The lighting was I think put in by the owner before the previous owners, who did a lot of work himself. And back then halogen downlights were popular...

• The entry hallway had five 40 watt GU10 halogens. Covering maybe two square metres, this made the hallway, even with only three of the lights working, the best lit area of the entire house.
• The sitting and dining room were lit with twenty one exposed 20 watt G4 halogens, nine of them in the sitting room and twelve in the dining room.
• The kitchen had four 60 watt R63 spotlight bulbs plus three 18 watt benchtop fluorescent bars and an 11 watt rangehood light; the breakfast area had four dimmable 35 watt GU10 halogen spotlights.
• The bathroom had five 20 watt MR16 halogens (I use "MR16" to refer to MR16 reflectors with GU5.3 connectors, as seems to be common usage).
• The upper hallway, with two 5 watt compact fluorescents, and the nursery and main bedroom, with one 11 watt compact fluorescent each, were comparatively sanely lit.
• The study had four 50 watt MR16 halogens and the ensuite one 20 watt MR16 halogen.
• The patio had ten 60 (?) watt incadescent multi-coloured party lights, of which only three were still working. The shed had several bar fluorescents.

Which came to something over 1.4kW, not counting the patio or shed lights.

What I did

The big constraint was that I didn't want to take down any ceilings or do anything structural. The following doesn't follow the order I did things in at all, and also elides some missteps where I installed or bought the wrong equipment.

1. The 40 watt GU10 halogens in the hallway were replaced with 4 watt LEDs (£15 for five). These are not as bright individually, but with five lights working instead of three the resulting light is just as bright and more evenly distributed. Score: -100/-180 watts, 120% quality.
2. I removed the dimmer switch in the dining room, replacing the four (buzzing) 20-60 watt transformers with a single 48 watt transformer and a wireless dimmer, and the twelve 20 watt halogens with 3 watt "daylight" disk LEDs (270 lumen each). The result is noticeably brighter, probably because the disc LEDs throw all their light downwards and don't waste any of it upwards or sideways, and provides a good light for reading or working. Score: -200 watts, 200% quality.
3. The sitting room followed the dining room, except that the transformers were only accessible through the narrow light fitting holes in the ceiling. This meant no wireless dimmer could be fitted in. Score: -140 watts, 80% quality (brighter, but losing the dimming is unfortunate).
4. The kitchen was easy, if not entirely satisfactory. I put in four R63 11 watt compact fluorescent bulbs. These are not quite as bright as the older 60 watt halogens (or 42 watt "eco"-halogens) and take quite some time to reach full light output. One advantage is that they aren't as glary as the halogens were. Score: -200 watts, 70% quality. (The light fittings are also ugly-as, so I'm thinking of replacing these with LED downlights.)
5. I replaced the 35 watt GU10s in the breakfast room with 6 watt dimmable LEDs. These are more narrowly focused and don't provide as even a light. Score: -115 watts, 80% quality. (I think alternative wider-angle GU10 LEDs would improve this.)
6. I replaced the MR16s in the bathroom with 4 watt "warm" high power LEDs (with three individual LED drivers replacing the dead transformer). These match the 20 watt halogens very closely, for beam angle and colour and brightness, and five of them is plenty in the bathroom. Score: -80 watts, 110% quality.
7. I replaced the 50 watt MR16s in the study with "9 watt" (actually 5 watt) warm white LEDs. These aren't as bright and are a bit more narrowly focused. Score: -170 watts, 70% quality. (If I can fit larger holes into the ceiling, putting in dimmable LED downlights here would be good.)
8. I replaced the MR16 in the ensuite with a 4 watt "daylight" high power LED. And put a new "daylight" 10.5 watt LED in the shower. Score: -5 watts, 150%.
9. I replaced the party lights around the patio with twenty LED party lights. Score: -150/-570 watts, 200% quality.

If we turn on every light in the house now, that would come to maybe 300 watts in total, at least nominally. (In practise the transformers add some power consumption on top of the rated light power consumption, so this might be more like 400 watts in practice; I haven't actually tried the experiment yet.)

How much did it cost?

None of the components were expensive: LEDs have really dropped in price and I bought a lot of them off ebay - the 4 watt MR16s in the bathroom, for example, were only £11 for four. Of course the cost of the electrician for the bits that involved rewiring has to be added to that. Even so, I estimate the "pay back" time for the whole switchover at two years at the most. Our household electricity meter arrived only a few days before the major conversion started, back in November, but we clocked a few 18kWh days. Since then, we've averaged 11kWh/day over the darkest part of the winter. Which is maybe 80p a day in electricity saved, though that will be less in summer.

Some of these changes were relatively involved, but some of them are quite straightforward. If you have 20 watt or 35 watt halogens in GU10 or MR16 fittings, and they aren't on a dimmer switch, you can probably just swap them for equivalent LEDs that draw a fifth the power, without changing transformers or needing an electrician. The pay-back time on this could be very short, depending on how often they are used.

