Archive for the ‘Reviews’ Category

The MyVaillant App: a review

February 6, 2023

Friends, regular readers will know that I love my heat pump, a Vaillant Arotherm plus model with a nominal maximum heating power of 5 kW.

But regular readers will also know that I have been very disappointed with the software and controls for the heat pump. Back in October 2022 I wrote:

Vaillant Arotherm Plus Heat Pump: The good, the bad and the ugly.

In that article the “good” referred to the mechanical and electrical operation of the heat pump; the “bad” referred to the mysterious absence of a user manual; and the “ugly” referred to the VaillantsensoApp‘ used to control a few of the functions.

Recently Vaillant have released a new MyVaillant app to replace the sensoApp and I was eager to try out it. Could it be the elegant swan that grew up from the ugly duckling of the sensoApp.

In case you don’t have time to read this finely-crafted article, here is a summary of my findings: the MyVaillant app is a big improvement, but the operational data it provides is – as best I can tell – still just as inaccurate as it was previously.


After logging on initially I was mildly impressed, but then the next time I opened the app, I was asked me to log on again: select my country location, e-mail and password. This has happened several times since and I have been told over that Vaillant are working on this. I won’t mention it again, but it is a sign of poor testing.

After eventually logging on one is faced with a pleasing simple ‘Home Screen’. A glowing green circle displays the current set point temperature with the actual temperature below it – these numbers change in increments of 0.5 °C. The glowing circle changes colour from time to time, but I have no idea why!

Plus and minus buttons allow the set point to be easily adjusted. Clicking on these brings up a dialogue box which asks how long to change the set point for. After the chosen period – default is 3 hours – the set point will return to it’s previous setting or programmed value.

Click on image for a larger version. The Home Screen of the MyVaillant App.

The Home Screen contains buttons which link to four more important screens.

Click on image for a larger version. The Home Screen of the MyVaillant App and the screens to which it links directly.

These screens (see-above) allow access to the basic controls. It’s nice to see that ‘Activate Hot Water Boost’ – the most common reason I need the app – is just one touch away from the Home Screen.

Perhaps the most important screens are those for planning the weekly cycles for (a) heating and (b) domestic hot water. These are – in my opinion – textbook good design.

Click on image for a larger version. The screens for adding an  additional regular period of domestic hot water heating. Notice that one days settings can be copied and pasted onto another day.

So the app is well-structured, pleasant to look at and easy to use. A big improvement.

System Performance

Even bigger improvements have been made to the screens showing the system performance. An example screen is shown below for the week beginning 23 January 2023.

Click on image for a larger version. Example page show energy information for the heat pump during the week beginning 23 January 2023.The screen is shown left and on the right the screen is annotated to show how the various quantities relate to one another.

The display page shows:

  • A: The electrical energy used to operate the heat pump – in this case 125.9 kWh
  • B: The thermal energy captured from the air – in this case 230.1 kWh
  • C: The thermal energy delivered to heat the house – in this case 332.1 kWh
  • D: The thermal energy delivered to heat hot water – in this case 23.9 kWh

From these quantities the app calculates the Coefficient of Performance (COP) which it calls as Energy Efficiency.

If one touches any of the small graphs, a more detailed version is shown.

Click on image for a larger version. Clicking on the small energy graphs shows more detailed versions.

This display structure has been well thought through and is well executed. I would wish that the data could be downloaded, but this presentation is basically excellent.

However sadly the performance data shown is not accurate.


The MyVaillant app warns people that it is not accurate. But I think that despite this warning, in the absence of any other information, most people will take these figures at face value.

Click on image for a larger version. This warning screen appears before one sees the energy information pages. I recommend that one does not click the box asking not to show the message again. This should remind one that the data can be significantly in error.

Please note: Energy consumptions, energy yields and efficiencies are extrapolated based on various parameters. The actual figures may differ substantially in some cases.

Fortunately I have a monitoring system which measures the electrical consumption by the heat pump and the heat output of the heat pump. This allows a direct comparison between the app’s estimates and a measurement system which is certified to be suitable for billing.

