Earth Notes: From the Inbox (and Outbox) 2008, 2009

Updated 2022-09-19 19:07 GMT.
By Damon Hart-Davis.
Read emails and queries from, and discussions with, readers of Earth Notes (2008--2009).
people meeting
Some interesting brief email interchanges (edited as necessary). I hope that you find them useful.

I receive a steady stream of emails about the site, some of which I expand into stand-alone articles (eg Going Green in Newcastle-Upon-Tyne and Solar PV in Diffuse (Cloudy) Daylight) and others of which I follow up privately. Also, I have sent unbidden an email or two to register an opinion...

Going Solar in North-West UK

Jason Garner sent me an interesting email on going solar at home headed "Powering a 5W Deltech 12V LED Bulb Using Solar Power: Help!"

Read some of our exchange.

General Permitted Development Rights for Air-Source Heat Pump

Where I live (London) as of November 2009 it is still necessary to obtain planning permission to install an air-source heat-pump, which clearly adds red tape, uncertainty and cost to getting one. The main issues still at odds are the looks and noise of ASHP which could prove very contentious especially in densely-populated urban areas. As of 2009-11-17 the UK Government is consulting on streamlining the process.

I submitted the following query:

May I make one suggestion or get some clarification?

We would like to replace our band-D gas combi with an ASHP equivalent (probably Eco-Cute-style CO2 refrigerant) but we have a very small (end-of-terrace) house so unless mounted at the back, well away from where it is needed, an external unit could be visible from a road for someone sufficiently determined.

(The optimal mounting I suspect, would be on our side wall, but that could be glimpsed from a road with effort.)

We already have extensive PV (indeed we are net generators) and the local authority has been very supportive of renewables, but it would be important to me to have some more clarity in what counts as "Not permitted if visible from and sited on an elevation which fronts a highway." so that we and the local authority could be happy that we were within the law. Would insertion of "clearly" before "visible" be the right sort of change?

Laundry Detergents for Cold(er) Clothes Washes

Given that most of the energy consumption of a typical UK domestic wash cycle is in heating the water, but compared to North America cold-wash detergents are hardly available here, I wrote to P&G to ask about the low-temperature performance of the new Fairy non-bio gel and received a quick response on 2009-04-06:

We appreciate not all washing machines have a 15o wash cycle, however you will get brilliant cleaning performance at low temperatures when using a cold cotton wash cycle (NOT the delicate/hand wash cycle though because of the much lower level of agitation). Fairy Gel contains technologies that are active from very low temperatures (15o) however the performance is also excellent at higher temperatures such as 30o or 40o. We do recommend you to try Fairy Gel at a low temperature if you can, using a cotton cold wash cycle, as it should give outstanding cleaning results and extra consumer and environmental benefits such as: less product to dose, less energy per wash, less packaging waste, easier to carry, store and dispense at home, less CO2 emissions and reduced transportation costs hence, a lot of benefits for you as well as for the environment.

I asked for clarification if P&G would recommend Fairy non-bio gel for the cold wash and I received this reply:

We wouldn't recommend that it is used on a cold cycle, only on a specified 15 degree cycle, as we know the temperature can vary depending on the season.

Note that P&G have another range, US-targeted, with a much lower minimum wash temperature than the UK/EU brands ("P&G Tide" email response 2009-08-18):

Tide Coldwater is able to perform in temperatures as low as 40 degrees F (4 degrees C). If the water in your washing machine is below 40 degrees F (4 degrees C), add a bit of warm water to bring the temperature to that level before adding your clothing.

I would very much like to try this or the "Tide Coldwater HE" variant for "High Efficiency (HE)" front-loaders.

Unfortunately the official UK response to my request for where to buy or sample Tide Coldwater or equivalent in the UK (2009-08-25) is:

I am sorry to inform you that Tide is not currently available in the UK or Ireland.

The various P&G companies around the world each manufacture and market products designed specifically to meet the needs and preferences of consumers in their own regions. However, we do constantly review the range of products available in the UK and Ireland and do welcome your comments as a helpful addition to our consumer research.

