2005 Copyright – Reflective Insulation Manufacturers Association Reflective Insulation Manufacturers Association.

2005 Copyright – Reflective Insulation Manufacturers Association

Reflective Insulation Manufacturers Association

R-Values and R-Values and Thermal Thermal

Performance of Performance of Reflective Reflective

Insulation, Radiant Insulation, Radiant Barriers and IRCCsBarriers and IRCCs

OverviewOverviewAbout RIMA

Thermal Resistance/R-Values

Reflective Insulation Installation and Applications

ASHRAE 90.1 and Reflective Insulations

Comfort

About RIMAAbout RIMAThe Reflective Insulation ManufacturersAssociation represents manufacturers anddistributors of reflective insulation,radiant barriers and IRCC materials.

RIMA activities are guided by an activeboard of industry members whoparticipate on national and local levels ofbuilding code organizations andgovernmental agencies.

Visit us at www.rima.net.

Thermal Thermal Resistance Resistance

R-ValuesR-Values

R-ValuesR-Values1.1. Are used to compare thermal Are used to compare thermal

insulation productsinsulation products

2.2. Quantify resistance to heat flowQuantify resistance to heat flow

3.3. Are used to calculate heating Are used to calculate heating and cooling loadsand cooling loads

4.4. Can be measured for specific Can be measured for specific conditionsconditions

5.5. Can be determined from Can be determined from physical property or system physical property or system measurementsmeasurements

R-Values for Reflective Insulations R-Values for Reflective Insulations and Mass Insulations are and Mass Insulations are Determined by Different MethodsDetermined by Different MethodsStart with the 1-D steady-state form of Start with the 1-D steady-state form of Fourier’s Law -Fourier’s Law - Q=-kQ=-k··AA··dT/dXdT/dXWritten in practical form -Written in practical form - Q=kQ=k··AA··ΔΔTT/L/LRearranged -Rearranged - k=Qk=Q·L/A··L/A·ΔΔTT

andand R=L/kR=L/k ASTM C 518ASTM C 518Heat Flow MeterHeat Flow Meter

alsoalso R=AR=A··ΔΔT/Q= T/Q= ΔΔT/qT/q ASTM C 1363ASTM C 1363Hot Box FacilityHot Box Facility

In both cases the R has units FT^2·HR·˚F./BTUIn both cases the R has units FT^2·HR·˚F./BTU

The equation used for mass insulations scales linearly with The equation used for mass insulations scales linearly with thickness. thickness.

Reflective insulation has a complex thickness dependenceReflective insulation has a complex thickness dependence

Many Insulations Derive Many Insulations Derive Performance From The Low Performance From The Low Thermal Conductivity of AirThermal Conductivity of Air

Air-based insulationsAir-based insulations Non-Air Based Non-Air Based InsulationsInsulations

CelluloseCellulose Closed Cell Foam w/Closed Cell Foam w/

FiberglassFiberglass Blowing Agent Blowing Agent

Rock WoolRock Wool Evacuated PanelsEvacuated Panels

PerlitePerlite Gas-Filled PanelsGas-Filled Panels

Open-Cell FoamsOpen-Cell Foams Nano-Scale MaterialsNano-Scale Materials

Reflective InsulationReflective Insulation

Product Design Requires Product Design Requires Consideration Of All Modes of Consideration Of All Modes of Heat TransferHeat Transfer

ConductionConduction RadiationRadiationConvectionConvection

Mass InsulationsMass Insulations IncreaseIncrease ReductionReduction Usually Usually ZeroZero

Reflective Reflective SlightSlight Near ZeroNear ZeroIntermediateIntermediate

InsulationsInsulations IncreaseIncrease EffectEffect

Air-Based Insulations Have Air-Based Insulations Have LimitsLimits

The maximum R-Values occurs when radiation and The maximum R-Values occurs when radiation and convection are absent.convection are absent.

