How should we measure the energy efficiency of a house?

You would think it was easy to measure the energy performance of a house. You probably think the key measure is the size of your annual energy bills. However, there are other ways. Are you interested in cost, carbon emissions or energy resources? To further complicate matters, measures such as carbon emissions and cost change over time, as prices change and our electricity supply mix changes.

There is a consultation on at the moment about changing the way we measure energy and carbon performance and standards for new housing - the Future Homes Consultation [1]. This is long overdue as the current methods have major flaws. However the proposed new standards have problems too and there are some very vocal critics.

Some bits of the proposals are excellent (in my view). For example the new approach is going to treat the energy from your solar panels differently according to whether you use it yourself or if you export it. Exported energy is worth only a third as much as energy you use. There is logic to this. The effect is to favour installations with battery storage because you can use much more of your own generation. Also the new standard is based on energy consumption rather than carbon emissions.

Beefing about meat

You may be sick and tired of hearing that we all need to reduce our meat eating because of climate change, especially beef. Most people like eating meat and learning how to use alternatives is not easy, though more and more convenience foods are now available. Anyway, the NFU tell us that farming can be carbon neutral [1]. So what is the problem? Here I go through some of the arguments.


Is it true that UK beef is so much better than the global average?

Yes it is certainly true that UK beef is several times better than the global average. This graph comes from an FAO report from 2013 [2]. It does not show the UK separately from Western Europe but there is not much difference. (There have been smaller studies since. A huge international meta-analysis published in 2018 also found a similar range between best and average across different regimes. However, these were not reported by region or country [3].)

Comparing carbon emissions from beef production in different parts of the world from [2]

Trees and carbon storage

Tree planting seems to be a hot topic in the election at the moment, with the Tories and the Lib Dems both offering lavish promises. The Committee on Climate Change also advises tree planting. How much difference will this make to climate change? How much carbon is stored in a tree, or in an area of forest and how much is added to this each year? Read on for the answers.

What next for the 2050 Pathways calculator?

The 2050 Pathways Calculator was a tool to help us understand how to reduce our CO2 emissions by policy changes and behaviour shifts across all sectors of the economy. It was originally developed by the Department of Energy and Climate Change for the UK and launched in 2010 – and then adapted for other countries and a global one. The UK one is out of date now but new versions are in active use by policy makers in governments, by children in schools, by NGOs and individuals. Last Thursday I spent a day at a conference about them, with delegates from all over the world – Mexico and the USA, Malaysia, and Thailand, India, Nigeria and many from Europe too. There is a new UK calculator in the pipeline and one for the EU - both are bigger, better and easier to use.

Upgrading our electricity distribution networks.

Electricity North West plans to reduce the voltage of their customers' electricity supply which will reduce bills by up to £60/year - and be hardly noticeable except it will take a little longer to boil the kettle [1]. In this post I take a look at the Smart Street trial they have run to test out their concept [2]. As well as energy savings a key purpose of the trial was to evaluate new voltage regulation equipment that could delay the need to upgrade the distribution network. Reducing the voltage reduces the delivered energy and peak load, so the existing infrastructure can cope for longer.

Savings on customers bills are welcome but even more importantly (for climate change) we need to be able to install more distributed generation and run bigger loads due to heat pumps and electric vehicles. How much will that cost? A case study on low carbon heating in a town in Scotland has some answers to that [3]. The cost of the network was much less than I expected - much less than the heat pumps anyway.

Where does your renewable energy come from?

Did you know that the renewable energy you are paying for with your green energy tariff does not actually have to be generated in this country - or even supplied to this country? For example it is quite possible your green electricity usage has been matched with generation in Italy. In the year to April 2019, 16 TWh of renewable energy certificates were imported into this country, almost half from Italy. This only adds around 15% to the green energy generated in the UK - but it does make you wonder if it is worth getting a green energy tariff at all. Fortunately some electricity companies either generate their own or buy direct from UK generators.

How, why and how far we travel: trends since 2002

The National Travel Survey for 2018 has been published - you may have noticed the reporting on aircraft travel. I have been looking at other aspects of our travel patterns: why we travel, how and how far. There are some interesting changes since 2002:

• Walking distance has hardly changed but we are cycling more
• All other modes of transport are down except for rail travel
• Business related travel, shopping and visiting friends all substantially down

The survey allows us to see more detail than this. For example, between 2005 and 2015 we walked less and less. In 2015 we took 15% less trips than in 2002 (though on average they were longer then now). Then we reversed those changes in the last three years. In contrast, for cycling we make no more trips now than before but we go 60% further each time and this trend has been fairly steady through the whole period.