Energy olympics

EXPERIMENTS IN ENERGY OLYMPICS

WEST OF ENGLAND CARBON CHALLENGE2012-11-07, 1600

Sukumar Natarajan with contributions from Julian Padget, Ian Walker

and Teresa Chiang, Nadya Dara, Gokhan Mevlevioglu

Climate Change

Energy Use / Efficiency /Security

Building Design

Energy and the Design of Environments (EDEn)

COPSE /Prometheus(both using

UKCP09 data)

ENergy Literacy through an

IntelligenT home ENergy advisor

(ENLITEN)

CONTEXT• Domestic:

• Users have control over decisions• Relatively easy to connect cause and effect

• Non domestic:

• Users generally have less control• More tricky to connect cause and effect

Does feedback affect energy consumption?

Question 1: (the type of)

Experiment 2: live (student residence)

Three types of displays were proposed in the literature

Experiment 1: laboratory test

Larger and longer term trials show less than 5% savings from control

Savings from various studies range from 0% to 22%

Does feedback affect energy consumption?

Question 1: (the type of)

Please cite this article in press as: T. Chiang, et al., A laboratory test of the efficacy of energy display interface design, Energy Buildings(2012), http://dx.doi.org/10.1016/j.enbuild.2012.07.026

ARTICLE IN PRESSG ModelENB-3818; No. of Pages 10

T. Chiang et al. / Energy and Buildings xxx (2012) xxx–xxx 3

Fig. 1. Numerical display [29].

Fig. 2. Analogue display [30].

Fig. 3. Ambient design [31].

easy to comprehend due to the consistent exposure in a numberof activities both at home (kitchen timer, alarm clock, TV, etc.)and work (security systems, vending machines, etc.). The presentwork intends to examine presenting energy information with purenumbers.

Analogue displays (e.g. Fig. 2) illustrate the scale of consump-tion usually without numbers, using graphs, charts, dials, columngauges and bars. Compared to numerical displays, these are oftenconsidered easier to read and interpret, especially when makingcomparisons, e.g. between current and target values [24]. Ana-logue displays can be effective in checking readings, evaluatingfuture states and conveying quantitative and qualitative informa-tion simultaneously in a direct and intuitive manner [24]. Andersonand White [25] found through working with focus groups that thedesign of a speedometer dial was particularly preferred for its qual-ities of eye-catching movement, intuitive scale and direction ofchange, and ease of making comparisons. It will be interesting tosee if similar preferences are seen in this study.

Ambient displays (Fig. 3) provide an overall indication of a situa-tion, sometimes make use of peripheral vision, and do not requireusers’ detailed attention [8,22]. No text or numbers are shown;instead, pictures, colours, sounds or flashing lights are used toconvey information. The present work attempts to introduce theinclusion of human faces in the design of user interface prototypes.Human faces are known to have the capacity to attract attention,even when reduced to cartoon form [26,27]. Presumably thanksto their social and biological significance, human faces seem tobe processed differently by the human brain: changes in faces aredetected faster and more accurately than in other objects [e.g. 28].The intention of this work is to find out if the face’s attentioncapturing property makes it a useful cue in the design of energydisplays. Specifically, the study looked at two-dimensional cartoon-like faces.

2.2.2. ColourA large number of studies [e.g. 32–34] on web page design

and screen design have shown that comprehension, distractionand directional attention are heavily influenced by the location,colour, size, orientation, shape and luminance of targets [e.g. 35,36]when people search or read displays. Colour, in particular, hasbeen found to have the capacity to attract attention to targetstimuli due to its highlighting and association effects, and to sepa-rate potential target stimuli from non-target stimuli [37]. It mightalso help to shorten search time more than shapes or numbers[after 5]. As colour is a basic element of visual perception, theprocessing of colour coded information does not require largeamounts of cognitive capacities [after 38,39]. For these reasons,the present work also investigates the effectiveness of coloured(i.e. non black-on-white7) display designs against black-on-whitedisplay designs (details of the experiment are described in Section3.2).

2.3. Users’ preferences

Previous research has shown mixed findings on what informa-tion people preferred to receive and which type of graphical designcould help to serve presenting information better. Researchers inthe USA designed two types of graphical displays to show energyconsumption: bar graphs and distribution graphs. Fig. 4 is one of thedistribution graphic designs that displayed little houses in a neigh-bourhood mapped on an x–y axis graph according to their energyconsumption [40]. This design was ranked most preferred, whilethe same design concept presented in Norway [41] was judged as“childish” and difficult to interpret.

