© Fraunhofer ISE
PERFORMANCE EVALUATION OF HEAT PUMP
SYSTEMS FOR HEATING AND COOLING NET
ZERO ENERGY BUILDINGS
Dipl.-Ing. Dominik Wystrcil
Dr.-Ing. Doreen Kalz
Fraunhofer Institute for Solar
Energy Systems
IEA HPP Annex 40, Workshop
Nagoya, Nov 11 2014
www.ise.fraunhofer.de
Case Studies from Germany
© Fraunhofer ISE
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Towards Net/Nearly Zero Energy Buildings
Examples of Convincing Projects
1989 1992 1999 2001 2005 2009 2010 2011 2012
Jenni
Energieautarkes
Solarhaus
Solvis
Hebel Sonnenkraft
Voggenthal
BMVBS
Plusenergiehaus
Bugginger 50
Solar Decathlon
Wuppertal
© Fraunhofer ISE
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Energy Optimized Buildings Germany, EnOB
nZEB
© Fraunhofer ISE
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Source: A.J. Marszal, J.S. Bourrelle, E. Musall, P. Heiselberg, A. Gustavsen, K. Voss: Net Zero Energy Buildings –
Calculation Methodologies versus National Building Codes, in: EuroSun Conference, Graz, Austria, 2010.
Energy Optimized Buildings Germany, EnOB
nZEB: Balancing
© Fraunhofer ISE
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Energy Optimized Buildings Germany, EnOB
Long-term Monitoring over several years
Primärenergiebilanz in kWh/m²a
-50 -25 0 25 50 75 100 125 150 175 200
EcoTec 99
Wagner 01
ISE-Büro 03
DB Netz 01
GIT 05
Lamparter 03
Pollmeier 03
KfW 05
Energieforum 05
Energon 05
TMZ 04
BOB 05
SIC 05
FH BRS 01
NIZ 04
ZUB 03
GMS 05
LEO 97
Hübner 01
SurTec 02
Solvis 05
Lebenshilfe 05
andere Energieträger Strom Gutschrift KWK Gutschrift PV
Bil
du
ng
Bü
rog
eb
äu
de
Teilbelegung,
ohne Bürobeleuchtung
keine Stromdaten
Referenzgebäude
Teilbelegung, ?
Teilbelegung, 60%
Teilbelegung, 75%
Pro
du
kti
on
ohne Strom für Beleuchtung
ohne Strom
Beleuchtung
Endenergieverbrauch in kWh/m²a
0 25 50 75 100 125 150 175 200
EcoTec 99
Wagner 01
ISE-Büro 03
DB Netz 01
GIT 05
Lamparter 03
Pollmeier 03
KfW 05
Energieforum 05
Energon 05
TMZ 04
BOB 05
SIC 05
FH BRS 01
NIZ 04
ZUB 03
GMS 05
LEO 97
Hübner 01
SurTec 02
Solvis 05
Lebenshilfe 05
andere Energieträger
Strom
Bil
du
ng
Bü
rog
eb
äu
de
keine Stromdaten
Teilbelegung, ohne Bürobeleuchtung
Teilbelegung, 60%
Referenzbürogebäude
Teilbelegung,
Teilbelegung, ?