So for the week illustrated in the figures above, the actual figures are shown in the table below.

Click on image for a larger version. Table showing the MyVaillant App estimates for electricity consumed and heat produced together with the measurements of these quantities by billing-grade instruments.

The MyVaillant estimates are seriously in error.

  • The estimate of the electricity consumed is in error by 9.3%.
  • The estimate of the heat produced is in error by 22%

Consequently, the estimate of the COP is seriously in error.

For the week in question, the average temperature was 4.0 °C and the minimum temperature was -5.1 °C, a cold week by London standards. A COP of 3.3 in such a week is quite respectable. A COP of 2.8 is not so great, and might lead someone to search for system improvements which would be illusory.

Click on image for a larger version. Temperatures in my back garden during the week in question.

The real problem with these errors is that the erroneous estimates are completely plausible.


Assuming that Vaillant sort out the problem logging on to their app, then this app represents a really significant improvement over their previous offering. To all the engineers who have worked on this I would like to say: Thank you.

But the inaccuracy of the reported quantities is significant and I feel that if Vaillant cannot improve these estimates, then they should be indelibly marked as ‘indicative’.

Greta’s Climate Book: An antidote to hope

November 21, 2022

Friends, as I have written before, I love and admire Greta Thunberg.

So when I heard that Greta had edited a collection of short essays on Climate Change, I ordered a copy immediately. Quietly I thought to myself: “Well that is Christmas gifts for everyone sorted.”

And when I collected my copy from the local bookshop I was delighted to find that Greta herself had signed the book! When I got home I sat down eagerly to read.

The book is attractive, covered in Climate Stripes but at 446  pages and 1.383 ± 0.002 kg, it was larger and heavier than I had anticipated.

It is also well-written. Greta’s essays that introduce the various sections are excellent: she writes with outstanding clarity. And the general standard of the short essays is excellent. I learned a lot about many different aspects of Climate Change that I had not previously focussed on.

However, I will not be gifting this book to anyone I love. Why? Because I found it overwhelmingly depressing.

Antidote to hope

Friends, Climate Change scares me. I feel the fragility of our way of life and I feel terrified for my children. And I am acutely aware of just how profoundly bad our situation is. In many ways, I am a natural ‘Doomer‘. But I resist that temptation and prefer to focus on what I can do to try to improve things – however marginally.

My resistance is not really supported by the weight of evidence which is probably on the side of the doomers. It’s a choice I have made.

And that’s my problem with the book. It amplifies every negative aspect of our situation in a way which I found overwhelmingly depressing. I appreciate the book’s straightforward honesty, but it doesn’t help me get by from day to day.

The book implies that there is no solution to the problem of climate change without simultaneously solving multiple problems of inter-national, inter-ethnic, inter-gender and inter-generational justice – problems that seem to me to be much harder than the fundamentally technical problem of stopping emitting carbon dioxide.

There is more than one thing happening

At the moment on Earth there are two epochal changes taking place. Climate Change is one of them, and its multiple levels and scales and implications of that change are well-described by Greta’s book.

But we are also undergoing an Energy Transition which I estimate will have impacts on the same scale as the Industrial Revolution.

Solar Energy, Wind Energy and Battery storage have plummeted in price and their deployment is accelerating exponentially. I’ll be writing more about this in coming weeks, but by most measures, some combination of these technologies provides the cheapest electricity humanity has ever known.

As someone who is planning to operate their home entirely from solar power for 6 months of next year, this technological shift feels very real. And this change has taken place in my lifetime.

Cost is the key. Because these technologies are cheaper than building any other kind of power, they will – even in the face of strong opposition – inevitably win. In the end, the fossil fuel technologies will simply not be able to compete. In the end we will make the energy transition, not because it is the moral thing to do, but because it is economically essential.

And this transition seems to me to offer some hope to people living in both developed and developing countries.

The Energy Transition will not bring with it solutions to the multiple problems of inter-national, inter-ethnic, inter-gender and inter-generational justice. But it does offer at least a realistic opportunity to reduce carbon dioxide emissions relatively quickly.

