This document summarizes a study on the optimal integration of net zero energy buildings (ZEBs) with photovoltaics (PV) in Scandinavia between 2010 and 2050. ZEBs have low energy demand met through on-site renewable energy generation. The study uses an energy system model to analyze the impacts of increasing ZEBs with PV on the energy system and finds that it reduces heat demand and increases PV production. While some electricity from PV will be lost, the Scandinavian energy system is well-suited to integrate high levels of ZEBs with PV through 2050 with only 2% of unutilized PV production and without requiring local energy storage in all buildings.

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Optimal integration of net
Zero Energy Buildings in the
Scandinavian energy system
71TH SEMI-ANNUAL ETSAP MEETING
Maryland, USA 10.07.2017
Pernille Seljom (pernille.seljom@ife.no),
Karen Byskov Lindberg (kli@nve.no) &
Asgeir Tomasgard (asgeir.tomasgard@ntnu.no)

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• net Zero Energy Building (ZEB)
• Low energy demand and renewable energy generation
• Energy generation = energy demand
• PV is a suitable energy generation technology
• EU’s Energy Performance of Buildings Directive (EPBD)
• All new buildings shall be nearly ZEB from 2020
• The definition of a “nearly” and Primary Energy factors are member specific
• Scandinavia; Denmark, Norway & Sweden
• Solar irradiation is high in summer when electricity demand is low
• ZEBs with PV require electricity trade with the electricity grid
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Motivation
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• If all new and rehabilitated buildings are ZEB with PV
• How will this change the cost-optimal development of energy system
towards 2050 ?
• What is the optimal heat design in buildings ?
• Is it possible to integrate substantial PV production in Scandinavia ?
• What is the future role of the flexible hydropower ?
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Research questions
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• Scandinavian TIMES model
• Model period 2010 - 2050
• 48 time-slices
• 4 seasons
• 12 daily periods
• End-use sectors
• Buildings
• Transport
• Industry
• Perfect foresight investments
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Methodology
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• ZEB definition
• All new and rehabilitated buildings have a passive house standard with on-
site PV. In 2050:
• 50 % of the Scandinavian building stock is ZEBs
• Expected heat demand is reduced from 192 TWh to 157 TWh
• PV production = Electric specific consumption on an annual basis
• 2030: 25 TWh
• 2050: 53 TWh
• No use of local energy storage
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Methodology
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• Stochastic Programming is used to consider short-term uncertainty
and to value flexibility
• Investments are made with respect to the short-term uncertainty of
• PV production
• Wind power production
• Hydropower production
• Heat demand in buildings
• Electricity prices outside Scandinavia
• Grid interaction with ZEBs is particular dependent on PV production &
heat demand
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Methodology
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• Model input on non-residential heat demand without ZEBs
• 21 stochastic scenarios
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Methodology
0
50
100
150
200
250
300
350
400
2 4 6 8 10 12 14 16 18 20 22 24
Non-residentialheatdemand
NO1Winter2050,GWh
Hour
no ZEBs
25/75 Quantile Min Median Max
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• Model input on non-residential heat demand with ZEBs
• 21 stochastic scenarios
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Methodology
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0
50
100
150
200
250
300
350
400
2 4 6 8 10 12 14 16 18 20 22 24
Nonresidentialheatdemand
NO1Winter2050,GWh
Hour
with ZEBs

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• Model input on PV production
• 21 stochastic scenarios
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Methodology
0.00
0.05
0.10
0.15
0.20
0.25
2 4 6 8 10 12 14 16 18 20 22 24
PVavailabilityfactor-SE3Summer2030
Hour
25/75 Quantile Min Median Max
Availability factor =
hourly production/ capacity
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• Two different case assumptions on new and rehabilitated buildings
• Heat demand (TWh/y) 2030 2050
• REF 177/194/222 179/192/224
• ZEB 162/178/203 145/157/183
• PV production in ZEB
• 2030 25 TWh
• 2050 53 TWh
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Results
Case Passive building standard Building integrated PV
REF No No
ZEB Yes Yes
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Electricity generation capacity
- 51 %
- 17 %
- 4 %
0 %
0 %
REF ZEB REF ZEB
2010 2030 2050
Total 73.8 83.3 107.0 88.0 139.1
PV 0.0 0.0 29.4 0.0 62.6
Wind 6.3 13.0 8.6 17.5 8.6
CHP 11.9 10.4 9.6 10.4 8.6
Non-flexible hydro 15.0 19.8 19.2 20.0 19.2
Flexible hydro 31.4 33.4 33.4 33.4 33.4
Nuclear 9.3 6.7 6.7 6.7 6.7
0
25
50
75
100
125
150
Electricitygenerationcapacity,GW

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Wind power capacity
- REF ZEB REF ZEB
2015 2030 2050
Total 11.0 13.0 8.6 17.5 8.6
SE 5.4 3.9 0.8 5.3 1.5
NO 0.8 2.2 1.4 4.3 1.1
DK 4.8 7.0 6.4 8.0 6.0
0
5
10
15
20
Windcapacity,GW

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Building heat supply
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REF ZEB REF ZEB
2030 2050
Total 192 174 190 155
District heat 85 78 82 68
Gas 14 14 15 13
Heat Pump 36 27 38 27
Electricity 32 35 31 31
Biomass 24 20 24 17
0
50
100
150
200
Expectedbuildingheatsupply,TWh
- 17 %
- 13 %
- 29 %
0 %
- 29 %

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• With no storage in ZEBs & no new Scandinavian transmission
• Expected loss of electricity in 2050 = 1.3 TWh/ 2.4% of PV production
• Example: Electricity balance in the Stockholm region
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System integration of PV
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-20
-15
-10
-5
0
5
10
15
20
25
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Electricitybalance-Summer2050-
S16,GW
Hour
Export from SE3
Consumption SE3
Import to SE3
Other production SE3
PV production SE3
Lost PV in SE3

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Net electricity export
-6
-4
-2
0
2
4
6
8
10
12
14
2 4 6 8 10 12 14 16 18 20 22 24
Netelectricityexportspring2050,GW
Hour
ZEB no ZEBS in Europe

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• Implementation of ZEBs with PV
• Influences cost-optimal investments and operation of the energy system
• Lower heat demand & PV production
• Reduces the competiveness of CHP, wind power and non-flexible
hydropower
• Increases the share of low-cost electricity heating
• System integration of PV
• Scandinavian energy system is well suited to integrating a large amount of
ZEBs with PV
• 2 % of unutilized PV with no building storage in 2050
• Scandinavian energy system does not require local energy storage in all
ZEBs
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Conclusions
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Thank you for the attention
pernille.seljom@ife.no
10/07/2017
Acknowledgements to:
For more details:
Seljom, P., Lindberg, K.B., Tomasgard, A., Doorman, G., Sartori, I., 2017.
The impact of Zero Energy Buildings on the Scandinavian energy system.
Energy 118, 284-296.
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