New Scientist - USA (2019-11-09)

18 | New Scientist | 9 November 2019

GAS boilers make for an unlikely

UK election battleground, but

politicians have been competing

on who will phase them out the

fastest. Last week, the opposition

Labour party said it would

make all new homes net-zero

carbon from 2022, beating the

Conservative government’s plans

to rule out gas boilers from new

homes by 2025. The Liberal

Democrats in turn said they will

make new homes net zero by 2021.

Whoever wins next month’s

election, the flicker of gas boilers is

long due for extinction. The UK’s

26 million homes are responsible

for about a fifth of the country’s

carbon emissions, making the

greening of them a key plank of

slashing net emissions to zero by

2050 – now a legal requirement.

Retrofitting those buildings will

be a huge undertaking (see “How

to green your home”, opposite).

New build

Meanwhile, some 230,000 new

homes are built in the UK every

year, most of them reliant on fossil

fuels for heating and hot water.

That will radically change with

the government’s recent future

homes standard, which will apply

to England from 2025, and could

be followed by similar rules in

Scotland, Wales and Northern

Ireland. What will new homes

then look like?

Ministers hope the building

regulations mean an average

home’s carbon emissions will be

80 per cent lower in 2025 than one

built to today’s standards. To reach

that goal, the government isn’t

explicitly banning gas boilers,

but is implicitly ending them by

proposing a reduction in home

CO 2 emissions that would be

impossible to meet with one.

Crucially, a home’s source of

heat will have to be low carbon.

For some, such as blocks of flats,

it may come via a heat network,

where a central boiler pipes hot

water to every property. That is

still likely to involve fossil fuels in

the near term, but a central system

is much more efficient than a

block full of individual gas boilers.

For many homes, the answer

will be a heat pump – effectively

a refrigerator in reverse – which

uses a fan to extract heat from the

running costs roughly equivalent

to those of gas boilers.

However, doing away with a

gas connection means a financial

saving both to society – because

the cost of connecting the home to

the pipe network is paid through

everyone’s energy bills – and to the

owner of the home, because they

will no longer need to pay the gas

standing charge that energy

suppliers impose.

Changing behaviour

Jenny Hill of the Committee on

Climate Change, which advises

the UK government, says the

switch to heat pumps is likely to

require some adaptation. “It does

absolutely require behaviour

change. We don’t currently know

how people are going to react

to not being able to install gas

boilers in their homes.”

For one thing, gas cooking hobs

will be replaced by induction hobs,

which are not only more efficient,

but can now match gas for

responsiveness when it comes

to turning the heat up and down.

“But they do require you to have

a new set of pans, so there is some

inconvenience there,” says Hill.

It isn’t just boilers: the fabric

of future buildings will be

transformed (see diagram). Their

walls, floors and roofs will have to

be much better at retaining heat

than today’s, and they will need

high-performance windows.

Homes will have to be airtight,

but still well-ventilated.

Richard Lowes at the University

of Exeter, UK, says walls are likely

to look the same, but have more

efficient insulating materials

inside them. With windows,

double glazing is so good now

in performance that triple glazing

is unnecessary. Other potential

changes include a growing use of

timber frames for buildings, which

Net-zero carbon

80 %

How much lower the carbon

emissions of new homes

in England will have to be

News Insight

Home of tomorrow

Radical plans are set to slash the carbon emissions of UK homes.

Will people accept them, asks Adam Vaughan

Homes that are net zero when it

comes to carbon emissions will

require many features that most

current homes lack

Double glazing

Green roof Ground source heat pump

Air source heat pump

Induction hob

Insulated walls and floors

Timber frame construction

Car charging point

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ground, water or the air, even on

a cold day. Most will be air source

pumps, which involve a box like

an air conditioning unit on the

home’s exterior. Like a traditional

boiler, these pumps can be used

for hot water or space heating,

so the inside of future homes

won’t look much different.

“It’ll have bigger radiators,

running on lower temperatures,

but otherwise it will look pretty

much the same as a house today,”

says Jenny Holland of the UK

Green Building Council.

There is a cost: heat pumps

are about £3000 compared with

about £1500 for a gas boiler, and

they consume electricity, with