Thermal Rehabilitation of Existing Building Enclosures by ...€¦ · Thermal Rehabilitation of...

Thermal Rehabilitation of Existing Building

Enclosures by Using

VIP (Vacuum Insulation Panel) Sandwich and

Timber Based Panels

Arch. Dr. Christoph Buxbaum

Carinthia University of Applied Sciences

School for Civil Engineering & Architecture

Department of Architecture

www.cuas.at/bph

BEST2 – Building Enclosure Science & Technology Conference April 12-14, 2010; Portland / Oregon

• Ornamented or Listed facades

• Building regulations

• Encroachment of the road

building line with external

insulation is not allowed

therefore

Reasons for choosing inside insulations systems?

Only way to improve the indoor comfort conditions and to

reduce the buildings energy demand and thus CO2 emissions


Interaction of interior retrofit systems on the hygrothermal

performance of existing (heritage-protected) masonry walls.

Analyzing the influence of different exterior climate conditions on the

drying potentials of retrofitted constructions.

Analyzing the „real“ hygric conditions and probable durability using

transient simulations – no steady state analysis regarding to austrian

codes!

Purpose of our Research Study:


Clay Brick Masonry

500mm

(19,7in)

Typical historic Austrian walls

Outside

Lime-Cement Stucco

~ 20mm

(0,79in)

Inside

Lime Stucco

~ 20mm

(0,79in)

= Base Case

(Case 1 & 2)

Thermal Performance: U- value = ~ 1.10 W/(m²K) or R = 5,16 (hr.ft².°F/BTU)


Base Case

Investigated Cases – inside retrofit systems

Woodwool-

Panels

50mm

(1,97in)

&

stucco

Mineral-bound (magnesite)

Woodwool- panels

(Case 3 & 4)



Base Case


Mineral Wool

20mm

(0,79in)

Woodwool-

Panels

50mm

(1,97in)

&

stucco

Additional Mineral

wool, without

vapor retarders

(Case 5 & 6)



Base Case


VIP Sandwich-Panel

80mm

(3,15in)

&

stucco


Combinded VIP

Sandwich Panel

(Case 7 & 8)


Prefabricated VIP Sandwich assembly

Woodwool-

Board

20mm

(0,79in)

Vacuum

Insulation Board

10mm

(0,39in)

Woodwool-

Board

50mm

(1,97in)

20 10 50 [mm]

Exis

ting S

tucco

Vacuum Enclosure

Multilayer laminate

Main Enclosure

Fleece

Core material

Pressed pyrogene

Silica with

IR clouding agent

Woodwool Boards

protecting the VIP Core

on building site!

Heat capacity cp woodwool: > 2 kJ/kgKThermal conductivity λ woodwool: 0,09 W/mK


Custom-made VIP Sandwich panels


Overview - Investigated Cases:

• Different retrofit systems on the inside


Analyzing the influence of different

orientations?

Driving rain, reduced radiation, etc.

Investigations made for Austrian Climate

Vienna North

and

West orientation

(prevailing weather side)


Transient Simulations for

typical cross section of walls -

theoretic analysis close to reality

Critical areas (fixing-in timber beams,

corners, etc.) should be analyzed

separately in each case


Default Program Settings & Boundary Conditions

Analysis performed with WUFI ©

Heat Transfer Coefficient - exterior variable W/(m²K)

Heat Transfer Coefficient - interior 8 W/(m²K)

Short-Wave (Solar) Radiation Absorptivity External stucco 0,40 -

Long-Wave Radiation Emissivity 0,9 -

Initial Temperature in Components 20 °C

Initial Moisture in Components 80 %

Climate exteriorVienna / Austria

North and West Orientation

„Normal“ indoor climate conditions Sine curve between:

20°C / 40% RH. in winter &

22°C / 60% RH. in summer

Calculation Period 10 years, start in october

Impact of reduced radiation or

driving rain penetration, etc??


