1.
low carbon housing for
non-experts: usability in
whole house retrofit
Marianne Heaslip
URBED

2.
Most low carbon
‘retrofits’ designed by,
and for, experts and
enthusiasts

3.
But we need to hit the mass-
market to achieve carbon
reduction targets....
...the equivalent of a city the
size of Cambridge every
month ‘til 2050

4.
Encouraging technology uptake..?

5.
Potential pitfalls...
Building performance doesn’t match design stage predictions:
• Due to build quality and changes during procurement?
• Due to inaccuracies/ false assumptions in modelling?
• Due to user behaviour?
How can we convince people to opt for the measures if:
• It involves ‘letting the builders in’?
• Their homes become less ‘user-friendly’?
• The cost savings aren’t guaranteed?

6.
Significance of usability?
'e extent to which a product can be used
by specified users to achieve specified goals
with effectiveness, efficiency and satisfaction
in a specified context of use'
(ISO/TR 16982:2002)

7.
Context ,&1-7D ,&1-7D
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8.
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9.
Userʼs goals for retrofit
• Reduced bills (6)
• Interest in ‘green issues’ (2)
• Relative had solar panels and they wanted them too (1)
• Peer pressure (neighbours wanted their house ‘done’) (1)
• Doing their ‘civic duty’(1)
• Work needed to be done to the house anyway (2)
• Wanted the house to be more ‘modern’ (1)
• “Just wanted new windows”(!) (1)
(of 7 households)

10.
Userʼs ʻeverydayʼ goals
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11.
System Controls (effectiveness)
Control/Interface Usability Rating House Comment on Resident Use
1 2 3 4 5
Residents don’t use timer, just flick on
clarity of purpose A and off as needed, using thermostat as a
limit, but often switching off before this
Central Heating Control
intuitive switching B temp is reached.
usefulness of labelling C
ease of use D
indication of system
E
response/feedback
degree of fine control F
Cover is fiddly to flip up to make adjustments, screen is not very Use manual control and thermostat with
clear or big. Symbols hard to understand. Small buttons. G thermostat as limit.
Control/Interface Usability Rating House Comment on Resident Use
1 2 3 4 5
clarity of purpose A
Central Heating/ Solar Control
intuitive switching B
Understand some settings, but don’t like
usefulness of labelling C not being able to switch ‘off’.
ease of use D
indication of system Understand some settings, but only use
E to adjust temp up and down a bit.
response/feedback
Very good understanding of system,
degree of fine control F navigates menus to control as needed.
Lots of digital menus and sub-menus to navigate. Labelling very
abstract. Constant temperature read-out. Small backlit display. G
Control/Interface Usability Rating House Comment on Resident Use
1 2 3 4 5
Central Heating/ Heat Pump Control
clarity of purpose A
intuitive switching B
Displayenhet Menysystem
usefulness of labelling
När dörren till värmepumpen öppnas visas menysystemets C
fyra huvudmenyer samt viss grundinformation på displayen.
Inomhustemperatur – Varmvatten- Very good understanding of system,
ease of use D
Utetemperatur (om rumsgivare finns) temperatur
including adjusting ‘heatcurves’ etc.
A Display
indication of system
B Statuslampa response/feedback E
C OK-knapp
degree of fine control F
D Bakåt-knapp
Digital screen is hard to read in bright light and usually hidden.
E Manöverratt Symbols hard to understand without handbook. G
Extra varmvatten Uppskattad mängd
F Strömställare (om aktiverad) varmvatten
Control/Interface Usability Rating Houses Comment on Resident Use
F470 Meny 1 - Inomhusklimat
Inställning och schemaläggning av inomhusklimatet. 1 2 3 4 5
Meny 2 - Varmvatten
A Display Inställning och schemaläggning av varmvattenproduktionen.clarity of purpose A
På displayen visas instruktioner, inställningar och Meny 3 - Info
en)
driftinformation. Med hjälp av den tydliga displayen
Visning av temperatur- och annan driftinformation samt
och ett lättanvänt menysystem kan du enkelt navigera
tillgång till larmloggen. intuitive switching B

12.
Fuel usage and costs (efficiency)
• Early results based on resident reporting......not robust yet!
• Residents report cost savings - but these vary significantly
• Several residents report significant savings - and appear to be
undershooting design targets for energy use and CO2 emissions
• One resident reports small savings - but issues with thermostat
setting and MVHR/window opening
• Will only be able to make a proper assessment once one year+
of data available

13.
Control Over Heating
Comfort (satisfaction) A
B
• Residents report increased C
thermal comfort: D
E
“I don’t have to go to bed in F
thermals and a jumper anymore” G
0 1 2 3 4 5 6 7
No Control More Control
Comfort Overall
• Appears to be correlation between A
comfort, control and satisfaction - B
adaptive comfort (?) C
D
• Noise from MVHR an issue E
F
G
0 1 2 3 4 5 6 7
Unsatisfactory Satisfactory

14.
Other factors affecting satisfaction
• Stress of construction process
• Quality of finish
• Responsiveness of maintenance
• Quality of aftercare and support
• PV + behaviour change
• ‘Added bonus’ e.g. window cills, master-
switch+parental control, reduced clothes
washing
• Improved environmental awareness

15.
Initial conclusions and implications
• Cost savings of measures/households vary significantly -
- a significant issue if cost is a major motivator?
- implications for the ‘Green Deal’ and fuel poverty?
• Some approaches more ‘fit and forget’ than others - can’t rely
solely on ‘techno-fix’
• Feeling of ‘control’ very important - related to satisfaction and
usability
• Huge variations in ability to cope with change, level of interest
and motivations among residents
• Residents want to be involved throughout the process and
need support afterwards - customer care needs to be a priority
• Usability is key!

16.
Evolution in design?
Computers have evolved...can retrofit?
....BUT Even iPhones aren’t always ‘useful’...

17.
“I made up my mind . . . that I would
never try to reform man—that’s much too
difficult. What I would do was to try to
modify the environment in such a way as
to get man moving in preferred
directions”
R. Buckminster Fuller