A USER CENTRIC APPROACH TO THE DEVELOPMENT AND

TESTING OF A HOME ENERGY MANAGEMENT SYSTEM

Jeroen Stragier

and Jan Derboven

Interdisciplinary Institute for Broadband Technology – Research Group for Media and ICT (IBBT-MICT)

Department of Communication Sciences, Ghent University, Korte Meer 7-9-11, 9000, Ghent, Belgium

Interdisciplinary Institute for Broadband Technology – Centre for User Experience Research (IBBT-CUO)

Faculty of Social Sciences, Katholieke Universiteit Leuven, Parkstraat 45 bus 3605, B-3000, Leuven, Belgium

Keywords: Home Energy Management, Smart Grids, Smart Metering.

Abstract: The development and small scale field trial in Flanders of a home energy management system is presented.

During the development, a user-centric approach was used to create interaction between developers and

possible end-users in a living lab setting. This allowed actively addressing people’s needs and wants in the

development process and testing the system in their homes. The preliminary results of the field trial indicate

a high usage during the starting week, which gradually slows down over the weeks that follow. Usage of the

different elements in the system varies over the weeks but a consistent “top 3” of elements remains.

Dynamic pricing is used by a small but consistent part of the participants. They actively adapt their

appliance usage to these prices.

1 INTRODUCTION

Smart grids are high on the agenda. While the focus

of the benefits of these improved electricity

infrastructures are mainly on the technical and

structural side, end-users and more specifically

households can also benefit from the new

possibilities of smart grids and especially smart

meters that are to be installed in their houses. These

new meters can provide the end-user with detailed

information on their energy use, something that

many households find lacking today. Moreover,

many studies have indicated that information or

“feedback” is indeed an effective means to create

awareness and possibly reduce energy use. Not only

information on energy use can be improved, new

energy pricing strategies can be developed, such as

dynamic pricing, in which varying electricity prices

can be used over the course of the day, with e.g.

high prices at peak moments and low prices at off-

peak moments. The delivery of detailed information

to the end-user can be done in many ways starting

with e.g. more detailed billing over online

monitoring portals to full scale home energy

management systems. This paper presents a user-

centric approach to the development of a home

energy management system. The research involved

the constant interaction between system developers

and the panel of users, whose input was of vital

importance to the development of the system, in a

living lab setting. Stahlbrost (2008) defines a living

lab as a “human-centric research and development

approach in which IT-systems are co-created, tested,

and evaluated in the users’ own private context”.

This has been the main approach from the start of

the development to the final testing. Currently, a

small scale field trial is in progress in the homes 21

families in Flanders, Belgium. Preliminary results on

usage of the developed system are presented.

2 EFFECT OF FEEDBACK ON

ENERGY USE

Feedback can have a positive effect on a households

energy use, as research has indicated many times

(Darby 2006; Dobson and Griffin 1992; Fischer

2008; Froehlich 2009; Ueno et al. 2006; Wood and

Newborough 2003). It provides users with

information on the results of the energy efficiency

measures taken. Home energy management systems

can be an effective means to provide tailor-made

185

Stragier J. and Derboven J..

A USER CENTRIC APPROACH TO THE DEVELOPMENT AND TESTING OF A HOME ENERGY MANAGEMENT SYSTEM.

DOI: 10.5220/0003948101850190

In Proceedings of the 1st International Conference on Smart Grids and Green IT Systems (SMARTGREENS-2012), pages 185-190

ISBN: 978-989-8565-09-9

 2012 SCITEPRESS (Science and Technology Publications, Lda.)

feedback to households. Evidence for this has been

found in several experiments in which feedback was

provided to household by means of computer

systems or in-home displays (e.g. Brandon and

Lewis 1999; Ueno et al. 2006) ). However, although

the effect of feedback of energy use on behaviour

has been indicated by many studies, similar studies

also argue that its effect on behaviour and awareness

is likely to fade away when no further feedback is

provided (for instance, when proof-of-concept

technology is removed from the house). This implies

that giving feedback on energy use does not

necessarily lead to long-term changes in the users’

behaviour. Darby (2006) argues that continued

feedback is necessary to create persistence in the

change of behaviour. Home energy management

systems offer an excellent means to provide end-

users with persistent feedback on their energy use.

