Proceedings of Clima 2007 WellBeing Indoors
Household Energy Consumption under Different Lifestyles
Wee-Kean Fong1, Hiroshi Matsumoto1, Yu-Fat Lun2 and Ryushi Kimura1
1
2
Toyohashi University of Technology, Japan
Tohoku University, Japan
Corresponding email: [email protected]
SUMMARY
This study investigated the impacts of lifestyle in terms of family patterns, life schedules and
climate factors upon household energy consumption, as well as to unfold the main causes of
household energy consumption under various climatic lifestyles. Based on the findings of the
previous studies, it was assumed that space heating, cooling, lighting and entertainment/media
equipments usages are the major lifestyle and climate related sources of household energy
consumption. Based on these aspects, together with the typical life schedules of different
occupation groups, climatic data and typical family patterns, lifestyles related household
energy consumptions were calculated for Hokkaido (cool temperate climate), Saitama
Prefecture (temperate climate) and Kogoshima Prefecture (varies from temperate to subtropical climates) of Japan, for years 2005, 2010, 2015, 2020 and 2025. The results
confirmed that regional basis lifestyles in terms of family patterns, life schedules and climate
factors are significant in dictating the household energy consumption trends.
INTRODUCTION
The Intergovernmental Panel on Climate Change (IPCC) has predicted a rise in the average
global surface temperature of about 2°C between 1990 and 2100, and the average sea level is
also projected to rise by about 50cm over the same period [1]. The projected climate changes
are expected to result in significant adverse impacts on ecological systems and socioeconomic sectors. In view of the continued rise of greenhouse gas (GHG) concentrations in
the atmosphere, which may lead to dangerous interference with the climate system, the United
Nations Framework Convention on Climate Change (UNFCCC) sets an ultimate objective of
stabilizing GHG concentrations in the atmosphere. Under the Kyoto Protocol, the
participating developed countries are committed to reduce their GHG emissions on an average
of about 5% by the target years of 2008 to 2012 [2].
GHG emission is closely related to energy
consumption. Based on the projection by the
International Energy Outlook 2006, world carbon
dioxide emission from the consumption of fossil
fuels is expected to grow at an average rate of 2.1
percent per year from 2003 to 2030 [3]. The
world CO2 emission from the consumption of
fossil fuels is predicted to increase from less than
20,000 million metric tons in 2003, to more than
40,000 million metric tons by 2030, as shown in
Figure 1. Hence, in handling GHG emission issue,
energy consumption should firstly be looked into.
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Figure 1. World CO2 emissions from
energy use, 1990-2030 [3]
Proceedings of Clima 2007 WellBeing Indoors
In response to the above issues, the present authors had previously undertaken a study to
investigate the urban energy consumption trends [4]. The said study was based on an
integrated approach to investigate the embodied urban energy consumption over a period of
50 years using the System Dynamic model (SD model). The study found that household
energy consumption and lifestyle aspects are among the significant factors in dictating the
overall urban energy consumptions trend. The current study is a continuous work from the
previous investigation and it was focusing on understanding of the interrelations between
household energy consumption, lifestyle and climate factors.
In Japan, there are a number of existing researches on household energy consumption and
lifestyle. However, little has been done in cogitating about the effects of lifestyle in terms of
family patterns and life schedules of family members on household energy consumption. In
view of these shortfalls, the purpose of this study is to shed new light on the impacts of
lifestyle (in terms of family patterns and life schedules) and climate factors (under different
climate zones of Japan) upon household energy consumption.
In most the previous studies on lifestyle and household energy consumption, questionnaire
survey and long-term on-site monitoring/measurement methods were commonly used.
Despite the better accuracy of data, the disadvantages of these methods are that they are very
costly and time consuming. This study thus stressed to estimate the lifestyle related
household energy consumption using on the existing life schedule data, which is low cost and
time saving, and yet able to provide reasonably accurate estimate of energy consumption.
The objectives of the study are to understand the effects of family pattern, life schedule and
climate aspects on household energy consumption.
METHODS
N
The climate of Japan is predominantly temperate, but
Hokkaido
due to the large north-south extension of the country,
the climate varies strongly in different regions.
Generally, northern Japan is experiencing cooltemperate climate, central Japan is temperate, while
southern Japan is under sub-tropical climate. In order
Tokyo
to understand the differences in domestic energy
Saitama
consumption patterns under different climatic
Prefecture
characteristics, the case study was divided into three
parts according to the climate zones i.e. Hokkaido for
Kogoshima
cool-temperate zone, Saitama Prefecture for temperate
Prefecture
zone, while Kagoshima Prefecture is experiencing
climates that varies from temperate to sub-tropical. (cf. Figure 2. Locations of case study areas
Figure 2).