And for me, that would be enough.


Global Warming Trends

December 3, 2016


The anomaly in the Earth's temperature based only on thermometers in meteorological stations and excluding the oceans which cover about 70% of the Earth's surface. The Daily Mail only draw your attention to a small fraction of the data - and they include monthly fluctuations which disguise the clear warming trend.The anomaly in the Earth’s temperature based only on thermometers in meteorological stations and excluding the oceans which cover about 70% of the Earth’s surface. The Daily Mail only draw your attention to a small fraction of the data – and they include monthly fluctuations which disguise the clear warming trend.

Why do I ever even look at the Daily Mail website?

The other day I came across this pernicious article purporting to describe a plummeting of global temperatures above the land surfaces of the Earth. The article states:

Global average temperatures over land have plummeted by more than 1C since the middle of this year – their biggest and steepest fall on record. [P.S. by 1C they mean 1 °C not 1 coulomb]

The news comes amid mounting evidence that the recent run of world record high temperatures is about to end.

Some scientists, including Dr Gavin Schmidt, head of Nasa’s climate division, have claimed that the recent highs were mainly the result of long-term global warming.

Others have argued that the records were caused by El Nino, a complex natural phenomenon that takes place every few years, and has nothing to do with greenhouse gas emissions by humans. The new fall in temperatures suggests they were right.

It is accompanied by a misleading graphic:

Graphic from the Daily Mail website. Notice their graph only runs from 1997 and includes large fluctuations due to sub-annual changes. It describes only the changes in temperature above the land surfaces of the Earth.

Graphic from the Daily Mail website. Notice their graph only runs from 1997 and includes large fluctuations due to sub-annual changes. It describes only the changes in temperature above the land surfaces of the Earth.

The article is nonsense from start to finish, but I just thought I would show you how to get at the data for yourself so you can make up your own mind.

Decide for yourself

This excellent NASA web page allows you plot various graphs of temperature data, and change the degree of smoothing applied to the raw data. I invite you to try it out for yourself.

This NASA web page has excellent links and descriptions

You can choose to include land stations only, or combine land and ocean data. Remember that the land surface of the Earth represents less than 30% of our planet’s surface, and so the most relevant measure of global warming involves both land and ocean data.

As well as generating graphs, you can use the website to download data and then graph the data in Excel™ as I have done for the graph at the top of the page.

I don’t fully understand where the data in the Daily Mail graphic comes from. They appear to have picked only recent data and included monthly data rather than annual averages to increase the noise and de-emphasise the obvious trend in the data.

The background colouration in the Daily Mail graphic implies that the high temperatures are all associated with the El Nino conditions. This is not correct. As the graphic below (from skeptical science) shows, years with and without an El Nino are all showing a warming trend.

An animated file showing global surface temperatures in El Nino years, La Nina years, and neutral years. The graphic is from sceptical science.

An animated file showing global surface temperatures in El Nino years, La Nina years, and neutral years.

For the technically-minded reader, this article from Victor Venema may help.

The Trend 

What struck me as shocking was what happened when I set the smoothing of the data to 20 years – so that the trend represented a trend in climate rather than annual or multi-annual fluctuations.

In the figure below I show the data for the land and ocean mean temperature anomaly and the red line shows the smoothing with a 20-year running average. Since 1980 – which was 36 years ago – the data is essentially a straight line.

The estimated change in the temperature of the air above the oceans and the land. The red line shows a smoothed version of the annual data with a 20-year window to reflect changes in climate rather than the internal fluctuations of the Earth's complex weather systems. Source: NASA-GISS: see article for detailsThe estimated change in the temperature of the air above the oceans and the land. The red line shows a smoothed version of the annual data with a 20-year window to reflect changes in climate rather than the internal fluctuations of the Earth’s complex weather systems. Notice that since 1980 , the smoothed line is essentially straight with a gradient of approximately 0.017 °C per year. Source: NASA-GISS: see article for details

What if…

Friends, just suppose that NASA had spotted not a global warming trend, but an asteroid headed straight for Earth. Suppose they calculated it would not destroy civilisation, but it would nonetheless be devastating: its tidal disturbance would cause widespread floods

Would we want to know? Well Yes!

