UK households are four degrees warmer now than they were in 1970, when ice used to form on windows in the coldest rooms, a Government-backed study has found.
Research for the UK Housing Energy Fact File shows the average property is kept at around 17.7C during the winter months - a significant rise on 13.7C four decades earlier.
Greater insulation, new building regulations and improvements in boilers are all credited with helping lock heat into modern homes, according to analysts at Cambridge Architectural Research, Eclipse Research Consultants and Cambridge Energy.
With a small decrease in those deemed to be in fuel poverty during the last decade, the report examines how those in 1970's chilliest living rooms were quite used to reaching for the woolly jumpers and thermal insulation when the mercury dropped.
The report, commissioned by the Department of Energy and Climate Change, said: "Much of the UK's housing was built before the links between energy use and climate change were understood. Much of it was also built when there were very different expectations of thermal comfort.
"To put it simply, most families in 1970 lived in homes that would be cold by modern standards in winter - as cool as 12C on average.
"There may have been ice on the insides of the windows, and nearly everyone accepted the need to wear thick clothes at home in winter."
The report said few homes had central heating four decades ago, while many homes in the 21st century are stacked with energy-guzzling appliances such as large televisions, computers and consoles.
Yet average household energy usage has declined by 18% since 1970 - prompted by the decrease in the number of people living in each residence. However, the growth in the number of households more than offsets this efficiency improvement, and overall energy use in homes has increased by 17%
And despite a culture of having to watch the pennies as the energy firms ratchet up their prices, the report states modern h ouseholds are not typically aware of how much gas they use, either in absolute terms or in relation to others.
Researchers said: "Paying by direct debit, fluctuating energy prices, variations in how cold the winter is, and changing household circumstances - all of these appear to cloud people's understanding of how much energy they use."
The study also shows carbon dioxide emissions from housing have fallen more than a fifth since 1990. This was despite increases in the number of homes and changing expectations about energy use in the home.