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WITH the publicity given to chlorofluorocarbons in refrigerators, we
tend to forget the amount of energy that fridges and freezers consume. In
Britain, 8 per cent of the electricity produced is used to cool food in
our homes, a proportion that has been rising for the past 15 years. While
electricity suppliers have spent billions of pounds on raising the efficiencies
of power stations by 0.1 or even 0.01 per cent, they have almost ignored
the equipment that uses the electricity. The efficiency of the average domestic
fridge, especially in Britain, is poor despite the emergence of new technology,
since the 1973 oil crisis, that would enable it to run on less energy.

To a householder, the power used to cool food may seem modest: after
all, even a large fridge-freezer costs only about 12 pence a day to run.
But there are more than 30 million fridges, freezers and fridge-freezers
in British homes, which between them consume more than Pounds sterling 1
billion worth of electricity in a year. The average demand on the national
grid, measured at consumers’ meters, is at least 2000 megawatts, the equivalent
of the continuous output of two large power stations. If these two power
stations generate electricity from coal, Britain’s fridges and freezers
are responsible for emitting about 15 million tonnes of carbon dioxide a
year into the atmosphere.

In February 1989, the electricity supply industry and manufacturers
of appliances in Britain gave evidence to the European Affairs Committee
of the House of Lords that energy savings of between 10 and 20 per cent
might be possible. But this is a very conservative estimate, as a quick
walk down a row of identical-looking fridges in a department store, such
as John Lewis, would show. John Lewis is one of the few retailers that displays
the running costs of domestic appliances on sale: these labels show that
some fridges, freezers and fridge-freezers cost twice as much to run as
others. In evidence to the House of Lords’ committee, Friends of the Earth
identified a technological chasm between the fridges offered to consumers
in Britain and those available and being developed elsewhere, using more
energy-saving technology.

The efficiency of fridges and freezers can be roughly measured by dividing
the annual electricity consumption by the storage volume. Typical mass-produced
fridges, freezers and fridge-freezers consume between 2 and 3 kilowatt-hours
per litre annually (kWh/litre). Worldwide, mass-produced models that incorporate
the latest technological advances consume only 0.4 to 1.3 kWh/litre, while
state-of-the-art appliances use just 0.2 to 0.4 kWh/litre. Researchers in
the US and Denmark estimate that manufacturers could produce appliances
that use 0.1 kWh/litre. Fridge-freezers sold in the US 40 years ago used
electricity more frugally than most of those now on sale in Britain (see
Table).

These differences reflect how well the appliances use the long chain
of conversion processes that provide the cold storage space. Since the 1970s
at least, typical British fridges have incorporated a string of inefficiencies.
They have a flimsy 20 to 25 millimetres of insulation; poor door seals that
let the cold air escape; an inefficient motor, with weak magnets and cheap
wiring for instance, driving a poorly designed compressor that dissipates
energy in turbulence instead of in compression of the fluid, and both in
a position so that their unwanted heat re-enters the cool cabinet; and undersized
heat exchangers (condensers and evaporators) that, compared with appropriately
sized ones, demand more electricity to remove heat from the cabinet, thus
lowering the so-called ‘coefficient of performance’ of the refrigeration
system.

All these stages could use less energy. Early appliances displayed sensible
design features that were forgotten in the age of cheap energy from 1955
to 1973. Try finding a fridge in the shops with as much insulation as models
from the 1950s, some of which are still in use.

Several modern companies, however, have managed to improve on the classic
design. Europe’s most efficient mass-produced fridge, launched in 1988 by
Gram, a Danish manufacturer, began life as a prototype four years earlier
at the Technical University of Denmark in Copenhagen. Developed by Jorgen
Norgard, a civil engineer in the university’s physics department, it has
65 millimetres of insulation instead of the 30 to 45 millimetres found in
other models; well-fitting door seals and catches; a small, efficient motor/compressor;
and large enough evaporators and condensers in the heat exchange system
to make the refrigeration cycle efficient. The Norgard fridge consumes 0.4
kWh/litre annually.