VIENNA NORTH- Orientation

Calculation Results - Extract


Cases 1, 3, 5, 7 – Vienna North – Years 1 to 10Total Water Content

TWC decreasing

in all cases

Constant Trend

after about 5 years

Higher TWC

in Case of VIP Panels

0 8760 17520 26280 35040 43800 52560 61320 70080 78840 87600

Time - 10 years [hours]

5

7.5

10

12.5

15

17.5

To

tal W

ate

r C

on

ten

t -

Ca

se

s N

ort

h,

VIE

NN

A [

kg

/m²] TWC_Case-1

TWC_Case-3

TWC_Case-5

TWC_Case-7


Cases 1, 3, 5, 7 – Years 5-10Relative Humidity on Surface of old interior stucco

> 80 %

Case 5, Temperatures > 5 °C, mold growth cannot entirely be excluded

Critical

Limit

For

Mold

Growth

Interface

Drying Performance

Case 5

43800 52560 61320 70080 78840 8760040

50

60

70

80

90

100

RH

In

terf

ace

Wa

ll -

Insid

e I

nsu

latio

n,

Ca

se

s N

ort

h [

%]

RH_W-Surface_Case-1

RH_Interface_Case-3

RH_Interface_Case-5

RH_Interface_Case-7

Time years 5 to 10 [hours]


VIENNA WEST- Orientation

Calculation Results - Extract


Cases 2, 4, 6, 8 – Vienna West – Years 1 to 10Total Water Content

Case 4 & 6

(inside woodwool

panel and additional

mineral wool)

TWC leveling off

after some years

Constant Moisture

accumulation in

case 8 with VIP

Sandwich Panel!

Exposition to prevailing weather side - higher TWC!

0 8760 17520 26280 35040 43800 52560 61320 70080 78840 87600

Time - 10 years [hours]

5

10

15

20

25

30

35

40

45

Tota

l W

ate

r C

on

ten

t -

Ca

ses W

est,

VIE

NN

A [kg

/m²]

TWC_Case-2

TWC_Case-4

TWC_Case-6

TWC_Case-8


Cases 2, 4, 6, 8 – Years 5-10Relative Humidity on Surface of old interior stucco

> 80 %

Critical

Limit

For

Mold

Growth

Interface

In case with vapor retardent VIP Sandwich Panel the RH. increases!

43800 52560 61320 70080 78840 8760040

50

60

70

80

90

100

RH

In

terf

ace

Wa

ll -

Insid

e I

nsu

latio

n,

Ca

se

s W

est

[%]

RH_W-Surface_Case-2

RH_Interface_Case-4

RH_Interface_Case-6

RH_Interface_Case-8 Time years 5 to 10 [hours]

Drying

Performance

Case 5


Dryability of inside insulation systems

Inward drying

possible!

Inward drying

limited due to

vapor retardent layers!

Source: Fraunhofer Institut fuer Bauphysik


2nd Step

Field Testing and In-Situ Measurements


20ûE

Finland

English Channel 2 Testhouses in

Southern Austria

In-Situ measurement under natural weather conditions


HOUSE 1: Wall Exposure north- & westward

West- facade North- facade


Inside view of test setupWoodwool-

Panels

50mm

(1,97in)

on

Mineral Wool

20mm

(0,79in)

Masonry

VIP Sandwich-Panel

80mm

(3,15in)Masonry


Inside view of test setup


Positioning of sensors


Measurement results (Relative Humidity)

40

45

50

55

60

65

70

75

80

85

90

0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000

Tem

pe

ratu

re [°

C]

Time [Hours]

Humidity

0.10 - RH-VIP-W1

0.11 - RH-VIP-W2

0.12 - RH-VIP-N1

0.13 - RH-VIP-N2

0.14 - RH-BM-W

0.15 - RH-BM-N

Higher RH due to

adhesive

> 80 %

Critical

Limit

For

Mold

Growth

40

45

50

55

60

65

70

75

80

85

90

0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000

Tem

pe

ratu

re [°

C]

Time [Hours]

Humidity

0.10 - RH-VIP-W1

0.11 - RH-VIP-W2

0.12 - RH-VIP-N1

0.13 - RH-VIP-N2

0.14 - RH-BM-W

0.15 - RH-BM-N

Start 04/2009


HOUSE 2

Testraum

(Nordansicht)Testraum

(Ostansicht)

Woodwool-

Panels

50mm

(1,97in)

on

Mineral Wool

20mm

(0,79in)

Masonry


Demounting of inside

insulation

No mold growth observable!


Conclusion?

Thermal improvment of existing

enclosures with inside insulation

systems is possible

BUT

Hygric conditions must be analyzed!


Conclusion?

Moisture response of retrofitted masonry

walls highly depends on orientation!

The impact of driving rain should always

be observed!

Vapor retardent layers inside may reduce

inward drying processes!

Thanks for your attention!!!!

Research work funded by:

www.cuas.at/bph

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