2a.heat Transfer GBI MS1525 2007

MS1525:2007Clause 5 : BUILDING ENVELOPE

GBI CPD SEMINARGBI CPD SEMINAR

GREENBUILDINGINDEX SDN BHD | www.greenbuildingindex.org

25 July 2009 Penang

Ar Von Kok LeongB. Arch (Auckland), P.Arch, APAM, AIPDM

GREEN BUILDING INDEXGREEN BUILDING INDEX

BUILDING ENVELOPE

the external portions of a building through which thermal energy is transferred


which thermal energy is transferred and this thermal transfer is the major factor affecting interior comfort level and energy usage.

MS1525:2007


ENERGY USAGE IN BUILDINGS



ENERGY USAGE IN BUILDINGS

Wasteful use of energy is affecting our planet and our environment. If we design, build


environment. If we design, build and manage our buildings so the need for energy is reduced, only then our effort will make a real difference.

Reuse, Reduce, Recycle

1. MS1525:2007 is a Code of Practice (CP), andis intended to be incorporated into UBBL,hence a CP becomes part of a By-law.

a) Applies tonon-residential,

MS1525:2007 KEY ISSUESMS1525:2007 KEY ISSUES


non-residential,air-conditioned buildings,> 4,000 sq m.

b) Architects and Engineers must submitOTTV & RTTV calculations.

c) Requirement for Energy ManagementControl system is under Clause 9.

2. MS1525:2007 provides the baseline minimumstandard for the GBI rating tools for energyefficient design.

a) If design falls below the requirementsof MS1525:2007, it is unlikely to be

MS1525:2007 KEY ISSUESMS1525:2007 KEY ISSUES


of MS1525:2007, it is unlikely to berated.

b) Reward for designs that arebetter than the baseline minimumrequirements of MS1525:2007.

c) GBI (Residential) adopts same methodsof measurement found in MS1525:2007.

5.1 General Requirement5.2 Concept Of OTTV5.3 Shading Coefficient

BUILDING ENVELOPEBUILDING ENVELOPE

MS1525:2007 Clause 5


5.3 Shading Coefficient5.4 Daylighting5.5 Roofs5.6 Roofs With Skylights, RTTV5.7 Daylight Credit5.8 Submission Procedure5.9 Air Leakage

Fundamentally, the building envelope has toblock out heat gain into buildings via conduction

MS1525:2007 Clause 5.1 says



block out heat gain into buildings via conductionand radiation.

In other words, the building envelope shallprovide resistance to heat gain.

THERMAL RESISTANCETHERMAL RESISTANCE


Heat energy flows from a hot object to a cooler object. Whenever there is a temperature gradient, heat transferwill always occur. It can never be stopped, and it can only be slowed.

1. In heat transfer, the Thermal Conductivity, k of a material is its ability to conduct heat.

2. Generally, thermal conductivity approx tracks

Relationships between thermal resistance, thermal conductivity and U-value



2. Generally, thermal conductivity approx tracks electrical conductivity, as moving electrons transfer not only electric current, but also heat energy.

3. Therefore, heat conductivity through layers of materials in a composite wall construction is analogous to adding up the resistance in an electric circuit connected in series.

4. Thermal Resistance, R of each material isR = (material thickness) (thermal conductivity, k)

5. Increasing the thickness of the material will




5. Increasing the thickness of the material will increase its thermal resistance.

6. In a composite wall construction, the total R isRtotal = R1 + R2 + R3 +...+ Rn.

7. Therefore, Rtotal is the sum of the thermal resistance of all the respective materials making up the composite wall.

8. U-value of the wall is the heat transmission value of the composite wall in W/m2K, and is inversely proportional to the total R,




proportional to the total R, ie,

U = 1 / Rtotal.9. The higher the R, the lower the U, the better.

Material k (in W/mK)Mineral wool insulation 0.039Mineral fibreboard 0.053

Examples of thermal conductivity, k



Mineral fibreboard 0.053Plasterboard 0.160Common clay brick 0.950Glass 3mm thick 1.050Concrete 2.160

The roof plane receives the most Solar Radiationand for the longest period through the day

Roof thermal resistance is one of the most important design decisions for energy efficient designs



>75% of the Solar Gain by a typical Intermediatesingle storey terraced house is through its Roof>50% of the Solar Gain by a typical Intermediatedouble storey terraced house is through its Roof>40% of the Solar Gain by a typical 5 storey block offlats is through its Roof


Roof Thermal Resistance and SRI


1. SRI is a measure of a roofing materialsability to reflect solar heat, and hence, reduceheat absorption;

Solar Reflectance Index (SRI)



heat absorption;2. Standard black is 0, standard white is 1;3. Materials with the highest SRI values are

the best (and coolest!) choices for roofing.

