Tuesday 31 August 2010

Eco-refurbishment - cavity wall insulation

Last week we had cavity wall insulation installed. It's well worth anyone doing, as there's grants available in the UK (some people even get it completely free!), and even if there weren't it would pay for itself in heating costs within a couple of years. Make sure you get it done by a reputable installer though - ask your local council who they use. Our installers turned up early morning, and unloaded bales of insulation material:

These are fed into a machine in the back of the installers' van, which shreds the material...

and blows it down a hose into the wall:

Before filling the walls the installers drilled a couple of holes with a core drill and put in vents. One is required to let air in for the wood stove we're having installed shortly, and the other is to provide ventilation for the place where I'm planning to install a lead-acid battery to connect to solar panels for off-grid electricity.

We've also had our new water cylinder arrive, which has two coils in it - one for the wood stove's boiler, and another for solar water heating, which will also be coming soon. For now though, it's just sitting in a bedroom waiting for the plumber...


Related posts:

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Sunday 29 August 2010

Moving house...

If you were wondering why our blog has gone quiet, it's because we've been moving house! The broadband is still not up, so I'm writing this via a mobile connection, hence no pictures.

Anyway, it's been a busy period, not just with moving house but also getting the cavity walls insulated and arranging visits from various people who will be installing a wood stove with a back boiler, solar thermal panels, and then the plumbing to connect it all together. The gas boiler will be coming out, and then we'll have heating with minimal fossil fuel input, and not much cost, seeing as we'll be supplying all our own logs!

There'll be more info and some photos to follow in a few days...


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Saturday 21 August 2010

More Camber Sands sunsets

Some more sunset pictures from the dunes...

I'm getting all the sunset pictures I can at the moment, as we're moving house soon so won't be right next to the dunes any more...


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Wednesday 18 August 2010

Driving the Land Rover through the woods

The previous post included pictures of us extracting logs in the Land Rover - this time I have a video of it! I've given a bit of a commentary as we drive along, if you can hear me over the engine. Thanks to Tracy for filming!


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Sunday 15 August 2010

Extracting firewood

We've finished the work levelling the tracks (or rides, if you want the forestry term) in the wood, and now we can start moving out the wood we cut last winter:

With logs sticking out the back, we have about two cubic metres of space in the land rover, though some of that is air between the logs, so we're probably looking at 7-800kg of wood in the back of it!

We've been able to drive right the way to the top of the hill, where we were coppicing last winter:

From there it's pretty easy to get down the hill back into the woods...

and onto the section we've levelled out along the edge of Sweep Wood:

and from there back into Chestnut Coppice:

We're also able to drive up the hill between Sweep Wood and Chestnut Coppice now, which we'd never tried before:

We intend to only drive on the tracks when they're dry, so that they don't get rutted. This should work OK, as we can fell in the winter and stack the wood near where it falls, then extract it the following summer.

There's some changes in the wood at this time of year, such as fungi coming up:

Cob nuts growing on the trees we planted in November:

and our first chestnuts on the trees we coppiced in 2007/8:

It was pretty windy today, and bizarrely an Ash tree fell over in Sweep Wood in between two trips past it moving logs:

It was one that had bracket fungi growing from the base, so I suspect that had weakened it. It'll be interesting to see if it recovers - if not, there are plenty of other Ash trees in that part.


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Saturday 14 August 2010

Sunset at Camber Sands

I popped up on to the dunes at Camber Sands this evening with Tracy, and got a few pics of the sunset. I'll start with my favourite, then the rest are in time order. Enjoy!


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Using a moisture meter to check firewood

People tell you that wood needs to be seasoned before it is burned as fuel, but what does this actually mean?

When a tree is felled in winter, the moisture content of the wood will be over 50%, and even higher if it is felled in summer. By splitting the logs and/or cutting them to short lengths, you can accelerate the rate at which the wood will dry out. You can check how dry it is using a moisture meter. The picture below shows the spikes on the end of my moisture meter - you just jab these into the end of a log and it gives you a reading. Better still, split a log and test what had been the inside of it, to see the moisture content at the centre.

The reason the wood needs to have dried out is that when you put a log into a fire or stove, before it can burn all of the moisture must be driven off, and this uses some of the heat from the fire - so, the wetter the log, the less heat you get out. But there's another problem too - wet wood doesn't burn as cleanly, which is bad from the point of view of pollution, and also can deposit tar in the chimney, potentially creating a fire risk.

So how dry should your wood be before you burn it? This varies from one stove to another, but the moisture content should be 30% at most, and ideally should be 20%. How long it takes to get this dry depends on how the wood is stored. Ideally it should be split as soon as possible, then stored off the ground in a place where air can circulate through it and the rain is kept off it. Drying to 30% should usually happen within a year, and 20% in two years, although in ideal conditions these times can be reduced.

