Diagramas de casos de uso

New heating controls may not be the most obvious thought for a household when looking for potential ways to improve energy efficiency in their home. Focus in recent years has been more on insulation measures such as cavity wall or loft insulation, therefore public awareness of such measures is a lot higher. However, the Green Deal, the last large scale energy efficiency improvement program within the UK, listed heating controls as one of the approved measures which could

receive funding towards as a means of improving energy efficiency. Shipworth et al (2010) highlighted the saving potential reported by the Energy Saving Trust that correct heating controls such as having a timer, room thermostat and thermostatic radiator valves could save 17% of a typical heating bill, however noted that there was no evidence given for how this saving was calculated. Shipworth et al (2010) also emphasised the lack of evidence from research into the energy and cost saving potential of heating controls prior to their research. SAP 2005 adds the assumption that thermostatic controls being added to a central heating system would reduce the living room temperature by 0.6^oC helping to reduce the energy consumption within a home (BRE, 2008). The Energy Saving Trust website (EST, 2013)

recommends various thermostat control options and makes a point of stating the benefit of having proper controls regardless of boiler age to help save energy and money. Table 2.3 shows the level of savings they would expect in a typical

three-64 bedroom semi-detached gas central heating home. Similar to that reported by Shipworth et al (2010) no evidence is given with these figures as to how the savings were calculated. However the author uncovered details regarding EST calculations stating that calculations are based on modelled predictions or field trials of products.

The heating calculations are based on a SAP model using the assumption that 21^oC is used for the living area and 18^oC for the remaining areas with a central UK location. The three bed semi-detached house has a floor area of 89m³, with 17m² window area, 94% double glazing, a roof U-value of 0.34 W/m²K and an exposed wall U-value of 1.42 W/m²K. Although it mentions making regular adjustments for energy prices (EST, 2016), it could be assumed that the modelled dwelling

assumptions and temperature assumptions were the same for the saving potentials reported in 2013.

Table 2.3 Potential emissions and money savings from installing new controls in a 3-bed semi-detached home(EST, 2013)

Measure Installed CO2 saved/ per year

Money saved £/ per year

Room thermostat (if one not already there)

280 kg 70

Hot water tank thermostat 130 kg 30

Turning room thermostat down by one degree

260 kg 65

Recent research has shown that the use of smart heating control technologies such as those which offer zonal control could save a potential 12% of annual heating energy consumption within an un-furbished home (Beizaee, 2015). Potential energy consumption savings of 25% are possible from new technologies, including new space and hot water controls, however occupants need to be invested in the new technologies and use them effectively for this to be reflected (Cosar-Jorda et al, 2013). Therefore it is important to understand how occupants interact with heating controls to see if they will adapt to new heating control technologies well.

65 2.3.3.2 Use of heating controls

Upgrading the domestic sector so that homes have both a room thermostat and thermostatic radiator valves has the potential to reduce the domestic sectors emissions by 8% (Consumer Focus, 2012). However potential energy savings and emission reductions are only possible if occupants are able to use them effectively.

Shipworth et al (2010) reported that simply adding controls does not lead to a reduction in average maximum recorded temperatures within living rooms, however the potential to save energy is there if new heating control technologies are both appealing to and usable by occupants. Therefore it is important to

understand in detail the ways in which occupants interact with controls so that new technologies can meet users’ needs in a way which is energy efficient. Table 2.4 shows a summary of thermostat studies found during the literature review and the subsequent findings regarding the level of interaction found.

Shipworth (2011) is the only selected study which analysed UK data however it is worth noting that it was a comparison of reported thermostat settings not

measured settings, which, as Vine and Barnes (1989) show, there can be substantial differences between the reported values and measured thermostat settings. It should also be noted that the comparison between the two different surveys in Shipworth’s work do not cover the same geographical location and only two of the 2007 sample met the same geographical and energy consumption criteria as shown in the 1984 sample. There is an obvious lack of UK based studies which do not only rely on reported values from occupants. The use of heating controls can reflect occupants’ lifestyles, understanding of their heating system and their heating preferences (Consumer Focus, 2012). Rathouse & Young (2004) identified that comfort and cost can influence occupants’ use of their controls, highlighting the importance of understanding the drivers behind occupants’ use of controls in relation to how occupants use the controls.

66

Table 2.4 Summary of thermostat studies found within literature

Author Year Location Building types Measurement methods Findings Karjalainen 2009 Finland Domestic

properties and offices

Quantitative interview survey (telephone)

3094 out of 34935 phone calls took part in the study

<20% of them used their thermostat weekly in domestic properties

~ 60% said they do not use it at all or use it less than once a month in homes Brown et al 2013 France Office building Randomized controlled

experiment

Decreasing the default thermostat setting by more than 2˚C caused the office workers to override the default to

an increased temperature (which often exceeded the original default)

Residential Survey and temperature measurements

The reported thermostat settings were on average 2˚F cooler than the recorded

measurements.

The properties which were classed as being more energy efficient tended to have smaller observed differences in

reported and measured values.

