The Cropthorne Autonomous House

Style and Interior Design
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This page maintained by Lizzie:
Any architectural drawings shown on this page are © Neill Lewis, chartered architect.

In most new-builds the design is led entirely by aesthetic choices and the house is built and decorated to fit a chosen style. With our house, energy-efficiency came first. Its design is based on the Nottinghamshire house built in the 80s by architects Robert and Brenda Vale (see the Technical Design page for more on how the two designs compare). Even its quirky position on the plot (below right) is not a whim of ours, but because the back of the house must face south for maximum solar gain. There won't be any heating system at all, so maximising heat gain from the sun is crucial. If the house was positioned straight on to the road, as you might expect it to be, the back would face south-west, which wouldn't bring in as much sun/heat. We will have a tiny woodburning stove, which we can use in extremely cold weather, if necessary. But, in practice, we will probably only light it on three or four days of the year.

THE INTERIOR

With the internal layout, bizarre as it may sound, our starting point was the composting-toilet system. The toilets (a maximum of two) must be sited directly above the basement composting chamber, so the bathroom and the upstairs toilet were the first rooms to appear on our rough plans. Everything else had to be designed around them. Our brief to the architect was that we wanted a house that would suit a family of four comfortably, without being lavish, with bedrooms downstairs (to be cooler in summer) and the living area upstairs (warm air rises, so it should be warmer in winter). There's also a fantastic view - so why not make the most of it?

Downstairs we decided on four bedrooms, one bathroom containing the downstairs toilet, a separate shower room, and a utility room. Upstairs we wanted a kitchen that opens through an arch onto a dining area that is part of an open-plan living space. The only other rooms upstairs will be the toilet and a study. We supplied the architect with rough plans incorporating these ideas, which were a series of uninspiring boxes. He then cleverly transformed them into the plans you can see on the left.

Spanish Terracotta Floor Tiles

We had no fixed style ideas for the look of the house, but as the energy-efficient design of the structure has taken shape in plans and discussions, the style has created itself. For instance, the thermally massive concrete structure acts as a giant heat store, absorbing the heat from the sun during the day and slowly giving back that heat at night. Because of this, we can't use carpets or wood flooring, as they would impede the absorption process, but tiles (with rugs) are OK. As all the floors will be tiled, we decided to use warm terracotta (right), giving the house a rustic/Mediterranean look. We tried to source the tiles locally, but couldn’t find anything suitable, so we’re using tiles imported from Spain. Spanish terracotta tiles are fired in kilns at a much lower temperature than anything available in the UK, causing lower carbon emissions. We also decided to have tiled skirtings, inspired by the photo below left.

This is aesthetically pleasing and should work well, especially on the curved walls. We may use off-cuts from marble kitchen worktops for the floors in the bathroom, shower room and toilet. (These off-cuts are usually dumped, so we may be able to pick them up cheaply or even for free.)

The mass of insulation in the exterior walls will mean that the window reveals will be very deep - adding to the rustic look. If possible, the reveals will be splayed to help bring in more light and the edges rounded off, as they are in the picture on the left. The windows themselves will be high-performance triple-glazed units. As there is so much south-facing glazing, we’ve opted for wooden windows with low-maintenance powder-coated aluminium on the outside.
Batten Door Example


To add to the rustic look inside we were going to choose wooden ledge-and-brace doors, like those found in old cottages, but their construction means they can't be glazed. As some of our doors need glazing, we've opted for a style similar to the door in the picture on the right, known as a batten door. The external doors - the two at the rear that open into the conservatory, upstairs and down, and the front door - will need to be Passivhaus standard, with triple-glazing where applicable, as they are part of the insulating envelope of the house and mustn't be a source of air leakage. (The front porch and the conservatory also act as 'buffer zones', so that these doors don't open straight outside.)