Now suppose that the entire world got together in, say, Paris, and developed a plan to deflect the asteroid. The plan would be expensive and risky – costing about 1% of global GDP – but after about 100 years of effort we would be freed from the risk of a collision.

Would we follow the plan? Well Yes!

Friends, Global warming is equivalent in its impact to an asteroid headed to Earth, and the Paris Accord, while inadequate in itself, represents the start of a plan in which the disparate governments of Earth have agreed to slow development (that brings direct benefit to their citizens) in order to tackle this threat.

Please don’t let the Daily Mail deceive you into thinking global warming is not happening: it is. It is happening slowly – 0.017 °C per year  – and the odd year of inaction makes no difference.

But year upon year of inaction condemns us to a fate that is out of our control.


1001 grams: Film Review

March 19, 2016

Scene from the film ‘1001 grams’ showing delegates to the BIPM ‘Kilo Seminar’ holding their respective national kilograms.

It has been one year, 5 months and  23 days  since I posted a trailer for the Bent Hamer movie “1001 grams”. And this week I finally saw the film.

I had sought it out many times with no success, but a couple of weeks ago I managed to obtain a DVD encrypted as DVD Region 1. And so when the DVD arrived, I then needed to buy a new multi-region DVD player just to watch the film!

The story follows Marie, who works at the Norwegian National Measurement Institute, her relationship with her metrologist father, her trip to Paris with the Norwegian prototype of the kilogram, her adventures with the kilogram and her relationship with Pi, a scientist who is now a gardener.

Sadly I have to report that although I enjoyed the film, I was disappointed.

The whimsy and insightful observation that characterise Hamer’s films is certainly there. But whereas it is concentrated in the trailer, it is diluted in the film itself.

The film has many great features:

For this metrologist as least – it had many many laugh-out-loud moments. The casting and characterisation (caricaturisation?) of the delegates to the BIPM meeting (i.e. people like me and my colleagues) is shockingly perfect; the scene in which the camera fleetingly captures two delegates asleep in a seminar is also true to life.

The metrologist’s obsession with minutiae and attention to detail is well-captured, both in Marie’s day-to-day work calibrating ski-slopes and petrol pumps – and in relationship to the kilogram. The moment that the delegates peer in to see the ‘Mother of all kilograms’ is exquisite.

And the cinematography is beautiful. The filming of the metrological artefacts and activities is delightful, and the depiction of the International Bureau of Weights and Measures (BIPM) is charming.

And I have to admit that tears did fill my eyes at the point where the meaning of the film’s title is revealed.

But overall I felt the film was just a little light on content, in both the storyline and dialogue. This may be because I lack Hamer’s Norwegian perspective. Or perhaps silence is a bigger part of personal interactions between Norwegians than it is between English people.

The lingering shots at the start and end of scenes that establish a sense of continuing stillness can eventually become irksome for the non-auteur. After a while I got the sense that these were simply padding to get the film past the 90 minute mark.

But overall, I do not regret the £62 I spent to see the film!

Back in 2014 I wrote:

Bent Hamer’s films about IKEA researchers and retired railwaymen were not really about IKEA researchers or retired railwaymen. And I am sure this film is not really about the kilogram.

It is probably about the same thing that every other Bent Hamer film is about: the weirdness of other people’s ‘normal’ lives, and by implication, the weirdness of our own lives. And how important it is to nonetheless grab whatever happiness we can from the passing moments.

I was right.

You can catch a more detailed review with spoilers here


SI Superheroes

January 12, 2016

Somehow this episode of SI Superheroes came out last May (2015) and I didn’t notice!

If anything, this is even better than the first episode – perhaps because it’s more focussed on a single theme without the need to introduce all the characters.

In case you are unfamiliar with the work of NIST, the US National Institute for Standards and Technology, they are basically the US version of NPL and are a very serious organisation. In my recollection, this is only the second output from NIST that has featured laugh-out-loud moments (which I will not reveal!).

I can foresee great things for these characters.

