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Russell griffiths

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1 hour ago, joe90 said:

But is it not this slow burning that produces the most nasties?, I was told burn hard and hot for the least pollution.

 

Yes.  Burning with a deficit of oxygen creates a cocktail of toxic volatiles, like creosotes and tars, plus it produces many times more particulates.

 

It's why rocket stoves are generally a better idea if you really have to burn wood, although they create a different problem, which in some ways is almost as nasty.  They burn with excess oxygen, so the temperature is high and pretty much all the volatile products of combustion are burned further down the flue.  This reduces the emissions of particulates a bit, too.  The down side is that like a lean burn car engine, they generate nitrogen oxides, as there is an excess of nitrogen in the feed air that can be oxidised at the high burn temperature.

 

Generally this is the lesser of two evils, though, as in terms of health risk it's primarily the organic volatiles and smaller particulates (the PM10s and PM2.5s) that are probably the greatest health risk.

 

To put this in perspective, some of the data from Australia seems to have been reasonably well validated, and there are some health risk factors that do seem to generally fit with the observed data, accepting that the study samples have not been very large, or conducted over long periods of time, so they are broadly indicative, rather than definitive.

 

A three month winter average reduction in particulate emissions, just from wood burning stoves, of 40% resulted in the following observations:

 

For men,  deaths from all causes over the next 6 years reduced by 11.4%, deaths from cardiovascular disease reduced by 17.9% and deaths from respiratory disease reduced by 22.8%

Results for just the winter months, for both men and women, over the same period, showed  that deaths from cardiovascular disease reduced by 20% and deaths from respiratory disease reduced by 28%.  These were benchmarked against deaths from an earlier 7 year period immediately  before the restriction on burning wood came into force.

 

Politics here is clearly getting in the way of science and the facts.  By our governments own data, 79% of harmful emissions in the air that the government is trying to reduce are coming from burning wood, yet who are they targeting?  The 14% of emissions that come from vehicles.  The reason is plain to see, they can tax and legislate "dirty vehicles", but they simply do not want to tackle the enforcement of the Clean Air Act..............

Edited by JSHarris
typo
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4 hours ago, Onoff said:

More the worry is drowning in an airtight building if a pipe bursts and you sleep on a futon! :) Presumably it'd only ever get as high as the lowest wc?

In ours - when it is built, the water will rush down the wetroom shower trap, 20mm lower than the floor, what with the water and the UFH I expect the house would become a steam room!

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5 minutes ago, MikeSharp01 said:

In ours - when it is built, the water will rush down the wetroom shower trap, 20mm lower than the floor, what with the water and the UFH I expect the house would become a steam room!

 

So the moral is always have a ground floor shower! :)

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2 hours ago, Onoff said:

Wrong place to post I'm considering a WASTE MOTOR OIL burner for the garage.....

 

Good place to burn tinned fish and frying pan oils too...

 

:ph34r:

Keep yourself up to date on current legisation with this.

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3 hours ago, JSHarris said:

 

Politics here is clearly getting in the way of science and the facts.  By our governments own data, 79% of harmful emissions in the air that the government is trying to reduce are coming from burning wood, yet who are they targeting?  The 14% of emissions that come from vehicles.  The reason is plain to see, they can tax and legislate "dirty vehicles", but they simply do not want to tackle the enforcement of the Clean Air Act..............

 

in a nutshell ^^^^^^

 

Eventually something will happen, but when?

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10 minutes ago, Roger440 said:

Eventually something will happen, but when?

 

When the powers that be find a way of getting a revenue stream from those burning wood.  It's dead easy to slap another tax or charge on motorists, even though they are a tiny part of the problem, but it's very much harder to come up with a way of taxing wood and those who burn it. 

 

For a start, many people burn wood in cities and towns as a "fashion statement", rather than because they have too.  I can have a guess that a lot of city wood burners are Conservative voters, too..............

 

The other point is that many of those who still have open fireplaces or stoves that burn wood are relatively poor, living in areas where there isn't ready access to gas and who don't have the capital needed to change their way of heating.

 

Politically, trying to reduce wood burning  is a real poisoned chalice, that I doubt that any political party would tackle, even if it is 79% of the particulate pollution.  Motorists are, as always, an easy target.

Edited by JSHarris
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Guest Alphonsox
44 minutes ago, JSHarris said:

I can have a guess that a lot of city wood burners are Conservative voters, too..............

 

Just to be clear.......is this just personal prejudice or do you have some form of evidence for this statement?

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1 hour ago, JSHarris said:

 

For a start, many people burn wood in cities and towns as a "fashion statement", rather than because they have too.  I can have a guess that a lot of city wood burners are Conservative voters, too..............