7 The present work studied black-on-white design instead of white-on-blackdesign, as previous studies have shown that dark text on light background (positivepolarity) resulted in better performance compared to light text on dark background(negative polarity) [56,57].

digital

detailedquantitativeinformation















analogue

illustrate scale of

consumption















ambient

provide an “indication”

of the situation

☺we wanted to control these quite carefully, so COTS were not an option

How good are we at detecting change in information: speed and accuracy

Experiment 1: The key question is

Let’s do a quick test



6 T. Chiang et al. / Energy and Buildings xxx (2012) xxx–xxx

Fig. 8. Reference image (top); test image (bottom).

had three consumption ranges: low, medium, high, which werederived based on data from an average UK household’s annualelectricity consumption.8 Finally, each display design had a black-on-white version (Fig. 6) and a coloured version (Fig. 7). The overallbackground colour for all test images was white. Red and greenin the colour version were chosen for their associative meanings,representing high and low consumption ranges, respectively, andblack was used to represent medium consumption range. In theblack-on-white version, no colour other than black was used to rep-resent the three consumption levels. Low consumption levels wererepresented by lower numerical values in the numerical design, theleft-hand end of the dial in the analogue design, and a happy face inthe ambient design. Accuracy rate was calculated in percentage ofcorrect answers, and response time was measured in milliseconds(ms).

3.3. Experimental procedure

Participants received oral instructions and had a practice sessionof ten pairs of test images. As shown in Fig. 8, the first test image ineach pair was the “Reference” and was displayed for seven seconds;this was followed by the “Test” image, which was displayed untilthe participant responded. Each pair of images used the samedesign (numerical/analogue/ambient), and the design changed ran-domly from trial to trial. The Reference and Test images differedby a change in the value of one of the five display components.Participants were asked to determine as quickly and accurately aspossible if the consumption value of the changing display compo-nent had increased or decreased. In order to ensure that the timelapse between comprehension and response was minimised, theresponse for “increased” was mapped to the “@” key (next to the

8 For example, to determine what the day-to-day (“Today so far” and “Yester-day”) average consumption range was, the annual average electricity consumptionof 3300 kWh [15] was divided by 365 days to give an average daily consumptionvalue of 9 kWh. The figure was then doubled to give the full range and divided by3 for three daily ranges, i.e. the low range would be 0–6 kWh, the medium rangewould be 6.1–12 kWh, and the high range would be 12.1 kWh and higher. It is worthnoting here that these are realistic, albeit crude, approximations appropriate to theexperiment. While ranges in the real world will no doubt be different, these are notexpected to significantly affect results since participants were focused on changesto displays rather than the values themselves.

Fig. 9. Mean accuracy rates.

Fig. 10. Mean response times.

“Enter” key) and the response for “decreased” was mapped to the“A” key on a standard UK keyboard. Note that the task involvedidentifying which component had changed in addition to detectingthe nature of the change.

3.4. Interviews

Participants were interviewed after the computerised task toexpress their views in the following core questions:

• Which type of display design was the easiest to read?• Did you find the colour version more helpful in seeing the change?• How did you read and compare the information?• Which type of display design would you prefer to have at home?• Would you prefer to have the display design at home in colour?

The interviews were semi-structured, such that discussionstemmed from the core questions. In many instances, more than

Fig. 11. Display design preferences.












3.4. Interviews
















3.4. Interviews








Table 3Summary of response time and accuracy.

Response time Correct Preference

Design typea Ang > Amb = Nmr Nmr = Amb > Ang Nmr > Amb = AngColourb B/W = Clr B/W = Clr Amb > Ang = Nmr

Amb B/W > Amb Clr

a Amb: ambient, Ang: analogue, Nmr: numerical.b B/W: black-on-white, Clr: colour.

> means significantly greater than, = means marginally different.

found that if users find the product features similar to their previ-ous experience, they are more likely to perform tasks better [51,52].This raises the question of why the dials used in the analoguedesign, which should similarly be familiar to participants from ana-logue clocks, gas and electricity meters and from car gauges, led topoorest performance. Whilst it is possible that analogue displays,whilst common in everyday life, are substantially less commonthan numerical displays, at present the advantage of numbers overdials is not clear, and future work might usefully look in moredepth at analogue representation, including other forms such asgraphs and charts. Despite the special attention-capturing qual-ity of faces seen in earlier research, the emotional faces used inthis work gave no advantage to identifying changes in consump-tion nor did they appeal to many of the participants subjectively.However, for the minority who preferred or performed well withthe ambient design, the simplicity of the facial expressions was saidto be the key feature that helped them see the changes quicker andeasier.

