Understanding household energy use

By Nigel Gilbert

The 2008 Climate Change Act committed the UK to reduce its greenhouse gas emissions by at least 80 per cent compared to 1990 levels by the year 2050.  This is a very ambitious target, and if achieved will change our world in many ways, some of them unexpected.  For example, the majority of homes nowadays have gas central heating – if the target is to be met, it is likely that by 2030 most households will have to be using electric heat pumps, even though the number of these installed to date is tiny.  Since about one third of all energy consumed in the UK is used in homes, such changes are important. No less important is finding ways to reduce the amount of energy people use at home.  If energy use goes down, energy bills go down as well, and this is especially significant for poorer families.

All this points to the need to understand how energy is actually used in homes, and how it might change.  If one goes back 40 years, the situation was very different and there is no reason to suppose that in 40 years time it won’t have changed again dramatically.  For example, the average indoor temperature in ordinary homes in 1970 was about 13 degrees, but had risen to 17 degrees by 2008 (although the outside temperature, averaged over the whole year, remained roughly constant) (DECC 2011).  In 2010, about half the energy used in the typical home was consumed by appliances that hardly existed forty years ago – freezers, flat screen TVs, mobile phone chargers, dishwashers, and so on.

We do know something about the level of energy consumption in the home: not surprisingly, it varies according to the size of the household (the number of adults and children), the stage of life of the household (whether it consists of students sharing, a young couple with children, a single retired person, and so on), the type of the home, the number of rooms and the tenure), and to a certain extent according to household income.  But we know little about other factors that affect energy use, and in particular, what might persuade or permit people to use less energy.

One factor that doesn’t have any straightforward relationship to energy use is the cost of energy.  One might expect that as energy prices go up, people use less, but the effect is quite modest.  The lack of price sensitivity (what economists call the ‘elasticity’) accounts for the low rate of people ‘switching’ from one energy supplier to another offering lower prices, and may also partly explain the poor take-up of the government’s “Green Deal”, which provides loans for insulation and other energy saving improvements.

So what can we say to explain domestic use of energy?  As part of the WholeSEM project, Tom Roberts, Tina Balke, Maria Xenitidou and Nigel Gilbert are studying domestic social practices as they relate to activities in the home, taking a social practice theory approach.  “Practice theory focuses on how routines, technologies, infrastructure, skills and meanings together constitute the many different unnoticed everyday uses of technologies in households, which result in the households’ energy consumption” (Gram-Hanssen, 2013).  For example, consider the task of getting clean: thirty years ago, you would most probably have had a bath once or twice a week.  Nowadays, most people shower once or even twice a day.  There has been a change in routine, and alongside and supporting this are changes in ‘technologies’ (the installation of showers, products such as shower gel and frequent use shampoo coming on the market, etc.), new ideas about what it means to be clean, and new skills – singing in the shower, for example.  A by-product of this changing social practice is a change in the amount and timing of energy used for personal hygiene.

One of the ways that we are investigating domestic energy using practices is by interviewing people in their homes, including using ‘walking interviews’, in which people are asked to walk the researcher through their daily routine and explain how they use energy during a day. Five practices dominated the conversation: heating, food preparation, laundry, entertainment and communication, and in many cases these were interconnected.  For example, someone who is able to work from home a couple of days a week because they have fast broadband will be using a lot more heat than if they were working at the office.  The implication is that if people want to reduce the amount of energy they use, they will often need to rethink not one, but several social practices.  This gets complicated to think about, so we are also developing a computer model of the interconnection and evolution of domestic social energy practices.  When complete, it will be possible to do ‘what-if’ trials on the model to see the effect of varying options.


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