Energy 26 (2001) 187–196www.elsevier.com/locate/energy

The structure of residential energy use on a North Aegeanisland: the town of Mytilene

D.A. Haralambopoulos*, P. Fappas, M. Safos, H. KovrasDepartment 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 capitalof a relatively large Aegean island and to propose remedial actions in order to reduce consumption andavoid 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 cultivationof olive trees, the use of these two renewable resources should be encouraged. It was also realized thatthe enactment of a heating insulation law has had substantial results. 2001 Elsevier Science Ltd. Allrights reserved.

1. Introduction

The North Aegean region, comprises of nine relatively large islands and a number of smallerones, is located in the Eastern part of the Aegean sea, at a significant distance from the mainlandof Greece. The islands lack any indigenous solid fuel sources and depend upon imports to coverthe 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 verysmall.

The total population of the region is around 200,000 inhabitants (1991 census), which amountsto 1.9% of the total population of Greece. The main activities of the people are concerned withagriculture, 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: S0360-5442(00)00069-4

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during recent years and is the main culprit, together with the increasing standards of living, forthe ever increasing energy consumption. It must be mentioned that the peak demand in electricityconsumption is currently during the summer months and this is attributed to the operation of thelarge hotels.

In this study we focus on energy consumption in the residential sector of Mytilene, which isthe capital of Lesvos, the largest island of the North Aegean. A suitable questionnaire wasdeveloped that addresses the energy consumption characteristics of the households and three teamsof two people each were trained to fill the relevant forms. The analysis of the data gave valuableinformation 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 about25% of the total energy demand in most OECD countries [1]. This fact has prompted a numberof investigators to examine the interconnections of various parameters in order to deduce appropri-ate policy measures to reduce energy consumption in this sector [2,3]. The vital components ofhome energy conservation programs were found to be residents’ energy use behavior, a dimensionthat is not always included in local government home energy conservation programs [4], and theopportunities 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 from1991 to 1997 that has prompted the current study, since there is mounting pressure to install newpower plants. This increase reflects the increasing standards of living, since the population hasremained 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 influ-ence total energy consumption, one must focus on these two sectors. The tertiary sector, whichincludes 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.

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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 combus-tion engines burning crude oil and one gas turbine which serves peak load and burns expensivediesel 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 theimmediate future. The overall cost of electricity production is high and the nationalized PublicPower Corporation (PPC) subsidizes electricity generation, maintaining the same prices in themainland and the islands. More specifically, the fuel cost for electricity production is approx. 15drh/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), whichimplies a large subsidy for electricity and creates incentives for the Government to reduce elec-tricity consumption.

The diurnal distribution of electricity consumption follows a rather typical 24-h pattern withtwo peaks, one during 12:00 midday and the other at around 18:00–20:00 in the evening. InFig. 3, the diurnal distribution for a day with the maximum and a day with the minimum loadare 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 wasfound that space heating was the main energy consumer for the residential sector [7]. It accountedfor 52% of the total and, together with cooking (16%) and hot water heating (11%) was respon-sible 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 coastin the south-east corner of the island and is exposed to northern winds. To the west, smooth hillsgive shelter from the weather. The thermal plant that supplies the island grid with electricity islocated a few hundred yards from the north edge of the town, and the prevailing winds bringmost of the air pollution over the town. The number of households in the town is 8572 (1991census) 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 asurvey for the residential energy consumption in Mytilene. A relevant questionnaire wasdeveloped that took into account data concerning:

O house characteristicsO electricity consumptionO heating energy consumptionO domestic hot water production applianceO lighting (structure and number of bulbs)O building envelopeO floor areaO year of constructionO type of buildingO number of occupants.

Fig. 4. Domestic energy consumption in the N. Aegean islands by end use (1988).

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Table 1Electric appliance penetration in the 571 households examined

Total PenetrationType of appliance Households by No. of appliances

appliances (%)

0 1 2 3 4

Oven 20 544 7 – – 558 97.7Refrigerator 3 529 35 3 1 583 102.1Electrical hw heater 203 365 3 – – 371 65.0Kitchen hw heater 396 173 2 – – 173 30.3Rapid hw heater 555 16 – – – 16 2.8Washing machine 63 502 6 – – 514 90.0Dish washer 415 152 1 – – 154 27.0Iron 36 525 5 4 1 551 96.5Television 12 406 128 22 3 740 129.6Computer 489 76 6 – – 88 15.4Freezer 549 22 – – – 22 3.9Microwave oven 556 15 – – – 15 2.6Gas cooker 528 43 – – – 43 7.5Iron press 554 17 – – – 17 3.0Toaster 560 11 – – – 11 1.9

The work involved the completion of the energy questionnaire for 571 households, which amountsto 6.7% of the total number. The study was completed during 1998 and executed by speciallytrained students on a door-to-door basis. Each interview lasted an average of 30 min and it estab-lished a relatively good basis for information gathering. The results of the survey are shown inTables 1 and 2 and in Figs. 5–10.