Perhaps surprisingly, given that most participants said they sub-jectively liked colour displays, the presence of colour only slightlyincreased the accuracy rate of all design types, and this was not sta-tistically significant. It was more helpful in reducing the responsetime of the ambient design than in the numerical design, but theresponse time increased in the analogue design. However, evenif participants took longer to respond in the coloured analoguedesign, a higher accuracy rate compared to black-on-white wasachieved like with the other two designs.

Although the presence of colour did not help them perform tasksbetter, a majority of participants believed that colour was helpfulin reading information and seeing changes, and preferred informa-tion to be colour coded, for reasons of extra information, ease ofdistinguishing differences, visual aesthetics and learning experi-ence. Participants who felt colour was unhelpful were unfamiliarwith colour coding and found it “untrustworthy” and “distracting”.They did not find colour coding intuitive and felt that they had tospend more time on re-checking the information, and were stillnot sure if they had made correct answers. Participants pointedout that colour provided extra information which they found wastoo much to take in at a time, therefore they reverted to ignoringthe colour. Some participants were not aware that colour was usedeven though they reported to have normal vision. This could bedue to either mis-reporting of normal vision or the possibility thatnot everyone is receptive to the use of colour. In summary, then,designers might note that whilst colour displays are likely to beaesthetically pleasing to the majority of users, they appear to con-vey no advantage for highlighting changes in energy use and seemto be actively disliked by a minority.

6. Limitations to the study

A number of limitations to the results above have beenidentified:

(a) Sampling bias: The study attempted to recruit participants fromthe general public with as a wide range of socio-economic

backgrounds as possible. However, a majority of the partici-pants had undertaken tertiary education. This would suggestthat the participants are mostly in the middle-income classor higher, and therefore not fully representative of the pop-ulation at large. Further investigation is therefore required torule out a correlation between education, income and taskperformance.

(b) Lab based experiment: The experiment was conducted under“laboratory conditions” and therefore might not adequatelycapture perception in a real-world setting. On the other hand,by removing the distractions people are likely to experiencein their domestic environments, it could be argued that thisstudy provided a useful upper-bound on people’s ability to spotchanges in smart meters. If they were poor at using a certaintype of display when they were entirely focused on the task, itseems unlikely they would work well with that display whentheir attention was divided as in a household setting, althoughthis is, of course, an empirical question.

(c) Task based experiment: In the experiment, participants wereasked to undertake a specific task with the identified goal ofdetermining which one of five displays in a series of test pairshad changed. In a real-world setting, information will changeunpredictably and occupants will not be focused on detectingchanges. Again, however, one might argue that by asking peoplespecifically to focus on spotting changes, the study provided theupper-bound on the ability of these displays to communicatechanges in energy use to people.

(d) Design decisions: Particular design decisions were made inconstructing the experiment. For example, the numerical dis-play design was constructed using a seven-segmented format,which is a very common format found on simple LCD dis-plays. Similarly, the JFreeChart Java library was used to producethe analogue display as it is a freely available resource butled to a specific design of dial being displayed. Such decisionscould affect the perception of information and influence testresults.

Field trials are currently being undertaken to address (b)and (c). Work is also underway to test if education or incomeaffects performance on the computerised test, addressing (a)above. Further work is planned to examine the sensitivity ofthese results to different representations of the same designtype.

7. Conclusions

This paper presents a laboratory study in which three prototypesof display design (numerical displays, analogue displays using dials,and ambient displays using emotional faces) were compared to seewhich best communicated changes in energy use to participants.The role of colour coding was also examined.

Effectiveness (accuracy and response time) and subjective pre-ferences were used to measure how useful each design was. Thenumerical design was the all-round winner in task performance,leading to enhanced communication of energy-use changes com-pared to the analogue and ambient designs. Unexpectedly, thepresence of colour in a smart meter display led to no change inparticipants’ abilities to spot changes in energy use, although sub-jectively people tended to prefer colour displays to black-on-whitedisplays.

Further work will include testing on a larger sample to explorewhy numerical displays are working better, and to see whether it istrue for all people. Work is also planned to look at how effective thedisplay designs used in this work are in realistic residential settings,by displaying live energy consumption data using combinations of

How good are we at reducing energy when presented the same information in different ways?


