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Layman’s Report
Supermarket retrofit for zero energy consumption (LIFE12 ENV/ES/000787)
www.lifezerostore.eu
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Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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GOAL AND SCOPE OF THE
PROJECT
The main objective of this project is to
demonstrate the technical and economical
feasibility of an innovative integral highly
reliable solution for supermarket retrofitting
to make them auto sufficient from the
energy point of view.
In a conventional supermarket almost 70%
of energy is used for cold production by
electric compressors. LIFEZEROSTORE
project develops an innovative system
based on the combination of three very
different technologies working together:
biomass, absorption and co-generation, all
together receiving the name of trigene-
ration. This, along with other energy saving
measures, makes this supermarket the
first store aimed at energy self-
sufficiency.
This integral solution will allow savings
between 60 to 65% of electric energy and
avoid a high percentage of the energy
purchased from the electric network.
Applied in other stores and supermarkets in
Europe, a reduction of up to 3% of the
electricity consumption in Europe was
initially estimated according to the most
theoretical case.
Consortium:
• EROSKI S. Coop.: First retailer group ofthe cooperative type in Spain.
• CENER-CIEMAT Foundation: Techno-logical centre specialized in solutionsbased on renewable energies.
• L Solé, S.A.: Leader company inbiomass plants.
• Expander Tech S.L.: Specialists incogeneration systems.
• Ipar Hotz S.L.: Specialists in theinstallation and maintenance of industrialcold systems.
Duration: Del 2013/07/01 al 2017/06/30
Budget: 1.924.479 €
Funding LIFE+: 887.239 € (50% budget)
Location: Vitoria-Gasteiz, Spain (Fig.1)
THE WAY TO THE
LIFEZEROSTORE
The commitment of EROSKI with sustaina-
ble development implies improvements of
the design and execution of our activities in
order to ensure the preservation of the
environment. This commitment is inte-
grated across the whole organization by
our Environmental Policy. Among the work
lines derived from it is the implementation
of sustainable construction criteria in our
stores. The progress achieved in this area
during the past years led us to start the
LIFEZEROSTORE project in 2013.
2008
2009
2010
2011
2012
2013
A global environmental risk and
impact map and a guide about
sustainability construction were
created.
Pilot tests to check the improvement
measures previously identified were
conducted with satisfactory results.
ECOEFFICIENT STORE of Gros
(Gipuzkoa), with between 15 and
20% less energy consumption than
a conventional store.
ECOEFFICIENT STORE of Castro
(Cantabria), with improvement
measures and energy savings
similar to the store in Gros.
ZERO EMISSIONS STORE of
Oñate (Gipuzkoa), the first in the
Spanish State with BREEAM
(Building Research Establishment
Environmental Assessment Metho-
dology) sustainable construction
certification and the first in Europe to
obtain energy management certi-
fication ISO 50001. It is a zero CO2
emission store thanks to green ener-
gy purchase and the incorporation of
energy efficiency measures and
sustainable construction criteria,
which led to the achievement of
60% saving in energy consumption
in comparison to a conventional
centre.
LIFEZEROSTORE project starts in
Vitoria-Gasteiz (Araba).
Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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Vitoria-Gasteiz(Basque Country,Spain)
Fig. 1. Location of the LIFEZEROSTORE
METHODOLOGY, ARCHITEC-
TONICAL AND TECHNOLO-
GICAL SOLUTIONS AND
INTEGRATION
A trigeneration system based on
biomass was installed in the supermarket
“EROSKI Center” of Ali-Gobeo (Vitoria-
Gasteiz). The biomass is provided by local
sawmill companies which generate as
residue splinter of wood certified by PECF
(Programme for the Endorsement of Forest
Certification). The splinters are burned in a
boiler, thus heating oil to a temperature
between 180 and 205ºC. The heat from this
oil is used by a Organic Rankine Cycle
(ORC) to generate electricity, as well as
two circuits of hot water as by-product: one
at medium-to-high temperature and other at
medium-to-low temperature. The resulting
ashes from the biomass are used as
fertilizer in agriculture.
