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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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