Monday, 4 August 2014

Get more by using less

I have been meaning to post some tiny tips to help things go further, thereby reducing the environmental impact of making stuff.  Each small act of resurrection or reduction gives me a sense of fulfilment, even pride, that no retail therapy can match.  Here are three!

1 Go halves
We are lucky enough to have a dishwasher, which lightens the burden of keeping house and - some people say - uses less energy than running enough hot water to do the same amount of washing up by hand.  Recalling my postgraduate process engineering at UCL, cleaning is a function of temperature, time, chemical strength and shear.  This last is the physical work done by a brush, or a water jet, to dislodge the soil from the surface being cleaned.  Several years ago, I ran the dishwasher with a tablet in a plastic packet that I believed would dissolve to release the chemical.  At the end of the cycle, I was amused to discover the intact tablet, still in its durable wrap.  What really surprised me was that all the dishes were clean!  The lack of detergent had no perceptible impact on the wash - the mechanical cleaning factors (temperature, time and shear) were sufficient without any soap.

Unilever's business model depends upon you not knowing that we can run our dishwashers and washing machines without detergents.  Of course, the reality is more complex than this.  The sophisticated chemistry of a good quality dishwasher tablet keeps your glassware, crockery and cutlery sparkling after every wash. But I learned that we need LESS of these cleaning products than we are told and I have proved this by repetition over several years.

I now chop each wrapped dishwasher tablet in half with a large blade, on a chopping board - with care because the tablet is hard and the chemicals caustic - and use half the tablet for a full load, on the ECO setting to reduce the electricity needed to run the cycle.  I normally use a dirty knife which then goes back in the dishwasher, rather than making more washing up!

2 Re-enlightenment
As earlier posts in this blog will show, I have been an early adopter of LED lighting in my home.  This has cut my family's electricity use - just for lighting - from 2200 kWh in 2007 (half incandescent, half fluorescent) to just 760 kWh in 2014 (half fluorescent, half LED).  A big factor has been the switch from halogen to CFL to LED.  I won't dwell on the relative merits of fluorescent vs LED halogen replacements but the brightness and colour of GU10 LED lamps are now more than adequate to replace 50w downlights, at around £4 a pop.

These cheap and cheerful lamps run on mains voltage but the LED chips require a constant current at 12 - 18v DC.  For instance, a 12 watt LED lamp needs 1 Amp at 12 volts (W = A x V).  This direct current is delivered by a cheap inverter, housed in the white plastic base.  This is the Achilles heel of the current generation of cheap, bright GU10 lamps.  The state-of-the-art diodes have an expected lifetime of a quarter of a century.  They are mounted in exotically beautiful, machined alloy heatsinks.  Their emitter surfaces are encased in plastic lenses that focus and disperse the white light into the required pattern.  Yet their power supply is cheap and failure-prone.  I have had three fail within a year of purchase - one within a day.  I get replacements under warranty from my supplier but am unwilling to throw away this pinnacle of twenty-first century technology for the sake of a burned-out power supply.

So I turned to Amazon and bought a separate 12W constant current LED driver for a fiver.  This powers the LED lamp beautifully, so now I can fit it in a ceiling lamp, where the exposed low-voltage wiring will not be a problem.

This design flaw in such cheap GU10 LED bulbs is actually an argument in favour of low voltage MR16 LEDs.  These replace 12 volt halogen lamps directly but you MUST exchange the halogen power supply (black box) with a suitable LED driver (white box) in order to achieve the long lifetime anticipated for these new photon factories.

3 Shut down MVHR in summer

When I worked in Pennsylvania in 1990, one of my colleagues in R&D used to lampoon the company's aggressive asset management strategy by saying, "You don't rip your central heating out in summer".  This is, of course, true - but you DO shut it down in summer.  A Twitter exchange with Sofie Pelsmakers at UCL alerted me to the fact that the same can be true for whole-house mechanical ventilation.

I had this fitted in 2007 because we need fresh air in the bedrooms at night but live right under the Heathrow fliightpath and so are woken at 4 or 5 am when the long-haul flights from the far East come in to land.  It uses electricity to pump fresh air into the bedrooms and living room, while extracting stale air from the bathrooms and kitchen.  The energy used to move air is offset by the heat exchanger, 90% efficient, which retains warmth in the house.

Heat-recovery ventilation (HRV) or, more specifically, mechanical ventilation with heat recovery (MVHR) depends on the building being airtight - all pipework penetrations must be sealed with expanding foam, airbricks must be filled in, and so on.  In hot weather, it is preferable to throw open the windows and let any breeze blow through the house.  In this situation, MVHR is a complete waste of energy, like running a fridge with no door!  At the start of this season's hot weather in June, I switched off the MVHR.  Since then our electricity consumption has fallen to its lowest level in the 10 years since I began to record it - just 60 kWh a week in July.  We are a family of four adults in quite a large, detached house but this frugal electricity use would be more typical of a 2 - 3 bedroom flat or terrace.

The message is clear - to save money, cut carbon and reduce energy use, shut down mechanical ventilators when the central heating is off and the windows are open!

Wrapping it all up
In conclusion, much of sustainability is about avoiding waste.  These three little tales of saving - soap, energy or things -  show the lengths to which we can go to avoid waste in our own homes.  I am fortunate to have time to examine things in such detail.  If you have read this far then you too have time to repair and reuse things that fail, to cut down on consumables and to find small ways to save energy at home, at work or in your community.  There is great pleasure in making the most of the things that we find, to quote the Wombles.

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