We have installed underfloor heating.
The bottom floors and the bathroom floor came up and underfloor heating fitted.
The heating is all run off a Vaillant condensing combi boiler.

Insulation

The replacement windows are all Andersen windows from USA, they are wood with a pvc outer liner - minimal use of PVC and solid wood on the inside. All double glazed.
The big sash on the front was rebuilt in situ and draught proofed - it retains the original glazing.
The front door has been fitted with double-glazed glass. Both front and back door are draught proofed.

The house has a very standard insulated loft conversion but with brick cheeks - meaning it looks more like a house than a conversion.

The bricks for the conversion were new instead of reclaimed, but in retrospect I could've used reclaimed brick quite easily and cheaply since so many bricks came out of the house.

The loft's insulation is to modern building specs.

Loft floor is oak parquet from e-bay reclaimed.

We built a large office at the end of the garden using as much material reclaimed and recycled from the house renovation (and elsewhere!) as possible.

Foundations from inner wall hardcore:
All the hardcore from the house's inner walls was reclaimed and used as foundation for office at the end of the garden.

Framing from recycled timber:
All the timbers from the roof that were removed to make the loft were used in framing the office.
The short stuff was used to build a bicycle shed outside.

Doors and windows:
The double-glazed door and windows of the office were rescued off the side of the road (bargain!).

Locally sourced timber for the office and fencing:
All timber for cladding the office and fencing came from local sources: Eynsham park sawmills.

Heating:
Office will be heated from a small woodburner - Danish 1950s model, v pretty from e-bay.

Water supply:
Office will have a water butt to collect for watering garden. Sadly I can't figure out a system for the house roof catchment.

What's bad?
Here are a few of the problems and solutions I have encountered going about my eco-renovation.

CHIMNEYS: I have left the chimneys in - so I have the option of fitting a small wood burner to keep the front end warm - though when I asked about a flue it was said to cost in the region of £800 up. I begged off it. The fireplaces look nice but are draughty as heck so I've bought some chimney vent balloons (http://www.chimney-balloon.co.uk/), and will probably get some terracotta flue vents to minimise downdraughts at some stage (http://www.hepworthterracotta.co.uk/).

HEATING: I should have put a big solar panel on my flat roof and a small photovoltaic cell to circulate the water to tank which would then feed into the boiler (I didn't know this was possible until I went to COIN meeting where someone described his system).

I should have built two loops in my CH system: one for the regular radiators upstairs, one for the underfloor heating - which takes much much longer to heat up.

Both these things could be added in but would take time / make mess and cost me around £2,000 all in.

LIGHTING: The back room / dining room is dark and I am considering cutting a hole in the wall and implanting glass bricks to let light in - having that light on all day in the winter is annoying.

This one I have yet to overcome:
The one gadget I'd like is the 'smart meter' something that can tell you how much electricity (and gas) you are using and what it costs.
The one on the market is a bit naff for £80 (http://www.electrisave.co.uk) I only want a simple one to tell me what all the standby stuff is using, this unit will tell me what it cost and my carbon emissions. And it uses AA batteries, pffffff. One could do this with a fairly useful clamp multimeter for £25-30.