Remember that Superman, Batman and their friends and foes inhabited a (DC) universe of paper comics for decades.

Then they became TV cartoon characters.

And only relatively recently have they become the stars of the current genre of all action, computer-graphic laden movies.

I wonder if they will be recruiting for a male with slightly older looks to play Dr. Kelvin…


Incidentally, the number 9,192,631,770 displayed on the side of the cartoon satellite is the number of oscillations a Caesium atom that defines what we mean by the passage of one second.

At places like NPL and NIST we can make clocks based on Caesium atoms that very perfectly realise this definition.

The atoms in these super-clocks vibrate at  9,192,631,770.000 000 ± 0.000 001 oscillations per second and form the basis of Universal Coordinated Time (UTC)  that is used throughout the world.

One of the difficulties which Major Uncertainty may have tried to exploit is that the number of oscillations per second changes very slightly with changes in the physical environment of the atom.

Some of the environmental parameters that matter for clocks mounted in space are:

  • the strength of the gravitational field,
  • any accelerations that the atom experiences,
  • the  speed of the clock with respect to the person (often on the ground)  counting the oscillations,
  • the temperature of the walls surrounding the atoms.

Anyway – all is well now that the League of SI Superheroes has done their job again.

How Apollo Flew to the Moon

September 6, 2015
The Moon photographed above some beach grass in Northumberland

The Moon photographed above some beach grass in Northumberland

On my recent holiday in Northumberland, I both photographed the moon, and read about how almost 50 years ago, human beings landed on its surface.

This article is a review of the book I read: ‘How Apollo Flew to the Moon‘ by W. David Woods.

Staring at the moon and considering what we now know about its distance from Earth, its size, and its inhospitable surface, is an exercise in bridging emotional and intellectual understanding.

I have long-considered that the Apollo programme of manned spaceflights to the Moon to have been an exemplar of the power of human intellect, and overall one of humanity’s exceptional achievements.

The enormous cost of the programme (4% of the US Federal budget in 1967) was – in my opinion – well justified by the cultural shift it engendered.

We went to the Moon and discovered the Earth‘ is a truth expressed by many, including several of the early astronauts.

However this book is not about the cultural impact of the programme, but about how the journey was made. For anyone with a technical disposition the book will fascinate.

I took all 500 pages of the book on holiday with me and self-indulgently read it slowly from cover to cover: it was enormously enjoyable.

After an overview, the book follows the Apollo 11 mission through all its stages, sprinkling in astronaut comments and explaining the differences between earlier and later missions.

There are many fascinating details, but what came through to me above everything was NASA’s pervasive mindset of constantly, painstakingly, meticulously and expensively planning for failure.

The philosophy of not just being aware that an operation may fail, but making detailed plans for what you will do when it does is a lesson for anyone who wants a complex plan to succeed.

And not only were there back-up plans for failure, there were plans for failure of the back-up plans! Only at one or two key points in the entire mission were there operations which simply had to work.

So, for example, when their spacecraft fired a rocket engine to leave Earth’s orbit and head towards the Moon –  or rather where the Moon was going to be in three days time – the rocket burn placed them into a so-called ‘free-return trajectory‘.

Thus if something went wrong on the voyage, or the rocket engine failed to fire – the spacecraft would sail around the Moon and head straight back to Earth.

When launched towards the Moon, the Apollo spacecraft was placed in a “Circumlunar-free-return-trajectory” . This meant that unless they did something positive to enter the Moon’s orbit, they would return to the Earth. Picture by NickFr Licensed under Public Domain via Wikipedia

Overall, the book is a great read for the technically minded. And in addition to the narrative there are occasional superlatives – like ‘vista-points’ on a highway – where you can stop and simply wonder.

  • The total mechanical output power of five first stage rockets was 60 GW. This is equivalent to peak electrical supply of the entire United Kingdom.
  • On its return from the moon, its speed just before entry into the Earth’s atmosphere was more than 11 kilometres per second.
  • Since Apollo 17 returned in 1972. no human being has been more than 500 miles from Earth’s surface.

