Visit to Ecobuild at the massive Excel Exibition Centre in east London
Spent a very busy 6 hours dashing between stands, laptop in hand to iron out a few details and check specifications used in the Tender.

Rationel (timber, clad externally with aluminium) have updated their handles with a standard design rather than different for each window type which is good, though the design does not look especially robust with some plastic bits.  Also find out the the windows cannot be supported by the cavity closers and will need to be brought closer to the face of brickwork for support because some units are very heavy.

NBT (insulated render) have some mock-ups that allow me to kick some render to give me some reassurance that it is robust.  In a 2-way discussion with Rationel we work out that the render needs to be applied to the openings in advance of the windows to maintain a ventilation gap around the perimeter of the windows and avoid damage to the windows when the render is applied.

Baumit (Render)  The render specialist at NBT, a very knowlegeable guy takes me to the Baumit stand to show me some devices to allow mechanical fixings through the render for the planned Brise Soleil, solving a problem that has troubled me.  A core of insulation will be drilled-out replaced by a 'plug' and rendered over; so long as we remember where the fixing plugs are!  The Baumit rep. also gives me a colour swatch to select a colour for render and obtain a sample requested by the planners.

Karcher (handles) Happen to pass a stand with my selected stainless steel handles on display - so I have a go.  Not much to say they look just like the catalogue.

Rainwater Harvesting My specification seems OK but seems like the control panel needs to be a certain distance directly beneath the header tank which is useful to know and that it requires the mains supply at this point as back-up.  The header tank has precious little headroom for maintenance due to the flat roof construction but lowering it means that there will be insufficient head of water to feed the 2nd floor WC.  Will have to leave this one until we are on site, practicality will prevail although will be a real shame to have to use mains water for WC - maybe a big diameter fill pipe and a weak valve can be made to work to refill the cistern in minutes rather than hours.  Also complain about the high cost of the vertical format RainwaterHOG tanks we are using for stormwater attenuation.  5 are needed and space is at a premium in the small yard and garden, but choice seems to be restricted to about 2 manufactures.  These are a trendy Australian design for the retro-fit market, maybe an alternative can be found before we need to install them.  Also find that the underground tank must be located a minimum distance below ground level - this is problematic because the foundations of the existing and new building are so very close. We must keep clear of the '45º zone of influence' or push the foundations deeper that will add to the costs.

Viessman (Boiler and solar heating)  Learn that the zoned control system that I had understood  the boiler came with does not quite match earlier information from their technical department.  Good to know this now, although very difficult to come up with a simple and efficient control system where I do not know for sure how the various spaces are going to be used.  The size of hot water cylinder is questioned and is potentially too small (150 litres each for boiler and solar = 300 L) to supply 2 showers and a bathroom. 

If the sun is not shining we only have 150L, so this a worst case situation - overcast + winter a bit like today!  The next size tank is 500L so this is not an option, does not fit, and seems potentially wasteful and not really dealing with the problem.

I know nothing about showers so have done some research and calculations; survey by Unilever suggests that average length of shower is 8 minutes and my friends teenage son drains a 160L tank in about 25minutes!!!!!  Key thing seems to be the shower head: Traditional shower head ranges from 12-16 L/min.  Some stopwatch and measuring jug work; with friends shower is a surprisingly low 8L/min and my own a pathetic dribble of 3L/min.  After some research  I find a pulsing shower a Nordic Eco Galant in a Which? 

report.  http://www.which.co.uk/energy/creating-an-energy-saving-home/reviews-ns/water-saving-products/water-saving-shower-heads/ 

It uses down to 6L/min and has a pulsing mechanism so the water is more like a dashed line, on the same principle as a flashing bike light - so seems to make sense.

If I use these shower heads and assume that showers of around 10mins are slightly staggered then the cylinder can cope if the boiler is working flat out. Teenagers and dreamers can only use the shower when the sun is shining, although if they get up late and miss the morning rush and book evening appointments there will be no problem.