Wood-burning – Inconvenient Truth

There’s ever-growing  evidence that wood-burning is a big contributor to air pollution, especially in cities.

On January 22nd London had a major air pollution incident, with Camden, Westminster and The City hitting 10 out of 10 (worst) on the Air Quality Index.  “We think about half of the peak was from wood smoke” said Timothy Baker, air pollution expert at King’s College London.  Wood smoke pollution is most on cold evenings and weekends – this was a cold, still Sunday.  Small smoke particles have the worst health effects, especially PM2.5 (smaller than 2.5 micro-meter), which get deep into your lungs.    During that incident Cambridge levels of PM2.5 were  9/10 on the index. Domestic wood smoke contributes about a third of all UK PM2.5, which is  2.4 times more than traffic

UK government’s best estimate is that 29,000 extra deaths a year are caused by PM2.5   Public Health England estimates that 5% of mortality of people aged 30+  in Cambridgeshire is due to PM2.5 pollution. So this really is a major health problem, with wood smoke a significant contributor.

This is an ‘inconvenient truth‘ for Anne & me, because we really enjoy our small woodstove, which provides over half our heating, burning scavenged wood.  It’s renewable fuel with much lower CO2 emissions than gas or electricity.  Carbon emissions from wood-burning vary depending on whether the trees are re-grown, how the land-use changes, if the wood is kiln-dried and its transport.

Our government is being dragged towards action on air pollution: ClientEarth won court rulings to make them produce realistic plans for meeting EU air pollution limits and now the EU has issued a final warning. Sadiq Kahn’s tougher action in London  includes an extra £10 charge for pre-2005 diesel cars from October.  In Cambridge a ‘Clean air zone’ and emission charging are on the cards, while an NGO coalition is calling for a Clean Air Act for the 21st Century.

The Clean Air Act enabled local authorities to introduce smoke control areas, like Cambridge’s, where you’re only allowed to burn smokeless fuel or, if you burn wood, only in a DEFRA approved stove.  An EU directive, ecodesign lot 20, requires more efficient woodstoves by 2022, with about 1/5 the particulate emissions.  The UK Stove Industry Alliance already lists ecodesign-ready stoves.

Burning wood on an open fire is about 6 times more polluting than in a simple stove and loses a lot of heat up the chimney when the fire is out.

Expect tighter regulation on wood burning  before long, particularly in cities.  Even in rural Hampshire woodstoves can cause dangerous air quality. I suggest you think twice about installing a woodstove in a city, while this becomes clearer.

In the meantime, if you use a woodstove, please be neighbourly by running it hot and efficient to reduce smoke,  not lighting it when bad air pollution is forecast:

  • burn dry wood  15-20% moisture is best. You can check this with a moisture meter.
  • get it hot quickly by lighting your fire with dry kindling and then small pieces of wood. Keep it hot, burning the wood gradually and efficiently. A magnetic flue thermometer helps check  this at a glance. No smoke should be visible emerging from the chimney or tar deposited on the stove window if it’s burning well.
  • add more wood before the fire dwindles, so it gets burning quickly too. Avoid burning big chunks which smoke while they gradually catch fire. Re-reading our stove’s manual I found it recommends wood less than 10cm across – so we’re now doing more wood-splitting.
  • don’t shut off the air or keep the stove burning overnight, as this causes more pollution
  • avoid producing other toxins: don’t burn plastics, cardboard or glossy paper. Avoid particle-board, plywood, salty, treated or painted wood.
  • check a local air pollution forecast and avoid lighting your stove if high particulate PM10 or PM2.5 pollution is current or forecast the next day. If it’s raining it’s probably ok, as it washes particles down. Air Visual’s forecast app is good.

If you notice wood smoke indoors, you may be exposed to dangerous levels if it persists – at levels you may not smell.  Do you have a chimney problem?  Ask a chimney sweep or stove installer. Fitting a Carbon Monoxide alarm  is good for safety too.

People who bought diesel cars because of their lower carbon emissions are now joined by woodstove owners in facing the inconvenient truth of their bad health effects. They’re both still relatively low carbon, but good health needs good air quality. It’s time to re-think.

Tom Bragg

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Thermal Imaging Guide

You can reveal where buildings are wasting heat with vivid thermal images… this guide shows how with lots of practical examples.

I’ve been testing the £200 Flir One smartphone add-on. It’s as good as CCF’s £1,800 thermal imaging cameras with smartphone advantages, although not so rugged.  Many more community groups and individuals can now afford to use thermal imaging to show poor insulation, draughts and other ways our homes loose heat.