 

The other point is that many of those who still have open fireplaces or stoves that burn wood are relatively poor, living in areas where there isn't ready access to gas and who don't have the capital needed to change their way of heating.

A bit tongue in cheek BUT my immediate reaction was 'those that don't care'  (not necessarily conservative) and 'those that can't care'

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8 hours ago, JSHarris said:

 

When the powers that be find a way of getting a revenue stream from those burning wood.  It's dead easy to slap another tax or charge on motorists, even though they are a tiny part of the problem, but it's very much harder to come up with a way of taxing wood and those who burn it. 

 

For a start, many people burn wood in cities and towns as a "fashion statement", rather than because they have too.  I can have a guess that a lot of city wood burners are Conservative voters, too..............

 

The other point is that many of those who still have open fireplaces or stoves that burn wood are relatively poor, living in areas where there isn't ready access to gas and who don't have the capital needed to change their way of heating.

 

Politically, trying to reduce wood burning  is a real poisoned chalice, that I doubt that any political party would tackle, even if it is 79% of the particulate pollution.  Motorists are, as always, an easy target.

 

Since when did Tories do "fashion" :P ?

Edited by Ferdinand
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I recall Andrew Neill roasting some Greenpeace chief recently about how vehicle emissions cause 40,000 deaths a year. A bollocks claim that had been massively distorted and misrepresented. 14% of harmful emissions come from vehicles and 79% from wood burning stoves? As we say in Scotland. 'Aye right'. 

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They had recently been accused of distorting figures by lumping together various sectors within differing types of output - residential and commercial for example - but not splitting the actual emission type. For example, large scheme pellet heating for district heating also got dropped into the same category as power generation which has vastly different controls 

 

I don’t disagree though that it does contribute however when you live 100 yds from a main line station and you see the diesel fumes coming from the “clean” trains then you do worry .... 

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21 hours ago, JSHarris said:

As an aside, our MVHR has had to be turned off three times over the past week.  The combination of cold, still, nights has meant our valley has filled with woodsmoke from open fire and wood burning stoves.  Leaving the MVHR on resulted in the whole house being filled with smoke..................

Might some kind of snorkel be an idea / fix? Maybe it's best to consider where you glean intake air from for the mvhr at the design stage ? This could be super problematic for some ?

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10 hours ago, Alphonsox said:

 

Just to be clear.......is this just personal prejudice or do you have some form of evidence for this statement?

 

Just tongue in cheek - should have put a smiley in there.  Apologies to any non-wood burning stove owning Conservatives........

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52 minutes ago, Nickfromwales said:

Might some kind of snorkel be an idea / fix? Maybe it's best to consider where you glean intake air from for the mvhr at the design stage ? This could be super problematic for some ?

 

 

It's a good idea, but living in a sheltered valley means the whole valley tends to fill with smoke, from the inversion layer** at the top of the valley downwards.  This means that over a period of hours the smoke descends from the inversion layer down to the base of the valley.  This pattern is only disturbed if either the inversion layer dissipates or the wind speed and direction increase/change so that the valley is blown clear of smoke.

 

The photos of Launceston, Tasmania, that head one of the papers I cited earlier shows this effect:

 

Launceston-clear-and-smoky.jpg

 

You can see the line of the inversion layer in the right hand photo, with relatively clear air above it (you can see the distant mountains) and also see that the smoke initially rises, hits the inversion layer, starts to cool and then sinks to gradually fill the valley from the top down.

 

Any upwards pointing snorkel arrangement would initially make things worse, and to be effective would need to poke out above the top of the inversion layer, several hundred feet up, perhaps.  As another illustration of an inversion layer over the UK, here's a photo I took when flying back to Dover from a trip to France, where you can see the "dirty" faintly yellow, air trapped by the inversion over London in the far distance (around 80 or so miles away from where I was over the Channel when taking this photo).  London sits in a bowl-shaped depression, so tends to be prone to having local inversion layers over the top of it, one thing that contributed to the very bad smogs of the 1950's :

 

5a23bdcb6f5c2_ApproachingDover-small.JPG.aeec9821194ee66c3931b084408fadcc.JPG

 

**  An inversion layer forms when a layer of warmer air overlies a region of colder air.  In the specific case of hollows in the ground, like valleys, what tends to happen is that the ground in the valley radiates heat to a clear sky overnight, so the ground temperature, and surrounding air, get very cold (the "frost hollow" effect).  Meanwhile, the air above stays warmer, often because there will be a gentle flow of warm air above the inversion, in the UK often as a consequence of Oceanic air movement coming from the West. 

