Thursday, 25 August 2016

Electricity is getting cleaner - should you heat or drive with electricity now?

Increasing renewable electricity (and less coal) in our mix is having a real impact on the carbon emissions from electricity. I used to say that electricity cost (roughly) three times as much as gas and generated three times as much carbon emissions - but now electricity is only twice as much as gas for carbon emissions. This has implications where you have a choice of fuels. For example, heat pumps for heating will now generate less carbon emissions than gas even if their performance is well below average. Also it increases the benefits of switching to electricity for cars. However, decisions made today are often based on out of date carbon factors.


Carbon emissions factors for grid electricity. DUKES is most up to date - DEFRA lags by 2 years (other differences are described below). Natural gas is added for comparison, based on gross calorific value (as appropriate for a condensing boiler)

Wednesday, 17 August 2016

The Hempcrete Book - review

The Hempcrete Book: Designing and building with hemp-lime by William Stanwix and Alex Sparrow. Green Books.
Hempcrete is an alternative building material with excellent sustainability credentials. It can be used instead of masonry or SIPs to build walls and to insulate roof and floors. If you are thinking of an eco building project you should at least consider using hempcrete for the construction – and in that case you should definitely read this book. It is an easy and fascinating read with a huge amount of advice about what hempcrete is good for, how to use it and other important details such as how to deal with building control. (Most council building inspectors have little knowledge of it so you are usually better off employing an authorised inspector who does.)

Thursday, 11 August 2016

Our personal energy use matters

A friend recently complained to me that it was pointless trying to save energy at home because our domestic energy use is a tiny proportion of the overall impact from business and industry - whatever we could do personally would not make any difference. This post refutes her statement, at least for the UK. Depending on how you count things, between 25% and 33% of greenhouse gas emissions are due to our activities at home and for personal travel.

The first figure is based on statistics recently released by DEFRA on greenhouse gas emissions by final consumption - this includes emissions due to imported goods and excludes emissions due to imports. The second figure is based on emissions generated within the UK. The chart below shows my best estimates for emissions on personal consumption in 2014. It shows a fairly even split between heating, electricity use, car travel and air travel. Together these add up to 3.7 t COe.

Monday, 8 August 2016

You can switch energy suppliers - why not water suppliers?

Currently we can choose and switch between energy suppliers but not water companies. Until now water companies have been allowed to enjoy a natural monopoly in each area, with regulation from OFWAT to ensure that prices are fair and services are good. However, as from April next year business customers will be able to switch supplier and OFWAT has produced an evaluation of costs and benefits from extending this to residential customers. They report a number of potential benefits [1]. But given our experience of energy suppliers, do we really expect competition between water companies to realise those benefits?

Sunday, 24 July 2016

Never mind the EU - we still need smart meters

Now that we are leaving the EU we don’t have to go ahead with the smart meters rollout [1]. However, the reasons why smart meters were proposed in the first place have not gone away. Smart meters are vital for a truly responsive electricity market. British Gas are leading the way on this, offering their smart meter customers free electricity at weekends, when demand is normally low [2].

Smart meters get a bad press because they don’t save much money by themselves. However they are a vital bit of technology that enables a whole raft of other savings possibilities.

Tuesday, 12 July 2016

How bad is bottled water, really?

I have been asked to look at the relative carbon emissions from tap water versus bottled water. Many people seem to think that our mains water supply is a significant source of greenhouse gas emissions. It is not, at least in the volumes we use for drinking. However bottled water certainly is - partly due to the bottle and partly due to the distance it is transported. The greenhouse gas emissions for bottled water are 200 - 600 times as much as tap water.

Here are some summary figures.

WatergCO2e/litre
Tap water
0.5
Bottled water best case: from local source in 1.5 litre bottles, 50% recycled plastic
118
Bottled water worse case: from a distant source such as San Pellegrino, in 0.5 litre bottles, virgin plastic
322

For comparison, a typical UK resident will generate about 30kg CO2/day so one litre of bottled water per day could be 1% of this.

Friday, 8 July 2016

Goods vehicles versus cars - the emissions race

Since 1990, carbon emissions from road transport has been almost stable. In 2013, they were just 2% less than in the base year. However, within the sector there have been ups and downs. Cars and taxis have reduced emissions by 14% while those from light goods vehicles have increased by 68%. Cars are still the biggest offenders but the other road users are catching up. In 2013, cars were 58% of road vehicle emissions, down from 66% in 1990 [1]. Our strategies for cars are working - now we need new strategies for the goods delivery sector.

Data from [1] ENV0201