Energy 26 (2001) 187–196
www.elsevier.com/locate/energy
The structure of residential energy use on a North Aegean
island: the town of Mytilene
D.A. Haralambopoulos *, P. Fappas, M. Safos, H. Kovras
Department of Environmental Studies, University of the Aegean, 17 Karantoni Str., Mytilene 811 00, Greece
Received 22 July 1999
Abstract
The focus of this work is to investigate the structure of residential energy consumption in the capital
of a relatively large Aegean island and to propose remedial actions in order to reduce consumption and
avoid environmental pressures. It was realized that unless policies to curtail electricity use are enacted
(e.g., more efficient appliances, more high-efficiency lighting, curtailment of electricity-based heating,
restructuring of tariffs), a great deal of money would be spent inefficiently on increasing electricity supply.
Since the island has high solar radiation levels and a high biomass potential due to the extensive cultivation
of olive trees, the use of these two renewable resources should be encouraged. It was also realized that
the enactment of a heating insulation law has had substantial results.  2001 Elsevier Science Ltd. All
rights reserved.
1. Introduction
The North Aegean region, comprises of nine relatively large islands and a number of smaller
ones, is located in the Eastern part of the Aegean sea, at a significant distance from the mainland
of Greece. The islands lack any indigenous solid fuel sources and depend upon imports to cover
the needs for electricity production, transport and heating. The renewable energy potential (solar,
wind, biomass and geothermal) is quite significant but its contribution to energy supply is very
small.
The total population of the region is around 200,000 inhabitants (1991 census), which amounts
to 1.9% of the total population of Greece. The main activities of the people are concerned with
agriculture, fisheries, cottage industry, poultry farms and tourism. The latter has been expanding
* Corresponding author. Fax +30-251-36099.
E-mail address: dharal@aegean.gr (D.A. Haralambopoulos).
0360-5442/01/$ - see front matter  2001 Elsevier Science Ltd. All rights reserved.
PII: S 0 3 6 0 - 5 4 4 2 ( 0 0 ) 0 0 0 6 9 - 4
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D.A. Haralambopoulos et al. / Energy 26 (2001) 187–196
during recent years and is the main culprit, together with the increasing standards of living, for
the ever increasing energy consumption. It must be mentioned that the peak demand in electricity
consumption is currently during the summer months and this is attributed to the operation of the
large hotels.
In this study we focus on energy consumption in the residential sector of Mytilene, which is
the capital of Lesvos, the largest island of the North Aegean. A suitable questionnaire was
developed that addresses the energy consumption characteristics of the households and three teams
of two people each were trained to fill the relevant forms. The analysis of the data gave valuable
information regarding energy policy activities in the region.
2. Energy production and demand in the island of Lesvos
The residential sector is one of the fastest growing electricity consumption drivers, with about
25% of the total energy demand in most OECD countries [1]. This fact has prompted a number
of investigators to examine the interconnections of various parameters in order to deduce appropriate policy measures to reduce energy consumption in this sector [2,3]. The vital components of
home energy conservation programs were found to be residents’ energy use behavior, a dimension
that is not always included in local government home energy conservation programs [4], and the
opportunities for substantial equipment efficiency improvements [5,6].
As can be seen in Fig. 1, there was a 43.9% increase in electricity demand in Lesvos from
1991 to 1997 that has prompted the current study, since there is mounting pressure to install new
power plants. This increase reflects the increasing standards of living, since the population has
remained stable. Fig. 2 shows energy consumption on Lesvos by sector. Transport (with 40%)
and households (with 37%) are the main energy consumers. For any attempt, therefore, to influence total energy consumption, one must focus on these two sectors. The tertiary sector, which
includes the hotels, is expected to rise with the increase of tourism. The power plant, serving an
Fig. 1. Electricity consumption on the island of Lesvos from 1991 to 1997.
D.A. Haralambopoulos et al. / Energy 26 (2001) 187–196
189
Fig. 2. Energy consumption by sector on the island of Lesvos (1997).
autonomous grid, has an installed capacity of 58.5 MW and is comprised of eight internal combustion engines burning crude oil and one gas turbine which serves peak load and burns expensive
diesel oil. In addition, there are three wind turbines connected to the grid (total capacity 0.9 MW),
while the commissioning of another nine wind turbines with a 2.5 MW capacity is due in the
immediate future. The overall cost of electricity production is high and the nationalized Public
Power Corporation (PPC) subsidizes electricity generation, maintaining the same prices in the
mainland and the islands. More specifically, the fuel cost for electricity production is approx. 15
drh/kWh ($0.0375/kWh) for the IC engines and 60 drh/kWh ($0.15/kWh) for the gas turbine.
This cost is contrasted with the basic retail tariff which is 20.5 drh/kWh ($0.05/kWh), which
implies a large subsidy for electricity and creates incentives for the Government to reduce electricity consumption.
