GF Blog 23 – Week 30

25th August

Fires + late summer mending & maintenance round the site. These lead me to think about resilience of homes and hobbit houses

At last we have got some sunshine back, and it came at just the perfect moment for my house guest, Anna. Until she departed Cornwall, we used to be regular walk companions, exploring the coast or inland mining areas of the moors and this past weekend we struggled through bramble-filled canopies above old farm lanes, down to the south coast for a surf-buffeted swim.

We reach the beach, hot and happy
All possible places for composting are over filled! Need a chipper!
Me bad, resorting to a bonfire.

Beach was a rare break, between tackling numerous areas of bushes and some of the worst looking windswept wildflower areas, to clean and tidy things in the Meadow. But I am seriously short of places to dump the off-cuts, which is why I eventually succumbed and used the fire-pit. Already thinking a lot about fire hazards, with so many wildfire hotspots in the news at present, my defence is that in a dryer period, at the drop of a match, the pile of conifer cuttings I can see over the gate next door would go up in an instant and probably burn all of the hedges around. My fire was carefully controlled, lasted maybe half an hour and was not near enough to any residence to need to worry about particulates.

What is the official line about this?

Bonfire rules in the UK can be complicated by their vagueness. It’s not illegal to light bonfires, and there are no official restrictions on when or how often they can be burned. The main concern with bonfires is safety, environmental damage – mainly from excessive smoke – any nuisance caused to neighbours or the public, and any danger to wildlife. It’s key to prepare yourself correctly before even considering lighting a bonfire in the garden for your friends and family to enjoy.


Don’t burn wet or green matter: This will almost certainly cause excess smoke that will annoy your neighbours. Most councils collect green garden waste separately – or you can compost it. ‘One tip is to try and bend any wood before throwing it into the fire. Any wood that bends rather than breaking is too moist and should not be used.’   MY COMMENT There was a bit of soggy stuff in the bottom of the barrow, but it was helpful at the end to damp the fire down. Smoke lasted only a short time.

Don’t burn or build your bonfire with straw, bark or hay: This is a fire hazard and prohibited by most councils. MY COMMENT I used straw to help get started, rather than firelighters or petrol (see next entry)

Do not use any fire accelerants: Using petrol, paraffin or other accelerants can too easily lead to a loss of control of the fire (I think straw was OK).

Don’t let smoke drift into a public highway: It is against the law to have smoke drift onto a public highway. You could be fined £5,000 if this happens.  MY COMMENT I had no idea about this rule. Whoops!

So that was the legal stuff but what about impacts on the Environment and Health?

Open burning of any kind is generally bad for humans and the nearby environment. Compared to controlled burning, such as in boilers, large outdoor fires tend to produce “highly mutagenic and carcinogenic emissions” that can affect any humans in the vicinity. (Mutagenic chemicals, as the name suggests, are those that tend to cause genetic mutations.) The fine particles in smoke, meanwhile, can find their way into eyes and lungs and cause bronchitis, as well as aggravate existing conditions like heart and lung disease

Temperature matters. If the fire is hot enough, many of the toxic molecules will break down into simpler, less toxic ones. But open fires rarely reach those temperatures, meaning toxic molecules are released as a gas that can easily find its way into lungs and the environment. As opposed to high-temperature incinerators, bonfires also tend to produce more carbon monoxide, which is harmful when breathed in and can form toxic ozone. The report continues, “It almost doesn’t matter what you burn but, instead, how you burn it.”

From an environmental perspective, the smoke from any bonfire—including normal ones built with wood or paper—adds particulates and carbon to the atmosphere. These can act not only as air pollutants, but also as “climate forcers,” meaning they can contribute to climate change in the short or long term—albeit on a much smaller scale than industry or automobiles do. Particulate pollution can lead to lung and nose irritation, and possibly even lung cancer if exposure is severe and prolonged. 

I went into one other source, briefly, which added a different dimension: – The Guardian

A team of French scientists has been investigating air pollution from bonfires. They used a specifically constructed fire chamber: a big room that could easily accommodate one or two whole houses, added instrumentation in the extract ducts, spread a bed of sand on the floor and set about burning leaves and hedge trimmings.

Unsurprisingly, for each kilogram burned, garden waste on bonfires produced up to 30 times more particle pollution (smoke) than burning logs in a stove, BUT smoke from the wood stove contained up to 12 times more cancer-causing polyaromatic hydrocarbons.

On balance, standing out in the fresh air, with a big blue sky above I sense that not too much damage was done to anyone and the CO2 emission was miniscule. Does this mean I feel brave enough to encourage a larger, public bonfire at the end of our Harvest Ceremony 4 Climate Hope in October? I think probably not! I will be looking for braziers to be lit along the riverbank instead.

Summer evenings by the water are easy
This looks lovely, but maybe not right for us? 

Fire-proofing houses

I have continued keeping ears and eyes alert for further news from Hawaii and was amazed to see a surprising aerial picture in Euronews (see the pic in a comparison a little later):-

Homeowner Dora Millikin has revealed to the press why her house survived the blaze.

While restoring the 100-year-old property Mrs. Millikin and her husband chose to replace the asphalt roof with a heavy-gauge steel one. They also cut down foliage surrounding the property as a preventative measure to stop termites from reaching the house’s wooden frame.

These actions were not intentionally taken to protect the building from fires, but they prevented the property from igniting while flaming pieces of wood were carried by the wind through the air and landed on the roof and in the garden.

For years I have been writing that timber frame buildings are not the best choice for the future, because we know we will face more extreme weather. The structures are not strong enough to survive hurricane-style storms, major floods or fires. Here is another very similar headline and related image, this time one house surviving in Mexico Beach, Florida when a hurricane arrives.

