4 Ecological aspects: House design, materials

Ecological aspects: choice of house design, materials and systems .

House orientation:

The limitations as to where the house could be located on the plot of land was discussed in the implantation of the house section. However factors that had to be considered were the climate (the most desirable orientation for warmth/light in winter but protection from the heat in the summer) and prevailing winds which here is the infamous 'Mistral'. Fortunately both favoured the house facing SE! The Mistral coming from the NW and the most used outside area of the house being the SE – avoiding the full summer strength of the sun. The nicest views were in that direction too!

The covered terrace – half with insulated roofing and half double glazing, fronted with galandage windows spanning the 4.5m. In the summer a motorised blind on the outside will cover the glass part of the terrace roof to protect from the summer heat and the galandage windows will be left open (sliding completely into the walls) giving a covered terrace with side totally open to the garden. On colder evenings in spring or autumn the windows can be closed to keep the day's heat in extending the period you can eat out on the terrace - in comfort.

In the winter the electric blind can be stored back and the galandage windows mainly closed to create a solarium or winter garden. The big windows from the terrace into the living room will ensure maximum natural light in winter and passive heating too from the low sun. Provence enjoys 300 days of sunshine a year – many of these in the winter! I really think this terrace will be one of my favourite areas of the house – hence it being central with the living area created around it.

Room organisation – the second bedroom will only be used periodically for guests. With the double door onto the guest rooms this area can be cut off from the rest of the house and be heated less when not in use. The main living part will be open plan giving one main area to heat. Shower rooms will be flanking the utility room with the water heater to avoid waste of water while waiting for the hot to arrive. Mezzanine wont be heated – hopefully the heat will rise sufficiently to keep this area pleasantly warm.

Walls

There seems to be only 3 real options for walls now –

1. Concrete blocks (breeze block) all sizes but 20cm is normally used, with 10cm insulation (usually polystyrene on the inside) covered with plaster board or brick which is then plastered. Concrete blocks are the cheaper choice but needing more work with the 3 layers. A positive point with the blocks is that the insulation is on the inside so lintels and concrete reinforcing are easier to deal with and don't cause cold-bridging. No very ecological a material.

2. Monomur which is a honeycombed baked red brick of 20, 30 or 37.5 cm wide and an impressive range of lengths, heights and forms. These can be rendered directly on the outside and plastered directly on the inside and don't need any further insulation. Building with Monomur requires real precision on the builder's part – the blocks are glued not cemented and there mustn't be any gaps. Cold bridging through lintels and reinforced sections are reduced by the specially designed blocks for these areas – with a deep channel for the concrete surrounded by honeycombed brick. When a good builder uses these as building material you shouldn't see any concrete anywhere showing! Considered ecological when considering toxicity in production and degradation but still need baking which takes a fair bit of energy (can't win can you!).

3. Ponce stone (spelling?) which is a light-weight pumices like material which can be rendered on the outside and plastered on the inside. But - it seems a bit friable for hanging any weights direct onto it (kitchen units or shutters on the outside). Doesn't need further insulation. Damp resistance comparable to Monomur – better than breeze blocks. Considered the most ecological.

I chose Monomur - considering it to be ecological, really good for insulation / damp and they retain a lot of heat. Just wish they didn't need baking in their production! One big reason for choosing them was that the builder I had selected - Antoine Nalin (an ecology conscious builder) was familiar with working with them and I had confidence in his ability to carryout the necessary high standard of work. We chose to use 37.5cm block to bring the insulation value up to 'RT12' which is a government given standard for houses of low energy consumption. For the walls giving onto the covered terrace, which aren't external walls, and other internal support walls we went down to 20cm to reduce price and maximum internal space. This however meant we would be a bit low on Tw (insulation) for the external part of the walls of the 1^st floor. So – the walls of the mezzanine and attic will be clad with rock-wool and then brick-faced to solve this problem.

Roof Insulation
 We have to keep with traditional Pan-tiles (rounded long clay tiles originally shaped on the thigh) but today the water proofing is ensured by panels of PST which are made of fibre-cement and undulating to be able to place the tile cover. Under the PST is a wooden armature for airflow between it and the 28cm of rock-wool insulation/roof frame. On the ceiling side will be fixed a light-weight aluminium mesh for plastering. Apparently plaster-board is also a no no (non non) for ecologists.

Central Heating system (7kw needed)

I turned all possibilities for heating the house around in my head for months, read articles from numerous experts advocating one system over another and had meetings with even more sales reps than I would like to remember to hear their suggestions. First clear choice was that I wanted low temperature under floor heating. But I couldn't decide what heating system to link to this. Initially I had hoped to have a system using solar power as the main energy form and a heat pump (air/water) for the back-up. However the size of the water tank which would act as a heat reservoir would have had to be 900 litres, requiring some 12 m2 of solar panels. Also even if this were the main heating system the back-up (heat pump) would also be essential for the over-cast days and very cold periods. The cost of paying for 2 complete systems was crazily high – sadly. So I had to think about heat pump systems only. However even there there were so many choices. With the area of land I had I could have had geothermal heating either from deep well or a horizontal closed system, or an air heat pump.

The cost of drilling two 60m deep bore-holes (one to bring up and the other to return) plus the cost of pumps and piping and a water-water heat pump would have been over 23 000 Euros. One bonus would have been free water. However there is plenty of water on the land for watering the garden and WCs relatively free. The efficiently of the system would have been very high though with a COP of 5.0.

For the Canadian style geothermal system, only 300m2 of captor piping at 1m under the ground would have been needed. To set up the system, digging, laying the serpentine and refilling, would have cost 3500 Euros plus the heat pump (10 000). Apparently the heat exchange fluid in the external serpentine needs changing every 7 years (not sure this is really true though). And still the 6000 for the under floor heating system (but this would be necessary for any of the systems).