 

Normally, air gets colder as you go higher, according to a rule called the adiabatic lapse rate.  In rough terms, the dry adiabatic lapse rate here tends to be around 2 deg C per 1000ft, which means that normally  warm smoke will continue to rise, even though it is cooling down.  The rate of cooling of the smoke only needs to be slightly lower that the adiabatic lapse rate to ensure that it carries on rising.  As soon as warm smoke hits warmer air above it stops rising, and continues to cool, so starts to sink towards the ground, where it cools faster as it encounters cooler air lower down for the second time.

Edited by JSHarris
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9 minutes ago, Nickfromwales said:

@JSHarris

My bad. I meant snorkel down. 

Just thought that air from the ground may be clear enough. 

 

 

Funnily enough, but I was just re-reading this and had the same thought, move the MVHR intake down towards ground level.

 

Practically this isn't that hard for me, as the intake is out of sight, high up around the back of the house, so I could add some external ducting to bring the intake around the corner of the house (which then fix the other issue I have, of having the intake at right angles to the exhaust) so that it is on the East facing wall, lower down, by the back door.  This would also make it less susceptible to drawings in any smells that come with the wind, that tends to tunnel along the gap between the North wall and the retaining wall, especially in a strong Westerly wind.

 

Other advantages would be that the length of duct down the Eastern wall would warm up in the early morning sun (useful in winter for pre-heating the MVHR intake) and having the intake grill lower down would make it easier to clean out all the cobwebs and fluffy seeds that tend to clog it up.

 

It's an interesting idea, and one that I'll definitely give some further thought to.

Edited by JSHarris
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17 minutes ago, dpmiller said:

surely choosing to live in an area where the air was cleaner would've been a plan, if it's an issue?

 

Generally the air doesn't get much cleaner than the downs South of Salisbury Plain - we're miles from any industry and well South of the busy A303 trunk route, and well North of the slightly less busy A31/A35 route along the coast, and the prevailing wind means we have pretty low levels of air pollution most of the time.

 

The problem is specific to the nature of small population centres here, and over wide areas of the UK.  Settlements tend to be built down in valleys, not on the top of hills.  If the valley happens to have a number of houses where there are open fires or wood burning stoves, then there are likely to be times when these valleys will fill with smoke.

 

Where our old house was located was far worse.  That was in what amounted to a "blind valley", where there was almost no wind flow at all, even on extremely windy days.  During periods of cold weather, usually prolonged high pressure associated with very low wind speeds, not only would that valley get cold, but it would fill with smoke for days on end.  In the end a serious car accident, caused in part by the very poor visibility along the road at the bottom of the valley, caused the local environmental health people to start taking action over bonfires, and they are now in the process of checking excessive smoke from fires and stoves.

 

As you probably know, plot hunting is a challenge, and finding a plot in a general area where you want to live is pretty damned hard.  Finding one that is perfect, in all respects, is near-impossible, unless you happen to be very wealthy.  I spent well over two years full time plot hunting (as in out and about every day of the week for two years looking around at plots).  Eventually I found our plot, and it wasn't perfect, but was affordable, in a quiet rural location and oriented so that a passive house was an easier proposition.  It wasn't an easy plot to build on, and, until the past week we've not had a problem with smoke.  I strongly suspect that some people in the village have recently had stoves installed, as I've noticed wood stores that have been erected in the past few months.

Edited by JSHarris
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12 minutes ago, dpmiller said:

surely choosing to live in an area where the air was cleaner would've been a plan, if it's an issue?

What do you suggest just pick the house up and move it then?!

 

i suppose it's an unfortunate thing that gets overlooked or not noticed until you've had a winter on site.

 

if downwards snorkel doesn't work suppose you just have to turn off mvhr, crack a couple of windows a touch and maybe put a small bit of heat into dwelling?

 

this is what keeps me from wanting an all singing and dancing passive level house atm. A lot of issues to be ironed out. Ok if your a scientist like @JSHarris but a lot of it goes over my head!

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Actually the government COULD do a lot to reduce wood burning.

 

For a start they could stop paying the RHI for wood burning devices.  I have lost count how many domestic oil boilers I have seen removed, and replaced by pellet boilers, because of the salesmen pushing the RHI payments they will receive for doing so.  And the salesmen make the problem worse by selling it as a "green" , renewable and environment friendly source of fuel. Even those just installing a WBS  withour any RHI are doing so largely because they perceive it to be a "green" and environmentally friendly fuel.

 

Also, virtually every school and sports facility here, now has a container sized building alongside it, housing a big pellet stove to heat the building. Even those in town where mains gas is probably available.  These large scale projects have no doubt been installed under the guidance that they are environmentally friendly. THAT policy needs to be reversed.

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