I'm very sorry to disappoint you, but thank you again for getting in touch. Consumer feedback is really important to us so we've passed on the details of your message to the relevant department.

to which I responded:

Please let your marketing people know that (a) I am disappointed, clearly and (b) that I am forwarding this correspondence to Ed Miliband at DECC, as an example of market failure given that laundry water heating probably accounts for many percent of UK total energy consumption and that P&G will not make its existing energy-efficient brands available in the UK market.

On the back of P&G's unsatisfactory reply I sent the following to their main competitor, Unilever (2009-08-25):

I am trying to source a domestic laundry detergent that will work well in a cold wash year-round (ie down to ~9C in winter). P&G seems unable or unwilling to help as its primary UK Ariel Excel gel brand is only rated to 15C and they will not sell their US-brand Tide Coldwater (HE) product (good down to 4C) here.

Can you do better and point me to a UK brand that will work at 9C?

(As you are aware, ~90% of the energy in a typical UK domestic wash is heating the water. We are trying to reduce our carbon footprint but are only able to do about 20% of our washes cold right now due to inadequate detergents. Not selling such an energy-saving existing brand here seems very poor from an environmental and PR point of view and I already made my annoyance at this market failure clear to Ed Miliband today.)

And Unilever's response 2009-09-01 was far more satisfactory:

I wanted to let you know that any of our liquid detergents (NOT CAPSULES) will work at low temperatures, although it is worth noting that while they will work at low temperatures performance will not be as good because performance increases proportionately to an increase in temperature.

This is why we advise 30 degree washes-not because our products don't work at lower temperatures (they have been tested to work at temperatures as low as 10 degrees) but because performance is better from 30 degrees up.

We have been trying various detergents and wash temperatures in our new washer/dryer that will wash in cold water, and now maybe only 30% of our washes are at 40°C or higher (in summer) with about 50% at 30°C and the rest cold. Altogether this probably amounts to as much as a 50% energy saving.

AccordGuy's Off-Grid Solar in Crawley, UK

I received this from AccordGuy 2009-04-02 (AKA SolarBodge), who seems to have been having a lot of fun:

I've been following your pages for a year or so, and at the same time last autumn started to build my own off-grid system.

I started because my company chucked me out of my office and lots of us have to work from home now. I saw some cheap solar panels on sale at Maplins and had some bits and bobs like an old leisure battery and a 150W inverter kicking around the shed to build a simple system. I thought, how difficult can it be to power a 30W laptop from solar power if I'm going to have to work at home?

I'm now up to about 600Wp with the purchase of a pair of Sharp ND170 poly panels plus about 260Wp of those cheap amorphous panels from Maplins. I run a 220Ah 24V battery bank and a 1kW pure sine inverter. In the recent sunny days I've been able to use about 1kWh of sunshine and battery power each day and expanded the system from just the laptop and some table lamps to powering my whole house lighting circuits with a change-over socket for those circuits. I can choose grid or solar power for those two lighting circuits but haven't had to use grid power now since about mid-February.

My in-laws in Japan are all solar mad as well! My sister-in-law installed a 3kW Sharp system while my father-in-law installed a 5kW Sanyo system.

Where I live in Crawley, I've just this week noticed a big array go up on one of the blocks of flats near by. Curiously, they didn't use the sloped roof to mount them but rather steeper angled frames built on the flat sections of the rooftop. Either they are trackers or it wasn't allowed to mount them on the tiled roof.

Anyway, keep the updates coming. It's interesting to watch your plans develop.

I have some of those Maplin panels too: when they're on sale at ~£4/Wp they are difficult to resist. Can you say renewable retail therapy?

House Pressure-Testing

In connection with my item about pressure/leak testing my house with a view to heating energy efficiency, I was asked a few questions:

Where I live (no heating needed) if there is no outside air flowing in and out the natural way, the house feels unlivable and stuffy... Different perspective I guess.


