How energy efficient are you?

julia kukiewicz
By Julia Kukiewicz

energy efficiency©

Making the most of energy is good for the environment and not bad for the bank balance either.

Back in 2005, British Gas suggested that one pound in every three the average UK household spent on energy was wasted as a result of energy inefficiencies.

That's right - we could slash our bills by a third with improved insulation and more efficient heating, lighting and appliances.

But since then there's been serious effort to improve the energy efficiency of our homes - so what's average now? And how much could we really cut our energy bills by?

To find out, we decided to take closer look at efficiency upgrades in three areas, to see how much of a difference they really make. Skip ahead to find out more about:


Good insulation is generally agreed to be an energy efficiency must.

There have been more grants for this simple home improvement over the years than for any other energy efficiency saving. Even those who pay for it themselves, partly or in full, are likely to get good value for money - but it will take time.

The most efficient homes will have all of the following that apply:

Insulating the untouched loft of a three bedroom, semi detached home with 270mm mineral wool can save about £140 a year, according to the Energy Saving Trust.

Most houses older than 10 years old may well also benefit from wall insulation; cavity wall insulation can save up to £160 a year; homes built before 1920 with solid walls could save about £260 a year once they've been internally or externally proofed.

Under-floor insulation tends to be quite expensive, and saves around £50 a year.

Better insulation

Grants are available for wall and roof insulation through the ECO scheme for those in receipt of benefits. Those who don't qualify for help through ECO can find a list of estimated costs below.

ECO scheme: Energy suppliers must offer grants to help the most vulnerable people pay for energy efficiency measures. At the start of 2013, the Energy Company Obligation (ECO) Scheme replaced the Carbon Emissions Reduction Target (CERT) and Community Energy Saving Programme (CESP), which had been running since April 2008.

ECO is the main scheme offering help with these costs, but there are others operating at local and regional levels. We've a full guide on the help available here, including the all impotent eligibility criteria.

No matter the scheme, the process of getting insulation is broadly the same:

Paying for insulation: Insulation can be quite expensive: and unlikely to pay for itself in energy savings over a year, though it could within a few years.

Below are the estimated costs of insulating three types of three bedroom homes, from the Energy Saving Trust.

Detached house Semi detached house Mid terrace house
Roof £395 £300 £285
Cavity Walls £720 £475 £370
Solid walls From £3,000 to £18,000
Floor From £300 (cheapest suspended timber flooring) to £2,200 (most expensive solid floor installation)

Note that these costs, and the savings shown above, are for homes with no current insulation.

In the case of roof insulation, upgrading or "topping up" what's already there will cost about the same but give much lower annual savings: as little as £15 a year for a mid terrace house going from a 100mm of insulation to 270mm.

As some critics have pointed out, this means that the average house saves much less than they might have thought by changing their insulation.

Light and heating

Energy saving light bulbs are pretty much the definition of energy efficiency.

Even if it was kept on day and night, a high efficiency light bulb would still use less energy than a low efficiency bulb used minimally for a few hours a night.

Most people agree that replacing an old standard bulb with a similar compact fluorescent, those bulbs made of straight or twisted tubes, saves about £3 a year. Changing to LED lights, where possible, can save even more.

In August 2015, Ikea announced that they would only be selling LED bulbs in all their stores, wherever in the world they are, from September of that year.

Previously the bulbs have been considered incredibly expensive, but Ikea say their quality and price have "reached a tipping point". They say an LED bulb will last 25-30 times longer than other types of bulb, and save up to 85% of the energy older bulbs required.

What really makes savings, however, isn't light but heat.

Typically, more than half of a household's energy bill comes from the boiler alone. Newer boilers tend to be both more efficient and have better user controls, enabling households to make further savings.

The Energy Saving Trust say replacing a G rated boiler with an A rated one can save as much as £305 a year.

But most newer boilers - say, less than 10 years old - are already fairly efficient, so replacing them with a newer, more efficient, model won't save as much.

And unfortunately, they're a lot more difficult and costly than a light bulb to replace.

The average cost of a boiler and installation is around £2,500, according to the Heating and Hot Water Industry Council (HHIC).