3 USER CENTRIC

DEVELOPMENT OF THE

SYSTEM

In this section, the methodology and the results of

the user research are presented. The research part

first presents the actual user research consisting of a

description of the field research, and the further

(both qualitative and quantitative) analysis of the

field data. Preliminary results of a currently ongoing

field trial are subsequently presented.

3.1 User Research

3.1.1 Large Scale Survey

As a first step in the actual user research, an online

survey was held with a representative sample in

Flanders. The sample collected through this survey

would form the base of recruitment for the next

phases of the research. In the survey, structural,

behavioural and attitudinal data regarding energy

use in a domestic situation was collected. This

resulted in a database (N=1314) containing

information of the panel members on e.g. their type

of house, level of insulation of the dwelling, how

consciously they’re using energy, their

environmental attitude and so on. A number of

questions addressed the degree to which they already

monitor their energy use by keeping e.g. excel files

containing meter readings or by using existing tools.

We also asked how likely they would be to buy

devices helping them to monitor e.g. their electricity

use. From the database of the quantitative survey, a

list of interesting respondents was compiled to be

contacted for further participation in the

development.

3.1.2 Diary Study

In total, 30 households agreed to participate in the

diary study. This study was conceived as a small

snapshot of the participants’ daily energy use habits.

To get this snapshot, the interviewees were asked to

keep a diary during two weeks. Use of electrical

appliances, heating settings, bathing frequency,

specific actions taken to lower energy use, general

behaviour, such as talking about energy use,

searching for information, etc. were registered in the

diary. In order to make this as easy as possible to fill

in, a diary template was distributed to the

participants. In the templates, they were asked to fill

in a general section (especially heating settings that

are rarely altered), a daily section with a 24 hour

time window to specify when an appliance was used,

and a weekly section which primarily contained

questions asking about the participant’s general

behaviour during the past week (e.g. searching for

information about energy use, registering of meter

readings etc.). The daily section was the core part of

the diary. A 24-hour time window was provided in

the template to the participants. Per appliance used

during the day, start and end time of the use was

recorded down in the diary.

The diary offered insights in the participant’s

routines and in the reasons participants have for their

specific behaviour. Often it was observed that

people’s behaviour roots deeply in their specific

home and family situation. A quite obvious

observation from the diaries was that the general

family and housing situation has a very profound

impact on people’s energy related behaviour. Apart

from obvious differences based on specific family

and housing situations, differences in energy-related

behaviour often come down to quite small details in

behaviour. A lot of energy saving methods are that

common that almost everyone has the same energy

saving behaviour, for instance drying laundry

outside instead of using the tumble dryer when the

weather is good, or only turning on the dishwasher

when it’s full. Participants that went one step further

often focused on small improvements, such as

unplugging specific devices to reduce phantom

power. Only few participants took more drastic

measures to reduce their energy use, such as

consciously not owning/using energy devouring

appliances such as dishwashers or microwave ovens.

Often, luxury considerations prevent people from

going further in energy efficiency.

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3.1.3 Scenario Evaluation

All participants from the diary study agreed to

participate in a subsequent interview. The main topic

of the interview was the discussion of four scenarios

containing different functionalities of a home energy

management system. These scenarios were

developed based on the results of a market overview

and the input gathered in the diary study. They can

be seen as sort of a first product proposal. In these

scenarios several possibilities such as user feedback

and automated control were illustrated by means of a

fictitious family. The first scenario illustrated basic

applications of a smart meter such as detailed

billing. The second scenario elaborated more on

creating awareness of energy use (on a global level

for the household) by means of visualization through

mood lights, PC or smart phones. The third scenario

went more into detail and discussed feedback on

appliance level. Feedback in this scenario was

visualized through an in-home display. The fourth

and most advanced scenario illustrated the

possibilities of home automation in relation to

energy use.

