulation-reflector Open
Vs.
Closed
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Requires remote
apertures.
To provide heating
requires a different
system.
Lose heat via a remote system.
Isolated gain
ISO
LA
TE
D L
OS
S
INDIRECT LOSS:
Earth Tubes
Sainsbury’s passive grocery store North Greenwich
Daylighted &Earth Tube Cooled
2015 2017
Epilog
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ISO
LA
TE
D G
AIN
: T
her
mosi
ph
on
s
Air-based Collector with Rock Bed Storage
Remote collector
Radiant slab
Sun Spaces (Greenhouses)
ISO
LA
TE
D G
AIN
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Retrofit and
Low-tech
Problem?
Well-designed shading avoids summer gain and
promotes winter gain.
Insulation always reduces heat flow, so less gain in
summer and less loss in winter.
Insulating
AV
OID
ING
GA
IN/L
OS
S
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Lowering Internal Gains
Daylighting
Apertures that allow daylight in summer can
allow heat gain in winter.
40%
Each passive strategy can
imply significant savings.
100%
For IDL buildings:Cooling and lighting is 50%
of the energy use.
Heating only 25%.
For SDL buildings:Cooling and lighting is
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In arid climates
•Evaporation
•Ventilation
•Shading
•Mass
In humid climates
•Ventilation
•Shading
In both climates: solar gain
Shading line
US DOE insists that 80% of potential energy savings
Occurs during the schematic design phase.
BP Solar Showcase, Arup Associates
Davis Cabin, VA
Design for
difficult sites
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Stair-step house, Karen Terry, AZ
…but not foxes!
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