Monthly Archives: December 2015

The Year of Knitting Lacily: November Update Update

Well, Lila is finally finished! Kirsty at Wharfedale Woolworks came through with a matching skein of hand dyed Eirene, a little paler than the original skein but giving a nice contrast for the body. The body is straightforward short-row stocking stitch. The pattern says to use a firm cast off to help maintain the crescent shape of the shawl, but did not advise on which cast off to use. I opted for Slip Stitch Crochet Cast Off, which is quick and simple and very firm.

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Technical notes
Pattern: Lila, by Gillie Parsons
Yarn: Wharfedale Woolworks Yorkshire Rose BFL, colour Eirene
Needles: Pony bamboo 4.5mm circular 100cm
Yarn remaining: 83g (out of 220g), approximately 290m left
Finished dimensions: 115cm at neck edge,  275cm at hem edge, 51cm maximum depth

Additions: size 8 silver-lined clear beads, approximately 375 used

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Home Sweet Home; or There and Back Again

We moved out of our house in September 2014. It was a wrench but had to be done if we were to realise our dream of a comfortable home. Now, fourteen months later, we have moved back, to a completely new environment. The house has been remodelled internally (see Our House Reborn), completely insulated (see If in Doubt, Insulate It), made airtight and given a state of the art ventilation system (see Airtightness and Ventilation) that recovers 93% of the heat from the outgoing air and uses it to heat the incoming air. We have solar panels on the roof, and pipework under our field bringing us hot water and heating via a ground source heat pump (Renewables in a Low Energy House). We have lost a bedroom (knocked two into one) and gained a conservatory. This is going to take some getting used to!

Setting up the blower door test

Setting up the blower door test

Initial impressions are: what a lot of space (the remodelled rooms are roomier!), and isn’t it warm! We shall have to keep adjusting the heating controls until it feels right as we adjust to the climate within the house. So far, the underfloor heating on the ground floor is barely on and the radiators on the first and second floors are cold, but the temperature reads 20.5degrees Celsius. Admittedly, this has been a mild October but it has been very windy at times this week and we have felt nothing of this within the house (unlike in previous years when a windy day meant a very cold house!).

The old saying goes “the proof of the pudding is in the eating”.  In our case, the proof of the airtightness is in the blower door test. In an earlier post in this series, I mentioned that the blower door test performed before any work was done registered 16.9 ach (air changes per hour). In my second post, I said this:
“Although we cannot hope to achieve Passivhaus standard, and will struggle to meet EnerPhit, there is a lot that can be done to improve on 16.9ach. We have our fingers crossed for 3ach, but we shall have to wait and see”. Today, the waiting is over, the second blower door test has been performed, and the result is 2.5ach (an average of 2.2ach at 50Pascals pressure and 2.74ach on depressurisation).

Thermal image showing the "cold" spot on the old end wall

Thermal image showing the “cold” spot on the old end wall

The problem areas found were with the wall which was once the end wall of the original barn and is now an internal wall between the stairwell and the kitchen/living room/bedroom,  and the woodburning stove. The wall was always considered to be an issue, since its solid construction forms a thermal bridge; the test showed that junction points were one degree Celsius colder than adjoining walls, so 19degrees instead of 20degrees, which in a house where the internal temperature is maintained at a comfortable constant 20degrees, this should not prove a problem, condensation-wise. The woodburning stove is another matter. It is a Chesneys Milan 4 Passive, marketed as the only stove suitable for airtight houses. However, the installation instructions, which we only saw when we eventually took delivery of the stove, admit that the stove is not airtight. There is a row of slots behind the door which is inadequately sealed, and through which we had experienced draughts when the wind was blowing hard from the south, but in addition the flue connectors,  although correctly installed were also leaking at the junction with the fire. We removed the fire and sealed up the flue and retested, resulting in a 20% drop in air leakage.  Recalculating the result of the blower door test based upon the blocked up flue gives us a reading of 2ach. This is a phenomenal result! Our house is over 150 years old in places, with a mixture of solid wall and cavity wall construction, and to have reduced the leakiness to only 2 air changes per hour is wonderful! Huge kudos to Green Building Company for getting this result!

I shall be blogging about our first year in our reborn home at three monthly intervals, recording  what it is like living in such an environment. Look out for the next post in February 2016.

For other posts in this series, see:
Our House Reborn
Airtightness and Ventilation
Water, Water Everywhere
Renewables in a Low Energy House
If in Doubt, Insulate It

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If in Doubt, Insulate It

When we first discussed with Bill Butcher of Green Building Company the insulation techniques required for our house, using innovative materials was the last thing on our minds. We had assumed, in our naiveté, that Kingspan was our only option. We were so wrong!

I freely admit I don’t really understand what U-values are; I had never heard of interstitial condensation; I didn’t know that houses were supposed to breathe.

As the design of the renovation took shape, it became clear that our particular combination of extreme environment, solid walls, and rain penetration would require something more radical than just sticking Kingspan on the walls and hoping for the best.

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Innovative materials
Bill researched the available materials and found that the German company Knauf Aquapanel had been supplying an innovative product for passivhaus building, called TecTem. TecTem is made from perlite, an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. When heated to 900degrees Celsius, the water is driven off and the perlite expands, giving a lightweight material with the additional property of being able to absorb and dispel water. It is mold-resistant, fibre-free, eco-friendly, and completely recyclable. It has excellent thermal properties and breathability. It would be ideal for use in the barn part of our house, where the solid walls and lack of damp proof course mean that we have problems with moisture; moreover, the ground floor suffers from rising damp in one corner. Just one snag; TecTem is not currently available in the UK. But Knauf were interested in working with us to provide a solution to our problem and supplied us with the TecTem direct from Germany. In return, we are supplying them with data on the performance of the product. Within our walls, buried behind the insulation as well as attached to some of our beams, are over 50 moisture and temperature sensors. These report wirelessly to an Omnisense monitor that transmits the data gathered to a central database where it can be analysed, coordinated by Tim at the AECB. We are really excited that our project to give us a warm home will help future builders and architects to choose the right materials.