Although it has to be noted that the participants

were quite positive about most of the applications in

the scenarios, they generally preferred scenario 3.

Scenario 1 was a scenario on which they agreed that

it presented basic information that “should be

standard” - of course with today’s mechanical

meters, this is quite impossible. This scenario

offered the least added value to their present

situation. The advantage of scenario 3 over scenario

2 was the level of detail. Whereas scenario 2 was

limited to a visualization of overall meter readings

on the computer screen, scenario 3 added the in-

home display as a means of easy access to the data

and, more importantly, added more detail as it

showed the energy use per appliance. This last

feature was something that was clearly appreciated

by the participants as indicated by the following

quote:

“The increased level of detail really gives a

lot of added value. As long as the data is on

an overall level, it’s all interesting and you

might start thinking about it somewhat, but

I don’t think you will act on it, as you don’t

know where the problem is.”

3.1.4 Interface Design

The design process of the application consisted of

several stages. Besides the ethnographic data,

respondent interviews and qualitative data gathering

presented above, participatory design techniques

were used to involve end users in the actual design

of an energy management system (Schuler and

Namioka 1993). A total of 2 focus group discussions

(N=8) were held with members from our research

panel.

Focus group sessions allowed for a creative

approach. After an introduction and discussion of

the concept of home energy management,

participants were asked to design an energy

management system that would meet their needs. To

do this, participants received pencils, paper and cut-

out graphics and icons to design their system from

scratch.

In a final stage, the user research data, together

with the participatory design results were used to

create the design of the final smart application for

smart phones and tablets. The final application

design includes a competition-style home page, in

which users can compare their energy use of the

present day to that of the day before.

This allows users to see whether they are doing

better or worse, and can trigger them to try to do

better. In this way, the competition-style home page

can be seen as a quick, one-glance self-monitoring

screen that can persuade its users to try to do better

than the day before (Fogg 2003). Besides navigation

buttons, the home screen also offers a direct link to

relevant system messages about the users’ current

energy use, such as changing energy tariffs,

information about appliances that remain switched

on upon leaving the house, etc.

Beyond the home screen, users can access more

detailed information, such as detailed graphs with

their energy use and energy prices, estimates of the

yearly energy bill, etc. Apart from visualising and

comparing usage information, the system gives users

advice on their energy use behaviour in the system

messages, and warns them when an energy use

threshold has been reached.

4 FIELD TRIAL

The developed system was installed in 21 homes

spread out over Flanders, the Dutch speaking part of

Belgium. The households were selected from the

project panel. They were contacted asking for their

participation in the project. A total number of 43

households were contacted of which 21 agreed to

participate. An initial visit was scheduled in

September with the participants to explain the

purpose of the field trial, assess the applicability of

the dwelling (not every house was suitable for the

installation of the system) and consequently

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concretize what measures would have to be taken in

order to get the system installed. From October 17

until November 17

2011, a second appointment

was made with the participants for the actual

installation of the system in their homes. The

installation supports the measurement of the total

electricity use in the house, a number of sub

measurements of specific appliances or circuits and

in some cases a measurement of the gas use. The

total electricity measurement is possible through the

installation of a modern smart meter. The

submeterings take place in the fuse box of the

participant. Metering modules measure the current

and voltage of the circuits that the participant wants

to be able to monitor (up to 6 submeterings). The

impact on the existing electricity installation of the

house is limited because of the use of current clamps

that can be clicked around the conductor. If the

existing gas meter has a so called pulse output, the

gas use in the house can be monitored through a

module that counts these pulses. The smart meter

and the metering modules send their measurements

to the database in the home energy controller (HEC).

This HEC is incorporated into the home network and

has an internet connection. The user interface of the

system connects with the HEC through WLAN.

Since the actual technical installation of the system

is not the aim of this paper, we will not elaborate

any further on this. As a user interface to interact

with the system, the participating households were

given either an Android based tablet or smartphone.