T (T (˚F)˚F) k of AIRk of AIR R per InchR per Inch

-25-25 0.1480.148 6.86.8

00 0.1550.155 6.56.5

2525 0.1630.163 6.16.1

5050 0.1700.170 5.95.9

7575 0.1780.178 5.65.6

100100 0.1850.185 5.45.4

125125 0.1930.193 5.25.2

These R/Inch limits apply to both mass and reflective These R/Inch limits apply to both mass and reflective insulations.insulations.

How Do Reflective Insulation How Do Reflective Insulation Systems Fit Into This Framework?Systems Fit Into This Framework?

• Take advantage of the low thermal conductivity of Take advantage of the low thermal conductivity of airair

• Use enclosed air spaces with low emittance Use enclosed air spaces with low emittance surfacessurfaces

• Have a mass insulation component in many casesHave a mass insulation component in many cases• Aluminum foils or films have emittances in the Aluminum foils or films have emittances in the

range 0.03 to 0.05range 0.03 to 0.05

Emittance is a measurement of how efficiently a surface gives Emittance is a measurement of how efficiently a surface gives off heat in the form of thermal radiation.off heat in the form of thermal radiation.

Reflectance is the fraction of incoming radiation that is not Reflectance is the fraction of incoming radiation that is not absorbed by a surfaceabsorbed by a surface

In the case of opaque materials: reflectance+emittance=oneIn the case of opaque materials: reflectance+emittance=one

Radiation is a Major Heat Radiation is a Major Heat Transport Mode In Many CasesTransport Mode In Many Cases

An Example (no convection)An Example (no convection)One inch gap filled with airOne inch gap filled with air

Surface one at 50 Surface one at 50 ˚F˚F

Surface two at 100 ˚FSurface two at 100 ˚F

Effective emittance for the two surfaces E=1/(1/E1 + 1/E2 -1)Effective emittance for the two surfaces E=1/(1/E1 + 1/E2 -1)

q-conductionq-conduction 8.98.9 BTU/FT^2·HRBTU/FT^2·HR

q-radiationq-radiation 52.58E52.58E

q-Totalq-Total 8.9+52.58 E8.9+52.58 E

E=0.77E=0.77 q-Total = 49.39q-Total = 49.39 q-RAD is 82% of Totalq-RAD is 82% of Total

Three and one-half inch air gap – same conditionsThree and one-half inch air gap – same conditions

q-Totalq-Total 2.54 + 52.58 E2.54 + 52.58 E

E=0.77E=0.77 q-Total = 43.23q-Total = 43.23 q-RAD is 94% of Totalq-RAD is 94% of Total

Another Look at The One-Inch Another Look at The One-Inch Gap Without ConvectionGap Without Convection

q-Total = 8.9 + 52.58 Eq-Total = 8.9 + 52.58 E

EE qq ΔΔTT RR

00 8.908.90 5050 5.65.6

11 61.4861.48 5050 0.80.8

0.030.03 10.4810.48 5050 4.84.8

Convection is Important in Open Convection is Important in Open SpacesSpaces

Horizontal heat flow across a one-inch gapHorizontal heat flow across a one-inch gap

T-hot 100T-hot 100˚F˚F T-cold 50˚F T-cold 50˚F

EE q-radq-rad q-condq-cond q-convq-conv q-Totalq-Total

00 00 8.98.9 10.710.7 19.619.6

0.030.03 1.581.58 8.98.9 10.710.7 21.1821.18

0.050.05 2.632.63 8.98.9 10.710.7 22.2322.23

0.10.1 5.265.26 8.98.9 10.710.7 24.8624.86

0.50.5 26.2926.29 8.98.9 10.710.7 45.8945.89

0.770.77 40.4940.49 8.98.9 10.710.7 60.0960.09

11 52.5852.58 8.98.9 10.710.7 72.1872.18

Increase The Air Gap to Two Increase The Air Gap to Two InchesInches

Horizontal heat flowHorizontal heat flow

T-hot 100˚FT-hot 100˚F T-cold 50˚F T-cold 50˚F

EE q-radq-rad q-condq-cond q-convq-conv q-Totalq-Total

00 00 4.454.45 16.316.3 20.720.7

0.030.03 1.581.58 4.454.45 16.316.3 22.322.3

0.050.05 2.632.63 4.454.45 16.316.3 23.323.3

0.10.1 5.265.26 4.454.45 16.316.3 2626

0.50.5 26.2926.29 4.454.45 16.316.3 4747

0.770.77 40.4940.49 4.454.45 16.316.3 61.261.2

11 52.5852.58 4.454.45 16.316.3 73.373.3

(Same)(Same) (Less)(Less) (More)(More)