Recycling

Solsbury Court

Marlborough Court

Outdoor Tennis Courts

West Car ParkP W

East Car ParkP E

P C

P G

P D

P A

P B

P L

P JP K

Copseland

Woodland Court

Lyme Kiln FieldSports Pitches

WestwoodResidences

Norwoo

d Hou

se Wessex

House

Nursery

4S Annexe

3S Annexe

P C

a

Bath Cats and Dogs Home

BaleHaus

EastwoodResidences Eastwood Offices

20/21 22/23

6WS

East building

2 non-participating groups were used as control

Kitchens comparable to each other with 7 students per group

6 kitchens were selected, 2 each on floors 7, 8 and 9

Each “kitchen group” was sub-metered by lights and small power

Student residences with good wifi access, 4 x kitchens per floor

Baseline period for comparison was the average over a period of days immediately before the start of the experiment

colour blind safe

Cumulative consumption from 00:01 to time of

update (say 09:00)

Total Cumulative consumption from

00:01 to 00:00

Average daily consumption

this week

Average daily consumption last

week

GroupGroupGroupGroupGroupGroup

A B C D E F

Weeks

1-2

Weeks 3-4Weeks

5-6

“Winner takes it all” £20 per member of the group that reduced the most over 6 weeks

Plainspeak: there is a 95% probability that these results did not occur due to pure chance

Confidence intervals for the experiment groups did not include zero change, so these results are significant at the 0.05 level.

Plainspeak: the change for these groups from baseline are not reliably different from zero

Confidence intervals for the control groups did include zero change.

Participants preferred this the most, yet ambient seems to perform better!

Question 2: Is competitive ranking enough, on its own, to deliver savings?

We wanted to test if comparing against one’s own savings would be different

Further, this time every person stood to gain financially as rewards were calculated using an arbitrary fixed rate (35p) per kWh saved cumulatively compared to the baseline period.

However, this tends to favour groups starting from a low baseline

In the previous experiment, groups were competing against absolute savings

How good are we at reducing energy when comparing our performance against the

performance of others?


Mean change in consumption (kWh) compared to baseline

Questions 3 & 4: Will any of these ideas work in an office environment? Do rewards matter?

Instead of monetary units, performance was measured in “meters run”

Provide additional context to ranking information

Information was separated by lighting and small power

Applied the idea of self-relative ranking from previous experiment to BH offices

Test if rewards are essential and if (any) savings persist over time.

Information on how to save was given before the start of the competition

Environmental attitudes were measured before and after the competition

Due to technical problems experiment ran for 5 weeks instead of 6

The effectiveness of behavioural interventions to reduce office energy consumption

40/141

Figure 3.2.1. Building 1 energy consumption by energy sector for 11 weeks(26/Apr – 1/Jul).

Figure 3.2.2. Building 2 energy consumption by energy sector for 11 weeks (26/Apr – 1/Jul).

However, it has to be borne in mind that described above energy balance and

benchmarking is valid only for the obtained data from the period from the 16th of April to

the 1st of July. The situation for the whole year is going to be different as the coldest winter

months are not considered in analysis when the most amount of heat is required.

Therefore, the percentage of energy for heating would probably increase. For example,

Figure 3.2.3 illustrates the difference in percentage of energy subsectors in June and

April, where it is clear that heating is the first largest consumer in April whereas in June

small power consumes over a half of all energy.

Figure 3.2.3. Comparison of total Buildings energy consumption by sectors in June and April.

Small power40.54%

Lighting13.13%

Canteen4.79%

Lift0.38%

Server room14.98%

Printing room1.17%

Heating25.02% Small

power46.74%

Lighting23.02%

Canteen4.82%

Lift1.33%

AC0.92% Heating

23.16%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

Smallpower

Lighting Canteen Lift Serverroom

Printersroom

Heating

June

April

3.2.1 3.2.2

Proportion of total energy consumption in both buildings by end-use


53/141

Figure 3.4.1. Scheme of display screens.

Lighting Computer Floor Weekday

average Weekend average

Nominal Average Floor Weekday

average Weekend average

Nominal Average

B1 Ground Floor

88.00 22.00 74.80 B1

Ground Floor

263.00 41.00 218.60

Building 1

B1 First Floor 41.00 18.00 36.40 B1 First

Floor 135.00 72.00 122.40

B1 Second Floor

24.00 0.00 19.20 B1

Second Floor

87.00 24.00 74.40

B2 First Floor 69.00 7.00 56.60 B2 First

Floor 109.00 19.00 91.00

Building 2

B2 Second Floor

71.00 3.00 57.40 B2

Second Floor

103.00 13.00 85.00

B2 Third Floor 64.00 15.00 54.20 B2 Third

Floor 152.00 55.00 132.60

Table 3.4.1. Baseline values for savings calculation for displays.