The field trial started November 17

2011 and is

scheduled to end March 31

2012 (although

continuation is possible). The purpose of the field

trial was to get insights into the interaction of the

participating households with the system. To do this,

the following research design was set up:

1. A weekly questionnaire

2. A monthly questionnaire

3. A three monthly in-home interview with

the participants

Currently, 8 weekly questionnaires and one

monthly questionnaire have been sent out to the

participants. The scheduling of the first interview is

in progress at the moment of writing. The weekly

questionnaires are sent out at the last working day of

each week.

The weekly questionnaire is a short online

survey containing questions on basic use of the

applications such as whether or not they used it, how

many times per week, at which moment they mostly

use it, and of course, which of the features they use

the most.

The monthly questionnaire is a longer version of

the weekly survey. It allows to go more into depth

on issues identified in the weekly questionnaire and

their actual usage and liking of the different

elements included in the application. The following

section of the paper will summarize the results of

both questionnaire types. We will not go into detail

on the results of every question asked, but try to

summarize the general trends seen in the use of a

home energy management system. Since the field

trial runs for approximately six months only, our

focus is not on the actual potential of the system to

lower the energy use of the participating families,

but more on the way they interact with the system.

4.1 Preliminary Results

4.1.1 Application Features

Most of the participants consult the system at least

once a week. The frequency of consulting less

frequent however over the weeks (the percentages in

the figures have to be interpreted with caution given

the small scale of the field trial).

Figure 1: Degree to which the application is consulted

(week 1 to week 7, in %).

Figure 1 indicates that the proportion of respondents

that consult the app every day gradually reduces

over the course of the weeks (In week 4, the monthly

questionnaire was sent out. No data about weekly

use was collected in this week). The novelty aspect

of the system seems to fade out somewhat. The

share of participants consulting the app several times

a week instead, increases over the weeks.

The participants don’t quite have a fixed moment

at which they consult their energy usage data. Most

of them consulted the application quite randomly at

the start of the field trial. Over the course of the

weeks however, this is clearly showing a downward

trend. More participants seem to find somewhat

fixed moments to consult their data. However, we

need to be careful with interpreting these trends.

Results from weekly surveys in the next weeks will

provide more insights. During weekdays the app is

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mostly consulted in the evening, whereas during the

weekend, day-time consultations are seen far more

frequently.

An important question is of course what the

participants are doing with the application? What

elements do they use the most? According to the

answers of the participants, in the first week after

installation in their homes, most of the elements in

the system were tested. A top 3 of elements that

remained quite consistent over the weeks that

followed were “Checking my current energy use”,

“Following the energy use of my appliances” and

“Checking my historical energy use” (at that

moment only the previous days were consultable

however). Although these three elements remain the

most consulted ones in the field trial, the share of

“Following the energy use of my appliances”

gradually dropped over the weeks. Apparently, once

people know what an appliance uses, their attention

to this element seems to fade out. Two other

elements that were highly consulted were “Checking

my stand-by electricity use” and “Real-time

following of the electricity use of an appliance”. The

attention to this element also faded out over the

weeks. A growing attention was paid to “comparing

my current energy use to the past days/weeks” over

the course of the weeks.

In the first monthly online survey, more specific

questions were asked on the usage of some elements

in the application that are less frequently used: the

estimation of the yearly electricity bill, the

possibility to impose usage limits and the making of

comparisons between days, weeks or months.

The app provides the user with a comparison of

his energy use with that of the day before.

Depending on the difference between two days, a

green or a red smiley is shown in the application,

indicating a better or worse situation than the day

before. When asked if they believe that the

comparison with the previous day is correct, most of

the participants state that they do so. The question

that is often raised however is whether the

comparison is a relevant one. A comparison of a

Sunday with a Monday for example, is a comparison

of two worlds to some participants (a day where

everybody is at home all day versus a working day).

When asked what type of comparison they would

prefer, comparing a week with the previous one

seems to be more to the liking of the participants.

Given the fact that daily consultation of the

application doesn’t seem to be common with our

participants, this might indeed be a better way of

comparing.

The application also provides the possibility to

get an estimation of the annual electricity bill. 13 of

the participants state that this is a feature they use.