Once upon a time there was a special grant just for buying new boilers, through the Boiler Scrappage Scheme. But this was closed to new applicants in 2010 in England, and in 2013 in Scotland.

So now the majority of the financial help for replacing boilers is available through the ECO scheme - for those who get tax credits and have a household income of less than £15,860, or those who get certain benefits.

That said, households with younger, less inefficient, boilers will often be given help getting them repaired and made as good as they can be, rather than having them replaced it entirely.

Until very recently there was also help available in the form of the Government's Green Deal scheme: a low interest loan to homes whose energy efficiency could be expected to be significantly improved as a result of the purchase.

Households repay the loan based on the energy savings they're expected to make. Bills don't necessarily drop, as the loan is paid off using the difference between the new lower costs and the old bill amounts.

But the scheme was no way near as popular as was predicted or hoped, and the Government stopped funding it in July 2015.

There's more on how the Green Deal worked here.


Finally, appliances make up a fairly large proportion of household energy use and, consequently, efficiency differences between models are worth taking into account.

Computers alone account for about 13% of electricity used in the average household.

This is worth bearing in mind when buying new appliances - especially larger items like washing machines, dishwashers, and computing equipment - but isn't much help day to day.

Smart meters

That's where smart meters, which measure a household's energy usage, come in.

Two smart meters, one for gas and one for electric, are on the way to all households in the UK under new EU rules.

Post rollout the stakeholders say they hope that smart meters will cut British carbon dioxide emissions by 2.6 million tonnes a year, and reduce day to day energy costs for consumers significantly.

Some suppliers have been more proactive than others.

E.On have given customers with prepayment meters and those who pay on receipt of their bills the chance to access the same tariffs as those who pay by Direct Debit - if they choose to have a smart meter fitted.

In the meantime, meters that plug into any mains socket are available to buy, or can sometimes be nabbed from energy suppliers for no charge.

How much does energy efficiency save?

Becoming more energy efficient is undoubtedly worthwhile. But it's hard to quantify in terms of pound and pence savings because the level of the saving will depend on how far the house has been optimised for efficiency in the first place.

Remember that the British Gas statistic we quoted right at the top is from a 2005 Defra report - so the data was probably even older than that.

Now, after years of improving energy efficiency, it's likely that most households lose a lot less heat in the first place, so the potential savings are that much lower.

Does behaviour matter?

You'll notice in the article above we don't talk much about changing behaviour in order to save energy, except in the case of using a smart meter to monitor energy use.

That's simply because, although changing behaviour to conserve energy is great and we'll cover it in another guide, being more efficient simply saves more, more efficiently.

Asked to name the "most effective" way to conserve energy, just 11.7% of participants in this study [pdf] for example, talked about making efficiency improvements to their homes.

Meanwhile 55.2% mentioned curtailment - that is, slight modifications in behaviour such as turning off equipment at the socket - as the best strategy for conserving energy.

Similar findings have been made in other studies - like the survey that found that 19.6% of participants thought that turning off lights would be the single most effective thing they could do to conserve energy - but only 3.6% thought the same of switching to efficient light bulbs.

The fact is that more efficient technology conserves much more energy than cutting back on the use of older technology ever could.

"When people think of themselves, they may tend to think of what they can do that is cheap and easy at the moment," said Shahzeen Attari, one of authors of the first study cited above.

Indeed that perception has been reinforced over the years by energy companies and regulators keen to make customers change their behaviour.

Although videos such as the one below do note the use of energy efficient light bulbs, for example, their central message is still that modifications to our behaviour are the most effective way of limiting energy use.

However, Attari added that the results shouldn't be taken to mean that small changes in behaviour are entirely useless.

"Of course we should be doing everything we can," she says.

"But if we're going to do just one or two things, we should focus on the big energy saving behaviours. People are still not aware of what the big savers are."

Hopefully, this article has made the big savers a little more clear.

It's also worth noting, as we do in more depth in this guide that energy efficiency is just one side of the story.

At present the greenest energy tariffs come from smaller suppliers, from the seriously green such as Good Energy and Ecotricity, to the slightly less green tariffs offered by companies like Ovo and The Co-operative.

Given the standard methods of providing the energy we use, these may end up being far more beneficial to the planet than any amount of appliance switching, or turning off the lights.

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