Science Demonstrations: the art of seeing things differently.

April 6, 2014

One of the highlights of the last few weeks was attending the premiere of Demo: The Movie by Alom Shaha and Jonathan Sanderson.

Mingling with the gliterati of the science communication world, the event, the conversations, and the film all helped me to reflect on the purpose of science demonstrations.

To me the purpose of a demonstration is to highlight one aspect of the everyday world, and to allow us to look at it ‘differently’.

This is necessary because for most of us, for most of our lives, the world doesn’t seem mysterious: our world comprises familiar objects that behave in a familiar way.

So famously in 1848 Michael Faraday gave a series of six lectures about an object which must have been extremely familiar to his audience: a candle. And this ground-breaking lecture series is the starting point for Demo:The Movie.

From this point Alom, a teacher, travels from his classroom to San Francisco via the western deserts of the USA performing demonstrations and reflecting on the their role in teaching as he travels.

He concludes that performing a successful science demonstration is an art which incorporates elements of stage magic, understanding of teaching aims and objects, and that most difficult to pronounce word, pedagogy.

For me the most important point made in the film is the profound (and paradoxical) point that demonstrations are different from videos of demonstrations.

This point is made by showing a plastic bottle (which you previously saw Alom fill with air at the top of a mountain) has been crushed when he reaches Death Valley, exactly as viewers probably expected.

But Alom points out that seeing this on video, you have no idea whether this is the same bottle you saw filled earlier. Indeed, you have no idea whether that it was even ‘earlier’.

It is the power of seeing things for yourself which is personally challenging. In terms of my own favourite demonstration, anyone who has ever seen a sausage attracted to a balloon is in some way personally challenged to ask themselves’ What is going on?’.

I can strongly recommend this 30 minute epic to anyone who engages in science communication in any form, but most especially to teachers who might feel inclined to simply show a class a video of something happening instead of performing the demonstration themselves.

And if you want help on performing demonstrations and tips on ‘getting it right’ Jonathan and Alom have created a website which has many videos showing you how not to use videos in class!

Finally, if you love the movie as much as I do, you can check out the bloopers movie/trailer below.



Musical Inclusion: Ballads for the Age of Science

March 4, 2013
Album Covers from my favourite albums

Album covers from the series ‘Ballads for the Age of Science’

Last week I wrote about how the technical nature of professional music or professional science could lead to people feeling excluded from a musical or scientific cognoscenti.

This week the antidote:  – a series of songs (just recently available on iTunes) which will help everybody to feel included in the scientific endeavour. I recommend them to every parent, every teacher of science, and every science communicator.

Ballads for the Age of Science was written and performed in a different age – an age of scientific optimism: the 1950’s. An age when it was OK to sing about the Greenhouse Effect in a primary school classroom in the USA.

The album series consists of:

  • Experiment Songs, by Dorothy Collins (Link to iTunes)
    • My favourite? “It’s a magnet”, which is just a delight.
  • Nature Songs and More Nature Songs by Marais and Miranda (Link to iTunes)
    • My favourite? “Why is the sky blue?” which is not quite technically correct, but so ambitious!
  • Weather Songs by Tom Glazer  (Link to iTunes )
    • My favourite? That’s hard because every one is a gem. “What is the Climate?” is a classic, but “What does the Glass of Greenhouse do” is brilliantly ambitious – and bold in its use of banjo!
  • Energy and Motion Songs by Tom Glazer and Dottie Evans (Link to iTunes )
    • My favourite? It has to be the catchy “E-lec-tric-ity” which is a true work of genius.
  • Space Songs by Tom Glazer and Dottie Evans (Link to iTunes )
    • My favourite? Despite the naiveté it has to be “A scientific fact”, a paean to age when things were simpler .

These will become hits in the UK – they will spread first like a secret amongst friends and then like wildfire until you are sick of them. But by joining music to learning about science they unite two disparate ends of circle which has been cut for too long. Enjoy 🙂

Just in case you are interested, the songs we use in Protons for Breakfast are:

… and if we had the time we would use loads more!