The diurnal distribution of electricity consumption follows a rather typical 24-h pattern with
two peaks, one during 12:00 midday and the other at around 18:00–20:00 in the evening. In
Fig. 3, the diurnal distribution for a day with the maximum and a day with the minimum load
are presented.
Fig. 3.
Daily minimum and maximum electricity loads for Lesvos (1995).
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From a survey conducted in 1988 by the National Statistical Service of Greece (NSSG) it was
found that space heating was the main energy consumer for the residential sector [7]. It accounted
for 52% of the total and, together with cooking (16%) and hot water heating (11%) was responsible for more than 75% of the total figure (Fig. 4).
3. Analysis of residential energy consumption in Mytilene
Mytilene, with a population of approx. 23,000, is a typical island town situated on the coast
in the south-east corner of the island and is exposed to northern winds. To the west, smooth hills
give shelter from the weather. The thermal plant that supplies the island grid with electricity is
located a few hundred yards from the north edge of the town, and the prevailing winds bring
most of the air pollution over the town. The number of households in the town is 8572 (1991
census) and the majority of buildings are detached houses with one to two levels.
The 1988 NSSG analysis lead the Regional Energy Agency of the Aegean to commission a
survey for the residential energy consumption in Mytilene. A relevant questionnaire was
developed that took into account data concerning:
앫
앫
앫
앫
앫
앫
앫
앫
앫
앫
house characteristics
electricity consumption
heating energy consumption
domestic hot water production appliance
lighting (structure and number of bulbs)
building envelope
floor area
year of construction
type of building
number of occupants.
Fig. 4. Domestic energy consumption in the N. Aegean islands by end use (1988).
D.A. Haralambopoulos et al. / Energy 26 (2001) 187–196
191
Table 1
Electric appliance penetration in the 571 households examined
Type of appliance
Oven
Refrigerator
Electrical hw heater
Kitchen hw heater
Rapid hw heater
Washing machine
Dish washer
Iron
Television
Computer
Freezer
Microwave oven
Gas cooker
Iron press
Toaster
Total
Penetration
appliances (%)
Households by No. of appliances
0
1
2
20
3
203
396
555
63
415
36
12
489
549
556
528
554
560
544
529
365
173
16
502
152
525
406
76
22
15
43
17
11
7
35
3
2
–
6
1
5
128
6
–
–
–
–
–
3
4
–
3
–
–
–
–
–
4
22
–
–
–
–
–
–
–
1
–
–
–
–
–
1
3
–
–
–
–
–
–
558
583
371
173
16
514
154
551
740
88
22
15
43
17
11
97.7
102.1
65.0
30.3
2.8
90.0
27.0
96.5
129.6
15.4
3.9
2.6
7.5
3.0
1.9
The work involved the completion of the energy questionnaire for 571 households, which amounts
to 6.7% of the total number. The study was completed during 1998 and executed by specially
trained students on a door-to-door basis. Each interview lasted an average of 30 min and it established a relatively good basis for information gathering. The results of the survey are shown in
Tables 1 and 2 and in Figs. 5–10.
An initial finding concerned the awareness of homeowners with respect to energy issues. The
majority seemed to be indifferent to energy conservation practices, did not keep good records of
energy bills and electricity consumption was not top priority when choosing new appliances.
From the total sample of 571 households, 359 (65%) were detached houses and the remaining
Table 2
Distribution of fixtures in households
Type of lamp
Household penetration (%)
Incandescent
Fluorescent
Economic
Halogen
Total
100.0
59.7
16.6
9.8
Lighting capacity installed
(%)
92.1
5.7
1.0
1.2
100.0
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D.A. Haralambopoulos et al. / Energy 26 (2001) 187–196
212 (35%) were apartments in multi-family buildings. Fig. 5 shows the distribution of houses
according to type of building and year of construction. It must be mentioned that a heat insulation
law for the building shell was introduced for the first time in 1979 as a partial response to the
energy crises. This necessitated the installation of heat insulation in walls and other elements of
the building shell in order to reduce space heating. Other efforts on the demand-side management
of energy consumption included a wide campaign to promote compact fluorescent lighting, special
tariffs for night electricity consumption, subsidies for installing solar electric heaters and campaigns promoting energy conservation through rational use of electric appliances, space heating, etc.
The number of houses erected before 1979, i.e., with no thermal insulation, amounts to 67%.
The remaining 33% includes buildings that have some degree of insulation in the sense that, even
with the enactment of the heat insulation law, a significant number of houses were built with no
quality control whatsoever, or malpractices in the installation of the insulation have resulted in
its rapid deterioration [8,9]. The mean household area is 86 m2 with 3.2 inhabitants.
As it can be seen in Fig. 6, 34.4% of the houses are in the 61–90 m2 range. Households with
large floor area, i.e., ⬎120 m2, usually belong to detached houses, whereas the other categories
are more or less equally divided.