Figure 3 outlines the study methodology of the current investigation. From the literature
review, it was pointed out in the previous studies [5,6,7] that space heating, cooling, lighting,
electronic entertainment/media equipments and hot water supply are the major sources of
household energy consumption. The current study adopted these factors as the major lifestyle
and climate related sources of household energy consumption, however, hot water supply was
excluded in this study due to absence of life schedule data on this aspect (hereinafter,
household energy consumption by space heating, cooling, lighting and entertainment/media
equipments shall be referred as ‘lifestyle related household energy consumption’).
Proceedings of Clima 2007 WellBeing Indoors
Identification of main lifestyle and climate related sources of household energy
consumption (heating, cooling, lighting, entertainment/media usages)
Life schedule
Durations of:
Staying at home
Sleeping & non-sleeping time
Electronic media/entertainment
equipment usage
Family pattern
Climatic lifestyle
General and elderly families of
Single-member
Husband-wife
Husband-wife-child compositions
Lifestyles in:
Heating
Cooling
Lighting
Estimate of main lifestyle and climate related household energy consumption, 2005-2025
Northern Japan: Hokkaido
Central Japan: Saitama Prefecture
Southern Japan: Kagoshima Pref.
Scenario 1
Scenario 2
Scenario 1
Scenario 2
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Scenario 3
Scenario 4
Scenario 3
Scenario 4
Note: Details of Scenarios 1, 2, 3 and 4 are described in Table 1.
Figure 3. Study methodology
As mentioned above, the purpose of this study was to investigate the impacts of life schedule,
family pattern and climate factors on household energy consumption. For this reason,
detailed analysis had been carried out on these three aspects.
For the life schedules, typical life schedules of people of different occupation groups
(working groups, housewives, retirees, students, children below schooling age) were
identified based on the life schedule survey by the Japan Broadcasting Corporation in 2005,
on 12,600 respondents throughout Japan [8]. In this study, the extracted data include the
average durations of time staying at home, sleeping & non-sleeping times and for
media/entertainment equipment usages (television, radio, CD/MD/cassette player and video).
Based on the above life schedule data and climatic information (sourced from the Japan
Meteorological Agency and National Astronomical Observatory of Japan), as well as other
relevant studies [5,7] together with necessary assumptions, typical trends of heating, cooling,
lighting and media/entertainment equipment usages under the three climate zones were
determined.
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For family pattern, based on the projection by the
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Japan National Institute of Population and Social
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by the year 2025, about 79.5% of the families in
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Japan would be in the categories of single-member
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family (i.e. 1 person), husband-wife family (i.e. 2
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proportion of population age 65 and above will
increase from 19.9% in 2005 to 24.4% in 2025, and
Figure 4. Japanese family patterns [9]
35.7% by 2050 [10]. Based on this information,
this study focused on these three family groups and the elderly family groups for the estimate
and analysis of household energy consumptions.
Based on the above data and assumptions, typical lifestyles related household energy
consumptions were estimated for Hokkaido, Saitama Prefecture and Kagoshima Prefecture,
Proceedings of Clima 2007 WellBeing Indoors
for years 2005, 2010, 2015, 2020 and 2025. The projections were carried out according to the
official household projection data of each region [10]. The assumptions for energy
consumption rates were based on the typical energy consumption rates of the relevant
household electrical appliances in Japan, as well as reference to the household energy
consumption survey carried out by the Architectural Institute of Japan (AIJ) [5].
The projections for lifestyle related household energy consumption were carried out for four
scenarios as described in Table 1. Under these projections, it was assumed that there is no
change of energy efficiency and no extra energy saving effort as compared to the present
trend.
Table 1. Projection scenarios
Scenarios
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Descriptions
Projection based on the existing typical lifestyles and the official
population projection statistical data [10].
Instead of the official household projection data, it was assuming that
the proportion of family groups in year 2005 to be remained
unchanged over the projection period, while population growth was
based on the official projection data [10] as in Scenario 1, and other
factors as per Scenario 1.
Instead of being housewives in the traditional Japanese families, this
scenario assumed that the proportion of working women would be
increased, while other factors as per Scenario 1.
It is assuming that the average daily working hours of the working
groups would be reduced by 1 hour over the projection period, while
other factors as per Scenario 1.
RESULTS
Before presenting the analysis results, it is necessary to
describe the trends of population and household
growths in the three chosen case study areas. The 2005
populations of Hokkaido, Saitama Prefecture and
Kagoshima Prefecture were about 5.7, 6.9 and 1.8
millions respectively. Projection by the Japan National
Institute of Population and Social Security Research
shows that the population of Hokkaido and Kagoshima
Prefecture will gradually drop over the next 20 years,
while in Saitama Prefecture, the population will
slightly grow until 2015 then decrease gradually [10],
cf. Figure 5.