Drawing on CCF’s experience of thermal imaging since 2009, this guide aims to help many others get started and to supplement our training sessions.

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DETRITUS TRANSFIGURED – essay by Philip Vann

view of parade costume by Ann Templar cropped

DETRITUS TRANSFIGURED: The Cambridge CirculART Trail – essay by Philip Vann

Over three days in June 2016 I set out on quite an adventure – exploring on foot fifteen of the charity shops on the CirculART Trail in near-central Cambridge. Here, displayed in both shop windows and retail interiors for one month, was a dynamically diverse array of artworks made by over two dozen local artists. All had been sourced out of everyday scraps and bits of detritus; also from once perhaps individually treasured yet now abandoned oddments.

'Tetralogy of fallot' by Jane Helling, photo © Jenny Langley

‘Tetralogy of fallot’ by Jane Helling, photo © Jenny Langley

Jenny Langley, a local textile artist, imaginatively initiated and co-ordinated this ambitious project. She says, ‘I love charity shops. It’s my first port of call if I want anything. I love the serendipity of what I find there. I’ve got two thirds of the charity shops in Cambridge involved this year. We have a lovely mixture of artists now, some professional, some amateur, and two groups of artists with learning difficulties, who created fabulous window displays. Everything we’ve placed in the charity shops has been upcycled, reused, reclaimed, re-purposed in some way.’*

Alana Sinclair, Co-ordinator of Cambridge Carbon Footprint, explains how challengingly innovative this recycled art project has been. ‘We think we are the world-first in terms of pairing artists and charity shops together, and the first reclaimed art trail hosted in charity shops. The displays creatively showcase what can be done with recycled materials: waste isn’t waste until you waste it.’*

Just to single out a few highlights on this art trail:

Jane Helling’s immaculately crafted, hand-stitched soft sculptures (made out of recycled textile fragments) modelling human heart defects – one of which, Sacred Heart Defect, is, she says, ‘a 3D representation of my son’s unique set of defects, which he was born with 20 years ago’. Possessing their own surreally serene, upbeat beauty, these poignant works (at once semi-abstract and semi-anatomical) were displayed, suitably enough, in the shop window of the British Heart Foundation. Helling says, ”It makes a difference to your own whole creative process if you have to work with you’ve got or what you can find – and not go out and buy whatever you want. Happenstance is important in my work.’*

Judy Logan, 'I'M FREE'

Judy Logan, ‘I’M FREE’, photo © Judy Logan

view of parade costume by Ann Templar

View of parade costume by Ann Templar, photo © Janis Ford

Ann Templar’s outrageously exuberant yet deftly fabricated parade costume that she had worn at the Opening of Cambridge’s Strawberry Fair. She calls it ‘a political piece of art, incorporating a broken umbrella for the framework, sheet music and records and artwork donated by SENSE [the charity in whose window the costume was displayed] that I re-purposed into a plume of tail feathers’. Her visionary aim here was to reflect the soaring freedom of songbirds to transcend arbitrary human borders as opposed to the cruel silencing and ‘restrictions our brothers and sisters are suffering in the current refugee crisis’.

'The Lettuce Dress' by Cathy Dunbar

‘The Lettuce Dress’ by Cathy Dunbar, photo © Cathy Dunbar

Cathy Dunbar’s elegantly eclectic The Lettuce Dress – in which the ever-fluctuating fabric – and ephemeral beauty – of our lives is reflected in a design using many skilfully conjoined fabrics. Some of these came from clothes that the YMCA charity shop (where the work was displayed) was unable to sell, some from the artist’s own grandmother’s stash of 1920s and 30s’ textile bits and pieces. This is an audaciously harmonious creation fashioned out of a mass of fragments, including English chintz, chic French swatches, Nigerian cloth of bold archetypal design, and swirling sixties’ psychedelia of quite pungent saturated colour.

Judy Logan’s monumental, ominously swooping crow – its dark figure luminously splattered with turquoise and yellow (using reclaimed paints) against an asperous background of a recycled coffee bean sack sourced from a local café (with the engaging original packaging script still intact). Titled I’M FREE, this at once philosophical and visceral work was partly inspired by poetry – especially apt as the work was shown in the Amnesty Bookshop window – such as Ted Hughes’ lines: ‘Crow was so much blacker/ Than the moon’s shadows/ He had stars’, and William Blake’s ‘No bird soars too high, if he soars with his own wings.’

In 2012, the Cambridge Mill Road Oxfam Shop won the Joe Mitty Award ‘for the imagination, flair and enthusiasm that has made [it] a treasure trove for the eclectic – and a huge success in raising money for Oxfam’s work’. No small part in this success has been played by the artist Chris Gould’s subtly pervasive, inspiringly counter-cultural contribution to the shop’s overall fabric and atmosphere.