Sub-Divide The Air Space to Get Sub-Divide The Air Space to Get High R-ValuesHigh R-Values

T-meanT-mean ΔΔTT T-hotT-hot T-coldT-cold

49.8˚F49.8˚F 50.2 ˚F50.2 ˚F 74.9 ˚F74.9 ˚F 24.7 ˚F24.7 ˚F

Air spaceAir space 3.5 inches 3.5 inches

Heat-flow down Heat-flow down E=0.051E=0.051

Measured R Measured R 7.537.53

Calculated R Calculated R 7.587.58

With two air spaces of 1.75 inches eachWith two air spaces of 1.75 inches each

Space one Space one 6.446.44

Space two Space two 6.066.06

R Total R Total 12.512.5

Exterior air film resistance adds about 4.5 to obtain R 17Exterior air film resistance adds about 4.5 to obtain R 17

Material R-Value if any would be addedMaterial R-Value if any would be added

SummarySummary R-Values for reflective insulation and R-Values for reflective insulation and

mass insulation are based on the mass insulation are based on the same fundamental equations.same fundamental equations.

Both insulation types affect the three Both insulation types affect the three modes of heat transfer.modes of heat transfer.

R-Values for reflective insulation are R-Values for reflective insulation are the result of reduced radiative the result of reduced radiative transport.transport.

Reflective insulation products with R-Reflective insulation products with R-Values of practical significance are Values of practical significance are available.available.

Reflective Reflective Insulation Insulation

Installation and Installation and ApplicationsApplications

InstallationInstallationTypical Methods:

1. New Construction with screw down roofs and side walls

2. New Construction with Thermal Spacer Blocks

3. Bottom of Purlins – new and retrofit

4. Installation with Mass Insulation

5. Vapor Retarders

Typical New Construction: Typical New Construction: Reflective Insulation Installed Reflective Insulation Installed Over Purlins and GirtsOver Purlins and Girts

Cross Sectional View for New Cross Sectional View for New Construction:Construction:Reflective Insulation Installed Over Purlins and Reflective Insulation Installed Over Purlins and GirtsGirts

Cross Sectional View for New Cross Sectional View for New Construction:Construction:Reflective Insulation Installed Over Purlins and Reflective Insulation Installed Over Purlins and Girts with Thermal Spacer BlocksGirts with Thermal Spacer Blocks

Installed on the Bottom of the Installed on the Bottom of the Purlins and Inside of GirtsPurlins and Inside of Girts

Combined with Mass Combined with Mass InsulationInsulation

Mass Insulation

Walls

Roof / Ceiling

Reflective Insulation

Vapor RetardersVapor Retarders• Reflective

Insulation can function as a vapor retarder

• Two methods to seal the seams.

(1) Tape Tab

Tabs from Two Rolls of Insulation Attached Together(2) Staple

Tab

IRCCsIRCCsLO/MIT-I being applied to underside of galvanized roof in chicken house at University of Georgia, Athens, Georgia. LO/MIT-I is an excellent metal building insulation because it lowers interior radiant temperature, in this case, lessening heat loads and death rates during extreme summer heat.

ASHRAE 90.1 ASHRAE 90.1

and and

Reflective Reflective InsulationsInsulations

How we can help you meet increasing How we can help you meet increasing energy demands!energy demands!

What is ASHRAE 90.1?What is ASHRAE 90.1?

