Lecture 12 Green Building Features

7/17/2019 Lecture 12 Green Building Features

http://slidepdf.com/reader/full/lecture-12-green-building-features 1/39

Lecture 12: BuildingTechnology and Strategiesfor Sustainability

Material prepared by GARD Analytics, Inc. and University of Illinoisat Urbana-Champaign nder contract to the !ational Rene"able #nergy

$aboratory. All material Copyright %&&%-%&&' U.(.D.).#. - All rights

reserved



2

Importance of this Lecture to

the Simulation of BuildingsEnergy consumption of buildings (heating,

cooling, and lights) is a signicant fractionof energy consumption worldwide

Many energy sources are nite so we mustslow down energy consumption as muchas possible

Simulation can help reduce energyconsumption by modeling variousstrategies before they are built thusminimizing energy costs

Knowledge of various techniues for!sustainable design" and what can be

simulated is crucial



3

Purpose of this Lecture

#ain an understanding of$ Some basic strategies for reducing

the energy cost of buildings %arious technology solutions that are

currently available

& few !green" capabilities ofEnergy'lus



4

General Strategies for

Reducing Building eatingand !oolingonmechanical system approach

Should always try to minimize heating andcooling reuirements rst

Mechanical system e*ciency important also

+uilding Envelope$ nsulation and-orsolation

Solar Strategies ('assive .eating)

&lternate /ooling Strategies



5

Building "n#elope: Insulation

and$or Isolation#oal$ &ttempt to minimize the adverse

e0ects of the environment on a building ote$ e0ect of environment is always changing

ote$ in some cases (e1g1, temperate-mildclimates and high internally loaded buildings),we may want to ma2imize impact ofenvironment because it is benecial (/limateSpecic Strategies)

&d3ust volume to e2terior area ratio %olume-living space desirable (ma2imizevolume)

Minimizing e2terior surface area (usually) sinceit a0ects conduction, convection, and radiation



6

Building "n#elope: !hange

%all !onstruction 4educe conduction by adding insulation

!onduction &'() T$R* increase in R decreases ' +ote di,erences in R-#alues of #arious e.terior surfaces

and their relati#e areas

%indo/s #s0 /alls: /indo/s generally ha#e a lo/er R-#alue %alls #s0 roofs: building shape determines /here to focusattention

!onsider the possibility of mo#able insulation for#arious surfaces

'otentially reduce conduction by adding thermal mass Interior internal mass damps #arious short term

e,ects3 reducing or shifting conditioning needs ".terior thermal mass delays impact of e.terior

temperature s/ings3 may send some$much of e,ectbac4 to e.terior side

Thermal mass discussed in more detail later in thislecture



Building "n#elope: !hange

".terior Boundary !onditions /reate a local !microclimate" &ir vs1 ground temperature

Ground can be a thermal mass and insulator

)ir temperature changes more e.treme &harmor help5*

6odi7cation of air temperature using site/ater resources &e#aporati#e cooling to reducelocal air temperature*

5ind e2posure 8se of #egetation as /ind brea4s in /inter

&e#ergreens on north side9location speci7c* )llo/ air mo#ement for cooling5 +ote surroundings and impact on air

mo#ement around building

Surface properties



Solar Radiation: Light and

eat#eneral concepts

6se solar energy when heating reuired, avoid itwhen cooling is reuired

Sun angles (particularly altitude) can vary withtime of yearthis can wor7 to our advantage

Solar adds heat and light, but only during theday

8rientation of openings (windows) critical to thesuccess of the design9 in general$ 6a.imie southern e.posure

6inimie east$/est e.posure




eat &cont;d*!'assive solar" increasingly important

in design

) de7nition: a system that collects3stores3 and redistributes solar energy/ithout the use of fans3 pumps3 orcomple. controllers &Lechner*

Lo/er 7rst costs than acti#e solar

systems because they are part of thebuilding rather than an additionalsyste




eat &cont;d* 6sing :irect Solar #ain (5indows)

6tilize the !greenhouse e0ect" of windows which allowsolar radiation to be transmitted but bloc7 mostthermal radiation

+enet is ma2imized with south facing windows Lo/ /inter sun more directly impacts this direction igh summer sun has little e,ect on south