The albedo of an object or a surface is the extent to which it reflects light from the Sun.Generally, a light coloured surface has a higher albedo. It is shown as SRI, and ranges from 0 to 1.

Albedo and SRI



albedo. It is shown as SRI, and ranges from 0 to 1.

Eg Material SRIBlack acrylic paint 0.05Bare soil 0.17New asphalt 0.40New concrete 0.40 - 0.50Concrete w Portland cement 0.70 - 0.80White acrylic paint 0.80

5.1 General Requirement5.2 Concept Of OTTV5.3 Shading Coefficient


MS1525:2007 Clause 5


5.3 Shading Coefficient5.4 Daylighting5.5 Roofs5.6 Roofs With Skylights, RTTV5.7 Daylight Credit5.8 Submission Procedure5.9 Air Leakage

MS1525:2007 Clause 5.2OTTV applies to building envelope

MS1525:2007 Clause 5.5

OTTV, Roof U-value and RTTVOTTV, Roof U-value and RTTV


MS1525:2007 Clause 5.5Roof U-value refers to the thermal transmittance of the roof construction

MS1525:2007 Clause 5.6RTTV applies to roof with skylights

A design criterion for building envelope known asthe Overall Thermal Transfer Value (OTTV) has been


CONCEPT OF OTTVCONCEPT OF OTTV


the Overall Thermal Transfer Value (OTTV) has beenadopted. The OTTV aims at achieving the design ofbuilding envelope to cut down external heat gainand hence reduce the cooling load of the air-conditioning system.

The OTTVshould not exceed 50 W / m2

OTTV x A ......OTTV x AOTTV x A ++

The OTTV of building envelope is given by the formula:

OTTV FORMULAOTTV FORMULA

MS1525:2007 Clause 5.2.1 says


n21

nn2211

ooo

ooo

A ......AA

OTTV x A ......OTTV x AOTTV x AOTTV

++

++=

where A1 is the gross exterior wall area for orientation 1; OTTV1 is the OTTV value for orientation 1; andOTTV for the whole building < 50 W/m2

The formula for the OTTV of any given wall orientation is as follows:

SC) x WWR x CF x(194 U(WWR)6UWWR)(115OTTVi fw ++=


MS1525:2007 Clause 5.2.2 says





MS1525:2007 Clause 5.2.2 saysThe formula for the OTTV of any given wall orientation is as follows:



+ +OTTV =






+ +

HeatConductionthroughWalls

OTTV =






+

HeatConductionthroughWindows

+


OTTV =






+


+

Solar HeatGainthroughWindows


OTTV =






+


+



OTTV =

0.2% to 5% 10% to 20% 70% to 85%

15(1-WWR)Uw + 6(WWR)Uf + 194xCFxWWRxSC

HEAT CONDUCTION THROUGH WALLSHEAT CONDUCTION THROUGH WALLS


HeatConductionthrough Walls



+ + < 50W/m2

0.2% to 5%

15 (1-WWR) Uw15 x x Wall area ratio x U-value of Wall

MS1525:2007 Clause 5.2.2



15 x x Wall area ratio x U-value of Wall

where = Solar Absorption = Colour of walls

0.4-0.8Red Roof Tiles

0.09Aluminium Oxide Paint0.15-0.30White Paint

0.90-0.99Black Paint

Plastered Brickwall




Aluminium Composite Cladding without insulation



Aluminium Composite Cladding with insulation





+ +

HEAT CONDUCTION THROUGH WINDOWSHEAT CONDUCTION THROUGH WINDOWS

< 50W/m2


Walls Windows Windows

10% to 20%

15(1-WWR)Uw 6(WWR)Uf 194xCFxWWRxSC+ +

6 (WWR) Uf6 x Window to Wall ratio x U-value of Window


MS1525:2007 Clause 5.2.2


6 x Window to Wall ratio x U-value of Window

Glazing type U-values

Single glazed clear 5.7 to 6.2

Laminated clear / PVB / clear 4.5 to 5.5

Double glazed clear / air / clear 2.6 to 2.9




< 50W/m2+ +

SOLAR HEAT GAIN THROUGH WINDOWSSOLAR HEAT GAIN THROUGH WINDOWS


Walls Windows Windows

70% to 85%

15(1-WWR)Uw 6(WWR)Uf 194xCFxWWRxSC+ +

194 x CF x WWR x SC

194 x Correction Factor (Table 4) x Window to Wall


MS1525:2007 Clause 5.2.2


194 x Correction Factor (Table 4) x Window to Wall ratio x Shading Coefficient (Tables 5,6 & 7)

Table 4 specifies the CF for the various orientation of the fenestration. It is based on weather data for KL.