What's your position on air vents? I understand that they are mandatory if there are gas appliances, but they seem to completely undermine some of the insulation changes. Our lounge has a gas point that has never been used, because of this we have an air brick that was incorporated when the house was built - it's papered over because we couldn't live with the draft.

You have to (by UK building regulations) have enough efficiency and insulation elsewhere that you can afford the loses that go with adequate ventilation...

Part of UK building regs (Part F, I believe) deals with ensuring that there is adequate ventilation in the building, eg to avoid condensation/mould, and more dramatically sufficient oxygen to avoid CO (carbon monoxide) poisoning in rooms with an open flame such as a gas cooker.

Or you can do it the German 'Passivhaus' way and have an air-tight house with mechanical heat-recovery ventilation (MHRV) that ensures that the air changes frequently (is exchanged with outside air) but keeps the heat in the house.

We simply won't get as air-tight as Passivhaus here but the closer we get the more I shall have to think about 'trickle vents' and single-room or whole-house MHRV. We may well try MHRV in the bathroom first as our mould is starting to demand its own parliament and land rights.

So you fill the house with air like a balloon and measure the rate of pressure drop?

The test has to be done with planned ventilation blocked and is looking for unplanned leaks, eg from a heavy-handed workman cracking an otherwise airtight panel.

We did both under- and over-pressure tests (the latter are avoided if the house has chimneys full of soot!) and flow rate is measured while a constant over/under pressure is maintained by a fan. Only about 0.05%, so the same as a strong wind blowing through an open door.

(Note that in the US the process of reducing unwanted heat loss/gain due to unplanned air leaks is often called "weatherization".)

And Chris Benson wrote to me again with related experience:

I've recently bought for each of our 8 (unused) chimneys and have 5/8 installed. (Buried in the ash, cement dust and bird droppings I found that several of the fireplaces would have had closable flaps originally, but these are long gone :-()

They've made a considerable difference: no more rain/hail/soot/ash/bird[droppings] landing in the fireplace and bouncing onto the carpet/rugs, (presumably that will land if/when I remove them). And of course much reduced wind and bird noise. Some wind noise is still there: though now it's more like the sound from blowing across the neck of a bottle.

The balloons should still allow some air to pass to allow ventilation of the room and the chimney.

I had been wondering about getting the house pressure tested once I had done something about the glaringly obvious leaks: So now I know what to look and ask for!

And later, discussing why it may be hard to get good 'green' work done:

I've been thinking lately about the skills gap in green-building:

  • there's some new knowledge to be learned (often replacing existing ways of doing things which is going to make learning harder)
  • there's some trial and error required to find the pros and cons of different materials and techniques
  • materials and techniques are changing relatively quickly
  • different situations will require a range of materials and techniques depending on internal/external, construction method and materials, budget, legal restrictions, ...

It seems to me that the chances of getting and maintaining enough experience in any one area is going to be hard for most builders when most customers will be asking for the cheapest cost and damn the insulation...

G83-Lite Suggestion to Ed Miliband of DECC

Email to the Minister of Energy and Climate Change, Ed Miliband, 2009-03-28, subject "Suggestion for DECC for G83-lite":

I'd like to suggest creating a new light-weight form of the current G83/1-1 microgeneration spec/rules to allow consumers to connect very cheap and simple (and safe) microgeneration devices to the grid partly to help allow more urban area to contribute to renewables, and partly to get mindshare for more householders, eg renting, tower-block inhabitants, and other currently-excluded groups, to enable them to "be part of the solution" in at least a small way.

I've written up a little more detail here:

True UK Grid CO2 Intensity (kgCO2/kWh)

Paul Street of the London Development Agency wrote 2008-11-21 to point out:

You reference 0.43kgCO2/kWh (from Defra). This is the governments aspirational long-term target for grid carbon factor. And has little basis behind it. It would be better to use the Defra 3 year rolling average figure (currently 0.52kgCO2/kWh) which is far more representative of the current grid factor. Of course we all hope the grid factor will go down to 0.43 and beyond one day.

