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© 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
© Fraunhofer ISE
3
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
© Fraunhofer ISE
4
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
© Fraunhofer ISE
5
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
© Fraunhofer ISE
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]
© Fraunhofer ISE
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
8
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
© Fraunhofer ISE
9
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
© Fraunhofer ISE
10
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.
© Fraunhofer ISE
11
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%
© Fraunhofer ISE
12
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
© Fraunhofer ISE
13
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
© Fraunhofer ISE
14
after retrofit
Environmental Heat Sink Air
Night ventilation concept
Daytime: hybrid ventilation (natural and mechanical)
Nighttime: mechanical ventilation > 2 - 3 ACH
before retrofit, 1970s
© Fraunhofer ISE
15
Environmental Heat Sink Air
Night ventilation concept
© Fraunhofer ISE
16
© Fraunhofer ISE
17
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
© Fraunhofer ISE
18
-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
© Fraunhofer ISE
19
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
© Fraunhofer ISE
20
SURFACE-NEAR
CONDITIONING CONCRETE CORE
CONDITIONING
FLOOR
CONDITIONING
CEILING SUSPENDED
PANELS
LowEx Cooling Systems
Cooling with high supply water temperatures
retrofit retrofit
© Fraunhofer ISE
21
KfW-Bank Frankfurt/Main · Arch. RKW, Düsseldorf
Radiant Cooling
© Fraunhofer ISE
22
Cooling panels with phase
change materials
23 °C
29 °C
Radiant Cooling
Suspended Panels
© Fraunhofer ISE
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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
© Fraunhofer ISE
24
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
© Fraunhofer ISE
26
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
© Fraunhofer ISE
27
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%
© Fraunhofer ISE
28
BEFORE Retrofit AFTER Retrofit
Holistic Approach of total building’s performance
© Fraunhofer ISE
29
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
© Fraunhofer ISE
30
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
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