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Figure 5. Population projections
for Hokkaido, Saitama Prefecture
and Kagoshima Prefecture [10]
In the next 20 years time, as shown in Figure 6, the number of single-member families (SM)
and husband-wife families (HW) will increase steadily, while the number of husband-wifechild families (HWC) will continue to drop in all these three regions. It must also be noted
that the proportion of elderly families are projected to increase significantly, particularly in
the single-member family and husband-wife family sectors. Projection shows that the family
pattern in Japan is moving towards small family’s direction, whereby the single-member
families and husband-wife families will constitute more than 50% of the overall Japanese
families by the year 2025.
Proceedings of Clima 2007 WellBeing Indoors
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Figure 6. Household growth trends of Hokkaido, Saitama Prefecture and Kagoshima
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reference case for Scenarios 2, 3 and 4. Despite
the expected continuous decrease of population in Figure 8. Lifestyle related household
energy consumption under Scenario 1
Hokkaido and Kagoshima Prefecture, the total
(based on official household projection data)
lifestyle related household energy consumption
increases until 2015 and 2020 respectively. For Saitama Prefecture, the population is
expected to drop after 2015, cf. Figure 5, but the total lifestyle related household energy
consumption will increase until 2020. The increase of energy consumption despite population
drop is mainly attributed to the reduction of family sizes and growth of elderly households.
The calculated results also show that energy consumption in Hokkaido is higher compared to
the southern regions. It is basically due to energy consumption for heating. Similar findings
were also showed in the residential energy consumption survey carried out by AIJ [5].
Another reason of higher energy consumption in the northern regions was the energy
consumption for lighting. In Hokkaido, generally more than half of a year the sunset time is
earlier than 6.00pm, while in Kagoshima it is only about 3 months.
Proceedings of Clima 2007 WellBeing Indoors
Figure 9 shows the calculated results of Scenario 2 in comparison to Scenario 1. Under
Scenario 2, the energy consumption was calculated based on the assumption that the 2005’s
family pattern (the proportions of each family group) will remain unchanged over the
projection period. It is obvious that the energy consumption would be significantly reduced if
there is no change of family pattern. Under the official household projection, the shares of
single-member families and husband-wife families will significantly increase in future (cf.
Figure 6). The reduction of family size results in higher energy consumption because of
higher per-person energy consumption rate and increased number of households/residential
units. The result concludes that family size has inverse relation with household energy
consumption. In the case of Hokkaido, under Scenario 1, the energy consumption increases
until 2015 but under Scenario 2, the energy consumption consistently drops over the
projection period. The huge different of energy consumption under Scenarios 1 and 2 in
Hokkaido was because of drastic drop of husband-wife-child families and significant increase
of the share of single-member families under Scenario 1.
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Figure 9. Lifestyle related household energy consumption under Scenario 2
(assuming that the family pattern of year 2005 remains unchanged)
It was indicated previously in Figure 7 that households with housewives generally consumed
more energy because of longer hours staying at home. Scenario 3 attempts to validate this
statement. Under this scenario, energy consumption was calculated based on increased
proportion of working women (reduced proportion of housewives), which results in shorter
duration of energy usage for heating, cooling and lighting. As shown in Figure 10, regardless
of energy consumption at the workplace, increased proportion of working women will reduce
the household energy consumption.
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Figure 10. Lifestyle related household energy consumption under Scenario 3
(increased proportion of working women)
Scenario 4 calculates the lifestyle related household energy consumption under assumption of
reduced working hours. The Japanese Government is presently encouraging people to reduce
working hours and spend more time with family at home. This scenario investigates its
impact on household energy consumption if the average working hours of the working groups
were reduced by one hour per day. The calculated results obtained (cf. Figure 11) shows that
reduced working hour will result in increase of household energy consumption. It is because
Proceedings of Clima 2007 WellBeing Indoors
longer hours at home mean spending more household energy, particularly on space heating,
cooling and lighting.
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Figure 11. Lifestyle related household energy consumption under Scenario 4
(reduced working hours)
DISCUSSION
From the above results, it can be inferred that lifestyles in terms of life schedule and family
pattern, and climate factors have significant effect in predominating over the household
energy consumption trends.
In most of the previous studies on lifestyle and household energy consumption found in
literature, the focuses were put on the energy saving potential by practicing energy saving
smart lifestyle in term of the usage of energy consuming household appliances. However, it
is difficult to get long-term cooperation from all households. For example, in the survey
conducted by AIJ [5], the respondents were not practicing energy saving lifestyles in most of
the aspects in household daily life.
Besides the aforementioned lifestyle aspect, there are also some other aspects of lifestyle that
have indirect effect on household energy consumption. This study pointed out that lifestyles
in terms of life schedule and family pattern do have significant impacts on household energy
consumption. The longer time staying at home results in higher energy consumption, this is
even more notable in the northern regions where long hours heating and lighting are necessary.