 Lime plaster and natural paints will be used on the walls. The ceilings downstairs will probably not be plaster-boarded, leaving the underside of the concrete floor above visible. This will then be painted. The vaulted ceiling in the large living/dining area may be painted tongue-and-groove boards, or FSC-certified plywood with rush matting attached, which can then be lime plastered.


STAIRS

The staircase will be constructed in concrete and then tiled with Spanish terracotta tiles to match the floors. Inspired by this staircase from the Sunhawk House in Mexico (top left), we decided to source some decorative tiles for our own stairs. A chance visit to the Craven Dunnill Jackfield Tile Museum in Ironbridge, Shropshire, just as they were having a tile seconds sale, gave us the idea of using encaustic tiles. We were lucky enough to find several tiles we liked in the sale (bottom left), and have ordered the remainder at full price. It counts as one of the luxuries of the build, but we hope the results will be worth it, and it’s nice to be using local handmade tiles.

A wooden stair rail didn’t seem to fit with the ‘Mediterranean’ look of the tiled stairs, so we started looking around for alternatives. Then we saw this picture of a staircase in a French hotel (right) and decided that we had to have something similar. We’ve already visited some local blacksmiths, who are confident that they can reproduce the design for us. The basic components are fairly standard steel rods and much of it would be cold-formed, lessening the carbon footprint of the whole production process. It should look stunning when it’s finished.



THE KITCHEN

There are various interesting possibilities for the kitchen design and we haven’t made a final decision at the time of writing this. We could try to source some reclaimed timber and have units made by a local joiner or kitchen company. One very creative local designer has suggested making units from recycled pallets, which is an idea we’re quite drawn to. He might also be able to source some deep red Persian marble, which was imported for a large project that was then cancelled, so it is sort of ‘reclaimed’. We could use this for the worktops – it’s a really pretty and unusual colour.

Another option would be recycled plastic. Milestone Kitchens in Ilkley, Yorkshire, has designed and made a kitchen using recycled yoghurt pots for the unit doors and recycled vending machine cups for the worktops. We went to see them and they do look very good and there's no sense that it's inferior to a kitchen made from more conventional materials.

Fitting units into the kitchen is a slight challenge: one wall is curved, one contains the arch through to the main room and the other two each contain a large window. There’s very little wall left for high-level cupboards. As an additional small indulgence in the kitchen, we'll have three small stained-glass windows in the curved wall, commissioned from a glass artist in Malvern who uses recycled bottle glass. These will be back-lit by the light shining in through the kitchen windows and will enliven the area at the top of the stairs.

A House at The Wintles, Bishops Castle

EXTERIOR

The exterior design was partly inspired by The Wintles eco-house development at Bishop’s Castle, Shropshire, which we visited before we had even found our site (see example picture, right). The clay-tiled catslide roof, recycled bricks and lime render will give the house a ‘traditional’ appearance from the front; while, from the back, the large expanses of glass, and the double-height conservatory will look quite contemporary. Once again, this glass is not there solely for aesthetic reasons, but to make the most of the solar gain (with the added bonus of a wonderful view). The size and position of each window has been calculated carefully by the energy consultant, as each one plays an important role in the thermal performance of the house. Hence, there are fewer windows on the north (front), as there is little solar gain on that side and more chance of heat loss in winter. The circular window, high on the western elevation, was in a sense an indulgence, but it will bring evening sunlight into our expansive first-floor living room and will postpone the time until we need to turn on artificial lighting.
Exwood Decking - Made from recycled PVC and Rice Husks



For the outside decking, we plan to use a material called Exwood, which is made from recycled PVC mixed with rice husks (see left). It looks very similar to wood, but doesn't require any finishing or maintenance, even when used outside. We’ve already bought the outside staircase that leads down to the garden (see below). We found it in a reclamation yard near Coventry. It’s a Victorian ironwork staircase that came from a solicitors’ office in Leamington Spa. We’ll probably paint it to match the colour of the powder-coated windows and the conservatory (which will be a blue-grey colour).

Our Victorian Staircase from a former solicitor's office in Leamington Spa



 



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