You might also be interested in an obituary for Tom Glazer from The Independent and you can also read about his life on Wikipedia

Climate contrarians spreading confusion

June 27, 2012

XKCD wrote a cartoon about my dilemma

I write this blog to stop myself going crazy: but those Climate Contrarians over at The Register keep pushing all my buttons! Take this extract from the end of a recent article

Meanwhile there’s reason not to panic even though the 450 ppm target will never be achieved [1]. US government climate modelling now suggests that warming will only just exceed 2°C – or even come in well below – at 780 ppm CO2.[2] It has become clear that the Antarctic ice cap actually froze into being while levels stood at 600 ppm, and that no matter what happens it’s going nowhere for thousands of years [3]. Many scientists suspect that the Sun actually has much more effect on climate than current climate science suggests [4], and major physicists believe a period of low solar activity is approaching which could usher in a “mini ice age” of the kind seen in the 17th and 18th centuries [5].


Even if none of those reasons not to panic contains the slightest grain of truth – even if it really is time to panic about carbon – in the real world picture now developing, activists would surely be well advised to abandon their various marginal crusades – against meat, against mythical fat people, against wasted milk, against hosepipes and farting camels and coffee and all the rest of the silliness, and try to make a case for action that has some internal consistency. ® [6]

Let’s look at these six points in turn:

[1] Panic isn’t what anyone wants to create. We have lots of problems facing us(e.g. feeding ourselves, keeping healthy, world population etc.), and climate change is one more. Panic won’t help with any of them, but a sense of urgency and importance is appropriate. Why does The Register mock people’s perfectly reasonable concerns?
[2] Climate Sensitivity. By how much does global mean temperature change when carbon dioxide concentrations double? We don’t know, but estimates range from roughly 2 °C to 4 °C . It could be much larger, but even the smallest of these figures will usher in significant climate change. And if the permanent arctic ice cap disappears – as seems likely – then all of these calculations become irrelevant . Furthermore we are (realistically) going to at least double CO2 levels. Slowing down emissions now would probably be a good idea. Why doesn’t The Register recommend that?
[3] The Antarctic Ice Cap formed 34 million years ago when the continents were in different places. In particular the Atlantic and Pacific Oceans were connected through the Central American Seaway. The growth of the ice cap was triggered by the breaking off of South America from Antarctica which created a circular weather system which ‘sat’ on the south pole and reduced the flow of the heat from the equatorial regions. Frankly, the concentration of Carbon Dioxide in the atmosphere was a tiny perturbation on that kind of  gigantic change of oceanic and atmospheric circulation. Why does The Register write this irrelevant nonsense?
[4] Solar output has been pretty constant, and is certainly not responsible for the recent warming seen on Earth. Why does The Register write this irrelevant nonsense?
[5] The ability of scientists to predict solar behaviour is limited. At the moment all predictions are based on statistical correlations with previous solar behaviour. If there was a reduction in solar output and a mini-ice age that would probably help reduce global warming, but it is completely out of our control or knowledge. Why does The Register write this irrelevant nonsense?

and finally the truth

[6] The Register is fed up with ‘silly stories’ about Climate Change. Well so am I! But what I try to do is sift the wheat from the chaff. Climate Change is a serious issue and serious journalists should take it seriously.

Efergy e2 Wireless Electricity Monitor

June 20, 2012
Efergy e2

The Efergy e2 wireless electricity meter.

A while ago I reviewed a previous Efergy wireless electricity meter and commented on its usefulness, but noted that the unit wasn’t very accurate – it was about 25% in error when compared with my domestic electricity meter. In order to find that out,  I had to read the daily total of units used off the screen of the unit, and plot the data on a spreadsheet and then compare it with the domestic electricity meter over a period of many months. Not many people can be bothered with that type of kerfuffle.

But the device was still useful. Occasionally I would look at the amount of electricity being used in the house, and then walk around switching things on and off and see how much the consumption changed. However, the unit could only really detect changes in consumption of about 10 watts and so the readout could be a little bit noisy, but it was still useful.