I'm looking at variations and the mean intensity in the UK grid too.

In June 2009 John Stott wrote to me:

I notice you refer to various official average grid intensities in your note on variations in grid intensity.

A year or so ago, Carbon Offsetters used 430g/kWhr which you describe as an aspirational marginal cost. I have also seen 430g/kWhr used in a DEFRA Act on CO2 document circa 2007 or 8. Now the offsetters and carbon trust say about 530g which you describe as the rolling average. The latter I understand but the meaning of aspirational marginal cost is not clear to me. Is there a simple explanation of this term and why should DEFRA/ Carbon trust and the offsetters suddenly change to the higher value? Perhaps I should ask if you can say why they used the lower value since using the rolling average seems reasonable to me.

And my rather weak response is:

The government apparently aspires to the 430g figure for a marginal increase/decrease in consumption based on projections done some time ago and based in part on extrapolating the effects of the "dash for gas" if I understand correctly. And the marginal cost may not be the mean if the time of deferral or extra use is consistently at some part of the day with an intensity above or below the mean...

There have quite reasonably been other figures used concurrently, for example a higher value in Part L of the Building Regs I think for energy import deferred by microgeneration or somesuch.

And if, for example, you cared only about energy consumption in (say) winter for heat-pump based domestic space heating when grid CO2 intensity is higher then you'd maybe pick a higher value than the rolling mean I think.

One exercise I intend to attempt is a study of our month-by-month electricity CO2 emissions allowing for the hour of day of our typical consumption and microgeneration, intensity of the grid at that time...

But I think the short answer to your question is that I do not know for sure what goes on the in [the] minds of civil servants...

Generation at Existing Historic Tidal Mill Sites?

Tidal generation might be a very useful source of electricity for the UK, in part because it is predictable long in advance (unlike wind for example) even if still not (fully) 'demand callable' like fossil fuel generation. Having seen an item about Thorrington tide mill in Essex I wrote to Essex County Council 2008-11-09 asking if it had considered generating electricity and if that would indeed be possible without damage, etc.

Geoffrey Wood (Mills Support Officer) kindly wrote back as follows:

Your query referenc[ing] the possibility of generating electricity at the mill is one we are often asked. The short answer is that we have no plans to pursue the idea based on several factors.

  1. The mill pond is fresh water from Tenpenny Brook and is used for irrigation of crops.
  2. The tide gate is permanently closed to prevent saline water entering the pond and polluting the fresh water.
  3. Water is used from the mill pond to demonstrate the working of the waterwheel very sparingly; the majority of the mill pond is for irrigation.
  4. Models have demonstrated that the present existing machinery would have a very short life and would require constant hourly maintenance and repair.

The economics of producing electricity are just not practical using a 19th century machine with 21st century technology.

Thanks for asking the question though.

Letter to Mr Miliband at DECC

Ed Miliband has been made minister at the new UK Department for Energy and Climate Change, whose mere existence signals the connection between our energy use and what it is probably doing to the planet.

I sent him the following email 2008-10-13 entitled "Two Quick Green Actions":

Dear Mr Miliband,

Firstly, I wish you well with your new portfolio: it is a real opportunity to [do] good and you will need a will of iron to make progress in the face of brickbats and mad suggestions for perpetual-motion machines and punitive destruction of Big Oil, etc!

I have two of my own nutty suggestions for you, but I hope that these might be 'low-hanging fruit' that not involve money, only administrative fiat.

1) Ofgem seems rather to have lost the plot as to the benefit of real new build of renewables rather than shuffling certificates around, according to Dale Vince of Ecotricity:

I have no particular objections to shuffling of certificates as a secondary activity and have worked with energy traders fairly recently, but Ofgem surely is wrong-headed to regard Ecotricity's *50%* renewable generation for their own customers from their own plant as less green than their rivals' shuffled extant power which looks like a sop to the interests of the large providers and not in the customers' or planet's interests. Maybe you could persuade them to revisit their thinking? "You can get much farther with a kind word and a gun than you can with a kind word alone. Al Capone"

2) Instant CO2-emission savings from UK grid generation this (and each) winter without spending money.