Data shows East solar radiation is higher than West.


INFRARED : not visible; wavelength greater than 750

Solar radiation and glazing - key issues


greater than 750 nanometers

Long Wave EnergyULTRAVIOLET : not visible; wavelength less than 390 nanometers

Short Wave Energy

VISIBLE : visible to the human eye; wavelength between 390 and 750 nanometers.


Solar radiation and glazing - key issuesSOLAR RADIATION :

1. Reflected2. Transmitted


transmittedreflected

absorbed

INSIDEOUTSIDE

2. Transmitted3. Absorbed


1.Glass Shading Coefficient (SC)is the amount of solar energy that passes through the glass, relative to a 3mm clear glass tested



the glass, relative to a 3mm clear glass tested under similar conditions. A low value means less heat passes through the glass.

Eg, a glazing with a SC of 0.45 would allow only 45% as much solar energy to pass through as would a 3mm clear glass.


2.Visible Light Transmittance (VLT)is the fraction of visible light at a specified wavelength that passes through the glass. Usually



wavelength that passes through the glass. Usually quoted between 0 and 1, a high value means more light passes through the glass.

Eg, a glazing with a VLT of 0.70 would allow 70% of visible light to pass through.


3. Insulated Glazing Units (IGU)are multiple glass panes assembled into units to insulate against heat and sound. Most IGUs are



insulate against heat and sound. Most IGUs are double glazed (DGUs), but some IGUs have three sheets or more. IGUs are becoming more common due to higher energy costs.


Heat insulation of the IGUs can be further improvedthrough the use of:



1. Tinted glass

2. Coated glass

3. Low-Emissivity glass (Low-E)

- reflects away long-wave infrared radiation

- hard coat or soft coat


Low-Emissivity glass (Low-E)

Hard Coat

- liquid tin applied on-line at high temp (pyrolytic)



- liquid tin applied on-line at high temp (pyrolytic)

- coating fuses to the glass

Soft coat

- silver vapour deposited/applied off-line, in

vacuum

- does not fuse to the glass, very thin and delicate

- fragile, requires protection, surface 2

- better performance than hard coat


Solar radiation and glazing - key issuesair gap

1 2 3 4


Low-E coating reflects long-waveinfrared radiation

INSIDEOUTSIDELow-Ecoating

Glazing type U-values






Single glazed clear with Low-E 4.0 to 4.4

Laminated clear / PVB / clear 4.5 to 5.5

Laminated clear w Low-E / PVB / clear 4.2 to 5.3

Double glazed clear / air / clear 2.6 to 2.9

Double glazed clear w Low-E / air / clear 1.2 to 1.8

SHADING COEFFICIENTSHADING COEFFICIENT

MS1525:2007 Clause 5.3.1SC - major contributor to reduce OTTV .

SC can be in the form of horizontal and/or vertical


SC = SC1 x SC2SC1 is shading coeff of glazingSC2 is shading coeff of external shading device

shading devices that helps to reduce solar heat gain through the windows.

SunshadesSHADING COEFFICIENTSHADING COEFFICIENT


External Shading Devices are more effective than Internal Blinds.

External Shading Devices block out Direct Sunlight.



X =


Sunshades


y

=

SHADING COEFFICIENT - R1SHADING COEFFICIENT - R1

MS1525:2007 Table 5


If R1 falls between increments, adopt the next larger ratio.


MS1525:2007 Table 6


If R2 falls between increments, adopt the next larger ratio.


