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 1st
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!!
I have been in the house now for over a year - and what a joy it has been. I am relieved to say I haven't found many things I regret or wish I had done differently. Mostly I have experienced very positive discoveries. The wall of bamboos creates a such a cool green screen making the terrace so private. In the summer the trees at the front form a canopy giving welcomed shade from the heat and in the winter the lack of leaves permits the low sun to warm the sun loung and house. 
The BBQ with shed hidden behind is set 2m from the bamboos for obvious reasons! I'd looked at different ways of protecting the wall from the flames and blackening then decided to use some tiles left from the grey shower room, cut into thin strips to give a fire image. The tiles wash fine, don't crack and make the BBQ an attractive feature even when not in use.
I love the quilt Pat Seguare made me more than 10 years ago - around which I chose the colours of the room.xx