The water from the medium-to-low
temperature circuit exists the ORC at 50ºC
and it is used for heating the supermarket.
This is possible thanks to the heat exchan-
gers placed in the air handling units. When
there is extra heat available after heating
the store, the water circulates through a
heat dissipater located on the roof.
On the other hand, the heat of the water
from the medium-high temperature circuit
leaves the ORC at 88ºC. This heat is used
by an absorption machine of Lithium
Bromide (LiBr), which subcools the
condensation of the positive cooling plant.
The previous negative cooling plant with
R404A which condensed outside was
substituted by a CO2 refrigeration system
which condenses against the positive
cooling plant. Moreover, the refrigerant of
the positive cooling plant was also
substituted by another one with lower
environmental impact. This is possible
thanks to the combination of a zero ozone
depletion potential, a lower global warming
potential and a high energy efficiency.
Figure 2 shows an schematic diagram of
the integration of the different systems that
was carried out.
Fig. 2. Schematic diagram of the trigeneration system installed in the LIFEZEROSTORE
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Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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All this equipment was installed in a
flexible way guaranteeing the feasibility of
a later extension to future facilities.
Before selecting the solution described, an
in-depth assessment of the different
proposed technologies and the feasibility
of their integration into a trigeneration
system adapted to the needs of a
supermarket was conducted. Among other
considerations, the location choice, the
installation of systems for monitoring and
results analysis and the various options
possible for the integration of the systems
were reviewed.
The trigeneration system
provides a high percentage of
the energy necessary for the
cold for freezers and fridges,
the heat for climatization and
hot water and the electricity for
lighting and other uses
The trigeneration system was placed in a
way that it is opaque to the outside. This is
thanks to the building of a metallic structure
on the façade of the store covering the
equipment that supplies electric power,
climatization and commercial cold to the
supermarket. (Fig. 3).
Moreover, multiple energy efficiency
improvement measures were imple-
mented in the supermarket. Some of them
are:
• renovation of the lighting system by a
new one that adjusts the amount of light
provided depending on the levels of
ambient light in the room;
• placement of skylights on the roof to
allow the entry of solar light;
• installation of a glass structure at the
store’s main entrance to avoid the direct
entry of air; and
• removal of two “air curtains” (Joule
effect) installed over the entrance doors.
Fig. 3. Backside of the supermarket where the equipment of the trigeneration system is installed
Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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RESULTADOS DEL PRYECTO
Evolution of the electric consumption
for climatization
Two “air curtains” installed over the
automatic access doors that heated air at
the entrance by Joule effect were removed.
They were substituted by a glass structure
of double doors that avoids the direct entry
of air from outside, as shown in Figure 6.
These improvements led to a saving in
electricity consumption for climatization of
16.63% (Figure 7).
*It should be taken into account that at the beginning of the
project (year 2013), the values recorded for the “roof-top”
equipment used for climatization were not correct. Thus, in the
graph presented in Figure 7, the values used correspond to the
consumption from the “air curtains” during the first year and from
the “roof-top” during 2016.
PROJECT RESULTS
Evolution of the electric consumption
for cold
At the beginning of 2016 the previous cold
production plant was replaced by a new
one including a cascade cooling cycle (Fig.
4). This directly affects the negative cooling
plant, which uses CO2 (R744) as refrigerant
and which condenses against the positive
cooling plant, which uses R450A (also
known as N13) as refrigerant. This allowed
a 75% size reduction of the negative
cooling plant and the removal of the
condensers in the negative cooling plant on
the roof.
With those modifications the efficiency of
the system increased, as the negative
cooling plant reduces considerably its
consumption of electric energy. Specifically,
the decrease was of 17.15% (Fig. 5).