ohne Strom für Beleuchtung
ohne Strom für BeleuchtungPro
du
kti
on
OFFICE BUILDINGSP
roduction
Education
Offic
e b
uild
ings
End energy demand in kWh/m2/a Primary energy balance in kWh/m2/a
Others
Pel CHP PV
Pel
Others
© Fraunhofer ISE
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Buildings and
HVAC
Overview
� Buildings:
� Investigated projects: 16 (5 to follow)
� Projects: EnOB (15 new buildings, 1 refurbishment, 3 schools), LowEx:Monitor,
ModQS
� Office buildings, schools: 1.600 to17.700 m²
� Heat sink/source:
� Ground water (3), Borehole heat exchangers (11), Ground collectors/Piles (2)
� Various dimensioning of the BHEX-Field: 8 – 50 m/kWtherm HP
� Heat pump:
� Electric Compression-HP (13), Absorptions-HP (3): Power: 33 to 320 kWtherm
� Compressor stages: 1 to 4
� Heat supply:
� 5 monovalent, 11 bi-/ multivalent (Biomass, Gas, District heating, Solar)
� Waste heat recovery in 6 Projects (e.g. decoupling during cold production)
© Fraunhofer ISE
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Methodology for Analysis and Evaluation
Balance Boundaries I to IV
� Measurement data with high
temporal resolution from
demonstration projects over
several operational years
(1min - 10min increments)
� Standardized evaluation of the
plants with Datastorage
� Analysis and evaluation
according to operational
modes: Heating, direct and
active cooling, total operation
� Evaluation of 5 system
boundaries
� Energy and efficiency
� Operational Performance
USEFUL ENERGY
STORAGE
I
II
III
IV
HEAT SOURCE
HEAT SINK
HEAT PUMP
HP
GENERATION
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Methodology for Analysis and Evaluation
Balance Boundaries II and HP
I
II
HEAT SOURCE
HEAT SINK
HEAT PUMP
HP
GENERATION
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Heat Pumps in Heating Mode
Energy Performance
� Heat supply by heat pumps in the analyzed buildings 16,8 to 66,7 kWhtherm/m2a
� In most plants below 40 kWhtherm/m2a
� Monovalent and bivalent supply
Supplied heat by heat pump in kWhtherm/m2a
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Analysis of Efficiency
SPF Heat Pump
SPF Heat Pump System
Fraction Auxiliary Energy on Total Consumption [%]
SPF>4
* SPF according VDI 4650, Page 2 (ultimate energy
based, thermal and electric input)
� Efficiency of heat pump
� Electric HP: 2,4 to 6,6
� No clear difference between
monovalent and multivalent
operation
� Thermal HP: 0,8 – 1,3*
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Heat Pumps in Heating Mode
Impact of Auxiliary Energy
� Efficiency of heat pump
� Electric HP: 2,4 to 6,6
� No clear difference between
monovalent and multivalent
operation
� Thermal HP: 0,8 – 1,3*
� Efficiency of HP system
� Electric HP : 2,1 – 6,1
� Obvious reduction of SPF
of 6 – 15% in some cases
� Efficiency of system
determined by HP and
auxiliary energy
SPF>4
-6 to -
15%
SPF Heat Pump
SPF Heat Pump System
Fraction Auxiliary Energy on Total Consumption [%]
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Analysis of Operation Temperature Difference Primary Circuit [K]
Temperaturdifferenz: Sekundär [K]
Temperaturhub: Primär-Sekundär [K]
� Low temperature difference in the
primary circuit, often 1 – 3 K
Temperaturniveau: Sekundär [K]
SPF Heat Pump
SPF Heat Pump System
Fraction Auxiliary Energy on Total Consumption [%]
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Analysis of Operation Temperature Difference Primary Circuit [K]
Temperature Difference Secondary Circuit [K]
Temperaturhub: Primär-Sekundär [K]
� Low temperature difference in the
primary circuit, often 1 – 3 K
� Temperature difference in the
secondary circuit between 2 and 5K
Temperaturniveau: Sekundär [K]
SPF Heat Pump
SPF Heat Pump System
Fraction Auxiliary Energy on Total Consumption [%]
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Analysis of Operation
Temperaturhub: Primär-Sekundär [K]
� Low temperature difference in the
primary circuit, often 1 – 3 K
� Temperature difference in the
secondary circuit between 2 and 5K
� Temperature level in the secondary
circuit depends on the heat delivery
system
� Ventilation and surface-near
systems: 35 – 45°C
� TABS: 28 – 35 °C
Temperature Level Secondary Circuit [°C]
Temperature Difference Primary Circuit [K]
Temperature Difference Secondary Circuit [K]
SPF Heat Pump
SPF Heat Pump System
Fraction Auxiliary Energy on Total Consumption [%]
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Analysis of Operation
Temperature Lift: Primary-Secondary [K]
� Low temperature difference in the
primary circuit, often 1 – 3 K
� Temperature difference in the
secondary circuit between 2 and 5K
� Temperature level in the secondary
circuit depends on the heat delivery
