New research by a team from the University of St Andrews argues that energy policy must factor in increases in domestic square meterage per person in order to achieve climate change targets.
The new study, published in Nature Energy, identified a global increase in house size and parallel demographic trends of decreasing household size.
This has resulted in a global shift towards more domestic space per person. To meet climate targets, energy research and policy must therefore factor in changing trends in house size and household size.
With the decline of multi-generational households, "empty-nesters" may be advised to invest in energy efficiency.
However, the report authors suggest that downsizing or taking on lodgers would be more effective to reduce energy demand.
The reports' authors studied trends in the UK, USA, Denmark, Germany, Taiwan, Vietnam, Russia and others.
The research, led by Dr Katherine Ellsworth-Krebs at the School of Geography and Sustainable Development, University of St Andrews, highlights missed opportunities for governments to reduce energy demand in the face of the global climate emergency.
Dr Katherine Ellsworth-Krebs said: "Household size decline has important energy implications and shifts in household size are an important determinant of energy consumption and carbon emissions.
"Ensuring housing offers basic necessities of shelter and privacy are essential yet increasing space per person has implications for energy and these trends beg the question: why do we need larger houses for smaller households?"
The study argues that energy research must consider lifestyle expectations and demographic trends that are generally seen as outside the remit of energy policy.
Because the main energy use in homes is for heating space, the current trend of larger homes and fewer occupants risk being overlooked in government energy efficiency interventions and behaviour change campaigns.
The study points out that declining household size is a common feature of advanced societies, and can be attributed to a desire for increased privacy.
In the UK, poor sound-proofing and disturbance from neighbours is one of the most common complaints about living in flats and a justification for the desire for a detached house.
This suggests that improving standards of visual and acoustic privacy would be key to improving satisfaction with smaller, high-density forms of housing.