© Fraunhofer ISE

SUCCESSFUL RETROFIT OF NON-

RESIDENTIAL BUILDINGS: HEATING AND

COOLING CONCEPTS

Dr.-Ing. Doreen Kalz

Fraunhofer-Institute for Solar

Energy Systems ISE

Symposium IEA SHC Task 47

Frankfurt, 3. April 2014

www.ise.fraunhofer.de

© Fraunhofer ISE

2

Holistic Evaluation of Concepts

Energy Use – Energy Efficiency – Thermal Comfort

reduced heating

and cooling

energy demand

/

OCCUPANT

HVAC BUILDING

high plant

efficiencies

high working place

quality (thermal,

acoustic, visual)

objective

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Cross-Comparison

Delivered energy use: heating

delivery energy use for heating [kWhend/m²a]

0

25

50

75

100

125

150

175

200

225

250

DEN AT GER01 GER02 GER03

BEFORE

DESIGN

MEASUREMENT

MEASUREMENT

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Cross-Comparison

Delivered energy use: total building

delivery energy use for total building [kWhend/m²a]

0

25

50

75

100

125

150

175

200

225

250

DEN AT GER01 GER02 GER03

BEFORE

DESIGN

MEA1

MEA2

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Cross-Comparison

Primary energy use: total building

primary energy use for total building [kWhprim/m²a]

0

50

100

150

200

250

300

350

400

450

DEN AT GER01 GER02 GER03

BEFORE

DESIGN

MEA1

MEA2

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6 0

25

50

75

100

125

150

175

200

225

250

UB

BLA

BK

KS

KK

SK

WI

LTU

WIE

TH

IK

FW

REB

Cross-

Comparison

Germany

End energy

use for

heating

0

25

50

75

100

125

150

175

200

225

250

NIZ

NIZ

ZU

BZU

BG

MS

GM

SG

MS

SO

LSO

LIS

EIS

EIS

ED

BN

DB

NLA

MLA

MPO

LPO

LK

FWK

FWK

FWEN

GEN

GEN

GEN

GTM

ZTM

ZSIC

SIC

SIC

UB

AU

BA

BA

RB

AR

HdR

HdR

SD

HSD

HSD

HSH

D

0

25

50

75

100

125

150

175

200

225

250

DEN

DEN

DEN

AT

AT

AT

GER

1G

ER

1G

ER

1G

ER

2G

ER

2G

ER

3G

ER

3G

ER

3

NEW

RETROFITTED IEA

mean 60 kWh/m²a

mean 88 kWh/m²a

mean 52 kWh/m²a

cross-comparison

of buildings

IEA buildings

reach very

ambitious aims

according to

heating end

energy use

before

after

*not included in mean value

delivery energy use [kWhend/m²a]

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7

Holistic Evaluation of Concepts

Energy Use – Energy Efficiency – Thermal Comfort

reduced heating

and cooling

energy demand

/

OCCUPANT

HVAC BUILDING

high plant

efficiencies

high working place

quality (thermal,

acoustic, visual)

objective

© Fraunhofer ISE

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After Before

Heating Concepts

Ground-coupled thermal heat pumps

2 Gas boiler, 250 and 283 kWtherm

High temperature heating with radiators

Natural Ventilation

2 ground-coupled thermal heat pumps

each 35 kWtherm and 2 gas boilers (2x80

kWtherm)

Hybrid ventilation with heat recovery

Low temperature heating with radiators

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After Before

Heating Concepts

Ground-coupled electrical heat pumps

Gas boiler 280 kWtherm

High temperature heating with radiators

Natural Ventilation

Electrical heat pump 33 kWtherm, use of

waste heat from printing workshop, old

gas boiler as backup

Hybrid ventilation with heat recovery

Low temperature heating with radiators

and convectors

EN

VIR

ON

ME

NT

AL E

NE

RG

Y

US

EFU

L E

NE

RG

Y

PRIMARY ENERGY

HEATING

COOLING

VENTILATION

GR

OU

ND

A

MB

IEN

T

AIR

MV

BHEX

HR

WA

STE

HEA

T

SO

LAR

SC

FOSSIL FUELS ELECTRICITY

HP

BOILER

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Operation Performance of Heat Pumps

Cross-Comparison: analysis of efficiency

Cross-Comparison

Electrical: 2.4 – 6.6

Thermal: 0.8 – 1.3*

No significant

difference between

monovalent and

bivalent systems

Retrofitted Projects:

Electrical: 2.9

Thermal: 1.3

Higher supply

temperature

influence SPFel

* SPF according to VDI 4650, 2 (related to delivered

energ, thermal and electrical use)

SPF Heat Pump

SPF Heat Pump System

Fraction of Auxiliary Energy for Pumps on Total Use [%

SPF>4

G13

electrical therm.

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Operation Performance of Heat Pump Systems

Cross-Comparison: analysis of efficiency

Cross-Comparison

Significant electrical

energy use for

pumps in primary

circuit (5 to 20%)

Reduction of SPF by

6 to 15 %

Retrofitted Projects:

Well designed

systems with a

comparatively low

auxiliary energy use

for pumps

* SPF according to VDI 4650, 2 (related to delivered

energ, thermal and electrical use)

SPF Heat Pump

SPF Heat Pump System

Fraction of Auxiliary Energy for Pumps on Total Use [%

SPF>4

G13

electrical therm.