The nub of my suggestion is that grid electricity is most likely at its most carbon-intense when the very maximum demand is being serviced in the weekday winter peak 4pm--9pm since probably almost everything that can run has to, however dirty, so use demand control (as was applied by the DNOs at the request of National Grid in May when Sizewell tripped off for example, primarily voltage reduction in distribution) during those peaks to help shift demand away from the peaks and to within the capacity of less-CO2-intense generation.

If this mechanism works it might be an indication that longer-term Dynamic Demand would be a useful CO2-reduction tool as well as its more usual 'grid balancing' and intermittent-generation-friendly behaviour, eg see:

I hope these are of some interest.

Wind Energy Planning

Vicky Portwain wrote 2008-10-21 to say:

I have just set up an independent web-site called

The web-site has the aim of creating a forum where people can gain some further information about renewable energy but also to share their thoughts, actions and experiences, for example - my next post is going to be an interview with a someone who bought his own 6kW turbine and can give details of costs, and payback. It will also provide specialist guides for securing planning permission for renewable energy projects (small to large scale) and talk about wider issues including global politics.

Grid Connect Microhydro in Yorkshire?

On 2008-09-21 D Britton wrote to me asking:

I wonder if you can help! I have an old school house on the side of [a river] in Yorkshire. I make bio fuels, and have a 6kW lister generator that runs on straight recycled veg oil. It also kicks out 12kW of waste heat via the cooling system, which I am going to connect to my central heating & U Floor heating. I am also interested in a water turbine on the river, it's tidal, & quite fast flowing. I have looked at the ampair uw turbine, but it only produces 100watts and is expensive. I had a deal with npowerjuice to buy back exported KWh, but after 2 years of waiting for an export meter, I gave up and changed to Good Energy, who will pay for everything I produce, but will rely on generation meter readings, although they pay 2/3s less. I am struggling to find info on synchronising the genny to the grid though, do you have any advice at all please? Also, I would eventually like to run some PV, and wind, maybe into a battery bank, so I don't need to run the genny over night, do you have any advice on suppliers for switch gear, to switch from 1 supply to the other?

(I have a small steel fabrication business, so knocking any framework together for anything is no problem.)

To which I responded:

You need a special 'grid-tie' [inverter which deals with synchronisation] to export to the grid, pref to the standard G83/1. If you have three-phase power that will help.

For more help on hydro stuff look at which is fantastic and full of people who do this stuff all the time. Also they have a great IRC channel at irc://

Solar Power Map of London?

I wrote 2008-09 to the (new) mayor of London, asking:

Can we do something like this for London, possibly including solar thermal (and other microgeneration) too, possibly even off-grid systems?

Ofgem has the data already of course, by power (Wp) and location (address).

and 2008-09-18 I received the (trimmed) response:

Thank you for your email to the Mayor and your idea of creating a solar power map for London. Your email has been passed to the Energy Team and I have been asked to respond on the Mayor's behalf.

The San Francisco solar power map looks like a great way of promoting solar power and possibly other renewable technologies. Thank you for pointing it out. Officers at the GLA have similarly felt a map of renewable energy techonolgies in London would be useful and have in the past sought central government funding to develop this, however due to the existing resource explained below, it was difficult to justify setting up another system. It should be noted that in London solar power makes up only a small percentage of the city's renewable energy potential.

The Department for Business, Enterprise & Regulatory Reform (BERR) currently have a national system of collecting data on renewable energy technologies. This is presented on a map. However small scale renewables fall below the criteria for collection, which means that the renewables in London are not well reflected. Various organisations have in the past tried to persuade BERR to change the way they collect their data to rectify this. Please see the BERR website for more information: You may wish to convey your thoughts to officials at BERR.

~4173 words.