Even more striking models, including other prototypes from the Technical
University of Denmark and custom-built units available in the US, use between
0.2 and 0.3 kWh/litre. From a small workshop in California, Sun Frost has
been producing between 100 and 200 such units annually since 1984. These
models are mostly for homes that are ‘off the grid’ and dependent on 12-volt
power from solar cells. Their superb performance is due to further small
refinements: insulation between 80 and 100 millimetres thick; airtight doors;
efficient motors and compressors, well separated from the cold cabinets;
no internal fans, which generate heat in the cabinet; and a refrigerant
whose volatility and other characteristics are matched to the temperatures
and pressures in the refrigeration system. The condenser and evaporator,
however, need not be any bigger than the undersized ones in conventional
appliances because the increased insulation means they do not have to work
so hard.

For northern climates where average temperatures are between 8 and 10
Degree C, Danish engineers have developed prototype fridges that consume
even less electricity. They can improve the efficiency of the appliances
to 0.2 kWh/litre by placing the condenser outdoors or by using a special
pipe. The pipe contains a refrigerant that circulates under gravity between
the warm air inside the fridge and the cold air outside. In cold weather,
the pipe dispenses with the need to run a compressor. According to some
researchers, efficiencies could improve further within the next few years
to 0.1 kWh/litre.

The US Rocky Mountain Institute in Colorado has tested more radical
improvements, such as using winter ice as a natural cooling system. Rather
than run a refrigeration system, a pump would circulate meltwater between
the stored ice and the fridge cabinet. This would dispense with a compressor
and could reduce the electricity consumption of large refrigeration systems
almost to zero.

The case for fatter fridges

Many European companies believe that eliminating ozone-damaging CFCs
from domestic fridges, of which between 80 and 90 per cent are in the insulation,
will increase energy consumption by 10 per cent. Researchers in the US,
however, hope to dispense with CFCs without sacrificing energy efficiency,
simply by making fridge walls between 15 and 25 per cent thicker. This,
say the American researchers, would compensate for the higher thermal conductivity
of polyurethane turned into foam with gases such as carbon dioxide instead
of with CFCs. European manufacturers, on the other hand, seem reluctant
to make their fridges bulkier, even though they were happy to make better
insulated free-standing chest freezers, a trend that began in West Germany
and Denmark in the early 1980s.

Until the 1960s, most European manufacturers insulated their fridges
with mineral wool; 50 millimetres gave the same thermal resistance as 30
millimetres of polyurethane foam does today. The manufacturers took advantage
of the new material to produce slimmer appliances. In the US, where the
switch to polyurethane foam occurred only in the 1970s, manufacturers used
the polyurethane to improve the energy performance of the appliance – not
to make the walls thinner. According to European manufacturers, fridges
with more insulation are unacceptable because they will not match the standard
fitted kitchen module, which is 600 millimetres wide. Well insulated fridges
need an extra 200 millimetres in width; designers are only just beginning
to plan kitchens with this in mind.

Energy-efficient fridges are more expensive than typical appliances
– although not as expensive as some manufacturers suggest – but they represent
a better investment. Researchers at the Rocky Mountain Institute illustrate
the point with the Gram fridge that consumes 0.4 kWh/litre annually. This
200-litre model uses 80 kilowatt-hours a year and costs about Pounds sterling
3 more to produce than a typical fridge with similar storage space that
uses 350 kilowatt-hours a year. For the extra capital cost of Pounds sterling
3 plus Pounds sterling 2 worth of house volume that the bulkier, well-insulated
fridge occupies, the purchaser saves 270 kilowatt-hours a year. At the current
British rate for electricity of 6.3 pence/kilowatt-hour, this saving is
equivalent to Pounds sterling 17.

There are other benefits. The more uniform distribution of temperature
in well-insulated fridges and freezers means that food keeps better, even
in the corners, and that, during power cuts, it stays fresh for weeks rather
than hours or days. Tight door seals stop warm, moist air from entering
the cooler, which means that ice builds up more slowly and less defrosting
is needed.