Managed to classify some of the differences to be caused by energy behaviour of the occupants in some

cases.

Karjalainen 2007a Finland Residential, offices and University

Quantitative interview survey and controlled

experiments

Males tend to use thermostats in households more frequently than females indicating a gender difference.

Females tended to record a more thermal dissatisfaction.

Shipworth 2011 England Residential Repeated cross-sectional social survey (INT84 and CARB) and statistical analysis

Data gained in 1984 and 2007.

No statistical significance was found between comparing the reported thermostat settings between 1984 and

2007.

Reported mean setting in 1984 was 0.3˚C cooler than 2007

Meier et al 2011 US Residential On-line survey, interviews and laboratory experiments

~ 90% of those surveyed said they rarely/never adjusted their thermostat settings to separate difference between

weekday and weekend schedules.

The majority of the sample indicated that they chose to set their thermostats

manually than use programmable functions.

67 Investigating heating control use can often be limited by the research method. Self-reported heating use behaviours could fail to identify when controls are being used in a non-efficient way or differently to that of the designed use (NHBC, 2011) especially if the occupants are unaware of the designed use of the controls. Focus groups (NHBC, 2012 and Shipworth, 2000) and ethnographic methods typically identify when controls are not being used as designed or identify any lack of understanding regarding the use and/or design of the controls, and often these methods uncover more detail than survey use could. Ethnographic approaches can provide rich data on heating control use within homes however these studies can be influenced by occupants’ being overly aware of their use of controls being observed (Combe, 2011 and Meier 2010). However, these investigations also typically occur within controlled and unfamiliar environments to the occupants, use controls which occupants are not familiar with, and typically occur during a short monitoring period or even one-off measurements. Therefore there is a lack of knowledge regarding the longitudinal use of controls where occupants may become more familiar with the controls and as such may change their use of them.

The use of heating controls themselves can be hindered by many factors including unsuitable locations, illegible interfaces, being too difficult for occupants to understand and use, lack of support documents/advice for occupants and often a lack of an intuitive display (Consumer Focus, 2012). When these issues occur the occupant cannot use the controls as designed or occupants will use them in an ineffective manner. This could be detrimental to new heating controls saving energy and reducing emissions within the domestic sector. However improved controls can also lead to take back with occupants, so it is important to understand what type of heating control technology best suits each heating user type.

The design of the heating control is a vital part in how occupants use the control and the inclusivity of heating controls can be impacted due to visual aspects of the controls and the dexterity required. This has been shown by studies reporting large

68 variations with the use of controls due to difficulties from buttons, dials or tappets on the controls, ranging from their size, ease to press, located too close to other features (Combe, 2011, Ricability, 2004, Rathouse & Young, 2004, Meier, 2010 and Caird, 2007). Occupants may find difficulties from hard to read markings or display screens which could lead to occupant errors when using the controls.

The location of heating controls impacts their use with research showing that occupants use of their controls can often be made difficult and more challenging when controls are either too high or too low, or if they are installed out of the occupant’s reach, for instance, shut away in cupboards which are not easily accessed. Occupants’ also report that often they avoid adjusting thermostatic radiator valves due to them being located too low (Rathouse & Young, 2004), this is particularly the case for occupants with mobility issues or those who are elderly.

Often however occupants do not have much to say regarding the location of

controls as these are often decided by installers. The installers have been identified as being a key factor to occupants understanding of their heating system and controls due to the information they provide occupants regarding the new system or controls (Wade, 2016).

The occupants’ understanding of the controls is influenced by the design of the control itself and how intuitive it is to use but also by the information provided to the occupants about the control, such as the user manual or any help guides.

Various studies have identified issues surrounding the information provided to occupants as being overly technical and designed more for professionals, too detailed or ‘wordy’, not visual enough, not procedural, generic and therefore occupants found them not relatable to them and time consuming (Meier, 2010).

Often occupants misplace any supporting documentation, making it even harder for occupants to understand how to use their controls or change any settings.

However, occupants often report finding it easy to use heating controls when in reality they are using the controls in a way that was not intended or the way the

69 controls were designed to be used (Scottish Government, 2007), this highlights the importance in the intended use of controls being easy for occupants to understand as well as the design of the control themselves.

Occupants’ attitude towards new heating controls can also impact the way in which the controls are used. Research has shown that occupants do not necessarily link the environmental benefits of new improved heating controls as a direct impact (DCLG, 2010) and often the increased wellbeing and comfort, money savings, improved energy efficiency and improved control are the driving forces for

occupants to decide on installing new heating controls. However, new controls are often only thought about when the heating system requires a new boiler and therefore new controls are installed alongside the installation. Some occupants see installing new heating controls as more of a hassle due to the installation process and often believe that any potential savings are not worth the installation process and cost of buying the new controls (Consumer Focus, 2012).

These findings show that the use of heating controls is influenced by many factors and areas of further research have been identified. However ultimately the

occupant using the heating controls has the greatest influence on how the controls are used and this can be influenced by the heating behaviours of that individual.