2011-03-03 11:01:01
By Megan Lane BBC News Magazine
Couple in vest tops by a radiator Is winter really the time to expect to wear
vest tops?
Our homes are getting warmer just as the powers-that-be are asking us to turn
our thermostats down. How cool is too cool for a house?
Spring is in the air in the UK, but it will be weeks - if not months - before
the nation's radiators switch off.
The average indoor temperatures of British houses are creeping up now central
heating is the norm, and double glazing and insulation are added to older,
draughtier homes.
In the UK Department of Energy and Climate Change's new online modelling tool
My 2050, users can decide what they want the UK to be like in 39 years' time.
The only caveat? Carbon emissions must drop 80% while keeping the lights on.
It shows that hitting this target requires more than extra wind turbines or
nuclear power stations. How many cars should be electric? Should international
shipping grow or shrink?
Government drive
Screengrab of My 2050
And, most immediate to personal comfort, should the average indoor temperature
of British houses continue to rise, stay roughly the same at 17.5C (63.5F), or
fall?
Dropping it to 16C - the lowest setting in this virtual world - only shaves 7%
off carbon emissions. Even if we all get in the habit of wearing woollies
inside, this will still feel chillier than usual to most people.
David MacKay, the DECC's chief scientific adviser, practises what he preaches
in his once draughty semi-detached 1940s house. As well as double glazing and
insulation, he has turned the heating right down.
"When I'm at home, my normal thermostat settings are roughly 13C, but lower
when I am out, and 15C, briefly, at getting-up time in the morning. One
important additional rule is that whenever I feel cold, I turn the thermostat
up as high as I like. The automatic thermostat control then turns it back to
the normal settings a few hours later."
He hopes that insulating more homes, smarter thermostats and "the promotion of
sweater-wearing by sexy personalities" will encourage more people to follow
suit.
Sweater-wearers Cameron Diaz, Zac Efron and Michelle Obama Wrap up warm to get
cosy
But to many, a thermostat set in the low teens may sound unconscionably frugal
- especially when the range of numbers commonly goes from 10 to 30C.
Comfort cannot be defined absolutely, but the World Health Organization's
standard for warmth is 21C (70F) in a living room and 18C (64F) elsewhere.
Our expectations of thermal comfort have been raised by central heating at home
and at work, and because we are more sedentary at home and at work. Those
sitting still - in front of the TV or at a computer - feel the cold quicker
than someone moving about.
"A human's perception of whether they feel warm depends on what they are doing,
and what they've been doing for the past hour or so," says Dr MacKay in his
book Sustainable Energy - Without The Hot Air.
According to one widely quoted model, devised in 2008 by the Carbon Reduction
in Buildings project, average indoor temperatures have risen from 12C in 1970
to about 17.5C (63.5F) today.
But, says Michelle Shipworth of the UCL Energy Institute, this model assumes we
are turning our thermostats up, to explain why energy use hasn't gone down as
homes have become more energy efficient.
What has happened, she says, is that we now heat more rooms, and for longer.
Room temperature v health risk
Forty years ago, few houses had central heating, and chilly hallways and spare
rooms dragged the average temperature down. Radiators now warm rooms that
previous generations wouldn't have heated - corridors, bedrooms, and bathrooms.
The last comprehensive set of measured home indoor temperatures is from 1996,
when the English House Condition Survey found that although living room
temperatures in winter remained relatively stable, the nation's hallways were
getting warmer - up from 16.3C in 1986 to 17.9C.
"And for bedrooms, you'll be far more comfortable while you're asleep if it is
about 14C," says Shipworth.
Dr Lucy Worsley, chief curator of the Royal Historic Palaces, agrees. "My
grandmother wouldn't sleep in a heated bedroom, and would always have a window
open. You can't imagine many people today feel the same."
In our enthusiasm for cosy homes, she says many of us are like the profligate
Georgians.
Start Quote
Fair houses so full of glass that one cannot tell where to become to be out of
the sun or cold
End Quote Sir Francis Bacon on 16th Century fashion for huge windows
"A warm living room showed you were a good host and a generous person. They
thought an element of wastefulness showed you had enough cash to be generous,"
says Worsley, presenter of BBC Four's If Only Walls Could Talk, a history of
our homes to be broadcast in April.
"In medieval times, heating your home was akin to burning money. There was a
16th Century saying, 'the game's not worth the candle' - a task was only worth
doing if it justified the expense of illumination.
"But when people began to have more spare time and spare money, considerations
of waste became less important."
With energy bills soaring in recent years, and more people aware of energy
consumption, she expects frugality to be thrust upon us once more.
"I do think the future will be medieval, when the big bang comes and we run out
of oil. Small windows, shutters on the outside, a chimney for natural
ventilation."
Adjusting thermostat Learning to operate a smart thermostat takes time
And expectations can be adjusted down as well as up. In Japan, there is a move
away from super-cooling and over-heating office buildings. Government officials
are encouraged to abandon jackets and ties in summer, and some local
authorities have workers wrapped in blankets at their desks in winter.
"In 2005, Prime Minister Koizumi decreed that no government building should be
heated above 20C or cooled below 28C," says Professor Michael Kelly of
Cambridge University.
"That had quite an energy saving, but no drop-off in worker productivity.
Compare that to London, where the expectation is that buildings will be within
a few degrees of 22C year-round."
So will smart thermostats and radiator valves help, allowing homeowners to
target heat where it's needed at different times in the day?
Experts say technology can do only half the job. A smart thermostat is only as
smart as the person operating it.
I am in process of building a large house that will need less than 600 watts to
heat to 21c throughout. 1/20th of my current home. Design coupled to technology
can work to reduce both carbon footprint and keep me warm. The best way to save
is over-Insulate, then control the ventilation. My mother in laws house was
insulated recently, her Gas bill fell by 40%. You can all do it!
As a heating engineer for the past 16 years I am astounded by the amount of
people who have their thermostats set much higher than the 21 degrees that is
supposedly the norm. I often find the stats set at 25degrees or even higher if
it allows the user to do so!!!