1.1. ““The Purpose of this standard is to The Purpose of this standard is to provide requirements for energy provide requirements for energy efficient design of buildings except low-efficient design of buildings except low-rise residential buildings”rise residential buildings”

2.2. Takes into account your “U” value, not Takes into account your “U” value, not just “R” value-the entire building just “R” value-the entire building envelopeenvelope

3.3. Accepted standard across the countryAccepted standard across the country—code enforcement—code enforcement

4.4. California – Title 24California – Title 24

When does it Apply?When does it Apply?

• New buildings, new portions of New buildings, new portions of buildings, or new equipment in buildings, or new equipment in existing buildingsexisting buildings

• Buildings heated >= 3.4 BTU/h-ft²Buildings heated >= 3.4 BTU/h-ft²

• Buildings cooled >=5 BTU/h-ft²Buildings cooled >=5 BTU/h-ft²

• HVAC units, lighting, water HVAC units, lighting, water heaters, belt drives, electric heaters, belt drives, electric motors…motors…

• Residential dwellingsResidential dwellings• Buildings that do not use energy or Buildings that do not use energy or

other fossil fuelsother fossil fuels• Buildings used primarily for Buildings used primarily for

industrial, manufacturing, or industrial, manufacturing, or commercial processescommercial processes

Note:Note: These buildings still apply These buildings still apply

depending on heating/coolingdepending on heating/cooling

When does it Not Apply?When does it Not Apply?

Reflective Insulations and Reflective Insulations and ASHRAE 90.1 BenefitsASHRAE 90.1 Benefits

• Achieves high R-value in small Achieves high R-value in small amount of spaceamount of space

• Easy installation-no extra stepsEasy installation-no extra steps• Some reflective insulations can Some reflective insulations can

replace thermal blocksreplace thermal blocks• Added efficiency via low E-valuesAdded efficiency via low E-values

Technical NotesTechnical Notes• The following information is based on the The following information is based on the

NAIMA interpretation of ASHRAE 90.1. The NAIMA interpretation of ASHRAE 90.1. The HDD(heating degree days) and CDD(cooling HDD(heating degree days) and CDD(cooling degree days) are categorized into 8 average degree days) are categorized into 8 average climatic zonesclimatic zones

• The ICC Codes, which most major cities have The ICC Codes, which most major cities have adopted, have much higher R-value adopted, have much higher R-value requirementsrequirements

• To show an overall average we will To show an overall average we will demonstrate 4 zone U-value requirementsdemonstrate 4 zone U-value requirements

• All installed R-values on 3”, 4” and 6” All installed R-values on 3”, 4” and 6” fiberglass are from the NAIMA published fiberglass are from the NAIMA published document, “ASHRAE 90.1 compliance for document, “ASHRAE 90.1 compliance for metal buildings”, pub. # MB304 12/97metal buildings”, pub. # MB304 12/97

Technical Notes Technical Notes (continued)(continued)

• NAIMA-North American Insulation NAIMA-North American Insulation Manufacturers Association and consists Manufacturers Association and consists solely of fiberglass, rock and slag wool solely of fiberglass, rock and slag wool manufacturersmanufacturers

• R-Value numbers in yellow pass and red failR-Value numbers in yellow pass and red fail

• SDR-Screw down roofSDR-Screw down roof

• SSR-Standing seam roofSSR-Standing seam roof

• * 5’ purlin spacing, 24” O.C. clip spacing, * 5’ purlin spacing, 24” O.C. clip spacing, 1”x3” foam block on purlins1”x3” foam block on purlins

• ** This information is from the ASHRAE ** This information is from the ASHRAE 90.1, ENVSTD 4.0, not from NAIMA90.1, ENVSTD 4.0, not from NAIMA

All R-values are installed R-All R-values are installed R-valuesvalues

Building 1: Houston, TX-U-value .070/R-value Building 1: Houston, TX-U-value .070/R-value 14.3814.38

• * FiberGlass over purlins, 6” fastener spacing, SDR: * FiberGlass over purlins, 6” fastener spacing, SDR: 3” 3” R-6.25R-6.25; 6” ; 6” R-9.43R-9.43

