The purpose of this study was to explore the water usage profile of future Vietnamese households by carrying out a controlled living experiment with Vietnamese high-income households. By studying showering time, flow rate and toilet-use frequency of these households, the study revealed the water usage believed to be representative of future households in light of continued urbanization. This study also determined that the average time of showering was 9.7 minutes per person per day with an average flow rate of 12 L/minute for the existing shower head and 6.6 L/minute for the water-saving shower head. Toilet usage frequency was 5.25 times per person per day, and there was no difference with the results for an average (middle-income) household.
As a measure against climate change, the Japanese government is promoting the bilateral credit system (Joint Crediting Mechanism: JCM) in order to introduce Japanese advanced low carbon technologies to developing countries and using the quantified reduction in greenhouse gases to reach Japan’s reduction target. The authors focus on the cobenefit of climate change measures and conservation of water resources, and are progressing feasibility studies in the JCM’s aim of promoting water-saving products, such as water-saving showers and toilets [
This study found that while large-scale buildings in Vietnam such as hotels maintain sufficient water-supply pressure (henceforth, water pressure), in typical houses insufficient water pressure has created dissatisfaction among users with shower flow rate [
It is expected that the current lifestyle of high income groupspeople receiving more than 1500 US dollars per month in incomewill spread as urbanization continues. Therefore, this study aimed to predict the water usage profile of Vietnam’s future households, based on the expectation that urbanization will progress, by focusing on high-income households (income of more than 1500 US dollars per month) that had high water pressure. Hence, this study revealed the profile of showering time, flow rate, and water usage of future Vietnamese households by carrying out a controlled living experiment focused on high income groups in Vietnam living in buildings with high water pressure.
In order to set the reference scenario of water usage in Vietnamese households, 9 high-income households (35 Vietnamese people) who lived in houses with consistent water pressure, stayed in test rooms and carried out life as usual. For the test rooms, 3 rooms were used from the high-end Hanoi City serviced apartments. The experiment outline is shown in
In previous studies [
Vietnam extends 1650 km north to south and 600 km east to west. Due to its unique terrain, the northern part has a subtropical climate with four seasons, ranging from cold winter to hot summer, while the central part has a warm climate all year round. The southern part is divided into a dry season and a rainy season, with a tropical monsoon climate. This experiment was conducted in Hanoi city located in the northern part of Vietnam. The experiment was carried
Test period | 1-4 December 2014 |
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Participants | 9 high income households (35 people) living in Hanoi City with consistent water-supply pressure |
Test site | 3 rooms in a 5-star serviced apartment in Hanoi City |
Experiment method | 1) Install in each room’s machine room a flow meter (water supply sensor, hot water supply sensor), temperature sensor (thermocouple). 2) Install a water-saving shower (project device) in each room’s bathroom, and install a flow meter between the faucet and shower hose (cumulative flow display). 3) Measure the optimum flow rate of the existing shower using a representative of each household. 4) Each household in turn stays in one of the rooms for half a day and carries out usual life from dinner to the following morning’s breakfast. While the participants are staying, each person writes down on a set form the times of using the toilet, shower, faucets, washing machine, and dishwasher. 5) When participants use the shower they write the flow amount both before and after showering shown on the flow meter (2) on a designated form for showering. 6) Comparing the value on the flowmeter with the values written on the forms, deduce the amount of water used by each appliance. |
Study items | ・Hot and cold water usage and amount profile of 1 household per day ・Toilet・Shower・Faucets・Washingmachine・Dishwasher water amount consumed and time |
out in December in winter.
The background of participants is shown in
group, and the ages were distributed from 10 to over 60. In Vietnam, it is common to retire at 60, and all those over 60 were unemployed.