I have already written about the use of Foamglas in preventing thermal bridging on our steel i-beams, and its use as a tanking material along our dampest wall. In addition to TecTem and Foamglas in the barn half of the house, we have another Knauf product, Thermoshell, on the walls of the 1990s extention, that is in the kitchen, living room and master bedroom. Thermoshell consists of two parts. First, on top of the parged stonework, horizontal studs are fixed, comprised of very high density foam called XPS with a layer of OSB chipboard on the outer face. The whole stud is 100mm thick. In between the studs, 100mm batts of Earthwool mineral fibre are fitted. The whole is then covered by a sheet of Intello and a service void is constructed on top using ordinary timber 2×2, with plasterboard and plaster skim completing the wall. Of course, this does have the effect of reducing the dimensions of the room by about 120mm per wall, but once completed the difference in size is not noticeable.

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The really interesting thing about the wall treatments, whether TecTem or Thermoshell, is that the insulation and plasterboard is not just taken down to the floor on each level; it is carried down the whole height of the house in one continuous layer.  The floorboards along the edges of rooms were removed to facilitate this, and where floor joists impinged they were remodelled and ruthlessly taped for airtightness; stud dividing walls were cut away from their junction with the outer walls or removed altogether and rebuilt on top of the continuous insulation. This method ensured that there are no breaks in the insulation and the whole house is warmed as a consequence.

Bill Butcher has blogged about the technical choices for insulating our home on the Green Building Company’s website.

The third innovative material to be used in the house are Vacuum Insulation Panels (VIPs). These panels are attached to the inner embrasure of each window and external door. They were necessary to minimise the depth of insulation around each window where the window could not be enlarged. Our windows were mostly originally cut into a windowless barn, and were made deliberately quite small. The few windows in the newer extension were made to match the small size. We had had new Ecoplus doors and windows installed some years previously and so could not feasibly have the openings enlarged. Moreover, enlarging them would have required bigger lintels and the whole project would have just got completely out of hand! Vacuum panels were the answer.

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VIPs do require special handling. They are made to measure for each flat surface of each opening; they cannot be pierced, and so have to be stuck in place; any other covering material, for example window boards or plasterboard, have to be similarly fixed with adhesive. A far as aftercare is concerned, we do have to be careful not to puncture the panels, so roller blinds fitted into the embrasures are not allowed; but otherwise there is no problem as they are protected by window boards and plasterboard. They are only 10mm thick but have the insulating property of other insulation material that is 100mm thick. More technical information can be found on Bill Butcher’s blog.

Notes

The U-value is the overall heat transfer coefficient that describes how well a building element conducts heat or the rate of transfer of heat (in watts) through one square metre of a structure divided by the difference in temperature across the structure.

Interstitial condensation is a form of structural damping that occurs when warm, moist air penetrates inside a wall, roof or floor structure, reaches the dew point and condenses into liquid water.

For other posts in this series, see:
Our House Reborn
Airtightness and Ventilation
Water, Water Everywhere
Renewables in a Low Energy House

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The Year of Knitting Lacily: December Update

After last month’s failure to complete, I have been extra cautious about this month’s shawl. Even though I could have included an extra pattern repeat or even two, I have not done so. As a result I have a fair bit of yarn left over! This month’s shawl is the first to be taken from a published book instead of from individual designers on Ravelry. Sock Yarn Shawls 2 by Jen Lucas contains lots of nice patterns, ranging from simple to complex, and it was difficult choosing just one to start with. In the end I chose Monarda, using Wharfedale Woolworks Yorkshire Rose BFL sock yarn in Mahuika, a semi-solid in rich fiery tones, issued as part of the 2015 Colour Therapy Sock Yarn Club. It is well named after the Maori fire deity.20151127_122513.jpg

Monarda is an attractive all over lace shawl, well written and with easy to follow charts. The result is a beautiful mix of stocking stitch and garter, with lacy leaves and nice points.

 

The pattern says to cast off very loosely, and I thought I had done so, but when I came to try to block it to the nice curved shape required, I could not do so and maintain the pretty edging points. In the end, I blocked it to a straight top edge so that the points would show somewhat.

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Technical notes
Pattern: Monarda, by Jen Lucas
Yarn: Wharfedale Woolworks Yorkshire Rose BFL, colour Mahuika
Needles: Pony bamboo 3.5mm circular 100cm
Yarn remaining: 27g (approximately 94m)
Finished dimensions: top edge 144cm , widest point 38cm

December’s challenge
After my delight at the beading on October’s shawl, I really wanted to try adding beads again, and December seems like a good month to be giving my knitting a bit of bling! I also want to try another of Nim Teasdale’s designs, as I like her ethos of mix-and-match charts and knit-till-you-are-finished patterns. Slow Dance is another shawl from her Love is Friendship Caught on Fire collection, and features two charts which can be used singly or in combination. The overall effect is more geometric and less flowery (or leafy) than other designs I have completed in this challenge. Whilst the name of the shawl implies something potentially fiery, I wanted to keep the colour relatively low key and let the beads speak for themselves, and so I have chosen a lovely semi-solid turquoise yarn from Wharfedale Woolworks. It is called Laguna, and is a one-off hand dyed yarn in Kirsty’s beautiful Yorkshire Rose BFL sock range, so I am still restricted to 385m and 110g. I shall be using Debbie Abrahams silver-lined clear number 6 beads and a 1mm steel crochet hook.

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