Thursday 26 July 2012

Solar Panels, electrical wiring and hemp walling in the rain

The indoor work site
Sunday it rained heavily on and off throughout the day but this did not stop work continuing on the house under cover of the roof. The electric pan mixer was set up in one of the back bedrooms, beside it I had a barrel of water to dip my bucket into for water. The barrel could be kept always topped up by leaving the hose dripping into it. The wall mix was about a bucket and a half of water, 5.5kg of hemp, one 9kg bag of binder and 8.5kg of river sand.

The mix ingredients showing the difference between volume and weight
 I started with half a bucket of water in the mixer. I measured the hemp out from the bulk bags into three identical buckets, filling each to about where the ridges of the rim began. I added the weight of one bucket together with one third of 5.5kg of hemp and so measured out each bucket to a total weight of 2.74kg on my, newly purchased from e-bay, electronic hanging scales. The scales were set up under cover of the eaves in one of the sliding door openings next to where the hemp was stacked. I added two buckets of hemp then the rest of the bucket of water, the third bucket of hemp, the binder and the other half a bucket of water. I kept a bucket under the outlet to catch any water leaked and added this back to the mix. The amount of water and consistency was done by eye rather than strict measurement - the aim was a damp muesli. At the end the sand went in. When the mixer got really full after the sand sent in, it sometimes pushed the mix around the mixer rather mixing it. When this happened I just let a bit of the mix out into a bucket, the rest of the mix started mixing properly again and the part in the bucket was added back into the mixer again.

Large flexible buckets were useful to discharge the mix into, a bit at a time. A full load filled about 4 flexible buckets three quarters full. The flexible buckets have two handles and were light and easy to pick up and were able to be shaped as needed to pour the hemp mix into the formwork. A scoop made from a cut down juice bottle was very handy to get the hemp into small spots or to direct it into a specific spot. A range of timber and tampers was used to tamp the mix once poured and levelled in the formwork in layers of about 5cm. Short lengths of timber were useful to tamp in hard to get to spots. When I got up to under the first noggins the formwork, by luck rather than design, was higher on one side than the other and I was able to push the hemp in under the noggins by hand. This was easier because the noggins were right at the top of the formwork. And so I made the next rise on top of the two small sections of wall I had made previously. Working on my own was slow work. I think team of four, two preparing and mixing and two tamping, would be an efficient workforce.
Hemp wall second lift
7am Monday it rained again, but not long after Paul and the boys from Solar Connections arrived the sun came out and the solar panels went on the roof , despite the roof still being a bit wet. I had originally planned the put the panels on the back pavilion, but following discussions with Paul I changed this as some tall trees to the east meant that the back pavilion did not get sun until late morning. The main pavilion faces true north, but the roof slopes 12 degrees away from north, so the panels were put on a tilt up stand to get a better angle for solar collection. The eight panels make up a 1.5kw system.
Solar Connections installing the solar panels on the roof
The change to the location of the solar panels means that they are now visible from the back pavilion, particularly the west bedroom, but fortuitously they fall behind the wall between the highlight window and sliding doors and do not block and can not be seen from the highlight window. I am worried that they will block a bit of the sun coming through the glass door into the bedroom, but hopefully this loss will be made up for the higher amount of electricity they will generate in the sunnier location. I had thought that the panels could start working as soon as I got the meter changed over and start generating electricity for me. Unfortunately the inverter (that turns the DC current from the panels into AC that can be used for appliances and fed to the grid) needs to be mounted on an external wall, and as yet we have a frame but no wall, so I will have to wait until the final electricals are done to start generating solar power.
Solar panels hidden behind the wall between the highlight window and sliding door
Monday I also had another delivery, the 78 bags of hemp lime render for the inside and outside of the house. The pallet of render arrived in a large van rather than a truck and without a lifter on the back I wondered how they would unload the pallet. As the driver explained - by hand. The driver backed the van up to the end of the drive and started unloading, he was incredibly fast, practise from unloading beer kegs he explained. I had only taken a few bags into the house by the time he was finished. I then had the job of packing the bags from the end of the drive into the house. After doing five pallets two weeks earlier, one pallet was no worries. Just a few spots of rain and a quick cover of the load with a tarp got me hurrying along.

Paul and the boys from Solar Connections also did all the electrics. For the light switches and power points in the external hemp walls they ran the cabling in conduit to plastic boxes. Following discussions with Paul we worked out the easiest way to do them was to set the outer edge of the box 55mm from the frame, the same spacing my formwork will be. This way the formwork can be screwed on and the wall filled without either having to cut a hole in the formwork for the box or providing some sort of filler so the box did not fill up with hemp. The 55mm distance was used by placing a 10mm packer of timber behind each box. When we render the walls we will just have to remember to put some sort of packer on the box so that the render will not curve off at the boxes and will have a flush surface when the face plate of the switches is attached.
Plastic box for power point
Cables run in conduit to box
While the electricians worked away. I put duckboards around the outside of the back pavilion to keep us out of the wet and sticky mud as we make the walls and to give a hard surface to work on. I also made a ramp into the house so we could easily move the mixer in and out. After this I started working on the formwork for the first rise of wall around the back pavilion, so next time we are on site we can get started making a long length of wall.
Form work and duckboards

1 comment:

  1. Why did you add sand to the mix? I haven't seen that done before.