Only half of them however, believe that the

estimation is in fact an accurate one. The main

reason for this is that most of the participants are

aware that the prices used in the field trial are

fictitious. Others have questions on whether the

system uses relevant parameters such as seasons in

its calculation of the bill. One respondent however

gives the interesting remark that when dynamic

prices would in fact be used in the future, the

estimation would come in very useful as it would be

very difficult to make that estimation on your own.

Finally, imposing a (non-binding) limit to their

energy usage per day was considered not to be used

by the participants. Only two of the participating

households indicated to use the usage limit.

4.1.2 Dynamic Prices

Every day, the respondents are provided with new

electricity prices for the next day. When asked if

these prices have an influence on the moment of use

of their electrical appliances, 8 out of 21 participants

state that they do. Indeed, a small, but consistent part

of them actively adapt the use of certain appliances

to these dynamic electricity prices, as is seen in both

the weekly as well as the monthly questionnaire. The

appliances that are often shifted in accordance to the

dynamic prices are typically those with a large

flexibility such as dishwasher, washing machine and

tumble dryer.

The participants were asked to give a specific

example of a situation in which they shifted their

electricity use in accordance with the electricity

prices and a situation in which they didn’t. The

responses to these questions are quite

straightforward. While the answers to the first

question (a situation in which they did) are not

surprising and mostly related to shifting of the

appliances indicated above, the reasons why

someone wouldn’t are more related to the relative

inflexibility of cooking and watching TV or using

the personal computer. Other reasons not to use the

dynamic prices are forgetting to set timers or just

being in a situation where an appliance has to work

at that moment and can’t be shifted.

5 CONCLUSIONS

This paper presents a user-centric development of a

home energy management system and the

preliminary results of the ongoing field trial. The

user-centric approach has proven to be very useful in

the development stage. Constant feedback from user

AUSERCENTRICAPPROACHTOTHEDEVELOPMENTANDTESTINGOFAHOMEENERGYMANAGEMENT

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research was incorporated into the development. The

preliminary results indicate that while the first weeks

of the field trial were marked by a high application

consulting rate of the participants, this decreased

somewhat in the weeks that followed. It was clear

that the amount of daily consulting gradually

decreases in favor of weekly consulting. Day to day

comparisons of energy use doesn’t seem to be the

most interesting base of comparison. Week to week

comparing is indicated as a more interesting base.

Estimations of yearly bills are found interesting,

despite the fact that the prices provided in our setting

are not delivered by the energy supplier and

therefore not accurate. Because some of the

participants were clients with another energy

supplier than the one that is a partner in the project,

fictitious prices had to be used. It is indicated that

these calculation modules will be of great interest

when dynamic prices are in fact on the market.

These pricing strategies will make it very difficult

for the end user make decent estimation of their

yearly bill. Approximately one third of our

participants are currently to some degree adapting

their electricity usage in accordance to the dynamic

prices that are being provided the day before.

Shifting of usage mostly implies appliances with a

certain degree of flexibility such as washing

machines and dishwashers. Those who don’t adapt

their electricity use to these tariffs indicate that this

is mainly because of not being at home at the time of

low prices. Automation will be an important

function of home energy management in the future,

especially when using dynamic prices. The small

scale of the field trial makes overall conclusion

somewhat difficult, but still, general trends are

detectable. The personal interviews are currently in

the process of being scheduled, and will certainly

attribute to insights on the use of the system within

the households and its influence on household

dynamics and routines with regard to energy use.

ACKNOWLEDGEMENTS

The IBBT SmartE project is a project co-funded by

IBBT (Interdisciplinary institute for Technology). A

research institute founded by the Flemish

Government. Companies and organizations involved

in the project are IBBT, IBBT-iLab.o UGent-MICT,

UGent-IBCN, KULeuven-CUO, KULeuven-ESAT-

Electa, VITO, VUB-SMIT, Telenet, SPE-Luminus,

Alcatel-Lucent Bell, Niko, Ferranti and Xemex, with

project support of IWT.

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