Residential behaviour changes lead to a reduction in heating and cooling energy use by 2030

Behavioural changes and citizen participation can form part of a cost-effective solution to support the wholesale transformation of energy systems, including in the buildings sector. Behavioural changes involve people making low-carbon choices when purchasing products, or in everyday activities that reduce carbon emissions (e.g. transport mode, diet, temperature set points). In the buildings sector, one of the most significant behaviour changes relates to adjusting space heating and cooling temperatures. Lowering heating and raising cooling set points can save significant energy and carbon, as can varying the heating or cooling in different parts of a building (zonal control). Studies in occupied buildings show that any such changes are context-specific and must take into account technical, economic, social and physiological factors in people’s situations and environments.

A key global milestone for behavioural change in the building sector in the Net Zero Emissions by 2050 Scenario (NZE Scenario) requires space heating temperatures be limited to 19‐20°C and space cooling temperatures to 24‐25°C by 2030, alongside reductions in hot water temperatures.

Currently, high energy prices are concentrating the minds of building occupants on renewable resources, efficiency measures and behaviour changes that could save energy. This is being reinforced by messages from governments around energy-saving behaviours. IEA modelling suggests that thermostat set-point changes could immediately reduce energy use from buildings, allowing the time needed for clean and efficient measures to take place.

Behavioural changes are amongst the quickest and most cost-effective ways to reduce energy demand in buildings. They also support adoption of low-carbon technologies and can curb energy demand growth.

People’s energy behaviour is shaped by the design of physical and information technologies, from the planning of cities to the interface with smart heating controls. For instance, well-designed mixed-mode buildings on tree-lined streets provide better occupant comfort and satisfaction by allowing greater climate control through opening windows and adjusting fans and blinds. When buildings allow for effective temperature control, giving people power over, and responsibility for, their thermal environment, it reduces their thermal sensitivity – widening the temperature range they are comfortable in.

Between now and 2030, IEA modelling projects global building floor area will increase along with population and economic growth – especially in areas where demand for cooling is also growing fast (primarily in the developing world). In this decade, behavioural changes will play a key role in facilitating demand reduction and creating time for market uptake of low-carbon technologies.

While some occupants in buildings with mechanical heating or air conditioning heat to below the 19-20˚C, or cool to above the 24-25˚C NZE target, many buildings operate narrower set point ranges. As the prevalence of space conditioning increases globally, delivering changes in heating and cooling demand will be particularly reliant on widening thermostat set points in developed countries. For this, behavioural change will be needed. Doing so creates opportunities to both reduce energy use and increase the demand response from the built environment. 

Behavioural changes in buildings are facilitated by user-centred technologies. In relation to temperature set point change, one of the most promising approaches is local heating and cooling of occupants supported by Personal Environmental Control Systems (PECS). PECS, such as use of fans and heated surfaces, deliver heating and cooling directly to the individual occupant and are used in addition to the main conditioning system, allowing each user to customise their microclimate to their personal needs. By contrast, background space conditioning varies over a wider temperature range. PECS deliver comfort more efficiently than conventional conditioning systems through widening heating and cooling setpoints for background space heating. Additional energy savings may be achievable by integrated smart control of PECS and HVACs that can learn users’ preferences and provide comfort with less energy by presenting the lowest energy options first, making them easier to find and more likely to be chosen. Standards for these are currently being developed by various standardisation bodies globally including American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE).

Through applying insights from behavioural science, such as use of defaults more broadly, in building retrofit programmes they can be designed to support pro-environmental behaviours. For example, using behavioural science toolkits to design policies and programmes that shape expected behaviour can lead to better outcomes. There is also experience in national policy to support widening unconditioned temperature bands. The Japanese ‘Cool Biz’ (cool to 28˚C) and ‘Warm Biz’ (heat to 20˚C) programmes gave social permission for building occupants to adopt a wider variety of dress codes to match varying office temperatures. While there have been various policy initiatives relating to moderating building temperatures, there has been little evaluation of the efficacy of such measures.

Behavioural change is strongly linked to personal circumstances, preferences, and social context – making the outcome in individual cases difficult to predict. Occupants’ willingness to accept temperature fluctuations is heavily determined by a range of physiological, psychological, social, environmental, and technical factors. As ANSI/ASHRAE Standard 55 states, “thermal comfort is a condition of mind” and as such reflects the subjective experience of the occupant in their social, technical and environmental context. Analysis of the recently released ASHRAE global thermal comfort database show significant variation in thermal sensation as a function of gender, age, body mass index, environmental conditioning technology, country income, climate and building type. In addition, sensitivity to thermal variations differ by place. When individuals have greater autonomy and responsibility for their thermal environment, they report being satisfied over a wider range of temperatures.

Of these, one of the most notable differences is in building type. While occupants of residential and commercial buildings have similar preferred neutral temperatures, occupants of residential buildings will accept temperature variations from thermal neutrality between four and five times greater than those of commercial buildings while still remaining comfortable. The reasons for this are not fully understood, but are thought to lie in occupants’ perceived control over their environment. If energy use is to be reduced, and demand response increased in buildings, occupants will need to accept lower/higher ambient temperature and be empowered to adapt through changing their clothing and local environment to remain comfortable. This adaptation can be facilitated by giving users control over how they dress, how active they are, and how they manage their local environment. Intuitive, usable, smart appliances can facilitate this.

Technical challenges also remain around integrating control of PECS with building-level HVAC. Laboratory field trials demonstrate that PECS work well in delivering energy savings and occupant comfort – but market availability and commercial scaling are still challenging. In addition to standards, building codes, building services design, and building management systems all need to be adapted. For this reason, under existing conditions, a widespread adoption of PECS in residential and commercial buildings is unlikely to be rapid. To achieve a 12% heating and cooling energy demand reduction through temperature set point change requires behavioural changes in how we live and work, and for these to be supported by building occupants, owners, facilities managers and company management.

Currently, many smart home appliances lack usability and frustrate, rather than support, users’ needs. There remains a substantial gap between the visions held by the energy sector and the reality of household users’ experience of demand automation as well as a lack of transparency of who benefits from such programmes. This can negatively impact social acceptance and users’ trust resulting in some social groups, including vulnerable consumers, being less likely to acquire smart appliances – in addition to their high upfront costs. If the energy, health and wellbeing improvements offered by such technologies are to be realised, such issues will need to be overcome.

Policies for managing thermal environments in buildings should both provide minimal thermal standards to ensure occupant wellbeing and hygrothermal management, while expanding the buildings unconditioned temperature range to minimise energy use and maximise demand flexibility. Delivering both objectives will be a formidable challenge, requiring coordinated actions across policy, regulation, building codes, standards, technology development, construction, and facilities management. 

• Establishing design criteria and operation guidelines for PECS, quantifying health, comfort and energy performance benefits, and integrating control of PECS with HVAC systems.
• Determining the scope for machine learning approaches to identify energy-saving opportunities in buildings. For example, the Nest Learning Thermostat “aims to save energy by reducing the heating hours and the temperature at moments that are acceptable to the occupant”.
• Work on understanding and aligning construction industry incentives to deliver PECS solutions at scale.
• Research on the scope for informal personal comfort systems – supporting occupants to find their own solutions to broader unconditioned temperature ranges through uncontrolled use of fans, heaters and clothing variation – may allow faster and wider adoption, albeit within narrower unconditioned ranges and lower overall energy savings.