Fig. 4. New negative cooling plant that uses
CO2 as refrigerant
Fig. 6. Glass structure with double doors that
avoid the direct entry of air from outside
Fig. 5. Evolution of the energy consumption for cold
Fig. 7. Evolution of the energy consumption for
climatization*
Rooftop 1
Rooftop 2
Curtain 1
Curtain 2
START END0
50.000
100.000
150.000
200.000
250.000
En
erg
y c
on
su
mp
tio
n[k
Wh
]
START END0
50.000
100.000
150.000
200.000
250.000
En
erg
y c
on
su
mp
tio
n [
kW
h]
300.000
350.000
Ice machine 2
Ice machine 1 Positive cold
Others
Lighting
Negative cold
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Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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Evolution of the electric consumption
for lighting
The improvement measures implemented
included the installation of expansive sky-
lights on the roof of the supermarket to get
more solar light into the inside of the store
(Fig. 8 y 9). In order to make the most of
that increase of solar light in the inside, the
existing lighting system using fluorescent
lamps was substituted by LED technology
with illuminance control.
Evolution of the electricconsumption for lighting
All these improvements generated a
reduction of 30.07% in electricity consu-
med for the lighting of the sales floor
during working days (Fig. 10).
*With the aim of avoiding an overestimation of the savings, the
year within the four time periods for which there is data available
chosen to be represented in Figure 10 corresponds to the
period between the 1st of September of 2014 and the 31st of
August of 2015. This is the period with values most similar to the
average consumption but lower than it.
After all the retrofitting, the share of the
energy consumption in the supermarket is
48.8% for cold production, 27.04% for
climatization and 13.3% for lighting.
The energy efficiency improvement measures reduced
23,57% of the total electric energy consumption thanks to savings of 17% in cold, 16% in
climatization and 30% in lighting
Fig. 8. Lighting system with expansive
skylights
Fig. 10. Evolution of the energy consumption
for lighting*
Fig. 9. Skylights on the roof of the supermarket
CONVENTIONAL SYSTEM
Limited amount of light Hot spots
LLEDÓ SUNOPTICS®
Solution
Backery lighting
Lockers lighting
Sales-floor lighting
Outside lighting
START END0
10.000
20.000
30.000
40.000
50.000
60.000
70.000
80.000
En
erg
y c
on
su
mp
tio
n[k
Wh
]
Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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scenario number 5 and 66,45% of scenario
1 is obtained (Fig. 12).
The trigeneration system
functioning the whole year
achieves the objective of 65%
reduction in electricity
consumed from the network
Reduction in greenhouse gas
emissions
The European Union has the goal of
reducing 40% greenhouse gas (GHG)
emissions in 2030 in relation to 1990. The
LIFEZEROSTORE project aims to facilitate
the fight against climate change too.
Therefore, the reduction of CO2 equivalent
emissions generated due to the daily
activity of the store was calculated.
In the calculation of the total global
warming impact two types of emissions
were taken into account: the direct
emissions due to refrigerant leakages and
the indirect emissions due to electricity and
biomass consumption. The latter could be
also included as direct emissions, but
those emissions were considered to be the
consequence of burning biomass to obtain
the final calorific energy needed.
Reduction in electricity purchased
thanks to the trigeneration system
Five use scenarios for the trigeneration
system were simulated with the tool
TRNSYS in order to estimate the electric
energy that is necessary to buy from an
electric company to fulfil all the needs of the
supermarket (Fig. 11). It was checked that
the ORC works in a very regular and stable
way, with an electricity yield between 10
and 11%. But to achieve a suitable yield of
the installation is critical to use the thermic
energy obtained as sub-product in the
ORC, as well as minimizing the energy
dissipation in the medium-low temperature
circuit. Therefore, the two variables
considered in the design of the scenarios
are:
• functioning period: the whole year, only
during heating season (7 months per
year), or depending on daily demand of
heating; and
• oil temperature at the ORC entry: fixed at
205ºC or variable between 180 y 205ºC
depending on the heating demand.