An initial finding concerned the awareness of homeowners with respect to energy issues. Themajority seemed to be indifferent to energy conservation practices, did not keep good records ofenergy 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 2Distribution of fixtures in households

Lighting capacity installedType of lamp Household penetration (%)

(%)

Incandescent 100.0 92.1Fluorescent 59.7 5.7Economic 16.6 1.0Halogen 9.8 1.2Total 100.0

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212 (35%) were apartments in multi-family buildings. Fig. 5 shows the distribution of housesaccording to type of building and year of construction. It must be mentioned that a heat insulationlaw for the building shell was introduced for the first time in 1979 as a partial response to theenergy crises. This necessitated the installation of heat insulation in walls and other elements ofthe building shell in order to reduce space heating. Other efforts on the demand-side managementof energy consumption included a wide campaign to promote compact fluorescent lighting, specialtariffs for night electricity consumption, subsidies for installing solar electric heaters and cam-paigns promoting energy conservation through rational use of electric appliances, space heat-ing, 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, evenwith the enactment of the heat insulation law, a significant number of houses were built with noquality control whatsoever, or malpractices in the installation of the insulation have resulted inits 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 withlarge floor area, i.e.,.120 m2, usually belong to detached houses, whereas the other categoriesare 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 occupantfor households with six occupants (approx. 20 m2 per occupant).

As expected, annual electricity consumption per occupant for the various categories is high forhouseholds with one occupant (approx. 1400 kWh/occupant) and almost half for households withsix occupants (approx. 600 kWh/occupant). The average annual electricity consumption per occu-pant is around 1042 kWh/occupant.

Detached houses built before the enforcement of the heat insulation law of 1979 were foundto need 24.4% more energy for space heating compared to houses built after 1979 (Fig. 7). Itwas found that only 9.2% of houses had double-glazing installed.

Fig. 5. Distribution of houses according to type and year of construction.

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Fig. 6. Distribution of houses according to floor area.

Fig. 7. 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 canbe seen in Fig. 8. Energy conservation worries and environmental sensitivity has lead to theintroduction of a law that implies the regular checking of combustion exhausts in order to guaran-tee appropriate conditions of burning and minimization of pollutants. It can be seen that electricitycontributes to space heating by approx. 10%. This is a counterproductive way of heating and anyrationalization of energy use should address this issue, and try to eliminate such a means of spaceheating, 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 examinedin Mytilene (out of a total number of 8572 households). It is clear that a certain saturation levelhas 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, shouldattempt to provide an attractive framework for appliance substitution based on improved energyconsumption. As can be seen in Fig. 9, cooking is mainly done in electric ovens (ca. 86%) sincegas 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 stillhas a significant biomass potential that goes unexploited.

Residential hot water is produced mainly in electric heaters (59%), whereas solar hot waterheaters 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, providedthat the appropriate measures are taken.

Table 2 shows that all houses had incandescent lamps installed, and a significant proportionhad already started installing fluorescent or economic types. Still, the installed capacity indicatesthat overall it was the ordinary incandescent lamps that were mostly used, with fluorescent lampsrepresenting a very small 5.7%. It was realized that the high purchase price was the main deterrentfor installing the more energy efficient fluorescent lamps. This indicates an area where activepromotion of economic lamps and possible subsidies could have immediate results in reducinglighting electricity demand.

Finally, it was found that only 8% of households were using night tariffs for electricity con-sumption. It can be assumed that if a more rigorous policy promoting night tariffs was followed,

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Fig. 10. Domestic hot water heating production.

a more smooth diurnal electricity load could be attained avoiding the production of expensivepeak load electricity.

4. Conclusions

In this work, the structure of residential energy consumption in a small tourist town by fueland end use is described. The main conclusions are:

1. The impact of the 1979 heating insulation law has been substantial and new houses consumeless for space heating. Efforts should be directed towards enhancing the thermal performanceof old houses through external insulation and double-glazing.

2. Solar energy use for domestic hot water production should be further encouraged to replaceelectric 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-basedheating.

5. To reduce peak demand during certain periods of the day, restructuring of tariffs should beconsidered and night tariffs should be promoted.

6. Awareness of energy conservation was quite low among homeowners. Successful campaignsshould therefore tackle the issue and raise awareness to facilitate penetration of new, moreenergy conscious practices.

If these measures are carried out, the need to construct new electric power capacity should besubstantially reduced, with consequent economic and environmental benefits. It must also be addedthat, since most of the Aegean islands share similar energy consumption patterns and also haveautonomous 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 materialisedon a much broader scale.

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