GBI PRO SERIES

by

Ar Von Kok Leong

Walls and Roofs

GBI PRO SERIES

PASSIVE DESIGN Passive design strategy

to orientate,

to shade,

to insulate,

to ventilate and

to daylit buildings.

Building

Envelope

GBI PRO SERIES

Assumptions

The concept of OTTV is based on the assumption that the envelope of the building is completely enclosed.

In the OTTV formulation, the following items are not considered:

1. internal shading devices eg curtains

2. solar reflection or shading from adjacent buildings 3. green walls

CONCEPT OF OTTV

GBI PRO SERIES

THERMAL RESISTANCE Relationships between thermal conductivity, thermal resistance and U-value

1 R

U =

Material thickness

k R =

Thermal conductivity k =

GBI PRO SERIES

SC) x WWR x CF x(194 U(WWR)6UWWR)(1α15OTTVi fw

MS1525:2007 Clause 5.2.2 says

+

Heat

Conduction

through

Windows

+

Solar Heat

Gain

through

Windows

Heat

Conduction

through

Walls

OTTV =

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

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

CONCEPT OF OTTV

GBI PRO SERIES

15 (1-WWR) Uw where = Solar Absorption = Colour of walls and WWR = Window-to-Wall Ratio and Uw = U-value of the wall 15 x x Wall area ratio x U-value of Wall

Heat Conduction through Walls

GBI PRO SERIES

Black glass 0.99

Red brick, dark brown paint 0.88

Asphalt pavement 0.82

Bare uncoloured concrete 0.65

Green paint 0.47

White semi-gloss paint 0.25

Silver paint 0.25

Polished aluminium sheet 0.12

Absorptivity, for Wall and Roof Surfaces Heat Conduction through Walls

GBI PRO SERIES

Plastered Brickwall

GBI PRO SERIES

Aluminium Composite

Cladding without insulation

GBI PRO SERIES

Aluminium Composite

Cladding with insulation

GBI PRO SERIES

External walls

Aircond

zone

Non aircond

zone

Plan View

OTTV

GBI PRO SERIES

External walls

Aircond

zone

Non aircond

zone

Plan View

External walls

Aircond

zone

Non aircond

zone

OTTV

X

GBI PRO SERIES

External walls

Aircond zone

Aircond zone

Core

Plan View

OTTV

GBI PRO SERIES

Plan View

External walls

Aircond zone

Aircond zone

Core

External walls

Aircond zone

Aircond zone

X Core

OTTV

GBI PRO SERIES

External walls

Aircond zone

Aircond zone

Core

External walls

Aircond zone

Aircond zone

Core

Plan View X

OTTV

GBI PRO SERIES

OTTV

applies to

external

walls only Highrise

aircond zone

Lowrise aircond

zone

M&E

Plantroom

X

OTTV

GBI PRO SERIES

Highrise

aircond zone

Lowrise non- aircond

zone

M&E

Plantroom

OTTV applies to external

walls of aircond spaces only

OTTV

GBI PRO SERIES OTTV

Different types of finishes

to external walls

GBI PRO SERIES OTTV

Different types of finishes

to external walls

W1 : curtain wall type 1

W2 : curtain wall type 2

W3 : curtain wall type 3

W4 : brick wall, aluminium

cladding

W5 : RC wall, plastered and

painted

W6 : curtain wall type 4

W7 : shopfront glazing

W1 W2 W3

W4

W5

W7

W6

GBI PRO SERIES OTTV

Wall Area WWR Uw SC 1 SC 2 Uf

W1 365 0.45 0.15 0.8 0.32 0.79 3.8

W2 1,400 0.45 0.15 0.8 0.32 1 3.8

W3 895 0.45 0.15 0.8 0.32 0.86 3.8

W4 635 0.31 0.50 3.3 0.28 0.79 5.5

W5 480 0.25 0.75 3.3 0.55 1 6.7

W6 50 0.75 0.15 0.8 0.45 0.6 5.2

W7 180 0.55 0.25 0.8 0.56 0.6 5.2

Total 4,005

W1 W2 W3

W4

W5

W7

W6 West Elevation

GBI PRO SERIES

Plan View

OTTV Terraced Houses

GBI PRO SERIES OTTV

X Plan View

Terraced Houses

GBI PRO SERIES OTTV

Plan View

Terraced Houses

GBI PRO SERIES

Highrise

aircond zone

Lowrise non- aircond

zone

M&E

Plantroom

Section

Roof U-values

GBI PRO SERIES

Roof type

“A”