'Telephone', recycled artwork by Chris Gould

‘Telephone’, recycled artwork by Chris Gould, photo © Derek Langley

Everywhere are his magical transformations: for example, seventies chrome bar stools ‘upholstered’ with intricate découpage, juxtaposing a fantastically bizarre, often comical range of images from all kinds of popular newsprint and streetwise sources. Elsewhere, mundane objects such as redundant telephone kiosk hoods, basic, rather tacky clocks and antique, ramshackle suitcases are decorated, graffitied and découpaged – changed into something ‘rich and strange’ – by his fluent associative poetry. This encompasses hallucinogenic images of figures such as Bob Marley and Jimi Hendrix, apocalyptic skull forms emerging eerily from dense vegetation, compelling madcap cutouts from old Beano and Dandy comics, and exotic though quotidian folk culture references to items such as cheap Indian matchboxes. In this artist’s fertile universe, nothing is wasted; everything, however unpromising, can be playfully redeemed and vibrantly recycled.

Philip Vann is a writer on the visual arts. Since 1984, he has written a number of books on contemporary British and Irish artists, and is author of the critically-acclaimed ‘Face to Face: British Self-Portraits in the Twentieth Century’ (2004). He has written on art and design for RA Magazine, Galleries, World of Interiors, The Economist, The Guardian, The Independent and Resurgence Magazine. He lives in Cambridge.

* these quotations are taken from an illuminating new film, CirculArt. Or: How I learnt to stop worrying and love my stuff, Directed and Edited by Jonne Howard and Produced and Interviews by James Murray-White. It can be seen on Cambridge TV.

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Hempcrete workshop at Thoday Street

Today’s blog is another cross post from the Open Eco Homes blog. If this post gets you enthused about hempcrete make sure you check out the hempcrete workshop being offered at Thoday Street. At the time of writing there are two half price tickets up for grabs! 

Alex Jelly installing wood-fibre insulation 2This years Open Eco Homes features Thoday Street, a house where the emphasis is firmly on natural building materials. Alex Jelly (pictured here with her Cob pizza oven and installing wood fibre insulation) and partner Mike are determined to make their eco-renovation affordable and natural, and want to help others do the same. As Alex points out in her case study “indoor air pollution is generally far higher than outdoors (a fact that shocked me when I first found out)”.

Turning to natural materials reduces the potential for ‘off-gassing’ from more common synthetic insulation materials, and also allows for complete return to the natural environment once the material is no longer required. Affordability prevents many people taking on an eco-renovation but learning a DIY solution like Hempcrete can make a real difference to price, and bring it within the reach of more people.

At Open Eco Homes we’re really pleased to be able to work with Alex Jelly and Alex Sparrow of Hempcrete UK to offer you the chance to learn this great technique in-situ in Alex’s home. You can sign up for a tour of Alex’s home, take part in a workshop or attend an evening talk by Alex Sparrow (sponsored by Green Books).

But first, we’ve asked Alex Sparrow to explain a little more about what hempcrete is and why it is so beneficial.


Alex Sparrow, Director UK Hempcrete

What is hempcrete?

Hempcrete, or “hemp-lime”, is a mixture of hemp shiv (the woody stem of the industrial hemp plant) together with a lime binder. It is usually wet-mixed on site and cast in shuttering (form-work) around a structural frame, but it can also be pre-cast in blocks or panels.

Hempcrete is a non-load-bearing, medium density natural insulation material, which also has thermal mass, and is “breathable” (permeable to moisture vapour).

What you can use it for?

Hempcrete is most commonly used to make new-build walls, but can also be used to form floor slabs, ceilings, and roof insulation.

In contrast to conventional insulation materials (which tend to be installed in a cavity within the wall, or added to wall as an extra layer in the build-up) hempcrete in new build forms the wall and the insulation in one piece, with the only other materials being the structural frame (usually untreated softwood) and a lime or clay plaster internally and lime render externally, although cladding (timber, stone, brick etc.) can be used in place of wet finishes if desired.

Mixing hempcrete in a drum mixerHand-placed hempcrete cast around a central softwood frame.

In the repair and retrofit of (pre-1919) traditionally constructed buildings hempcrete is used to add insulation to existing solid walls or repair infill panels in timber frame buildings. It is ideal for use in traditional buildings because of its vapour-permeability and its ability (as a wet-mixed, loose-fill material which hardens once applied) to mould itself exactly to unevenly shaped walls in an old building, and support itself without sagging.