Other lights

We had three bedside and standing lights, with 20, 25 and 40 watt halogens in E14 and B22 sockets; I replaced these with 2.5 and 1.5 watt LEDs (about £3 each). Given how cheap LED lights are now, it's shocking that IKEA still sells desk/bed lamps with incandescent bulbs in them.

To provide the option of a warmer, dimmable light in the sitting room, I bought a "mother and child" uplighter/reading light combination. The uplighter of this had a 230 watt R7s J118 linear halogen, producing something like 5000 lumen - enough to light the room up quite decently just by reflection off the ceiling, thought that's probably the most insanely inefficient way of doing that. I replaced that with a 10 watt LED: this is only 900 lumen, but sends all its light upwards and is fine for mood lighting. If we want the room bright, the nine 3 watt disc LEDs in the roof will be plenty. The only halogen left in the house is the dimmable 40 watt G9 in the "child" reading lamp part of this light, for which I have been unable to find a replacement.

First of all, cycling around Oxford in winter means I'm carrying:
* a scarf
* a beanie
* gloves
* a bright yellow cycling shell - windproof and sort of waterproof
* nylon overpants (when rain seems likely)
* a bicycle seat cover (when rain seems likely)
* front and back bike lights

Then there's assorted electronics
* my iPod touch
* my little camera
* my Kindle
* my bank security device (aka a mobile phone)

That still leaves room for a couple of books, pens, boxes of tissues, and so forth, along with some spare bags for shopping. I usually do larger grocery runs on foot, so I can carry a couple of separate shopping bags, but I should perhaps get a set of pannier bags for that.

I have a full desktop computer with a decent monitor, but that sits upstairs and only really gets used for graphics or anything else that needs grunt (e.g. R), running video and audio downloads, for managing my web sites, and as my primary file server - it has a pair of RAID-1 1TB drives and is backed up regularly.

When working downstairs, or in the Bodleian library or in cafes, I've been using a little netbook, a first generation Acer Aspire One, which was originally intended just for travelling. It's a nice little machine, but it's been a bit frustrating, largely because the SSD is incredibly slow on writes: sometimes it locks up completely for five or ten minutes, and a Fedora distribution upgrade can take 40 hours or more. The slow SSD interacts badly with having only 1GB of memory. Also, the screen is small and the battery lasts only just over two hours.

I bought a fast SSD and extra memory to upgrade the machine, but that failed when I couldn't get the motherboard out - the screws had corroded on.

So I've been thinking about getting an ultrabook. The main requirement here is that it be light, ideally no more than 1kg, and robustly built, so the best candidate seems to be an Asus UX21a or, since that's not yet available in the UK, perhaps an 11.6" Macbook Air. The Air works nearly completely with Linux and is what Linus Torvalds uses.

The downside is that the Macbook Air is rather expensive, around £850, and the UX21a, US$1000 in the US, is likely to be as or more expensive in the UK. So this will probably be the first thing I buy myself if I manage to get a day job - especially if I can salary sacrifice it.

As far as usability goes, I'm impressed. The Kindle is vastly better than my iPod Touch, with the e-ink display, the larger screen, and the button-to-page instead of the touch scrolling all significant advantages. It's also much better than reading on a fixed monitor, where I've never managed to read an entire book before. The effect is to make the device "disappear", leaving one to focus on the text.

There are even some advantages over printed books. A Kindle is lighter and more compact than a stack of books (or indeed a single textbook or sizeable novel). It sits flat on the table, which makes it easier to read while eating. And it can be easily operated one-handed (and no, there was nothing salacious in Sophia's collection, not even a copy of Fanny Hill).

One drawback over the iPod Touch is that the Kindle requires external light, so reading in bed with the lights out isn't feasible, or reading in a car in the dark. (Amazon sells a leather case with built-in light, which uses the Kindle battery, but it's rather expensive and must reduce the battery life drastically.)

Another drawback is that the Kindle is black and white and its screen is still only 800x600. This is not a problem with a novel, but I'm not convinced that reading The Elements of Statistical Learning on a Kindle would be so much fun, even if there were an ebook version rather than a PDF. I should probably try reading some non-technical non-fiction, though, to see how footnotes and suchlike work.

The DRM is not an issue if I only read free (speech) books, of which there are more than enough to keep me going. Sophia hadn't run amok downloading the universe, but she had two dozen or more ebooks I could happily have read. (One of these was a conversion to fixed-size page format, leading to the book title appearing in the middle of "pages".) And the simple expedient of not registering with Amazon makes it easy to stick to free books.

If I don't want the whole Amazon ecosystem and just want to read free ebooks, other devices are possible candidates. A look at this comparison table, however, suggests that the Kindle offers by far the best "bang for the buck". (Is Amazon subsidising the hardware to make money selling Kindle books?) The 3G might be worth paying the extra for, if only for emergency web access.