A couple of months ago I was contacted by Efergy who asked me if I would like to test their new wireless unit, the Efergy e2. This one should be very accurate because it works by piggy-backing on the domestic electricity meter: simply measures the flashes of light that the meter produces for every one thousandth of a kilowatt hour (an electricity unit) that it uses. Additionally the unit connects to a PC or Mac and data can be downloaded to allow the user to monitor consumption trends over time. It sounded fantastic: accurate and convenient. I happily agreed to review the unit and Efergy kindly sent me one – free of charge! I always knew writing this blog would pay off one day!


The basic setup of the unit was easy – and I was quickly monitoring electricity consumption. However, the software installation was not so straightforward. Installation on my iMac was ridiculous, requiring installation of 3 separate programmes and then a re-start. And after all that, it still didn’t work. Efergy really need another way to do this. Installation on PC was a little more straightforward requiring only that I downloaded an up-to-date version of the software from their web site.


Efergy Software

The Efergy e-link Software. It has a non-standard interface, quirky controls, the scaling of the graphs is random and there is no way to get at your own data. Click for a larger version.

Once the connection problems were sorted out, I downloaded some data from the unit to the PC. The software allows you to see how your consumption has varied hour-by-hour through the day, or day-by-day through the month. However, the controls are quirky and non-standard: the graph’s scale changes from one day to the next making it difficult to visually compare one day with another; the units it uses to plot the data are -effectively – random numbers; and the writing is so small and written in green on grey so that it is almost unreadable.

However, after instruction from Efergy I did manage to download data to my PC – Ahhh!…At last I felt like I was in control. The software saves the data in an old Excel file format which is easy to open and plot. The graph below shows the number of kWhs used, averaged over a period of 1 hour – effectively the average power consumption – hour by hour for the last month. I could also have just downloaded the total number of kWhs used daily. Why the built-in software can’t plot these graphs is a mystery to me.

This is just the kind of data I love to see. I don’t mind the peaks on this graph – they are the dishwasher and the tumble dryer – but this data tells me that no matter what I do, my house uses around 350 watts of electricity (more than £1/day or £365/year) whether I am at home or not! I will get to the root of that!

Electricity Consumption

Electricity Consumption Click for larger Graph


Aside from reviewing your energy usage, one of the key uses of this type of device is to walk around one’s home and see the effect of switching things on and off – Efergy call this the ‘Energy Now’ function*. The previous model was just about OK at this, but it wasn’t very accurate at low power levels – as I mentioned above the readings fluctuated by a few watts making the useable resolution around 10 watts. But the technology Efergy have employed in this unit is potentially much more accurate. By simply recording the time between pulses from the electricity meter, they could have made an extremely accurate meter with a resolution of around 1 watt. But instead they chose not too – apparently in a bid to extend battery life. IMHO this was a poor decision.

Instead of recording the time between pulses, the unit records ‘How many pulses occur in 30 seconds’. Let me explain. For a typical meter, houshold consumption of 120 W will cause one pulse per 30 seconds. 240 W  will cause two pulses per 30 seconds etc. If you are using say 180 W, then sometimes there will be one pulse in a 30 second period, and sometimes there will be two. This unit will tell you that your electricity usage is oscillating between 120 W and 240 W and you will wonder what is switching on and off. But nothing is. In short the ‘Energy now’ function has measurement resolution of 120 W – around 10 times worse than the previous version of this unit, and functionally useless. Grrrrr…

The idea of piggy-backing on existing metering technology is smart and Efergy tell me that future units will incorporate my suggestion for measuring the time between pulses and so those units will also be very sensitive for monitoring consumption in the ‘Energy now’ mode. Sadly existing units won’t be able to be modified.

And presumably they will eventually make software that doesn’t irritate people and which works on Macs.

The selling point of this unit is the ability to download data to a PC and to look at usage over a long period of time in detail. This is very valuable and personally I would buy it just for this function. When they sort out the ‘Energy Now’ issue this will be a great little unit which I would recommend to anyone.

You can find the Efergy web site here

* It should be ‘power now’ not ‘energy now’, but Efergy say they used this metrological inexactitude in order to communicate more clearly.

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