Dr. B. E. Psiloglou, Dr. C. Giannakopoulos

1. Characteristics of energy consumption levels for areas in and around Athens Dr. B. E. Psiloglou, Dr. C. Giannakopoulos Institute of Environmental Research & Sustainable Development, National Observatory of Athens, Greece. A. Dagoumas Hellenic Electricity Market Operator S.A., Piraeus, Greece. PROMITHEAS: The Energy and Climate Policy Network 5th International Scientific Conference “Energy and Climate Change” 11 – 12 October 2012, Athens, Greece.

2. The AIM of this work • perform a comparative analysis of electricity consumption levels between Attica main basin and eight locations around Athens in order to … • identify whether locations around Athens that Athenians usually use as “weekend” or “short-break” or even “summer holidays” destinations, present any increases in their levels of consumption. These increases coincide with the periods that inner Athens consumption levels present substantial decreases. how … by presenting time series of diurnal, daily, monthly and yearly variations for each of the selected locations & Athens

3. Factors that Influence Energy Consumption • Human Activities – Habits • Prevailing Meteorological Conditions • (Air Temperature & Rel. Humidity, Wind, Solar radiation Intensity) Data Availability Total Hourly Residential & Commercial Electricity Consumption (kWh) for EIGHT selected locations AROUND ATHENS,spanning the period from January 2005 to December 2011 Divided in two sectors : Southern & Western areas Megara, Korinthos, Xylokastro, Salamina Northern & Eastern areas Nea Makri, Ag. Stefanos, Kalamos, Chalkida Source:  Hellenic Electricity Market Operator S.A. Total Hourly Residential & Commercial Electricity Consumption (kWh) for ATHENS,spanning the period from 1997 to 2001 Source: Public Power Corporation of Greece

4. Peaks in energy demand are linked with extremes in temperature GWh / GNP per capita Daily Mean Air Temperature, Normalized Energy Consumption for Athens, Greece, for the period 1997-2001

5. This pattern is occasionally interrupted on isolated holidays falling in the middle of the week, as well as during Christmas and Easter vacations and also in August for the Athens case. Daily Mean Air Temperature and Normalized Daily Total Energy Consumption, for Athens, Greece, for the year 2001. Energy consumption presents a clear WEEKLY VARIATION with MIN values on Sundays and MAX values close to midweek.

6. Increase in energy consumption mainly due to the extensive use of air-conditioning Lowest air temperatures MAX values in energy consumption Transient season periods The festive Christmas period Easter Holidays Summer Holidays 15th of August Daily Mean Air Temperature and Normalized Daily Total Energy Consumption, for Athens, Greece, for the year 2001.

7. Daily, Weekly, Monthly Variation of Energy Consumption Monthly Seasonal Variation Index(MSVI) MSVIij = MEij /MEj Index for month i in yearj MΕij: monthly energy consumption for month iin year j MΕj: monthly average consumption for year j The use of the MSVI index has the advantage that different levels of electricity consumption can be compared !

8. MAX values of electricity consumption are related to the appearance of the lowest temperatures. Need for space-heating. Increased energy requirements in December, even higher than those in January-February, due to the Christmas festive period. During August, the major part of the population of the greater Athens area is on summer vacation. Ag.Stefanos presenting similar behaviour, turns to be a location of permanent residence rather than a weekend/holiday destination. Increasing trend in electricity demand, mainly due to extensive use of air-conditioners. Need for space-cooling. More recreational activities as people prefer to stay outdoor and return home later. Increasing number of people residing at locations near the sea (country houses of Athens citizens)

9. Daily, Weekly, Monthly Variation of Energy Consumption Daily Seasonal Variation Index(DSVI) DSVIijk = DEijk /DEjk Index for day iof week j of year k DΕijk: energy consumption for the particular iday DΕjk: mean daily electricity consumption for week j of year k The use of the DSVI index has again the advantage that different levels of electricity consumption can be compared !

10. Electricity consumption is lower during weekends (especially during Sundays) due to the reduced economic activity. Lower levels of electricity consumption are also present on Mondays because of the inertia caused by the reduced economic activity during the weekends In the cases of Salamina, Kalamos and Xylokastro, electricity consumption increases during weekends with a peak during Saturdays. This reflects the fact that an additional number of people visit the locations from other areas, hence increasing the demand this day.

11. Daily, Weekly, Monthly Variation of Energy Consumption Hourly Seasonal Variation Index (HSVI) Index for hour i of the average 24-hours period, of month j in year k HSVIijk = HEijk /HEjk HΕijk: electricity consumption for a certain hour HΕjk: mean monthly energy consumption for month jin yeark The use of the HSVI index has again the advantage that different levels of electricity consumption can be compared !

12. During the working hours of the day, there is an extensive use of electricity both for household (cooking, heating) and business (office heating, server and PC usage) needs. During the late afternoon and early evening hours, there is a second max due to the use of lighting and heating/cooking using additional heaters or air-conditioners.

13. In all cases, during JANUARY, there are two distinct maxima: one close to midday (cooking, heating, office needs) and another in the evening (lighting, extra heating, home entertainment) as most people stay indoors. It is worth noting the differences in HSVI when studying it in different seasons, most notably summer (JULY) and winter (JANUARY).

14. Ag.Stefanos presenting a behaviour similar to Athens, turns to be a location of permanent residence rather than a weekend/holiday destination. During JULY, there is a midday max which occurs at the same hours as the January one and is greater, and an evening max which occurs much later and is much less pronounced. In the late afternoon/early evening hours, there is a decrease in electricity demand reflecting the fact that most people like to stay outdoors for dinner or other recreational activities and return home late.

15. Conclusions This work presents a comparative study of energy demand, in terms of electricity consumption, for eight locations around Athens, and the Attica main basin, seeking to identify which of these locations present increases in their electricity consumption levels during weekends and short-break holidays, when inner Athens consumption levels present substantial decreases. • For all areas, the winter peak is associated with low air temperatures • The summer peak is mainly linked to higher temperatures and increased air-conditioning use, with an exception for Athens center and Ag. Stefanos which turns to be more a location of permanent residence rather a location for weekend/holiday destination. • Summer peak is also connected to the increase in the number of people residing in the areas close to the sea for holidays. ……►

16. Conclusions … • Most locations, including Athens, exhibit lower energy demand levels during weekends (especially Sundays), with the exception of Salamina, Kalamos and Xylokastro, where electricity increases on Saturday signaling the arrival of extra weekend visitors. • The hourly variation of energy demand levels has two maxima in all locations (around midday and evening) • The hourly variation present differences when studying it in different seasons : during JANUARY there are two distinct maxima in electricity demand, while in JULY the midday maximum occurs almost at the same hour but the evening maximum occurs later and is less pronounced than the January one. • The main advantage of MSVI, DSVI, and HSVI indexes use is that different levels of energy consumption can be compared !

17. THANK YOU FOR YOUR ATTENTION E-mail: bill@meteo.noa.gr cgiannak@meteo.noa.gr