Considering as reference the typical energy
consumption in other supermarkets and
climates similar to the ones in the project
(824 MWh), an external electricity
consumption saving between 43,78% of
Fig. 12. Percentage reduction of the electricity
purchased to fulfil the energy needs of the
supermarket. Scenario number 0 corresponds
to the savings thanks to the implementation of
the energy efficiency improvement measures.
Fig. 11. Scenarios simulated to evaluate the
impact of the trigeneration system
Whole
year
Heating
season
Heating
daily
demand
205ºC
205ºC
Variable depending
on dissipation
205ºC
Variable depending
on dissipation
1
2
3
4
5
Functioning
periodOil temperature
Sce-
nario
24%
66%
54%
47% 46%44%
0%
10%
20%
30%
40%
50%
60%
70%
0 1 2 3 4 5
Re
du
ctio
nin
ele
ctr
icity
pu
rch
ase
d[%
]
Scenarios
8
Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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Economic savings due to ZEROSTORE
The reduction in the electricity consum-
ption may imply not only a lower environ-
mental impact but also lower costs. For the
calculation of the economic savings, the
needs of biomass and of electricity from
the network in each of the scenarios
simulated were considered. The price of
biomass used corresponds to data from
April 2018 of the Spanish Association of
Biomass Energetic Valorization (Asocia-
ción Española de Valorización Energética
de la Biomasa, AVEBIOM). It is foreseen
that the maintenance costs will be included
in the biomass price.
Direct GHG emissions
For the calculation, the substitution of the
refrigerants used in the cooling plants by
others with a lower global warming
potential (GWP) was taken into account.
The GWP is a relative measure of the
heat trapped by a gas in comparision to
the amount trapped by CO2.
Moreover, the leakages of refrigerants
decreased from 8% to 5% during the
project. All these improvements led to a
reduction of 94,87% in GHG direct emis-
sions. This implies that the emissions of
202 tonnes CO2 eq. were avoided.
Indirect GHG emissions
The emission factor of biomass is also
much lower than the one of the electricity
(0,018 kg CO2 eq./kWh instead of 0,331
kg CO2 eq./kWh).
The indirect emissions also vary between
the scenarios presented in Figure 11 as
each of them has a different electricty
consumption from the network and
biomoss consumption in the boiler. Thus,
the reductions vary between 39,69% of
scenario 3 and 49% of scenario 1. In
absolute values correspond to a yearly
decrease in the emissions of 134 tonnes
CO2 eq.
Total GHG emissions
Thanks to the new trigeneration system
and the energy efficiency improvements
implemented, reductions between
63,91% (scenario 3) and 69,20%
(scenario 1) of total CO2 eq. emissions
are estimated (direct and indirect
emissions). That is, up to 336 tonnes
CO2 eq. per year could be avoided.
Fig. 13. Percentage GHG emissions reduction
for each trigeneration system functioning
scenario
Start End
Positive
cooling
plant
R404-A(GWP: 3.922
kg CO2 eq./kg)
R450-A(GWP: 547 kg
CO2 eq./kg)
Negative
cooling
plant
R404-A(GWP: 3.922
kg CO2 eq./kg)
CO2 (R744)(GWP: 1 kg
CO2 eq./kg)
Table 1. Refrigerants used with their global
warming potentials
0%
10%
20%
30%
40%
50%
60%
70%
80%
1 2 3 4 5
GH
G e
mis
sio
nre
du
ctio
n[%
]
Scenarios
Directas Indirectas
1 2 3 4 5
Fig. 14. Percentage economic saving depending
on the electricity price and the trigeneration
system functioning scenario
-50%
-40%
Ec
on
om
ics
avin
g[%
]
-30%
-20%
-10%
10%
20%
30%
40%
50%
Electricity price [€/kWh]
Supermarket retrofit for zero energy consumption (LIFEZEROSTORE) - LIFE12 ENV/ES/000787
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As shown in Figure 14, if an average
electricity price of 0,07€/kWh was consi-
dered, the trigeneration system would
generate economic savings in scenarios
3, 4 and 5. However, it would not be pro-
fitable when the system is functioning the
whole year or during the heating season
at 205ºC (scenarios 1 and 2).