MS1525:2007 Table 7


SAMPLE BUILDING

OTTV CALCULATIONSOTTV CALCULATIONS


MENARA UAC

MENARA UAC



MENARA UACHEAT CONDUCTION THROUGH WALLS






+ + < 50W/m2

0.2% to 5%


MENARA UACHeat Conduction through Walls



MENARA UACHEAT CONDUCTION THROUGH WINDOWS






+ + < 50W/m2

10% to 20%


MENARA UACHeat Conduction through Windows



MENARA UACHEAT CONDUCTION THROUGH WALLS






+ + < 50W/m2

70% to 85%


MENARA UACSolar Heat Gain through Windows



MENARA UAC






+ + < 50W/m2

70% to 85%10% to 20%0.2% to 5%

OTTVOTTV

NNENW

For circular or symmetrical floor plates, divide into 8 zones


S

EW

NENW

SW SE

OTTVOTTV


OTTVOTTV

38m glazing, 10m solid wallNorth

Westaircond16m/18m

Total perimeter= 48+48+34+34= 164m


South

East

48m overall

34m 14m/20m

aircond

48m/0m

1. Identify which component contributes themost to OTTV.

2. Review Solar Correction Factor (CF) in Table 4.

WAYS TO IMPROVE OTTV

OTTVOTTV


2. Review Solar Correction Factor (CF) in Table 4.3. Review glass selection and its Shading

Coefficient (SC).4. Review sunshades and its Shading Coefficient

(SC) in Tables 5, 6 and 7.5. Review WWR.

The calculation of OTTV does not include theroof plane, but the thermal transmittance (Roof


ROOF U-valueROOF U-value


roof plane, but the thermal transmittance (RoofU-value) of the roof construction is important.

U-value OF ROOFSU-values are worked out from the Thermal Resistance of the respective materials making up the Roof.



U-value is the heat transmission value of the composite roof in W/m2K, and is inversely proportional to R,

ie, U = 1 / Rtotal

The higher the R, the lower the U, the better.

MS1525:2007 Clause 5.5.1Table 9. Maximum U-value for roof (W/mK)

Roof WeightGroup

Maximum U-Value (W/mK)



Group

Light(Under 50

kg/m)

0.4

Heavy(Above 50

kg/m)

0.6

1. Concrete tiled roofs (light weight) with NO INSULATION will have a U-value of 0.7 W/m2K

ROOF WITH INSULATION



2. With 50mm fiberglass, the U-value will be about 0.35 W/m2K

3. 100mm Concrete roof slab (heavy weight) will have a U-value of 2.762 W/m2K

4. With 60mm polystyrene foam, the U-value can be brought down to 0.537 W/m2K

1. If more than one type of roof is used, refer to Clause 5.5.2 for equations for U-value.

MULTIPLE ROOFS



2. If roof area is shaded from direct sun by a ventilated external shading device, such as a double roof, the permissible U-value (Table 9) may be increased by 50%.

3. If roof surface treatment is used where SRI >0.7, the permissible U-value (Table 9) may be increased by 50%.

R.C. Roof without insulation

HEAT CONDUCTION THROUGH ROOFHEAT CONDUCTION THROUGH ROOF


R.C. Roof with insulation



Metal Deck Roof without insulation



Metal Deck Roof with insulation



Clause 5.6.1The concept of RTTV applies if the roof is providedwith skylight, and the entire enclosure below is fully

RTTV - ROOF WITH SKYLIGHTSRTTV - ROOF WITH SKYLIGHTS



with skylight, and the entire enclosure below is fullyair-conditioned.

Clause 5.6.2The maximum recommended RTTV is 25 W/m2.


MS1525:2007 Clause 5.6.3 equation

)A( ASF)x SC x

s(ATx

sx U

s( A)

eqx TDrx Ur(ARTTV

+

++=

)


)s

Ar

( ARTTV +TDeq is equivalent temp difference (Table 10); and Tis the designed temp difference between inside andoutside (5K).

SF is the Solar Factor, where SF = 323 x CF; whereCF is the correction factor for the orientation of theroof and the pitch angle of the skylight (Table 11).

SUMMARYMS1525:2007 Clause 5.2OTTV applies to building envelope, where OTTV < 50 W/m2

OTTV, Roof U-value and RTTVOTTV, Roof U-value and RTTV


MS1525:2007 Clause 5.5Roof U-value refers to the thermal transmittance of the roof construction, where Roof U-value < 0.4 - 0.6 W/m2K

MS1525:2007 Clause 5.6RTTV applies to roof with skylights, where RTTV < 25 W/m2

SUBMISSION PROCEDURESUBMISSION PROCEDURE

Information to be submitted by a ProfessionalEngineer or Professional Architect:

a drawing showing the cross-sections of typical parts of the roof construction, giving details of the type and thickness of basic


details of the type and thickness of basic construction materials, insulation and air space;

the U-value of the roof assembly; the OTTV calculation; and the RTTV of the roof assembly, if provided with

skylights.

MS1525:2007 Clause 4.5The exterior wall and cladding systems should bedesigned to provide an integrated solution for the

DAYLIGHTINGDAYLIGHTING


designed to provide an integrated solution for theprovision of view, daylight control, passive andactive solar energy collection and moisturemanagement systems while minimizing heat gain.