/indo/s3 can be easily shaded 'otential for overheating during the day and

underheating at night

Thermal mass &interior* helps reduce this e,ect +eed to e.ercise caution about thermal mass color

and location relati#e to insulators such as carpet3furniture3 etc0

:irect gain easy to provide but there arelimitsincreasing windows to increase gain alsoincreases heat loss through windows (at night) or heatgain when undesirable (in summer)



11

Solar Radiation: Systems

;rombe 5all Systems (more details later inthis lecture)

Sunspaces (more details later in thislecture)

;ranspired Solar /ollector 'erforated metal wall covering

Solar energy heats up wall <an assists in drawing air through panels

'anels re3ect heat to air, heating the air beforeintroduction into building



12

Solar Radiation: Shading

&ttempt to bloc7 solar radiation from impacting thebuilding during cooling season

:evices can be$ +atural or constructed

<i.ed or #ariable &trees of di,ering types3 mo#ableshades3 etc0*

=pa'ue or some/hat transparent Indoor or outdoor

/ategories-characteristics =#erhang9panels or lou#ers3 can be rotated <ins$/ings9panel&s*3 slanted or rotating "ggcrate9reduced depth combined o#erhang$7n3

slanted or rotating Roller shades$a/nings Trees$#ines9free standing3 trellis3 attached



13

Solar Radiation: General

Shading Guidelines ".terior shading more e>cient3 but /eather can ta4e its toll

on mechanied #ariable systems that are outdoors South /indo/s

"asiest to shade3 o#erhangs #ery e,ecti#e <ins may be needed for early morning3 late afternoon

Trees typically not much help to the south "ast$/est /indo/s

?i>cult to shade due to lo/ altitude angles <ins &slanted* more e,ecti#e or eggcrates Trees best on the east3 /est3 southeast3 and south/est &northern

hemisphere*

+orth /indo/s

Little shading re'uired ?esirable and e#en di,use daylight <ins typically enough3 if needed at all

S4ylights can be problematic Potential for lea4s is greater Solar$light gain ma.imied at /rong time of year &summer* !an be more di>cult to shade

=ther orientations may re'uire combination solutions



14

)lternate !ooling Techni'ues:

)ir 6o#ement%entilation

/omfort ventilation$ increase comfort byincreasing air =ow rates with the building

ight purge ventilation$ ventilate (naturally ormechanically) at night when the outside airtemperature is presumably cooler than inside

;echnology 5indows (various types of openings) /ool ;owers (:own :raft /oolers) ;hermal /himney



15


Roof !ooling +asic concept$ bloc7 solar radiation during the day, then

ta7e advantage of radiation to cold s7y during the night(clouds will signicantly decrease nighttime performance)

4oof 'ond

Simply a layer of /ater contained on a @at roof orcontainers of /ater ?aytime operation

Pond is co#ered /ith insulation to de@ect solar heat andreduce connection to outside en#ironment

Thermal mass of /ater soa4s up heat from the interiorspace

+ighttime operation Pond is left unco#ered to reAect heat from /ater to outsideen#ironment

eat is reAected #ia con#ection to surrounding air and tos4y #ia radiation

!ycle can be re#ersed in /inter to pro#ide a Trombe %alltype roo7ng system



16

4oof 'ond$ :rawbac7s

)dded cost of system ande.tra maintenance

6o#able insulation systemsare typically not #erysuccessful

!oncerns about lea4s



17


Roof Radiator Similar in concept to roof pond3 but replaces

/ater and mo#able insulation /ith a metaldec4 that is ele#ated abo#e the roof !an use interior mo#able insulation /ith a

closed dec4 !an be fan assisted /ith an open dec4

!an be used as a heating system in /inter ifsolar energy is trapped bet/een metal dec4and roof