But one big question remains. How much would I actually use a Kindle? I think the answer is "not that much", unless perhaps when travelling. If we go back to Australia I might get one to provide reading material on the flight. And if travel guides work nicely on it - and I'm prepared to use DRMed guidebooks I can't pass on to other people - then it could be a replacement for the heavy and bulky Lonely Planet and Rough Guides I end up carting around. (And here the long battery life of the Kindle would really come into its own, as I wouldn't have to carry a charger on most trips.)

I had a brief play with Sean's first generation model) over lunch once and was pretty impressed. And at $139 from Amazon or £111 from Amazon UK (basic wifi model, prices current as of 5th February 2011), the Kindle is really not that expensive now.

There are three concerns for me:

First and foremostly, I'm perturbed by the idea of a locked-down device with everything DRMed, supported by a proprietary "ecosystem". Since I've (personally) only really used free software for fifteen years now, this seems strange and unusual, on top of practical or ideological concerns. (The Nineteen Eighty-Four deletion fiasco happened just before I saw my first Kindle.)

Secondly, I just want one device to carry around with me, not specialised devices for all the things I want to do. The Kindle looks like a really nice device for reading books on, but though one can apparently run an ssh client on one it really isn't designed for that kind of use. (Sean argues the advantages of a single-purpose device, however, and it's not clear the kind of tablet/PDA/mobile computer I want will ever be manufactured.)

Finally, books for Kindle are rather expensive - in many cases more expensive than the printed versions! - so I mostly envisage reading academic papers on one. But I'd need to do some more testing before being convinced that the PDF rendering was good enough to make this practical, especially for diagrams.

The Touch came with the MacBook Pro which Camilla bought just before we left Australia. (Don't worry. The OS X install is still on that, but it's running Fedora Linux, we haven't gone over to the dark side!)

The Touch is basically an iPhone 3 with no phone capability - so dependent on a wifi connection for any networking. It's crippled - I haven't jailbroken it - but it supports a web browser and an ssh client.

Uses

• as a watch, since I don't have one of those.

• for emergency access to email and the Web (if I can find a wifi hotspot).

• for reading news on. It's much lighter than a book, and can be used one-handed, so it's neat to check the news (or the weather, or foreign exchange rates) in bed.

• for specialised apps. Apart from the ssh app (iSSH) the only one I've paid for is a "British Birds" app which provides pretty much what a field guide does but in a much more portable format (we often don't have a bird book when we want it) and also has recordings of bird calls.

• (possibly) as a travel computer, for email, booking hotels, etc., in place of my netbook (Acer Aspire One, first edition 8.9" model with SSD). It's painful to use, but is also much lighter and more compact.

Drawbacks

• I haven't worked out how to get files onto or off it (using Linux) so I can't use it as a music player. (I should be able to do this, but Apple's insistence on proprietary interfaces is a real nuisance.)

• The storage isn't encrypted, so I'm unwilling to store contacts on it, or cache email or passwords. So if I want to read email, I use ssh, rekeying my passphrase every time. I really want encrypted storage, perhaps with some kind of biometrics + short PIN for access.

• The inability to multi-task makes it useless as a general-purpose computer. And I really miss having bash and Python.

So the iPod touch will remain a toy. For a proper mobile computer, I really want something that I control, which means a free software stack. Given that some Android phones are hardware rooted, and other concerns over Android, I may wait to see if MeeGo looks any good.

As far as hardware goes, I think a device 50% larger would fit my needs better - still pocketable, but the extra space would make web and ssh vastly more usable. A tablet is a possibility - if it's more robust and smaller than my netbook.

I bought the E-1 with a 14-54mm f/2.8-3.5 lens — a fast standard zoom (28-108 equivalent) with decent macro performance (0.52x equivalent) — and the combination has been with me all over the place. I've taken it to New Zealand, Mongolia, Vietnam and Cambodia, and most recently Turkey, among other destinations. I've taken 26,000 photos or so with it (not that many given the shutter is rated to 150,000 actuations) and it's performed admirably.

The one huge problem with it — and I knew this was going to be the big problem when I bought it! — is that it is a big, heavy camera, not really suited for someone who travels light. With a spare battery, my basic camera bag weighs in at 1.65kg, on top of which there's the battery charger and usually a light telephoto lens. (I realise this is not heavy by professional standards; you don't need to tell me how much heavier a Canon 1Ds is!)

What with the netbook as well, my luggage now can be two thirds electronics. And I sometimes go out without the camera, because it's so bulky, and miss photography opportunities as a result.

It would also be nice to have some of the features of more modern cameras: video capability, better high ISO performance, colour histograms, faster review times, a larger LCD screen, more than 4x zoom, and so forth.

The Problem

The problem is that, even after seven years of seemingly frantic camera development, there is no DSLR smaller and lighter than the E-1 which matches its features, in particular the weather-sealing and 100% viewfinder.

So I'm contemplating giving up on a replacement and instead supplementing the E-1 with a much smaller and lighter camera, maybe an E-P2.