Advantages of hempcrete

Hempcrete is a breathable (vapour permeable) material which is hygroscopic (it passively regulates humidity in the building by absorbing water vapour and releasing it in response to changes in the relative humidity). A hempcrete building’s thermal mass also means that it “buffers” changes in temperature, staying warm in winter and cool in summer with minimal use of heating or cooling systems.

OLYMPUS DIGITAL CAMERAHempcrete is naturally fire- and pest-resistant, meaning that there is no need for potentially toxic chemicals to be added to it. This fact together with its vapour-permeability and hygroscopic nature means that hempcrete buildings are healthy living environments.
Hempcrete is a natural material. The hemp plant used as the aggregate in hempcrete absorbs so much carbon during its rapid growth that more CO2 is locked up in a hempcrete wall than is used in its construction. In other words, hempcrete has negative net carbon emissions – it’s a “better-than-zero-carbon” material.

The exceptional eco-credentials of this natural, sustainable material make using hempcrete in your building the obvious choice if you want to reduce your energy bills, your carbon footprint and the overall impact of your building on the environment.

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Does your Combie fire up at odd times?

Today’s blog is a cross post from the Open Eco Homes blog. Written by Anne Miller, a former Eco Homes host this blog post is a great example of the sort of detailed advice you get on an Open Eco Homes tour. Bookings are now open for tours on September 18th and 24th.

Eltisley Av 150x150About a month ago, after we’d had a few plumbing jobs done, we noticed that our Combie boiler was turning itself on every time we used a cold tap. Or more precisely, the boiler turned itself on briefly, a few seconds after we turned a cold tap off.

This seemed very odd! The whole point of a Combie is that it only heats up the hot water when you need it. It was also very annoying, because we try hard to keep our energy usage and carbon emissions to a minimum, and this was clearly wasting energy. We subsequently estimated that it had increased our summer gas usage by about 10%.

It took a while to work out that the problem is what some plumbers call “bounce”. Not a bad name, because when a customer complains about it, plumbers often blame it on the boiler, and boiler engineers say, ‘it’s a plumbing problem’. I think it’s probably very common, but once you understand it can be easy to fix

It happens when air has been trapped in the pipework to the taps (note this is a completely different circuit to the one that heats the radiators). Because the trapped air acts like a bouncy cushion, when a cold tap is turned suddenly off, the shock compresses the cushion of air, which tricks the Combie into thinking that the hot tap has turned on. This means that to fix it, ideally you need to find a way to let out the trapped air.

Here are some simple things you can do before you spend money on calling out the professionals.

Start by running the taps, initially gently then increasing to full flow. You’ll know when air is coming out, because the flow of water will cough and splutter, then when the air’s out from that bit of pipework, the water will flow smoothly. Do this for all the taps, starting at the top of the house.

P1040471-2If this doesn’t fix it, the air may be trapped in a “deadleg”, in other words a bit of pipework that no longer ends in a tap.

The next thing to check is whether there are any connections for washing machines or dishwashers that are no longer in use. These are increasingly common, because whereas a few years ago plumbers would automatically install both a hot and cold feed to a washing machine, these days new washing machines tend to be cold fill only, so the hot feed will probably have been blocked off.

Hopefully this will have been done with a little tap, which makes it very easy to bleed the air out. In our case, I found three of these little taps: one for the unused hot feed for our washing machine, and another pair in a cupboard where our washing machine used to be. Once I’d bled the air out of these, the combie started working perfectly again.

If you’re unlucky, there might be a deadleg that a thoughtless plumber has left somewhere inaccessible, like under your bathroom floor. If this is the case, don’t despair, because a simple alternative can be to get a plumber to install a non-return valve on the cold feed to the boiler. It’s not the ideal solution, because the valve may get blocked someday, but with luck this will reduce the bounce effect enough to stop the boiler turning on despite the trapped air.

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Brexit and our Environment

Please ask your MP to support the Environment Pledge.

The Brexit negotiations pose many threats and opportunities for UK environmental protection and our urgent transition into a low-carbon nation.

If red-tape slashing vested interests get the upper hand, vital protections for our wild life, countryside  and seas will be swept aside. Also support for changing our industries, energy supplies, homes and lifestyles into the low-carbon future we need to avoid dangerous climate change.

There are opportunities to improve on EU regulations with better ones appropriate to the UK. For example the Common Agricultural Policy could be replaced with support for landowners and farmers, especially smaller ones, with the right incentives to take good care of the wildlife and land they know so well, as well as growing the food we love.  A majority of British public support environmental protection at least as strong as current EU rules.