3.5. Questionnaires on environmental awareness.

In order to determine the extent to which the environmental awareness of occupants might

be influenced by the competition two sets of questionnaires have been organised, before

and after the competition. The first questionnaire (Appendix H) comprises the part on the

environmental awareness that has been derived from Verplanken et al (2008) where the

version of Dunlap et al (2000, cited in (Verplanken et al, 2008) was shortened and the part

Equivalent of “net earnings” in the previous study

Provide context on “how far away” other groups are

Lighting

Computers

Total

�30%

�20%

�10%

0%

%reductionfrom

baseline

Mean percentage savings and ranges

-40%

-27%

-13%

0%

13%

27%

14/0

7/20

1222

/07/

2012

29/0

7/20

1205

/08/

2012

12/0

8/20

1219

/08/

2012

26/0

8/20

1202

/09/

2012

09/0

9/20

1216

/09/

2012

23/0

9/20

1230

/09/

2012

07/1

0/20

1214

/10/

2012

21/1

0/20

1228

/10/

2012

% sa

vings

from

bas

eline

Computer Use Lighting

End of competition period

The first data point is the average saving after one week

TabletsRemoved

Average savings over all groups split by end-use


68/141

P1). Figure 4.3.1 illustrated that the percentage of strongly agree people increased after

the competition, whereas before the answer ‘agree’ was greater. The questions that

confirm the environmental worries such as about overpopulation (Question 2), human

activities consequences (Questions 4, 6), and the rights of other species (Question 8)

were about the same level with the difference by 2-3% either, lower or higher. Bear in

mind that the proportion of response is slightly lower this time it can be assumed that the

general level of the awareness has not changed much.

Figure 4.3.1. Comparison of responses before and after the competition on Question 1.

In Building 1 on the Ground and First floors the amount of positive responses was lower

by 3-5%, whereas on the winning floor (the Second) the amount of positive answers

reached 100%, higher by 18.75% than before the competition (Appendix P, Table P2).

In Building 2 the change is slightly more significant (Appendix P, Table P2). On the First

and the Third floors awareness was higher by about 25%, whereas on the Second floor it

was lower by 14%.

The questions that represent environmental attitude (2, 4, 6, 8) in general received slightly

less positive response from both buildings (Appendix P, Table P2). However, for the

Second Floor of Building 1 (winner) some questions were answered more positively, such

as Question 4 (by 36%) and Question 6 (by 21%) whereas other questions (2, 8) were

about the same level.

0.00%5.00%

10.00%15.00%20.00%25.00%30.00%35.00%40.00%45.00%50.00%

1(Stronglydisagree)

2 3 4 5 6 7(Stronglyagree)

Q1. I am an environmentally aware person

before competition

after competition


69/141

However, questions about humans’ rights and abilities to prevent the destruction of the

Earth (3, 5, 7) in both buildings were more optimistic than in the previous questionnaires

and the percentage of ‘agree’ answers was by 8-12% higher.

4.3.2. Behavioural change.

Interestingly, the answers about behavioural actions performed by occupants have

significantly improved in both buildings by an average 15.6% (Figure 4.3.2, Appendix P,

Table P2). The most significant was improvement in turning off lights overnight by 50.25%

on the Ground floor of the Building 1 and switching off monitors on the Second floor of the

Building 2 that grew from 25% to 71% and the use of ‘sleep’ mode that increased form

33% to 71%.

Figure 4.3.2. The comparison of positive responses about ecological behaviour.

Nevertheless, there were a few reductions observed in the performing of ecological

behaviours such as in adjusting lighting level (Question 9) on the Second floor of Building

2 and on the First floor of Building 1 (by 15% and 30% respectively) (Appendix P, Table

P2). The Second floor in Building 2 reduced also the number of positive response in

turning lights off by 25%. Moreover, the First floor of Building 1 decreased slightly (by 5%)

the amount of positive response about turning off displays.

It has to be borne in mind that due to the difference in number of respondents the results

are not precise. However, the general conclusion might be drawn that the improvements

in ecological behaviour took place during the competition.

4.3.3. Energy competition and occupants’ engagement.

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

9. adjustlights

10. swtich offcomp

11. turn offlights

12. use'sleep' mode

13. switch offmonitor

Building 2beforeBuilding 2afterBuilding 1beforeBuilding 1after

ANSWERS• Simply putting something in place seems to have an effect•We need to be wary, however, of the Hawthorne effect•What people say and what they do don’t always match• Some designs may be better than others

WHAT WE DON’T KNOW• How do hybrid designs perform?• Are these savings sustained? How can we make them habitual?•What is an appropriate baseline measure?• Are rewards essential? Need they be monetary?

Energy olympics

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