Domestic energy efficiency improvements are undertaken with the intention of reducing energy demand and consumption, since less fuel is needed to heat the house to a comfortable level. In doing so, it is assumed that this will reduce the amount households spend on fuel and deliver more affordable warmth. However, some of the ‘gains’ may be offset by a general increase in internal temperatures following improvements as householders use the monetary savings to fund warmer homes, a phenomenon known as ‘temperature takeback’.
However, despite the implications for national energy and carbon reduction goals, temperature takeback remains poorly understood, including how it operates across different tenures, income groups and properties.
Key research Question
The study aimed to develop an evidence base on the key factors influencing temperature takeback in domestic homes following energy efficiency improvements.
Summary of activity
The study examined monitoring data from 13 energy efficiency projects in the UK that occurred between 1974 and 1992, which had all included monitoring of household temperatures.
The average internal temperature before improvements is the main guide to the level of takeback after work has been carried out. Low-income households are more likely to have resided in colder homes, creating a risk of higher takeback after improvements and thus lower energy savings. This may lead to energy efficiency programmes being targeted at more affluent households, which will provide higher measurable energy savings.
As the average temperature in low-income households before improvements is 16.5°C, the authors estimate that 30% of energy savings will be lost to takeback. For properties recording 19°C and above, the corresponding value is 20%. At the current rates of increase in household temperatures, it is calculated that it will take 15 years before efficiency programmes reach maximum savings of energy and carbon emissions.
Measures that increase radiant temperatures (e.g. double glazing) reduce the amount of takeback, as residents are more likely to feel comfortable at lower air temperatures.
Very little in-depth monitoring of improvement programmes has occurred, which means that there is a paucity of data from which to draw real-world conclusions. Energy modelling is increasingly used to estimate benefits, but this is likely to overvalue savings.
Comprehensive monitoring of energy efficiency projects should be implemented going forward. This should incorporate real measurements as well as detailed studies of the behavioural issues associated with energy use and not just rely on modelling profiles, so that an accurate picture of energy savings can be obtained.