The hot and cold water usage amount for each household is shown in
Excluding B-3, B-2 had the lowest level of water usage per person, and C-2 had the highest level: their hot and cold water usage profiles are shown in
The average hot and cold water usage profile of the 9 households is shown in
Family | Stay | No. of people staying | Per day | Per person per day |
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No. | date | Amount of hot and cold water used | Amount of hot and cold water used | |
[L/day] | [L/(person・day)] | |||
A-1 | 12/1 | 4 | 475.2 | 118.8 |
A-2 | 12/2 | 3 | 378.6 | 126.2 |
A-3 | 12/3 | 5 | 673.2 | 134.6 |
B-1 | 12/1 | 4 | 472.3 | 118.1 |
B-2 | 12/2 | 4 | 399.9 | 100.0 |
B-3 | 12/3 | 4 | 241.9 | 60.5 |
C-2 | 12/2 | 4 | 622.6 | 155.6 |
C-3 | 12/3 | 4 | 536.3 | 134.1 |
A representative of each household (total 9 people) used the existing shower in the serviced apartment and the flow rate used when showering normally at home was measured. A rate of 10 - 13.5 L/min was recorded. The average was 12 L/min and it was found that they were showering at a stronger flow rate than the assumed optimum flow rate of 10 L/min of the existing shower.
The distribution of shower flow rate, after changing to a water-saving shower (optimum flow rate 6.5 L/min, water-saving effect 35%), is shown in
We heard that the project device (water-saving shower) provided both water-saving and comfort.
The frequency of showering in one day is shown in
Regarding the showering time, the higher the frequency, the longer the showering time, however, for the people who had numerous showers, with each shower the time became shorter. Therefore, it was decided that it was valid to set in the shower use model “showering time per day (total value)”, rather than “frequency of showering per day × time per shower”.
The showering time per person per day is shown in
Each household’s toilet usage frequency (in this report, this refers to toilet flush frequency) is shown in
Family no. | Stay date | Staying | Toilet usage frequency | |
---|---|---|---|---|
person number | [times/day] | [times/person・day] | ||
A-1 | 12/1 | 4 | 15 | 3.8 |
A-2 | 12/2 | 3 | 19 | 6.3 |
A-3 | 12/3 | 5 | 30 | 6.0 |
B-1 | 12/1 | 4 | 24 | 6.0 |
B-2 | 12/2 | 4 | 11 | 2.8 |
B-3 | 12/3 | 4 | 11 | 2.8 |
C-1 | 12/1 | 3 | 5 | 2.5 (Note) |
C-2 | 12/2 | 4 | 23 | 5.8 |
C-3 | 12/3 | 4 | 17 | 4.3 |
Item name | Gender | Occupation | ||
---|---|---|---|---|
Range | 1.056 | 2 | 4.000 | 1 |
Simple correlation coefficient | 0.233 | 2 | 0.384 | 1 |
Partial correlation coefficient | 0.267 | 2 | 0.403 | 1 |
Pre-school | 2.7 times/(person・day) |
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Student | 4.5 times/(person・day) |
Worker | 4.6 times/(person・day) |
Unemployed (supplement value) | 7.3 times/(person・day) |
Although it is thought that a four-person household is typical, in Vietnam the number of people per household in 2002 was 4.44 and in 2012 it was 3.85 people (data from General Statistics Officer of Vietnam) and it is showing a slight declining trend. Also, in this study, as all the households were dual income, the average Vietnamese household model was a 4 person family with a dual-income couple, a student and an unemployed person. In this model, each person’s household toilet usage frequency was 5.25 times/(person・day), and this was similar to a 2012 study [
In order to establish a reference scenario of for Vietnamese household’s future water usage, a controlled living experiment was conducted with Vietnamese high income earners from houses with consistent water pressure. A water usage profile was revealed of Vietnam’s near-future households, based on continued urbanization, including their bathroom showering time, flow rate used, toilet use frequency. As a result, the showering time was on average 9.7 minutes/(person/day), flow rate of the existing shower was 12 L/minute, and the water-saving shower was 6.6 L/minute. The frequency of toilet usage was 5.25 times/(person/day), and there was no difference with the results of studies with average households (middle income earners). However, since the sample size was 9 households with 35 people, it is too small to say that the results represent Vietnam.
Future research will focus on Vietnamese homes and water used across a year, and further investigates the difference in water usage depending on income, in order to create a reference scenario.
This study was conducted as part of the Ministry of the Environment’s “2014 Feasibility Study on Spreading low carbon, water-saving water supply and waste systems for a Low Carbon Asia”. We thank all the stakeholders involved.
Toyosada, K., Otani, T., Shimizu, Y., Takata, H., Sakamoto, K., Murakawa, S. and Managi, S. (2018) Vietnam’s Future Water Usage Model: A Controlled Living Experiment. Journal of Water Resource and Protection, 10, 204-214. https://doi.org/10.4236/jwarp.2018.102012