“B”

“Pool”

“D”

“C”

Worst case applies

Plan View

Roof U-values

GBI PRO SERIES

R.C. Roof without insulation Roof U-values

GBI PRO SERIES Roof U-values

R.C. Roof with insulation

GBI PRO SERIES

0.6 Heavy

(Above 50 kg/m²)

0.4 Light

(Under 50 kg/m²)

Maximum U-Value (W/m²K) Roof Weight

Group

MS1525:2007 Clause 5.5.1 Table 9. Maximum U-value for roof (W/m²K)

Roof U-values

GBI PRO SERIES

Metal Deck Roof without insulation

Roof U-values

GBI PRO SERIES Roof U-values

Metal Deck Roof with insulation

GBI PRO SERIES

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 50 100 150 200 250 300 350

Insulation to lightweight roof

RO

OF

U-V

AL

UE

(W

/m2K

)

INSULATION THICKNESS (mm)

MS 1525 lightweight roof

< 0.4 W/m2K

Roof U-values

GBI PRO SERIES

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 50 100 150 200 250 300 350

INSULATION THICKNESS (mm)

RO

OF

U-V

AL

UE

(W

/m2K

)

MS 1525 heavyweight roof

< 0.6 W/m2K

Roof U-values Insulation to heavyweight roof

GBI PRO SERIES

– Polystyrene Foam

– mass, thickness and thermal resistance slow down heat transfer

– Mineral Wool (Rock wool)

– reflect radiant heat

– high thermal emissivity

Common roof insulation materials

Roof U-values

GBI PRO SERIES

Clause 5.6.1 The concept of RTTV applies if the roof is provided

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

Clause 5.6.2

The maximum recommended RTTV is 25 W/m2.

RTTV MS1525:2007 Clause 5.6

GBI PRO SERIES

Roof type

“A”

“B”

“Pool”

“D”

“C”

SKYLIGHT

Plan View

RTTV

GBI PRO SERIES

Difference in concept between Roof U-value and UHI

Roof U-value measures heat conducted through the roof construction AND

Applies where habitable or living spaces are found directly below it. Habitable spaces below roof need not be fully enclosed or aircond,

and includes pool decks, outdoor dining etc

UHI is about reflecting away solar radiation to achieve a cooler micro-climate.

Once heat comes in, it takes a lot of energy to get it out,

regardless whether the spaces below are occupied or not. OTTV vs ETTV

Roof U-values and UHI

GBI PRO SERIES

Difference in concept between Roof U-value and UHI

Can secondary roofs eg horizontal pergolas or screens be used to calculate Roof U-value?

No, because they can only provide shade but are not a part of the roof construction.

But they can be used to be a part of the calculation to reduce

UHI, ie SM12A of NRNC.

Roof U-values and UHI

GBI PRO SERIES

Plan View

Secondary

Roof Over

Secondary Roofs

Roof U-values and UHI

GBI PRO SERIES

Secondary Roofs

Roof U-values and UHI

Secondary Roof Over

y Primary Roof

Habitable space

Section

Roof U-value applies here

SRI (UHI) applies here

GBI PRO SERIES

Horizontal pergolas or vertical screens

GBI PRO SERIES

Secondary Roofs

GBI PRO SERIES

What are vertical planting?