The average floor area per occupant is approx. 27.5 m2. For households with one occupant,
the average floor area is 58 m2, which amounts to almost three times the average area per occupant
for households with six occupants (approx. 20 m2 per occupant).
As expected, annual electricity consumption per occupant for the various categories is high for
households with one occupant (approx. 1400 kWh/occupant) and almost half for households with
six occupants (approx. 600 kWh/occupant). The average annual electricity consumption per occupant is around 1042 kWh/occupant.
Detached houses built before the enforcement of the heat insulation law of 1979 were found
to need 24.4% more energy for space heating compared to houses built after 1979 (Fig. 7). It
was found that only 9.2% of houses had double-glazing installed.
Fig. 5.
Distribution of houses according to type and year of construction.
D.A. Haralambopoulos et al. / Energy 26 (2001) 187–196
Fig. 6.
Fig. 7.
193
Distribution of houses according to floor area.
Diesel oil consumption for space heating in detached houses.
Diesel oil, burnt in central boilers and stoves is the main fuel for space heating, and this can
be seen in Fig. 8. Energy conservation worries and environmental sensitivity has lead to the
introduction of a law that implies the regular checking of combustion exhausts in order to guarantee appropriate conditions of burning and minimization of pollutants. It can be seen that electricity
contributes to space heating by approx. 10%. This is a counterproductive way of heating and any
rationalization of energy use should address this issue, and try to eliminate such a means of space
heating, especially in islands with high cost of electricity production and electricity shortages.
Table 1 shows the penetration of electric appliances in the sample of 571 households examined
in Mytilene (out of a total number of 8572 households). It is clear that a certain saturation level
has been achieved for the main appliances like ovens (98%), refrigerators (102%), TV sets (130%),
washing machines (90%), and irons (97%). Any energy conservation attempts, therefore, should
attempt to provide an attractive framework for appliance substitution based on improved energy
consumption. As can be seen in Fig. 9, cooking is mainly done in electric ovens (ca. 86%) since
gas distribution is very limited (ca. 5%) and the old methods of using biomass, used extensively
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Fig. 8. Space heating fuel.
Fig. 9. Cooking mode in households.
until a few years ago, has now been phased out. This comes as a surprise since the island still
has a significant biomass potential that goes unexploited.
Residential hot water is produced mainly in electric heaters (59%), whereas solar hot water
heaters cover only one third of houses (29%), the remaining utilizing woodcuts and biomass (Fig.
10). This rather small proportion indicates a potential for wider solar energy exploitation, provided
that the appropriate measures are taken.
Table 2 shows that all houses had incandescent lamps installed, and a significant proportion
had already started installing fluorescent or economic types. Still, the installed capacity indicates
that overall it was the ordinary incandescent lamps that were mostly used, with fluorescent lamps
representing a very small 5.7%. It was realized that the high purchase price was the main deterrent
for installing the more energy efficient fluorescent lamps. This indicates an area where active
promotion of economic lamps and possible subsidies could have immediate results in reducing
lighting electricity demand.
Finally, it was found that only 8% of households were using night tariffs for electricity consumption. It can be assumed that if a more rigorous policy promoting night tariffs was followed,
D.A. Haralambopoulos et al. / Energy 26 (2001) 187–196
195
Fig. 10. Domestic hot water heating production.
a more smooth diurnal electricity load could be attained avoiding the production of expensive
peak load electricity.
4. Conclusions
In this work, the structure of residential energy consumption in a small tourist town by fuel
and end use is described. The main conclusions are:
1. The impact of the 1979 heating insulation law has been substantial and new houses consume
less for space heating. Efforts should be directed towards enhancing the thermal performance
of old houses through external insulation and double-glazing.
2. Solar energy use for domestic hot water production should be further encouraged to replace
electric heaters.
3. Biomass for space heating can and should replace, to a certain extent, the use of diesel oil.
This will provide an extra income for the olive tree plantations of the island.
4. Policies to curtail electricity use should be enabled. They should incorporate issues such as:
more efficient appliances, more high-efficiency lighting and curtailment of electricity-based
heating.
5. To reduce peak demand during certain periods of the day, restructuring of tariffs should be
considered and night tariffs should be promoted.
6. Awareness of energy conservation was quite low among homeowners. Successful campaigns
should therefore tackle the issue and raise awareness to facilitate penetration of new, more
energy conscious practices.
If these measures are carried out, the need to construct new electric power capacity should be
substantially reduced, with consequent economic and environmental benefits. It must also be added
that, since most of the Aegean islands share similar energy consumption patterns and also have
autonomous electricity grids, energy policy should be formulated along similar lines as concluded
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in this work. This would enable energy, economic and environmental benefits to be materialised
on a much broader scale.
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