system
� Ventilation and surface-near
systems: 35 – 45°C
� TABS: 28 – 35 °C
� Big temperature lifts between primary
and secondary circuit in some cases
� reduced efficiency
Temperature Difference Primary Circuit [K]
Temperature Difference Secondary Circuit [K]
Temperature Level Secondary Circuit [°C]
SPF Heat Pump
SPF Heat Pump System
Fraction Auxiliary Energy on Total Consumption [%]
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Efficiency+Temperature Level
SPF 6.1SPF 2.6
Tem
pera
ture
SC
[°C
]
Temperature PRIMARY Circuit [°C]
Temperature Difference Primary Circuit [K]
Temperature Difference Secondary Circuit [K]
Temperature Level Secondary Circuit [°C]
Temperature Lift: Primary-Secondary [K]
SPF Heat Pump
SPF Heat Pump System
Fraction Auxiliary Energy on Total Consumption [%]
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Heating Delivery Systems
SURFACE-NEAR
CONDITIONING
CONCRETE CORE
CONDITIONING
FLOOR
CONDITIONING
CEILING SUSPENDED
PANELS
retrofit new construction
decreasing temperature level
© Fraunhofer ISE
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Heat Pumps in Heating Mode
Impact of hydraulic connection
45°C
28°C
40°C
>45°C
Storage
HP
SPF 3.6
45°C
28°C
28°C/
45°C
Storage
HP
SPF 4.9
SPF 5.3
SPF 3.3
© Fraunhofer ISE
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Heat Pumps in the Future Energy System
Significant increase in installed heat pump capacity*
0
20
40
60
80
100
120
140
0
20
40
60
80
100
120
140
80% 81% 82% 83% 84% 85%
Ins
tall
ed
ca
pa
cit
y, G
Wel
Ins
tall
ed
ca
pa
cit
y, G
Wth
Reduction of CO2-Emissions compared to 1990
CHP BWK Gas HP HP brine HP air sol-thermal distr. heat
* source: Fraunhofer ISE, ReModD, 2013
© Fraunhofer ISE
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Heat Pumps in the Future Energy System
Why do we study demand response with buildings?
� The increasing share of Wind and PV
in the German energy system causes
strong fluctuations in electricity
availability
� Demand response is an affordable
way to reduce the demand for
� Electric storage capacity
� Electric storage power
Why demand-response? Why use buildings?
� The collectivity of heat pumps and
chillers has a high electric power
� The collectivity of buildings has a high
thermal storage capacity
� The electricity load for heat and cold
generation can be shifted, storing the
energy as heat or cold
Benefits
� It can be fully automated. Ideally, the user doesn‘t even notice
� Low hardware investments required (only controllers, no storages)
� Small temperature differences due to high thermal mass
© Fraunhofer ISE
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Stunde des Tages [h]
2468
1012
3 6 9 12 15 18 21 24
HC03
2468
1012
HC02
2468
1012
H02
2468
1012
H01
Heat Pumps in the Future Energy System
Towards grid-optimal operation of heat pumps
32%
36%
45%
46%
22%
19%
27%
19%
0
1
2
3
4
5
H01
0
1
2
3
4
5
H02
0
1
2
3
4
5
HC02
0
1
2
3
4
5
0 6 12 18 24
HC03
2011 2012
Defined time table
Load based operation
Defined time table
Load based operation
Ceiling
TABS
TABS
TABS+Ceiling
� Different operation
modes
� Load-based
� Time tables
� Heat generation
mostly during
night-time � Low
fraction of wind +
PV
Fraction on daily consumption [%]Average power of heat pump [kWel]
Building 01
Building 02
Building 03
Building 04
Consumption with
high
fraction wind+PV
Consumption with
low
fraction wind+PV
hour of dayhour of day
© Fraunhofer ISE
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Summary and Conclusion
Performance evaluation of heat pump systems
� Long experience monitoring and optimization of demonstration buildings
� Performance evaluation of 16 heat pump systems
� Seasonal Performance Factors between 2,3 and 6,1 kWhtherm/kWhel
� High impact of auxiliary energy
� High impact of hydraulic system design
� Analysis of heat pumps in the future energy system
� Significant increase in installed heat pump capacity
� Opportunity of demand side management
© Fraunhofer ISE
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Outlook
Heat pump systems in the electrical grid
� Buildings leave a lot of their potential for grid-interactivity untapped.
� The easiest way to improve grid-interactivity is to reduce electricity consumption in the
morning and the evening.
� In order to make buildings highly grid-interactive, large thermal storage capacities are
required, i.e. activation of the thermal mass. This requires sophisticated control
strategies in order to retain thermal comfort.
© Fraunhofer ISE
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Thank you for your attention!
Fraunhofer-Institut für Solare Energiesysteme ISE
Dipl.-Ing. Dominik Wystrcil
www.ise.fraunhofer.de