MS1525:2007 Clause 5.4.1Suggested Daylight Factor 1.5%

MS1525:2007 Clause 5.4.2



MS1525:2007 Clause 5.4.2VLT should not be less than 50%

MS1525:2007 Clause 5.4.3Daylighting controls within 5m of external walls

DAYLIGHT FACTOR

Conventional and innovative daylighting systems that collect, transport and distribute light deep into

MS1525:2007 Clause 4.4



that collect, transport and distribute light deep into buildings and systems that reduce the need for artificial lighting are recommended.

The simplest form of description of daylight distribution is Daylight Factor, DF where

DF = (Internal Illuminance External Illuminance) x 100%

Diffused Daylight levels in Malaysia


10 am 4 pm


50,000 lux

30,000 lux

Zone DF (%) DistributionVery bright > 6 Thermal and glare problems

Bright 3 - 6 Good

MS1525:2007 Table 1



Bright 3 - 6 Good

Average 1 - 3 Fair

Dark 0 - 1 Poor

Based on Malaysian data, the average Daylight level between 10am and 4pm is 32,000 lux.

Thus, a suggested DF of 1.5 = 480 lux (Fair);a DF of 4.5 = 1,440 lux (Good)!

DAYLIGHT GLARE CONTROL

Reduce discomfort of glare from natural light. Blinds or screens fitted on all glazing and atrium as a base building must meet the following



as a base building must meet the following provisions:

1) Eliminate glare from all direct sunlight;2) Eliminate glare from diffused sky radiation;3) Control with automatic monitoring system -

with manual override accessible to occupants.

DAYLIGHTING ESSENTIALS

1. Bring the light in from high, above the view plane2. Diffuse sunlight inside the space. Do not allow



2. Diffuse sunlight inside the space. Do not allow beam sunlight to strike work surfaces.

3. Use only North and South vertical windows4. Choose the glazing carefully.

1. Locate a continuous strip of narrow windows up high.

1

4

32

DAYLIGHTING STRATEGIES


1. Locate a continuous strip of narrow windows up high.2. Add a few view windows for visual connection to the

outside. These have a low visible transmittance (VLT 0.2 to 0.3), to balance the luminance of the walls with the luminance of the outside. Every work place in the building should have view windows.

3. Introduce light eggshell white color in the upper part of the room to bounce the light across the room.

4. Add mid-to-light colors in the lower part of the room.

Spectrally Selective Glazing lets in daylight, but blocks out the heat

Tinted Glazing

LightHeat



Spectrally Selective Glazing

LightHeat

Typical Values, Double Glazing : Light 60% TransmissionHeat 30 % Transmission

ideal window transmittance

CHOOSE SPECTRALLY SELECTIVE GLAZING



0 500 1000 1500 2000 2500 3000Wavelength, nm

solar spectrum

visible390nm 750nm

34% of NLA with DF = 1.0% to 3.0% Assuming average 32,000 lux,

North



32,000 lux, 1.0% DF = 320 lux3.0% DF = 960 lux

5m

South



No lightshelf and no louvres

A. External lightshelf and no louvres

B.

OUTSIDE INSIDE OUTSIDE INSIDE



With lightshelf and louvres

C. Lightshelf tilted at 30oand without louvres

D.




Lightshelf tiled at 30oand with louvres

E. With outer and internal lightshelves

F.


34

5

6 5.7

4.8

3.7

4.9 5.0

3.9Based on DF of 1.5%, ie approx

Lightshelf and Daylight Factor PerformanceLightshelf and Daylight Factor Performance


0

1

2

3

A B C D E F

Glarerisk

PreferredGlarerisk

Glarerisk

1.5%, ie approx 150 lux

DAYLIGHT FACTOR STUDY



External Views (Open Plan Office)DAYLIGHTINGDAYLIGHTING


The building envelope should provide adequate

MS1525:2007 Clause 5.9Air Leakage



The building envelope should provide adequatebarrier to prevent uncontrolled mixing of outsideair with air-conditioned space.

It is recommended that a door that separates

MS1525:2007 Clause 5.9.5Vestibules



It is recommended that a door that separatesconditioned space from the exterior is protectedby an enclosed vestibule, with all doors openinginto and out of the vestibule equipped with self-closing devices.

For Curtain Walls, Windows and Doors, SkylightSystems:

Building Envelope Testing



Systems:

1) Air Permeability Test2) Water Penetration Test3) Noise Penetration Test

Curtain Wall TestsBUILDING ENVELOPEBUILDING ENVELOPE


THANK YOU


Ar Von Kok LeongB. Arch (Auckland), P.Arch, APAM, AIPDM

2a.heat Transfer GBI MS1525 2007

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