• * FiberGlass over purlins, 6” fastener spacing, SDR * FiberGlass over purlins, 6” fastener spacing, SDR with foam blocks: 3” with foam blocks: 3” R-9.09R-9.09; 6” ; 6” R-12.98R-12.98

• * FiberGlass over purlins, 6” fastener spacing, SSR * FiberGlass over purlins, 6” fastener spacing, SSR with foam blocks: 3” with foam blocks: 3” R-10.30R-10.30; 6” ; 6” R-15.38R-15.38

• ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: 3” 3” R-6.53 R-6.53; 6” ; 6” R-15.38R-15.38

• ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity and ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity and reflective insulation as sheathing: reflective insulation as sheathing:

3”+R.I. 3”+R.I. R-21.73R-21.73(SSR); 3”+R.I. (SSR); 3”+R.I. R-17.85R-17.85(SDR)(SDR)

All R-values are installed R-All R-values are installed R-valuesvalues

Building 2: Kansas, MO U-.055/R-value 18.18Building 2: Kansas, MO U-.055/R-value 18.18

• * FiberGlass over purlins 6” fastener spacing SDR: * FiberGlass over purlins 6” fastener spacing SDR: 3” 3” R-6.25R-6.25;; 6” 6” R-9.43R-9.43

• * FiberGlass over purlins 6” fastener spacing SDR with * FiberGlass over purlins 6” fastener spacing SDR with foam blocks: 3” foam blocks: 3” R-9.09R-9.09; 6” ; 6” R-12.98R-12.98

• * FiberGlass over purlins 6” fastener spacing SSR with * FiberGlass over purlins 6” fastener spacing SSR with foam blocks: 3” foam blocks: 3” R-10.30R-10.30; 6” ; 6” R-15.38R-15.38

• ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: 3” 3” R-6.53 R-6.53; 6” ; 6” R-15.38R-15.38

• ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity and ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity and reflective insulation as sheathing: reflective insulation as sheathing:

3”+R.I 3”+R.I R-21.73R-21.73(SSR); 4”+R.I. (SSR); 4”+R.I. R-18.51R-18.51(SDR)(SDR)

All R-values are installed R-All R-values are installed R-valuesvaluesBuilding 3: Big Falls, MN U-.040/R-value 25Building 3: Big Falls, MN U-.040/R-value 25

• * FiberGlass over purlins 6” fastener spacing SDR: * FiberGlass over purlins 6” fastener spacing SDR: 3” 3” R-6.25R-6.25; 6” ; 6” R-9.43R-9.43

• * FiberGlass over purlins 6” fastener spacing SDR with * FiberGlass over purlins 6” fastener spacing SDR with foam blocks: 3” foam blocks: 3” R-9.09R-9.09; 6” ; 6” R-12.98R-12.98

• * FiberGlass over purlins 6” fastener spacing SSR with * FiberGlass over purlins 6” fastener spacing SSR with foam blocks: 3” foam blocks: 3” R-10.30R-10.30;; 6” 6” R-15.38R-15.38

• * FiberGlass 3” over purlins and 6”in cavity with 6” * FiberGlass 3” over purlins and 6”in cavity with 6” fastener spacing: fastener spacing: 3”+6”3”+6” R-19.23 R-19.23

• ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: 3” 3” R-6.53 R-6.53; 6” ; 6” R-15.38R-15.38

• ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity and ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity and reflective insulation as sheathing: reflective insulation as sheathing:

6”+R.I. 6”+R.I. R-26.31R-26.31(SSR); SDR not an option(SSR); SDR not an option

All R-values are installed R-All R-values are installed R-valuesvaluesBuilding 4: Anywhere required R-30Building 4: Anywhere required R-30

• * FiberGlass over purlins 6” fastener spacing SDR: * FiberGlass over purlins 6” fastener spacing SDR: 3” 3” R-6.25R-6.25; 6” ; 6” R-9.43R-9.43