In Europe, however, consumers still cannot reap the economic benefits
of energy-efficient appliances – they must pay a high premium because there
is little competition, and no legislation. Manufacturers, such as Gram in
Denmark and AEG in West Germany, charge what the market will bear, which
can mean as much as Pounds sterling 50 to Pounds sterling 100 over and above
the price of an inefficient appliance. Experience in Canada indicates that
if, by law, all new appliances had to be energy-efficient, we would not
have to pay such a hefty premium. Woods, a Canadian manufacturer, began
to improve the energy efficiency of its freezers in 1986 and says the extra
production cost was minimal. In Canadian shops, the company’s energy-efficient
freezers cost no more than earlier models. The Woods initiative was voluntary
although it was probably done to promote exports to the US, where the National
Appliance Energy Conservation Act of 1987 stipulates the minimum operating
performance of domestic appliances.

In Britain, the scarcity of energy-efficient appliances is exacerbated
by the difficulty of identifying those that are available. Until we have
some form of impartial energy labelling, which clearly highlights inefficient
machines, manufacturers have little incentive to improve their products.
Last year the government took a step in the right direction but it still
has a long way to go. In August, the Department of Energy announced that
every major manufacturer selling refrigeration products in British shops
would voluntarily list the electricity consumption of their appliances.
One drawback is that the department agreed that manufacturers would display
the information in the rather unhelpful units of kilowatt-hours per day,
which prevents consumers from comparing the efficiencies of appliances of
different sizes. A more appropriate unit is the annual consumption in kWh/litre.
Furthermore, many firms do not seem to have adopted the voluntary guideline.

Even with energy labelling, the British government needs to introduce
minimum standards of energy efficiency to clear shops of the most inefficient
fridges. In the US, the only country already with energy labels and laws
that lay down minimum standards, Congress was forced to toughen the standards
in January this year to rid the market of the cheapest and most inefficient
appliances. Washington found, for instance, that builders of new homes,
with no interest in the future running costs of the homes, chose the cheapest
appliances available. It also discovered that many consumers refused to
pay more for energy-efficient fridges because the returns on the extra investment
were not enough; typically, consumers demand a return of 50 per cent a year
on the extra cost against the 5 per cent that governments and electricity
suppliers require. Without stringent standards, manufacturers were not introducing
improvements to fridges that cost far less to society than new power stations.

The US’s new standards, which stipulate the maximum consumption for
particular sizes of appliance, will outlaw 90 per cent of the fridges and
freezers that were on sale in 1987. According to Howard Geller, director
of the American Council for an Energy-Efficient Economy, they will save
American consumers $28 billion by the year 2000 and avoid the need to build
25 large power stations. His organisation, based in Washington DC, led the
campaign for the introduction of the tougher standards.

Friends of the Earth estimates that Britain would need 600 megawatts
less generating capacity if it applied equally strict standards and cleared
the worst 90 per cent of fridges and freezers off the market. This is a
modest step, however, because British appliances are so bad. If we replaced
all the fridges and freezers in Britain with Europe’s best mass-produced
ones, our average electricity demand would be 1500 megawatts less than it
is.

Going one better, Britain could replace its existing stock of 30 million
fridges, freezers and fridge-freezers with state-of-the-art appliances and
run the lot on just 200 megawatts. This means that we would not need about
1800 megawatts of power and that we could therefore avoid building about
Pounds sterling 5 billion worth of power stations and infrastructure. Using
appliances with such a low power demand, Britain might even follow Denmark’s
example and take wind energy more seriously; 10 to 15 wind turbines, each
rated at 500 kilowatts and operating for about one-third of the time, could
run every fridge, freezer and fridge-freezer in a county of 500 000 people.
With efficient appliances, China’s 400 million households could each run
a 150-litre fridge and 100-litre freezer, smaller than the appliances used
by most households in Britain, on 3000 megawatts of electricity. This is
less than the output of the country’s largest hydropower plant. At the moment
in Beijing alone, around two-thirds of the city’s population use inefficient
fridges bought mainly from Japanese and American manufacturers, which cannot
sell the machines legally in the US. If every Chinese household had one
of the inefficient coolers, the total demand would be 30 000 megawatts of
electricity.