Uncertainty and frequent sudden changes are bad for business, as for several local firms installing renewables and home-energy improvements that have been forced to close recently  by the chopping and changing government support schemes.  Brexit is going to take years, so how can we help reduce the damaging uncertainty?

Cambridge Carbon Footprint is a member The Climate Coalition, who with Green Alliance, are today calling on MPs to support an Environment Pledge, below.
If a majority of MPs sign, that will indicate good support for strong action on these issues and  reduce the uncertainty.

Please ask your MP to support the following pledge:it’s easy

I believe that following the EU referendum, the UK government, working with administrations in Belfast, Cardiff and Edinburgh, must build a healthy and prosperous future for all.

This means a thriving natural world on land and at sea, clean air and water, communities connected to nature, and a sustainable economy. For the wellbeing of my constituents, for people at home and abroad, and for future generations who will depend on a flourishing and secure planet, I will do everything in my power to:

  • Establish the UK as a world leader on the environment by committing to match or exceed current environmental, wildlife and habitat protections.
  • Ensure the UK leads on climate change by publishing robust low carbon investment plans and ratifying the Paris Agreement this year. 
  • Create a countryside richer in nature by supporting farmers and landowners to deliver environmental benefits alongside a thriving farming sector.

Tom Bragg
CCF Trustee

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Climate Rising

climate_rising_teaser2A couple of weeks ago, just under 1,000 climate change activists (including 3 intrepid members of Cambridge Carbon Footprint!) met in London at the Climate Rising event to discuss what to do next following the Paris climate change talks. Continue reading

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Vacancy: Open Eco Homes

dream job

Open Eco Homes Project Worker?

Open Eco Homes (OEH) arranges for householders to show and explain to visitors on 2 weekends in September how they save home energy by their home’s design, retro-fitted improvements, smart behaviour, etc. Continue reading

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Seville Orange Marmalade

P1040028 (1024x574)Home made marmalade tastes fantastic: far better than anything you can buy in the shops. Not only is it lower carbon it’s also much cheaper, and it really doesn’t take long to make. Continue reading

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CCF office closure

CCF Christmas (Medium)

Well, it’s been quite a 2015! Here at CCF we’ve run many well attended events, had a run away success with our WWII Rationing Challenge, and had good fun at a good many stalls. All of which we could not have done without the help of our many wonderful volunteers. After such a busy year, it’s time we all took a rest! With that in mind the CCF office will be closed over the holiday period. We’ll be shut Monday 21st December 2015 to Friday 1st January 2016 inclusive. We look forward to catching up with you all in the new year.

Alana Sinclair
CCF Co-ordinator

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The Paris deal: a day to celebrate, but…

CoP21 Negotiators(640x360)

In what I think is genuinely a day to celebrate, we have a legally binding climate deal from the Paris COP21 negotiations.

The French did a great job on running the incredibly complex negotiations, resulting in an agreement that is stronger than anyone dared hope two weeks ago. The process was transparent, democratic and flexible and these values seem to have continued into the final text.

It is the first time in history rich, poor and emerging economies have made a joint commitment to tackle climate change, aiming to limit warming to “well below 2C”. There’s also the aspirational goal of limiting it to the safer 1.5C. Continue reading

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President Tong & Richard Denniss

President Tong & Richard Denniss

Last night we felt priveleged to hear Anote Tong, the President of Kiribati, call for no new coal mines. Before being invited I knew next to nothing about the pacific island state of Kiribati: straddling the equator and the international dateline, it was a British colony (The Gilbert and Ellice Islands) until 1979. Continue reading

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Climate Ribbons

Ribbon Tree (640x360)As part of the Climate Ribbon project we brought dozens of ribbons from Cambridge on which people had written WHAT THEY LOVE AND HOPE TO NEVER LOSE TO CLIMATE CHAOS. Thanks Jenny & other who  helped gathering them. Continue reading

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CCF Paris Workshop

Workshop (640x360)

We’d offered to run a CCF workshop about personal footprints: “How to stop feeling helpless” at Climat Forum at a fairly bleak school in the Paris suburb of Montreuil. We only had confirmation a week ago. Publicity was minimal. Would anyone come?  Continue reading

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UK Innovators in Paris

Outside Climate Solutions (640x360)

Extra security in Paris is undersandable but there were 2 events we couldn’t get into.

On Friday night we went to the launch of Energy Unlocked, a new UK organisation supporting low-carbon energy innovation. It’s a small startup, which attracted low-carbon business organisations over a remarkable range of scale:    Continue reading

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