-6 to -15%

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GEOTHERMAL ENERGY AMBIENT AIR

ground water surface

water

nat. / mech.

ventilation

cooling tower surface-near

ground

natural and

hybrid ventilation

dry / wet cooling

towers

Use of Environmental Heat Sink

Direct cooling

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before retrofit, 1970s

after retrofit

Environmental Heat Sink Air

Night ventilation concept

Daytime: hybrid ventilation (natural and mechanical)

Nighttime: mechanical ventilation > 2 ACH, ventilation slats

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after retrofit

Environmental Heat Sink Air

Night ventilation concept

Daytime: hybrid ventilation (natural and mechanical)

Nighttime: mechanical ventilation > 2 - 3 ACH

before retrofit, 1970s

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Environmental Heat Sink Air

Night ventilation concept

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GEOTHERMAL ENERGY AMBIENT AIR

ground water surface

water

nat. / mech.

ventilation

cooling tower surface-near

ground

natural and

hybrid ventilation

dry / wet cooling

towers

Use of Environmental Heat Sink

Direct cooling

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-10

-5

0

5

10

15

20

25

30

35

Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov

tem

pera

ture

[°C

]

return

supply

2004

ambient air

2005

Use of Environmental Heat Sink

Ground temperatures

Summer period:

Supply

temperature

12-18°C

Temperature

difference 1 to

4 Kelvin

Cooling power

10 – 40

W/mBHEX

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Use of Environmental Heat Sink

Direct cooling: analysis of efficiency

Cross-Comparison

Direct cooling via bore-hole heat

exchangers or groundwater

Efficiency between SPF 10 and 20

All systems studied reveal potential for

further optimization

Temperature difference in primary

circuit often smaller 2 Kelvin

High auxiliary energy use of primary

pump due to high pressure drops within

hydraulic system and oversized pumps

Retrofitted Projects:

Good performance: SPF 10 and 19

aux. electrical energy use [kWhel/m²a]

SPF

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6

Grundwasser

Erdreich

Target: SPF >20

Groundwater

Ground

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SURFACE-NEAR

CONDITIONING CONCRETE CORE

CONDITIONING

FLOOR

CONDITIONING

CEILING SUSPENDED

PANELS

LowEx Cooling Systems

Cooling with high supply water temperatures

retrofit retrofit

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KfW-Bank Frankfurt/Main · Arch. RKW, Düsseldorf

Radiant Cooling

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Cooling panels with phase

change materials

23 °C

29 °C

Radiant Cooling

Suspended Panels

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eff

icie

nc

y (

SP

F)

eff

icie

nc

y (

SP

F)

cooling energy [kWh/m²TABSa] cooling energy [kWh/m²TABSa]

0

5

10

15

20

25

30

35

40

I II III IV

024681012141618

0

5

10

15

20

25

30

35

40

I II III IV

024681012141618

16.8

8.1

10.0

5.1

-50%

considerable auxiliary energy use for distribution and delivery

reduction of energy efficiency: approximately 50 %

Cooling System

Impact on auxiliary energy use for pumps

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Holistic Evaluation of Concepts

Energy Use – Energy Efficiency – Thermal Comfort

reduced heating

and cooling

energy demand

/

OCCUPANT

HVAC BUILDING

high plant

efficiencies

high working place

quality (thermal,

acoustic, visual)

objective

© Fraunhofer ISE

25

operative room temperature [°C]

18

20

22

24

26

28

30

0 5 10 15 20 25 30ambient temperature [°C]

18

20

22

24

26

28

30

0 5 10 15 20 25 30

operative room temperature [°C]

ambient temperature [°C]

EGU, 2005 Static model (PMV) Adaptive model

Thermal Comfort according to DIN EN 15251

2 Comfort models

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Thermal Comfort according to DIN EN 15251

Summer

Local Comfort Evaluation Global Comfort Evaluation

Higher supply water temperature of

18°C

surface temperature 21°C

Low vertical temperature differences

Thermal comfort class II achieved

according to adaptive model

High influence of occupants

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Thermal Comfort according to DIN EN 15251

Monitoring and optimization

Global Comfort Evaluation

Continuous monitoring of HVAC,

building and interior room conditions

Performance of cooling system and

thermal comfort could be improved 2008

2010

86%

98%

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BEFORE Retrofit AFTER Retrofit

Holistic Approach of total building’s performance

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Summary and Conclusion

Building

Use of hybrid ventilation concepts and solar shading

Mechanical ventilation systems with heat recovery, if possible

Reduction of (specific) heating and cooling loads in order to use LowEx heating

and cooling systems in combination with environmental heat sources and sinks

HVAC

Primary energy consumption using ground-coupled (reversible) heat pumps is

lower than conventional systems with gas boilers and compression chillers

Use of waste heat is possible when radiant heating systems are applied

Directly cooling using environmental heat sinks is very energy-efficient

Auxiliary energy use for pumps and fans needs to be considered

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Thank you very much for your attention!

Fraunhofer-Institute for Solar Energy Systems ISE

Dr.-Ing. Doreen Kalz

www.ise.fraunhofer.de

doreen.kalz@ise.fraunhofer.de