While the ways of using electricity more efficiently have increased
continuously since the mid 1970s, putting the measures into practice depends
mainly on action by government. In Britain, for instance, the government
should encourage the privatised electricity industry to promote and finance
energy-efficient appliances rather than to build more fossil-fuelled power
stations. At the moment this is not the case. The new distribution companies
can recover the money they spend in supplying power to homes – and to the
energy-guzzling appliances inside – through the prices they charge for electricity;
they cannot recoup the cost of investments in energy efficiency in homes.

Sweden seems to be looking for a more positive approach. Over the next
two decades, it has decided to phase out nuclear power, which provides half
of the country’s electricity. It wants to do this without increasing emissions
of carbon dioxide, without building more hydroelectric dams and without
lowering living standards. In Stockholm last year, the State Power Board
staged a conference on how to bring the technology of energy efficiency
into use rapidly. Delegates from the US, with more than 10 years’ experience
in the field, told the Swedes that market forces, as defined in Europe,
could not work rapidly enough, if at all. Government intervention was essential,
they said.

The advice was not lost on some British delegates who wondered when,
if ever, their government will heed the overwhelming evidence. Will it,
or must sea levels rise and waves start to lap at the doors of the House
of Commons?

* * *

The way to make fridges and freezers more efficient

APPLIANCES that cool food combine two basic parts. They have a cooling
system to remove heat from the food storage compartment and devices to control
heat gains from the surroundings.

At the heart of the cooling system of most modern fridges and freezers
is a device, known as an electric compression-cycle heat pump, that pushes
a volatile refrigerant around a circuit containing two heat exchangers.
The choice of refrigerant is a complex matter. Among other things, it depends
on the ambient temperatures and pressures of the refrigeration circuit.

The heat exchangers comprise an evaporator inside the cabinet and a
condenser outside. Liquid refrigerant expands into a gas in the evaporator,
absorbing heat from the cabinet as it does so. The pump’s electric motor
drives a compressor that condenses the gas, forcing the refrigerant to give
up its heat as it becomes a liquid again.

A cooling system’s coefficient of perfor mance is a measure of how much
heat the system removes for every unit of electricity consumed. Many mass-produced
fridges and freezers have coefficients of less than 1; in the most efficient
appliances they are greater than 2.

The smaller the temperature difference through which heat must be pumped,
the higher the coefficient. Increasing the sizes of the condenser and the
evaporator reduces this temperature difference, and thus raises the coefficient.
All energy-efficient refrigeration units use generously sized condensers
and evaporators.

The motor and compressor of a modern fridge are usually sealed hermetically
and situated in the base of the appliance. In some energy-efficient fridges,
however, they and the condenser are above the cabinet. This minimises the
amount of heat re-entering the cabinet and it can allow the condenser to
be cooled better by currents of air.

Fridges and freezers use relatively little electricity to compensate
for their doors being opened or for the cooling of fresh food added to the
cabinet. They consume most energy in compensating for the heat that enters
the cabinet through the insulation or through gaps in the door seals.

By improving the insulation and door seals, manufacturers can specify
smaller and cheaper refrigeration systems. The thickness of the polyurethane
foam insulation varies from as little as 25 millimetres in mass-produced
fridges to about 100 millimetres in some high-efficiency models.

Doors were better sealed in old appliances with the help of catches
that compressed flexible gaskets around the edges of the doors. They were
effective but they were phased out partly for safety reasons; children tended
to lock themselves inside the cabinets. Fridges and freezers now use magnetic
door seals, many of which soon warp and distort with age. Effective magnetic
seals are available, however.

David Olivier, Principal of Energy Advisory Associates, Milton Keynes,
is a consultant specialising in efficient energy use and renewable energy
systems.