Further analysis was conducted for sce-
narios 3, 4, and 5 in order to determine
the minimum ratio between electricity
and biomass prices that is economically
advantageous. According to this assess-
ment, the most profitable scenario is
when the trigeneration system works
depending on the daily heating demand
and with variable oil temperature (sce-
nario 5). In that case, it is necessary for
the trigeneration to be profitable that
the electricity kWh is at least 1,6 times
higher than the price of biomass kWh.
Scenarios 3 and 4 require ratios of at
least 2,7 and 1,9, respectively. Conse-
quently, the achievement of economic
savings due to the installation of the
trigeneration system is likely for the
scenarios considered, as long as the
energy prices are stable and reasonable.
IMPACT IN EROSKI AND
EUROPE
In order to estimate the possible environ-
mental and economic impacts derived
from the use of the trigeneration system
in other supermarkets, a simulation with
864 EROSKI supermarkets and 8.000
stores in Europe that have a sales floor
of more than 400 m2 was carried out.
The calculated savings depend not only
on the sales floor surface, but also on the
location, climatic zone or country where
the store is located.
Although it was proved that the objective
of 65% reduction of electricity purchased
from the network could be achieved
when the trigeneration system was
working the whole year (scenario 1), this
option resulted not as profitable as other
uses of the system more rational in the
simulation. Thus, scenario 5 was used
for calculating the impacts. This resulted
in the possibility of 310 Mill. € saving in
electricity purchased and 1,2 Mill. tn
CO2eq. avoided in Europe.
But those environmental and economic
benefits are not the only positive impacts
in case of replicability at National and
European level. The socioeconomic
impact due to the jobs created in the sec-
tors related to the installation and mainte-
nance of trigeneration systems and to the
retrofitting of stores to implement energy
saving measures should also be
considered. For instance, around 45.000€
are estimated per year only for the ope-
rative costs for maintaining the installation.
PROYECT DISSEMINATION
Additionally to the notice boards placed in
the store, press releases and the website
www.lifezerostore.eu, the project was also
presented in different international con-
ferences and via several articles pu-
blished in technical journals. The project
also caught the interest of business
organisations, such as the New Energy
and Industrial Technology Development
Organization (NEDO) from Japan.
EROSKI EUROPE
No. stores
considered864 8.000
Network energy
savings
43,5%
(220 GWh)
49,98%
(2.862 GWh)
Indirect GHG
emissions
savings
38,7%
(63.000 tn
CO2 eq.)
46,97%
(1,2 Mill. tn
CO2 eq.)
Economic
savings
26,9%
(17 Mill. €)
35,02%
(310 Mill. €)
Table 2. Environmental and economic impacts
of replicating the trigeneration system in other
stores according to functioning scenario no. 5
Fig. 15. Visit of NEDO to the ZEROSTORE
This project is the first
step to reduce up to 3%
of electricity consumption
in Europe, in the most
theoretical case
Project name Supermarket retrofit for zero energy consumption (LIFEZEROSTORE)
Project number LIFE12 ENV/ES/000787
Location Vitoria-Gasteiz. Álava. Basque Country. Spain
Duration 4 years (from 2013/07/01 to 2017/06/30)
Budget 1.924.479 €
LIFE+ Funding 887.239 € (50% of the budget)
Website www.lifezerostore.eu
ContactEROSKI, S.Coop., Bº San Agustín, s/n, 48230 Elorrio (Spain)
Tel. +34 94 621 12 11. E-mail: [email protected]