Here's an example of how important it is to split logs. These two logs were both felled about two years ago, and have been freshly sawn from the centre of 2m lengths. The first one was split straight after felling, and the moisture content is just over 20%:

The second one has only just been split, and the moisture content is still over 40% (the meter only reads between 3 and 40%):

The good news is that a short split log like this dries out very quickly in the summer - I checked it again a week later and it had already dropped to about 30%, having been left in the sun.


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Thursday 12 August 2010

Visiting the Isle of Eigg (part 3)

OK, so here's the detail on why I was visiting Eigg. At the time, they were an applicant for an Ashden Award, which they went on to win this summer. The award was given for their work in cutting their carbon emissions by almost 50%! This has been done through a combination of renewable energy generation, energy efficiency and behavioural change. The renewable energy generation is the most visually impressive, so that's what most of the pictures are of - I'll talk about the other stuff at the end of this post.

The heart of the system is a small building which has two main rooms, one housing this huge bank of Rolls lead-acid batteries, sufficient to run the entire island for 24 hours without discharging too deeply:

The batteries work to smooth out the changes in supply and demand for electricity over time, thereby reducing the need for backup generation. The connections for these battery banks pass through the wall into the next room, which houses twelve 5kW inverters, four in parallel for each of the three phases used by the grid:

Also in this room is all the control hardware for the system:

including all kinds of live data from the weir and water turbine:

Just outside the control room is a pair of diesel backup generators, which operate alternately to provide redundancy. A generator will come on to top up the battery bank whenever the charge level drops too low. In practice they don't get use much - over 90% of Eigg's electricity comes from the renewable energy sources, and this will increase when they add more solar PV.

Not far from the generators is 10 kWp of solar PV, which is due to be increased to 30 kWp in the near future. It's in a great location, with no shading and a view of the Sgurr in one direction and the sea in the other:

To the south of the Sgurr is the wind farm, which uses four 6kW Proven wind turbines:
Inside the control room for them are inverters and equipment to divert power to dump load heaters in the event of there being excess power. Dump load electric heaters are also used in community buildings, and as the grid frequency rises with excess generation, they automatically come on in stages to make use of the spare power. The dump loads at the wind turbines only come on when all of the heaters in community buildings are already on.

As you can see, some of the roads are pretty rugged, hence the need for a 4x4. At least they don't get driven very far, and there's a lot of lift-sharing as well.

Near the centre of the island is a weir:

From here the penstock takes water out of the stream for the water turbine, with a valve controlled remotely to ensure some water remains in the stream:

There's a drop of over 100m from here to the turbine, and we walked down it, following the buried penstock across fields and streams:

You can still just about see where it was buried on its way to the power house where the turbine is located (strip running up from the bottom of the picture, just left of centre):

Inside the power house is the water turbine - these are never very interesting to look at, they just sit there and do their job. This one was painted in the traditional "hydro blue" that seems to be compulsory for turbine equipment!

It's a pelton turbine, here's the technical details:

Well, that's where Eigg's electricity comes from, but as as I said, that's just one aspect of how they've cut their carbon emissions. Another is switching from from fossil fuels to wood for heating - I saw forestry work in progress, and the production of logs for heating is ramping up rapdily now:

The wood is burned in stoves that either heat a room or have a boiler in them to run central heating:

Every home has an OWL energy monitor - this is crucial, as one of the constraints adopted to make the renewable energy supply practical and affordable was to limit every house to 5 kW, and businesses to 10 kW - if you go over, your electricity cuts out, and a technician must visit to turn it on again. The meters sound an alarm if consumption gets close to the limit, and very few people ever get cut off, as energy-saving habits are second nature to the residents of Eigg.

Every house on Eigg has to have it's own water supply, and it was nice to see a few ram pumps running - supplying water without using fossil fuels. We had an international Ashden Award winner using these a few years ago, in the Philippines.

Over at the school sustainability was high on the agenda too, with a geodesic greenhouse and raised beds in the garden (I was there in February, which is why there's not much growing):

The school is proud of its achievements and has won a Green Flag from Eco-Schools for its work.

There are numerous other initiatives in progress, such as home insulation, poly-tunnels to grow food (reducing food miles), increased cycling and the use of solar water heating:

Eigg's done an amazing job, massively cutting it's carbon emissions, and showing the rest of the UK the way it should be going with renewable generation. To finish, I'll leave you with the video that the Ashden Awards made about Eigg's achievements (you can download a copy from the Ashden Awards website):


Read part 1 of Visiting the Isle of Eigg
Read part 2 of Visiting the Isle of Eigg

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