Hence, the higher proportions of housewife and retiree population, who tend to spend more
time at home, implying higher household energy consumption.
In terms of family pattern, smaller family size results in higher per-person energy
consumption. In Japan, the family sizes are getting smaller and smaller (cf. Figure 4), as
mentioned earlier, smaller family size is expected to result in higher household energy
demand. The situation is worse when the smaller family size coupled with the rapid increase
of retired elderly who consumes more household energy due to longer duration at home.
Hence, in order to reduce energy consumption for space heating/cooling and lighting, it is
deemed necessary to encourage the usage of smaller power space heating/cooling and lighting
equipments. Besides improvement of energy efficiency, it can also be achieved by having
smaller and enclosed partitions/room in the residential buildings (particularly the living room
and dining room), so that same space heating/cooling and lighting effect can be achieved with
smaller power equipments. Also, in term of lifestyle, the family members should be
encouraged for shared usage of space heating/cooling and lighting by spending more times in
the common spaces such as living room, particularly during evening time when most of the
family members are at home.
Another aspect of lifestyle that has significant impact on household energy consumption is the
climatic lifestyle. This study indicated that households in the northern regions of Japan (cold
Proceedings of Clima 2007 WellBeing Indoors
region) generally consume more energy in comparison with the southern regions (warmer
region). As mentioned above, the main reasons are energy requirements for heating and
lighting. Thus, as part of the efforts to reduce the energy consumption in the northern regions,
it is necessary to reduce the heating and lighting requirement by passive design measures such
as introducing solar radiation in winter through windows facing south, double glazing
windows, airtight building, direct solar radiation for lighting, etc. for the residential buildings
in the cold regions. Besides, it is also important to reduce the energy consumption for heating
and lighting by introducing higher energy efficient heating and lighting equipments.
Although this study has effectively pointed out the importance of some aspects of lifestyle in
household energy planning, it must also be noted that there are some limitations with this
study. Firstly, fixed energy consumption rates were applied for the projections of future
energy consumptions. So it may not reflect the actual amount of future energy consumption.
Secondly, the household energy consumptions were calculated based on the typical life
schedules and energy consumptions of household appliances and climatic data. Thus, it may
not represent the actual energy consumption of each household. However, in this study, the
main purpose is to understand the energy consumption trend rather than predicting the future
energy demand. Hence, the results were deemed sufficient to illustrate the possible future
household energy consumption trends. Nevertheless, these limitations will be taken into
consideration in the future studies.
This study based on the case of Japan is deemed important as Japan is often used as a model
for development in other Asian countries, hence the findings will have implications beyond
Japan. Japan is now experiencing social change such as aging society and shrinking family
sizes. This study found that these social changes will indirectly result in increased household
energy consumptions. It is believed that the existing developing countries will also
experience similar social change in future, which will eventually affect the household energy
consumption trends. Hence, it is vital to take these aspects into consideration in their longterm energy planning.
REFERENCES
1. IPCC. 2004. 16 years of scientific assessment in support of the climate convention. Geneva:
Intergovernmental Panel on Climate Change.
2. UN. 1998. Kyoto Protocol to the United Nations Framework Convention on Climate Change. New
York: United Nations.
3. U.S. DOE. 2006. International energy outlook 2006. Washington DC: U.S. Dept. of Energy.
4. Fong, W K, Matsumoto, H, Lun, Y F, et al. 2007. System dynamic model for the prediction of
urban energy consumption trends. ‘The 6th International Conference on Indoor Air Quality,
Ventilation & Energy Conservation in Buildings’ (IAQVEC 2007) on 28-31 October 2007, in
Sendai, Japan. (To be presented)
5. AIJ. 2006. Energy consumption for residential buildings in Japan. Tokyo: Architectural Institute
of Japan. (in Japanese)
6. Takuma, Y, Inoue, H, Nagano, F, et al. 2006. Detailed research for energy consumption of
residences in Northern Kyushu, Japan. Journal of Energy and Buildings, Vol.38 (2006),1349-1355.
7. Tsurusaki, T, Murakoshi, C, Yokoo, M, et al. 2000. Measurement and analysis of residential
energy consumption in Hokkaido. Proceeding of the Conference on Energy, Economy and
Environment, Vol. January 2000, pp 417-422. (in Japanese)
8. NHK. 2006. Life Schedule Survey Report 2005. Tokyo: Japan Broadcasting Corp. (in Japanese)
9. Japan National Household Projection 2003. Tokyo: National Institute of Population and Social
Security Research. (in Japanese)
10. Japan Population Projection 2006. Tokyo: National Institute of Population and Social Security
Research. (in Japanese)