developing energy efficient building envelope (concrete)

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Developing

Energy

Efficient

Building

Envelope

(Roof)

Abdulkader Bengali, Head–Sales & Marketing, Indian Sub Continent

Agenda

• Why Insulation ???

• Energy Conservation Building Code

• Insulation

– Energy Conservation Building Code

– Selection Criteria

– Insulation Material – Comparison

• Roof System

• Wall System


Why Insulation ???

Where Energy goes from a house…

Energy Costs are going through

the roof, walls and windows

Energy Demand – Roof & Wall

Need for High Efficient, Insulated Building Envelope

Curbing Global Energy Demand Growth: The Energy Productivity Opportunity Diana Farrell, McKinsey Global Institute May 2007

BuildingInsulation

The Most Cost-effective Method for Decreasing Greenhouse Gas Emissions


Energy Conservation Building Code

(ECBC)

Energy Conservation Building Code

• Prescriptive Method

• Trade Off Method

• Whole Building Performance Method

Envelope Performance Factor (EPF)


Insulation – Selection Criteria &

Comparison

U Value

• Amount heat transmitted in

– unit time

– through unit area of a material or construction and the boundary air films,

– induced by unit temperature difference between the environments on each side.

– Units of U are W/m2-ºC (Btu/h-ft2-°F)

– U = k/t (k = thermal conductivity of material & t =

thickness)Area = 1 m2

T1 = 1oC

T2 = 0oC

U = 13 W/sqm K (6” RCC Slab)

R Value – Thermal resistance

• The reciprocal of the time rate of heat flow

– through a unit area

– induced by a unit temperature difference between two defined surfaces of material or construction

– Units of R are m2-°C/W (h-ft2-°F/Btu).

– R = 1/U = t/k

(k = thermal conductivity of material & t = thickness)

Selection Criteria – Insulation System for

Concrete Building Envelope

• Thermal Performance

– Selection – Thermal Resistance (R-Value) – not on density & thickness

– Eliminates or minimizes thermal bridging – Ideal Location

– Durable (weather-ability)

• Functional

– Absorbs minimum moisture

– Should not be exposed to fire risks

– Safe & Durable (aging and functional use)

Cell Structure – Insulation Material

Foamular Metric eXtruded

PolyStyrene (XPS)

Expanded PolyStyrene

(EPS)

PolyUrethane

Foam (PUF)

Property XPSa EPSa SPUb

Water Absorption, Vol. %< 0.3c 2.0 - 4.0c 5.0d

Water Vapor Permeanceperm 1.1e 2.0 - 5.0e 2.5 - 3.0e

ng/Pa.s.m2 63 115 - 287 144 - 176

Thermal Resistance°F.ft2.h/btu 5.0 3.1 - 4.2 6.2

Km2/W 0.88 0.55 - 0.74 1.10

Product Comparison–Moisture

Absorption

• Insulation should absorb minimum moisture for best thermal performance

– Very low water absorption per ASTM C578 standard

XPS – Extruded Polystyrene ; EPS – Expanded Polystyrene ; SPU – Sprayed Polyurethane

Notes : a. Data from ASTM C-578 ; b. Data from ASTM C-1029; c. Tested 24 hr ; d. Tested 96 hr ;

e. Desiccant Method

Product Comparison – R Value retention

CRREL : 80% Minimum Acceptable

• Moisture content affects thermal resistance

– Select an insulation product ( for building envelope ) which retains its thermal resistance – R Value

XPS

Retain R

Value v/s

Exposure

to time @

70% RH

New Wetting Curves for Common Roof Insulations, U.S. Army Corps of Engineers

Cold Regions Research and Engineering Laboratory (CRREL) April 1991


Prescriptive Method - Roof

Roof Assembly: Insulation

Requirements

As per Energy Conservation Building Code (ECBC) 2007

Insulation Material – Comparison

98 XPS = 116PUF = 175EPS = 420Bead Mortar=770 AAC = 2345 Clay Brick

R= 3.5 (m2· K/W) = 19.9 (F· ft2· h/Btu)

XPS = Extruded Polystyrene; PUF = Polyurethane Foam; EPS = Expanded Polystyrene;

AAC = Aerated Autoclave Concrete


Roof Insulation - System

Roof Assembly: Insulation

Requirements


Roof System – U Values

U Value : 3.19 W/m2.K

Brick Batt Coba

200

15

0

75

Chemical

Waterproofing Layer

RCC

Slab

U Value : 2.61 W/m2.K

U Value for 24 hour use : 0.261 W/m2.K

U Value for daytime use : 0.409 W/m2.K

Cement Screed

RCC

Slab

200

75

25

Chemical Waterproofing

Layer

U Value: 0.237 W/m2.K

A layer of Insulation reduces U value by >10 times

Water Proofing

LayerExtruded Polystyrene Insulation

Geo Textile

Screed

RCC Slab

Screed

Tile

As per ECBC

Water Proofing

LayerExtruded Polystyrene

Insulation Material

Protective Membrane

(Geo Textile)Pavers

Pebbles /

Gravels

Roof System

Concrete

Slab

Screed Mortar

TileScreed

PRMA System – Types

http://www.asla.org/meetings/awards/awds02/images2/imagesjpg2/Chicago City Hall-7.jpg

Long Lasting Durability – Dallas

Forth Worth International Airport

Project Highlights – PRMA System

• 3,036 squares re-roofed

• 88% of existing insulation reused

• $180,000 saved in new material cost

• $15,000 saved in hauling/landfill

• $100,000 saved in labor costs

Environmental Benefits

• Usable insulation recycled

• New product resource consumption minimized

• Saving in Fossil fuels

• Recycled insulation continues to save energy


Prescriptive Method - Wall

Wall Assembly: Insulation

Requirements


U VALUE COMPARISON – WALL SYSTEM

Source: Owens Corning

Double Wall (Brick)

with air gap

air

gap

U value: ~0.93

Double Wall + air gap +

50mm insulation

U value: ~0.37

Single (Brick) Wall

+ ACP

U value: ~1.40

ACP

U value: ~0.40

Brick Wall + ACP

+ 50mm

Insulation

insulation on

external

fascade

U value: ~0.39

Single (Brick) Wall +

50mm Insulation

Single (Brick) Wall

U value: ~1.78

cement

plaster

9”

thick

Unit in W/m2.K

Wall Solutions - External Insulation

(Wet Cladding – Paint )


(Wet Cladding – Tile )

Hangzhou Palm Bay


(Dry Cladding – ACP / Stone)

Metal Finish

Stone Finish

Beijing Orient Plaza

Wall Solutions - Internal Insulation

(Dry & Wet)


Thank You

[email protected] (+91- 9819987696)

developing energy efficient building envelope (concrete)

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