ot air is then circulated to interior spaces ?ra/bac4s

)dded costs of roof dec4 Reliability$longe#ity of mo#able insulation



18

4oof 4adiator$ /ooling

8peration?aytime operation

6etal panel re@ects a portion of thesolar radiation

Insulation bloc4s heat transfer tobuilding interior

=r #entilation air reduces heat transferfrom roof dec4 to actual roof

+ighttime operation Roof radiates heat to s4y Roof temperature may be lo/ enough

to actually cool outside air e#en further



19

"arth !oupling: ?irect "arth

!oupling8nderground or berms

Ground temperatures can be lo/er

than outside air3 ma4ing this a goodheat sin4

!oncerns about /inter may re'uireinsulation of ground and$or building

surfaces in contact /ith ground

Potential moisture problems



20

Earth /oupling$ ndirect Earth

/oupling Buried supply air tubes

Inlet air di#erted through pipes that are buried )ir is cooled by the cooler ground3 pro#iding

some free cooling Pipes must be buried signi7cantly deep 6aintenance and moisture issues

Ground micro-climate change usinge#aporation

!ool the ground surrounding a building usinge#aporation Ground connected buildings "le#ated buildings



21

"nergyPlus 6odeling

!apabilities ;hermal Mass

;rombe 5all

Sunspaces

Movable-transparent insulation



22

Thermal 6ass$"nergy Storage

/ithin Buildings: Theory Storage energy (heat) within building elements

(e2terior or interior) for use or release at a latertime-date (analogy of a sponge or a rechargeablebattery)

+uilding materials store heat as !internal energy"

;hermal mass a function of material properties(specic heat and density) as well as volume ofmaterial→how much thermal mass is !enough">

Energy stored in a building material willeventually be release?either to the interior ore2terior depending on placement of mass,environmental conditions, etc1



23

Thermal 6ass: ".amples

;raditional E2amples ?ense building types /ith #ery

thic4 /alls Ice bloc4s from La4e 6ichigan

More Modern E2amples

Trombe %alls Interior %ater %alls or !ontainers Phase !hange 6aterials



24

Thermal 6ass: Seasonal",ects

/ooling Season ?ampen the e,ect of outside temperature #ariations Shift time of highest cooling loads to the night hours

&o>ces*

)bsorb e.cessi#e internal gains during daytimehours &usually combined /ith night #entilationstrategies*

.eating Season Store solar energy absorbed for use during the

nighttime hours /hen temperatures are lo/ and thesun is not #isible

)#oid potential o#erheating problems due toe.cessi#e direct solar gains

+ote: thermal mass e,ects /ill not sho/ up in a/inter design day run9must loo4 at an annualsimulation /ith actual /eather data



25

Thermal 6ass: ey Terms in"nergyPlus I?<

6aterial:Regular9speci7cationof speci7c heat and density

!onstruction9reference to amaterial layer de7nition

Surface9reference to a

construction de7nition



26

Trombe %alls: Theory

'rimarily a passive heating elementused to delay the impact of solarradiation

ntended to cooperate with direct gainthrough windows to provide heating viasolar radiation during all parts of the

day and nightMost useful on south, southeast, and

southwest facades



27

Trombe %alls: Systemcomponents

Thermally massi#e /all &bric43concrete3 stone3 /ater* painted adar4 color to absorb solar radiation

)ir gap

%all co#er &transparent glass* toallo/ sun light to get through to

the thermal mass and to bloc4some of the heat loss to the outsideen#ironment



28

=pen #s0 !losed Trombe

%alls=pen System

Similar to a mini-sunspace /here the airin the gap bet/een the co#er and the

/all mass is allo/ed to circulate to aninterior space 6ore important if no #isual lin4 to the

outside These ha#e fallen out of fa#or &in 8S* due

to di>culty in controlling the amount ofe.change bet/een the air gap and theattached space and due to the loss ofdelay factor &easier to combine /all /ith/indo/s*C also maintenance issues



29

=pen #s0 !losed Trombe

%alls!losed System

)ir gap bet/een the /all mass

and the co#er is sealed eat is trapped and absorbed

better into the thermal mass



30

Trombe %alls:

Performance Best for heating /hen /all mass has both

a high storage capacity and a highthermal conducti#ity

igh thermal conducti#ity increases heatgain$loss of o#erall /all assembly %all co#er should be as transparent as

possible but also resisti#e Solar must be 4ept out of the Trombe /all

in summer through use of: Shading de#ices Specialied transparent insulation materials "lectrochromic or thermochromic glaing