• * FiberGlass over purlins 6” fastener spacing SDR with * FiberGlass over purlins 6” fastener spacing SDR with foam blocks: 3” foam blocks: 3” R-9.09R-9.09; 6” ; 6” R-12.98R-12.98

• * FiberGlass over purlins 6” fastener spacing SSR with * FiberGlass over purlins 6” fastener spacing SSR with foam blocks: 3” foam blocks: 3” R-10.30R-10.30; 6” ; 6” R-15.38R-15.38

• * FiberGlass 3” over purlins and 6”in cavity with 6” * FiberGlass 3” over purlins and 6”in cavity with 6” fastener spacing: 3”+6” fastener spacing: 3”+6” R-19.23R-19.23

• ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: ** ASHRAE 90.1, ENVSTD 4.0, FiberGlass in cavity: 3” 3” R-6.53R-6.53; 6” ; 6” R-15.38R-15.38

• ** ASHRAE 90.1, ENVSTD 4.0, 6”+3” FiberGlass in ** ASHRAE 90.1, ENVSTD 4.0, 6”+3” FiberGlass in cavity and reflective insulation as sheathing: cavity and reflective insulation as sheathing: 6”+3”+R.I. 6”+3”+R.I. R-30.30R-30.30 (SSR); SDR not an option(SSR); SDR not an option

ComfortComfort

Relating to ComfortRelating to Comfort

• Thermal Comfort is highly subjective Thermal Comfort is highly subjective but can be primarily related to:but can be primarily related to:

Air temperature – dry bulb Air temperature – dry bulb temperaturetemperature

Humidity – amount of moisture in Humidity – amount of moisture in the airthe air

Air velocityAir velocity Mean Radiant TemperatureMean Radiant Temperature

Air Temperature – Dry Air Temperature – Dry Bulb TemperatureBulb TemperatureDry bulb temperature Dry bulb temperature refers to the ambient air refers to the ambient air temperature. temperature.

It is called dry bulb It is called dry bulb because it is measured because it is measured with a standard with a standard thermometer whose bulb thermometer whose bulb is not wet. is not wet.

In weather data terms, In weather data terms, dry bulb temperature dry bulb temperature refers to the air refers to the air temperature. It is usually temperature. It is usually given in degrees Celsius given in degrees Celsius (°C) or degrees (°C) or degrees Farenheight (°F).Farenheight (°F).

Humidity – Amount of Humidity – Amount of Moisture in The AirMoisture in The Air

Humidity refers to the amount of moisture Humidity refers to the amount of moisture vapor in a specific volume of warm air.vapor in a specific volume of warm air.

The saturation point or dew point refers to the The saturation point or dew point refers to the maximum amount of moisture that the air can maximum amount of moisture that the air can hold at a given temperature.hold at a given temperature.

Relative Humidity, is therefore the ratio Relative Humidity, is therefore the ratio between the absolute humidity of the air in its between the absolute humidity of the air in its current state compared to this maximum current state compared to this maximum amount, expressed as a percentage.amount, expressed as a percentage.

Relative Humidity is important for human Relative Humidity is important for human comfort mostly for its effect on the evaporation comfort mostly for its effect on the evaporation of sweat.of sweat.

MeanMean Radiant Radiant TemperatureTemperature

• Black Globe Black Globe TemperatureTemperature

• This temperature This temperature refers to the refers to the temperature as felt by temperature as felt by a black globe or body a black globe or body and includes the effect and includes the effect of radiant energyof radiant energy

• We act like black We act like black bodies or black globes, bodies or black globes, absorbing more than absorbing more than 95% of the Radiant 95% of the Radiant Energy Energy

The Comfort IndexThe Comfort Index• Comfort prediction is the relationship Comfort prediction is the relationship

between climatic factors and the between climatic factors and the resulting comfort sensationresulting comfort sensation

• Comfort Index is the numerical measure Comfort Index is the numerical measure of a number of individuals that are of a number of individuals that are comfortable in a given environmentcomfortable in a given environment

• Humans are often not the most logical or Humans are often not the most logical or reliable test subjectsreliable test subjects

• Most models therefore depend on a Most models therefore depend on a survey of a large number of people in the survey of a large number of people in the same conditions same conditions

The Comfort IndexThe Comfort Index

• An ASHRAE exampleAn ASHRAE example• If at a comfortable air temperatureIf at a comfortable air temperature

The ceiling temperature is 40The ceiling temperature is 40° F above the air ° F above the air temperature then 60% of the people below the temperature then 60% of the people below the ceiling will be uncomfortable.ceiling will be uncomfortable.