The survival of this one was also down to construction decisions. Although there is no reference to a metal roof in the text it certainly looks like one: –

The house was fashioned from poured concrete, reinforced by steel cables and rebar, with additional concrete bolstering the corners of the house. The space under the roof was minimized so that wind could not sneak in underneath and lift it off. The home’s elevation, on high pilings, was meant to keep it above the surge of seawater that usually accompanies powerful hurricanes.

OK we are not renowned for actual hurricanes in Cornwall but my place, high on the hills with some of the strongest west winds in the country, could be a potential site in future. That’s why I feel that my decision to put metal roofs on my buildings and create massive wide walls with granite or concrete was a good one!

One reader, keen to build a sustainable home

A few months back I got an enquiry by email, with various questions about eco-building. This lady’s dream is to construct a hobbit-style house in the garden of her main residence in a rural hamlet. The questions have been simmering in the back of my mind ever since, until this week, where it ties in very well with our construction topic.

What is a hobbit-house? Quite a simple idea of a hole, burrowed into the side of a green, grassy bank, with windows and a front door to the outside world but everything else underground. It is modelled on the original idea of author Tolkein, who first combined 2 old English words – hol, “a hole or hollow”, and bytlan, “to build”.

Bit blurry sorry, a pic provided by a friend who visited there a lot of years ago.

But it does show how the Hobbiton hillside in New Zealand, made by Peter Jackson for filming Lord of the Rings looked at the time.

In March 1999 the crew began a 9 month quest to bring the ideas for Hobbiton to fruition; help was provided by the New Zealand Army, and soon 39 temporary Hobbit Holes were scattered across the 12 acre plot used for the set.

Secrecy was key, and strict security measures were put in place by the production company throughout construction and filming. Filming commenced in December 1999, and it took around three months to get a wrap on The Shire.

After an initial attempt at demolition, 17 bare plywood facades remained. These shells would serve as the catalyst that propelled Hobbiton forward into the public eye, with guided tours commencing in 2002. In 2009, Sir Peter Jackson returned to film The Hobbit trilogy, and he left behind the beautiful movie set you’ll see today; 44 permanently reconstructed Hobbit Holes, in the same fantastic detail seen in the movies.

Q1 Does it count as a house, and therefore require planning permission?

Here we are immediately into a confusing area. A garden house is a permitted development without planning permission, subject to some regs about distance from the road and height. But there is also, lurking in the small print, a rule that says you only can use the space in the daytime, for instance as an office or artist studio. It is not permitted to be accommodation, because then you will need to meet building regs.

I think that’s quite common knowledge about a traditional timber shed, but the rule for an underground ‘bunker’may be different, especially if you describe it as a fall-out shelter! Not sure I believe this; it’s only an online Forum here so please don’t rely on it.

A fallout shelter is exempt from planning permission and building regs, provided that its depth is no greater than the distance from the nearest building (this is nationwide, not dependent on Local Authority).

Q2) Is it a very good sustainable option?

In one major way an underground house should be hitting top performance, because all except one wall will be metres deep in insulation by the earth. This is what helps the best designed versions be so energy efficient, like this one on

Q3) Why such small windows? Surely, more light would improve outcomes even more? Seems to me these kind of windows are a fanciful, child-like indulgence! Far better would be a house with a full-width glass conservatory in front of the underground part, to maximise solar gain. This is how traditional Earth Ships were always made in the USA. I’ve shown images more than once in past blogs, of a typical one, where the conservatory is used as a greenhouse for growing vegetables, all year round. The Colorado one was massive but this is on YouTube as a mini Earthship example.  

 Apart from the very annoying (to me) repeating C6 chord on a ukulele in the background, this film is very good summary of elements that you would expect to find in an Earthship, whether little or large.

3) How much more difficult is it to build one of these, rather than an ordinary garden house?

Unless you are a particularly strong and fit person, with many hours spare for labouring, you wouldn’t want to tackle this without a digger and that also means having sufficient space for getting in and moving about the surrounding area. I know I am right to emphasise this, having built houses into hillsides myself, but also looking at photos on a website like this one, which is a very comprehensive overview of the self-build, hands-on process.  Clearly digging such holes is not for the faint-hearted!  and

Q4)  Remember also to be really careful about planning your levels. What is already beneath the ground (how many times have we heard of those unintended disasters, cutting through a neighbouring water, power or internet supply?) Do you need to put in a bore hole at the top of the site? Will you catch rain-water there too and run it down for flushing loos?

How about a septic tank, and/or reed bed, or simply a portaloo or composting one?

The model shown here is much quicker and easier to make than one that involves digging deep into a hillside. It is a bit of cheat, you only pile on a small amount of earth over a shell. In fact, you can buy the shell sections in kit form, for instance here  and

I was a bit naughty and phoned the Director of Revonia out of working hours, for a very quick word and indication of price levels. He told me, for the modules only and a minimum of 3 (which is more or less essential) it would cost you just under £20K including delivery.

This is by no means the only kit-based option, but as it is made of reinforced concrete it is probably a lot more substantial than some of the others out there. You can find some on e-bay, or another site could be and look for green-magic-homes. (the real link refused to function for me here).

The last one costs £16,200 on e-bay but looks way too dark internally and is prob not at all warm, unless perhaps there is a wood burner.

Last but not least

Meadow Barns cottage is made of insulated ‘form’ blocks, called Nudura. See them in my Green Build:-

I would opt to use the same blocks for a house with this footprint shape.

The whole front would be glass, for max solar gain.

And either side would be banks of solar PV.   

That’s an end to the dreaming about Hobbit Houses. Maybe of no relevance whatsoever to you, but I hope (like me) you love all these cute photos!

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