End of week seven

 

This week it looks like I've posted last week's photos back again but eagle-eyed readers will spot some subtle differences in the second of the photos with the shuttering for the pipe network at the back of the house and some changes at the top of the walls. The blue sheeting that you can see hanging down above the windows is part of the house's insulation and I will talk about that in a later post as it's more eco-science and worth a dedicated post.

At the top of the walls we now have floors and they arrived on site a couple of days ago. What larks that was - we had the massive JCB at the back of the garden digging the trenches, a massive flat-back lorry with the concrete slabs blocking the front entrance to the site (not to mention the street as it tried to back in through the narrow entrance without taking out a wall) and in between the massive crane to lift the slabs. It was quite hard to get a picture to show the scale of the crane but this is the best I've managed.

As it was on site at precisely the moment of the school run you can imagine the delight of the younger pedestrians and the less cheerful response of motorists to the scene.

I managed to get an action shot of the slabs being lowered onto the supporting walls. Here you go...

 

It was quite mesmerising to watch and I spent ages trying to suss out why the sight looked so familiar until I realised it reminded me of the scene in the street in Good Bye Lenin!, watched endlessly through A level German revision with number 1 daughter.

Yes, I know it's a crane not a helicopter and a concrete slab not V.I. Lenin but I said it reminded me - when you're researching this much German technology for a blog you get German on the brain.

Anyway, the slabs are now in place and here's what the floors look like:

The bit in the right-hand corner marks where the design includes provision for a lift at a later date in case of doddery occupants. Well, that's the party line anyway - I think it's in case later occupants are actually members of International Rescue. FAB.

Im Westen etwas Neues*

* (with apologies to Erich Remarque)

Last Spring my garden looked like this

and this Spring it looks like this

 

It looks more like a location for the next Daniel Radcliffe oeuvre. 

The trenches are at least 7 feet deep and, as you can see in this picture, the blue polypropylene pipes for the heating system are buried at the bottom of them. 

 

If the site were bigger the JCB could cut longer trenches but there's not really anywhere to fit the 12+ m² of soil that's being removed per pipe so they are having to cut trenches just long enough for one length and then fill the hole in before moving on.

If you're feeling technically minded you can check out the complexities of the heating system by looking at the website for the manufacturers, Rehau. Rehau are, seemingly like most eco innovators, German (although they have a base in Ross-on-Wye) and very clever they are too.

In the UK, soil below about 2m doesn't freeze but stays at a constant temperature so the warmth of the ground can be used to provide warm air or air conditioning for the eco house. The surrounding air is drawn into a pipe above ground and then moves through the underground pipe network and into the house before leaving through another pipe above the ground. As the air moves under the earth in the winter the warmth from the soil will warm it and in the summer it will cool it before it enters the house

You don't just want the air to be warm, you want it to stay fresh too and this illustration from Rehau's brochure shows how the air circulates in the house, where the blue marks the fresh air coming in and the red marks the stale air going out....

it rather reminded me of this:

While we're on the science bit it's probably worth talking about how the pipes are arranged under the ground. 

In smaller houses they just encircle the house but on larger buildings, like this they use an arrangement called the Tichelmann Grid, named after the famous heating engineer Albert Tichelmann(!). Apparently this system ensures that the flow of air is balanced throughout the network, a bit like opting for a parallel, rather than a series, circuit I guess.

The use of the Tichelmann Grid explains why our pipes are being put in bit by bit - you need a lot of land to store 18m x 2m x 5m x 3m of soil!

The dimensions of the pipes mean that the air will pass through at a speed of 3 m/s, which is the optimum speed for warming or cooling the air and this means that the house will have a change of air about every 30 minutes. The inlet and outlet pipes have filters to exclude pollutants and pollen and the inside of the pipes has a coating of an antimicrobial substance (c.f. every cloud...). If you look back at the previous entry with the photo of the pipes you will see the two Y-shaped pipes on the right, they are to sort out any condensation in the underground network. Inside the house there will be more gizmos but I'll talk about that when I've photos to show you.

End of week six

One week on and the external and internal walls have now reached the first floor so it's starting to really look like a house. It's possible to go inside and get a feel for the downstairs rooms and, with windows on all three outer walls, they seem incredibly bright. This will cut down on the amount of artificial light they need as well as maximising the warmth from any winter sun. Next week work starts on the first floor rooms so the scaffolding has been put up, which rather obscures the view of the house.

On Friday afternoon the JCB came back as one of the biggest jobs on the site is about to start. These pipes are the key part of the house's heating and will be buried under most of the garden that's visible in this picture. I'll tell you more about the heating when I've got my head round it as it makes no sense at all at the moment to me...

The JCB for the job is so large it made furniture in this house shake when it came on site so the next couple of weeks should be entertaining!

End of week five

I promised you walls and here they are:

The massive windows are because this is the south-facing wall and the sun will be one of the major sources of heating for the building. We will have electronic blinds on the outside of the windows on this wall for the summer time, to stop the rooms overheating. Presumably we will eventually tire of playing with the electronic blinds, but I expect it will take a while....

The walls are all made with blocks of recycled concrete. If you look at them close-up you can see they are flecked with black stuff that looks like charcoal, although it's not soft. 

They are made of about 90% recycled material and, according to the WRAP website (http://www.wrap.org.uk/), they are "sourced from a variety of material: arising from construction and demolition (concrete, bricks, tiles), highway maintenance (asphalt planings), excavation and utility operations".

Apparently the bricks have got an A+ environmental rating (similar to the energy ratings of white goods) and I think they're produced in this country so that helps their carbon footprint.Sadly, like energy efficient white goods, they are also more expensive than their non-eco counterparts... sigh.

I know it's obvious when you think about it, but bricks in a wall have to be strong enough to support the bricks above them without crumbling so here's a bit of physics for you. The pressure that something can withstand is calculated by the force of the weight from above divided by the object's area and is measured in Pascals or N/m². These bricks have a strength of about 9 N/mm² (or 9 megapascals). Whenever I've had to read about pressure in physics I'm always reminded of the time the lady from Weightwatchers left tiny pits all over the newly-restored parquet school hall floor with her stilettos.

End of week four

Here's the site at the end of week four - one month into the build. The leyland cypress has gone, as has the compost heap and the bricks have come. This time next week I should have some walls to show you. Apparently the site is about to get busy; not that I'd noticed it being particularly placid so far....

The (putative) wildlife area

So here, bathed in the setting sun (sorry about that!) is the site of the wildlife area. To give you an idea of scale, the tallest part of the wall is about 12 feet high.

It obviously looks a wreck at the moment but you have to see through the mess to the Eden it will become - imagine wild flowers and a pond and some sort of tree where the fence and the wall meet...

... and note the logs in the foreground, they're going to be part of the oasis too, forming a home for all those things that crawl over your feet if you're not careful.

Timber!

This was the south-west corner of the site before the build began, with the most enormous compost heap and a leyland cypress tree. Goodness knows how long the heap had been here but you can see how high it was and it was way too big for me to move on my own, so it's been bugging me ever since we moved in. This week the eyesore has gone and the final part of the clearance was the removal of the cypress.

It wasn't the most beautiful of trees and because it's an evergreen it was going to be a problem  in the winter as it would block the sun so it had to go. It took the tree surgeons just over 15 minutes to take the tree from this:

to this.

The orange machine to the left of the JCB is the shredder and all the tree was fed into it and turned into chippings apart from a series of logs that I'll keep on site. The removal of the tree and the compost heap has cleared a massive new area and this is where the pond and wildlife area are going to go in the new garden - plus a much smaller, deciduous native tree that supports more species than the cypress, maybe a crab apple.