If the ceiling temperature is dropped to 10° F If the ceiling temperature is dropped to 10° F above air temperature then only 5% of the above air temperature then only 5% of the people are dissatisfied or uncomfortable.people are dissatisfied or uncomfortable.

In the above examples the air temperature has In the above examples the air temperature has not changed, but the Mean Radiant not changed, but the Mean Radiant Temperature has.Temperature has.

Examples of Radiant Examples of Radiant TransferTransfer

• In a warm climate, the outside walls In a warm climate, the outside walls are warm and therefore are emitting are warm and therefore are emitting Radiant Energy.Radiant Energy.

• The opposite is true in cold climates.The opposite is true in cold climates.

• Since inside the room we act like Since inside the room we act like black globes – we absorb the radiant black globes – we absorb the radiant energy –raising our skin surface energy –raising our skin surface temperature without changing the temperature without changing the air temperatureair temperature

Changing The Emittance Changing The Emittance of The Wallsof The Walls

• If we now change the wall surface If we now change the wall surface from high emittance to low from high emittance to low emittance this radiant energy emittance this radiant energy from the walls disappearsfrom the walls disappears

The effect is we feel coolerThe effect is we feel cooler

There has been no change to the r-There has been no change to the r-value in the wallsvalue in the walls

We feel more comfortableWe feel more comfortable

Black Globe EffectBlack Globe Effect

• In Chicken houses it has been In Chicken houses it has been proven that by controlling the Mean proven that by controlling the Mean Radiant Temperature ( Black Globe Radiant Temperature ( Black Globe Effect)Effect)

The chickens are more comfortableThe chickens are more comfortable

They eat betterThey eat better

Become more efficientBecome more efficient

SummarySummary The emmissivity of the walls and The emmissivity of the walls and

ceiling on the interior of a building ceiling on the interior of a building dramatically effect the Mean dramatically effect the Mean Radiant Temperature and therefore Radiant Temperature and therefore the comfort indexthe comfort index

By changing the MRT it is possible By changing the MRT it is possible to save significant energy without to save significant energy without changing the comfort levelchanging the comfort level

In this case changing the In this case changing the emmissivity of the surface and emmissivity of the surface and saving energy does not change the saving energy does not change the r-valuer-value

In ClosingIn Closing• The physics behind the R-Values for The physics behind the R-Values for

reflective insulation systems was reflective insulation systems was reviewed in the opening segment of this reviewed in the opening segment of this program with examples of the modes of program with examples of the modes of heat transfer present in the building heat transfer present in the building envelope and some numerical examples.envelope and some numerical examples.

• Reflective insulations are an integral Reflective insulations are an integral part of the huge field of building part of the huge field of building insulation. The basis for evaluating insulation. The basis for evaluating these systems has been well these systems has been well established in recent years.established in recent years.

• Some common installation methods for Some common installation methods for various Radiant Barriers and Reflective various Radiant Barriers and Reflective Insulations have been discussedInsulations have been discussed

• We talked about ASHRAE 90.1 and how We talked about ASHRAE 90.1 and how reflective insulation and mass insulation reflective insulation and mass insulation combined can help meet these combined can help meet these increasing energy code requirements.increasing energy code requirements.

• And finally we showed you the added And finally we showed you the added benefit of controlling the MRT in a benefit of controlling the MRT in a building that is not related to R-values.building that is not related to R-values.

In ClosingIn Closing

Reflective Insulation Reflective Insulation Manufactuers Manufactuers AssociationAssociation

800/279-4123800/279-4123www.rima.netwww.rima.net