And finally – the air-water heat pump. Seemingly this system is the simplest to set up (no wells or ground to dig up) and very effective (COP of 4.2). In other words – for 1 kw of energy in you get 4.2 back out in the form of heat. Finally – it is a compact system, no moving parts and all parts are supposed to be easily changeable now.

So – I have gone for the air-water heat pump which including the underfloor serpentine will be 10 000 Euros. This will also heat the hot water for the house.

Log burner: One of the more ecological systems and cheapest to run – especially as I will have plenty of trees on the land that will need thinning yearly. With the house so well insulated – I shouldn't need to heat too much either (hopefully). With the design of the house (open plan) and 'square' with opening to mezzanine a log burner in the living room would heat most of the house very effectively. Now all I need to do is choose a nice design – not too big but big enough to take the logs I already have cut !! Another consideration with a log burner is the pure pleasure of sitting in front of a real fire on a cold night!!

Windows:

Choices: Wood, PVC and Aluminium – double glazing or triple, laminated (break resistant)

Wood: Great material, excellent insulation qualities, prices range depending on choice of wood – pine to oak but more expensive than PVC. Needs maintenance, acrylic, oil or varnish - hard wood needing least maintenance. Certain designs of frames not possible (sliding windows).

PVC: Top for insulation qualities, material lends its self to different moulding and the full range of opening systems, easy to keep looking perfect for 20 years or more with no maintenance, significantly lowest price but – and a big but – very poor rating for the planet. Highly toxic chemicals used in its production and huge problems for disposal of off cuts and old windows.

Aluminium: Poor insulation qualities – but new design improves on this by creating thermal breaks. Amazing options for colours and finishes (including bi-colouring – different on the inside to outside). Apparently you can even re-spray aluminium when you get fed-up with one colour. No maintenance needed. Material lends its self to most designs – but not quite as rigid as PVC. Can be dented. Triple the price of PVC but comparable to middle range of wood.

I chose- Aluminium finally. I couldn't accept the un-ecological PCV (sadly) and although I would have loved wood – don't want to have to deal with maintenance – and the sun is really strong here.

I also chose double glazing (triple not really worth the extra cost) and laminated on the windows without bars to increase security. To English this might seem unnecessary but here in France if you don't have shutters you will be attracting thieves – and the insurance companies up your premium.

For the design I have chosen sliding windows for the kitchen, the big living-room window and the mezzanine window so as not to have problems with the window sweeping things off the surface – remembering that in France windows open inwards. The other windows will be fitted in the thickness of the wall nearer the outer wall – opening inwards. The galandage glass door of the kitchen will have a sunken frame for wheelchair access.

Antoine (builder) had wanted to use his own supplier for windows, fitting them himself. However after getting quotes I found Vial to offer windows with the same thermal resistance quality and comparable design for 3000 Euros less. We had a meeting and looked at all the information and my choice of designs and I'm glad to say he is now fine about fitting the Vial windows! I really don't think I will even notice the frames once they are in – I'll probably be looking out at the garden thinking how it needs weeding!

Waste water disposal

The house location is half a km out of the village and in a valley not served by a communal sewer. Options are :

Septic tank, which would have to be 3m3, the outflow going into something like 45m of soak-away drainage. Not very ecological – not all the systems function well enough. From experience – this system can have smell problems, it needs pumping every 3 years and the biggest problem – it isn't possible to have a soak-away in the lower field (only possible place unless I have a lifting pump) because it is so marshy. The other option to a soak-away would be a reed bed set in a basin to treat the effluent. Tank and soak-away could be put in for 6000E, reed bed option would add to this price. And – I would have problems in lorry access for the emptying.

Micro-station, had been my first thought. You can find really nice compact systems on the market. However – they need electric power (not a big problem), still need emptying (access problem) and the local authorities wont allow you to let the water just flow out without a second treatment – soak-away or reed bed. So – although very ecological, the fact you have to have a second purification system makes them very expensive – and still doesn't get around the problem of the ground being too wet for a soak-away.

Reed beds, had not been in my original plan – but once I looked into it this certainly was the most attractive and natural system for the area. All the waste flows directly out and onto a first reed bed of 10m2 (2m x 5m) with special plants set in different graded stones to allow filtration of matter to lower levels. The natural bacteria around the roots of the reeds breaks down the matter in less than 5 days. The outflow of the first basin flows into a second basin (2m x 5m) of aquatic plants which finish the purification process. Apparently you can drink the water flowing out of this second basin. Not sure I'll try it – but I am seduced by the naturalness of this process. I would have to ensure no unpleasant products are used in the house which would kill the plants and organise a timer watering system if I am away in the summer. This wouldn't be too bad as I will have a well in the garden from which I am pumping water for the garden already. I am quite satisfied that smells wont be a problem – but I'll be glad once the reeds have established well enough to ensure I don't 'see' anything sitting in my reed beds! The cost is higher than I would have expected – minimum 8000E, because of the complexity of the system. The basins have to be dug to exactly the right size, depth and slant, then lined and filled with layers of the different grade chippings and stones before adding the correct range of plants. The lower field already being a reedy area – makes this system the most in keeping with the house and environment – and ecological. The only maintenance is annual cutting of the reeds.

Now I am waiting for the planning application (prepared by Alexandre Cras from Aquatiris) to be accepted by the local authorities. I have to say at this point that I initially had thought Alexander's quote for preparing the design and plans was a little expensive – but I have rarely seen a better prepared and detailed application. I hope it is accepted!!