Includes perimeter planting at edges of carparks

Can vertical planting outside building façade score? No, as mentioned in Innovation (FAQ11.1), vertical

planting must be part of the building facade. But will contribute towards greenscape areas under

SM4B NRNC or SM11 RNC

How to calculate OTTV if there exists double volume void decks or roof gardens? Show plan and perspective

Vertical Planting

GBI PRO SERIES

GBI PRO SERIES

GBI PRO SERIES

Can PV be used in calculating roof hardscape or Roof U-value?

Similar to pergolas. If PV is constructed as a feature above landscaped area, it

does not count. Same with PV on wall surfaces.

It will count only if it is BIPV, ie it forms part of the roof construction.

What is the SRI of PV surfaces?

SRI is about 40%

New technologies create PV with less SRI.

GBI PRO SERIES

Can insulation below rc slab be a part of Roof U-value? No, because the heat is already in contact with the

structure, and it will spread out into other structures. Hence, it is better to be placed above the structure.

But in renovation works, insulation below rc slab in ceiling space can be considered.

Can mechanical plant, equipment or water tanks be

calculated as a part of Roof U-value? No, for plantrooms exposed to the sky, Roof U-values are

calculated based on the construction of the roof, and excludes mechanical plant, etc.

GBI PRO SERIES

Can materials with low SRI, eg dark timber deck or dark

coloured tiles score under Roof Hardscape? In NRNC, can score in SM12A so long as SRI > 29

but cannot score in SM12B where SRI > 78

GBI PRO SERIES SM12A Hardscape & Greenery Application

Provide any combination of the following strategies for 50% of the site hardscape (including sidewalks, courtyards, plazas and parking lots): 1) Shade (within 5 years of occupancy); 2) Paving materials with a Solar Reflectance Index (SRI) of at least 29; 3) Open grid pavement system;

SM12B Roof Application 1) Use roofing material with a Solar Reflectance Index (SRI) equal to or greater than the value in the table below for a minimum of 75% of the roof surface; OR 2) Install a vegetated roof for at least 50% of the roof area; OR 3) Install high albedo and vegetated roof surfaces that, in combination, meet the following criteria: (Area of SRI Roof / 0.75) + (Area of vegetated roof / 0.5) ≥ Total Roof Area Roof Type Gradient SRI Low-Sloped Roof < 2:12, SRI > 78 Steep-Sloped Roof > 2:12, SRI > 29

GBI PRO SERIES

High albedo, high SRI

Vegetated roof

Hardscape with high albedo

Open grid paving

GBI PRO SERIES

NRNC SM12B (Area of SRI/0.75) + (Area of vegetated roof / 0.5) > Total Roof Area (1,743/0.75) + (630/0.5) = 3,586 sm Total roof area = 3,221 sm hence, 1 pt achieved

High Albedo

Vegetated

Roof

Hardscape w

high albedo

GBI PRO SERIES

NRNC RNC

EE4 RE Based on actual usage

EE3 RE Based on the total common area energy usage and is proportionally based on GFA of the project.

SM4 Landscape The computation of the landscape coverage area is proportionally based on the GFA of the project.

SM11 Greenscape & Water Bodies The computation of the greenscape and water bodies coverage area is proportionally based on the GFA of the project.

SM12 Greenery (Hardscape) The computation of the hardscape coverage area is proportionally based on GFA of the project.

SM12 Hardscape The computation of the hardscape coverage area is proportionally based on GFA of the project.

GBI PRO SERIES

NRNC RNC SM10 Parking Capacity The computation of the parking capacity is proportionally based on GFA of the project.

WE3 Irrigation Based on area of landscape irrigation needs defined in SM4.

WE3 Irrigation Based on area of landscape irrigation needs defined in SM11.

WE1 Rainwater Harvesting Based on actual usage including area of landscape irrigation defined in SM4.

WE1 Rainwater Harvesting Based on actual usage including area of landscape irrigation defined in SM11.

IN1 Herb Garden Based on area of landscape defined in SM4.

IN1 Herb Garden Based on area of landscape defined in SM11.

GBI PRO SERIES

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

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

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

SUMMARY

GBI PRO SERIES

Thank You