31

;rombe 5alls$ E2amples

;rombe walls are usually but notnecessarily restricted to simple =at southfacing walls (compare @ion ational 'ar7%isitorAs /enter to 4EB %isitorAs /enter)

'hotos courtesy of www1nrel1gov



32

Trombe %alls: ey Terms in"nergyPlus I?<

6aterial:%indo/Glass9speci7cation of /indo/properties

!onstruction9de7nition of /all and /indo/constructions

Surface9speci7cation of /all and co#er&separate* /ith /all de7ned as an interonepartition

Done9de7nition of Trombe %all air gap as aseparate thermal one !o#er is speci7ed as a /indo/ co#ering a 7ctitious

e.terior /all Trombe /all sho/s up in T%= ones &e'ual and

opposite interone partition* Done de7nition must include synta. to use special

Trombe /all coe>cients



33

Trombe %alls: ".ample ofTrombe /all synta. &Done*

ZONE, Lounge, !- Zone Name

0.0, !- Zone North Axis (relative to Building)

0.0, !- Zone Origin "m#

$.%, !- Zone & Origin "m#

0.0, !- Zone Z Origin "m# , !- Zone 'e

, !- Zone *ultilier

$.0, !- Zone +eiling eight "m#

0.0, !- Zone olume "m/#

'rome1all2 !- Zone 3nside +onve4tion Algorithm



34

Sunspaces and ?oubleS4inned Buildings

Sunspaces and double s7inned buildings canalso be modeled as separate zones +ote that in "nergyPlus solar radiation /ill

pass through one space and into another butthat once it gets to the second one it isassumed to be all di,use

Both sunspaces and double s4inned buildingspro#ide an e.tra bu,er from the outside

Sunspaces add potentially usable space <or systems /hich e.change heat through air

transport3 de7nition of a 6IEI+G or !R=SS6IEI+G statement re'uired &not #ery accurate*



35

6o#able Insulation:

Purpose&pply insulating layer to e2terior (or

interior) of building that can be scheduledfor various times of day or year

ntended to trap heat inside a building orbloc7 heat from coming into a buildingduring certain times

Many applications, but in reality, most ofthese are not feasible due to comple2ityof the systems



36

6o#able Insulation:

Processn Energy'lus, movable insulation

can be applied to the interior or

e2terior side of a surface (but notwindows)

5indow insulation must be

specied as window blindsE2terior insulation may be

transparent



37

6o#able Insulation:

Synta. Insulation type: must be 4ey/ord

Interior or ".terior Surface name: surface that insulation /ill

be applied to &lin4 to a surface de7nition/ithin the input 7le* 6aterial name: composition$description

of material layer that ma4es up theinsulation &lin4 to a material de7nition/ithin the input 7le*

Schedule: /hen the mo#able insulation isapplied &lin4 to a schedule de7nition/ithin the input 7le*



38

Movable nsulation$ E2ample

E2ample of :: format and :<$

*ovale3nsulation,

A, 56ield 3nsulation 'e ( Exterior or 3nterior )

A7, 56ield 8ur6a4e Name (heat trans6er sur6a4e to 9hi4h insulation alied)

A/, 56ield *aterial*ov3nsul- Name o6 the material used 6or movale insulation

A$2 56ield 84hed*ov3nsul-84hedule 6or movale insulation

*ovale3nsulation,

Exterior,

Zn00:1all00,

*ovale3nsulation*aterial,

ON2

*A'E;3AL:;E<=LA;-;,*ovale3nsulation*aterial,;ough,7.0,0.%,0.>,0.>2

6aterial layer can be transparent if e.teriorinsulation

Schedule controls if insulation is presentand acts as a multiplier on the R-#alue of the

material



39

Summary

/areful attention to climate and buildingheating and cooling needs as well as7nowledge of passive strategies can

help signicantly reduce the amount ofenergy consumed to condition a buildingEnergy'lus !green" building modeling

capabilities$

;hermal Mass ;rombe 5all Sunspaces Movable-;ransparent nsulation

Lecture 12 Green Building Features

Documents

Transcript of Lecture 12 Green Building Features