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In an extremely vague broad measurement of Domestic Hot Water consumption, the average house was found to use about 120 litres. About 4% of houses consumed more than 300 litres. The Hot Water Association says that, for high consumption, one should allow up to 70 litres of water per person. Imagine and large and full…

Where I used to work, I could buy Duracell Professional batteries at low prices through a buying agency. These prices were comparable with prices available on Ebay. Why did I buy Duracell? Because I could get, for instance, AA cells, of a good quality, for about 25p. But of late the prices have rather climbed,…

This is an update – simpler than the original – of an adjacent post. Bikes ‘gear up’ our feet’s movement so we can travel more quickly than with feet alone. A numerical representation of the gearing enables us to make comparisons. Gearing up, the Gear gain, happens in two stages.   Radius ratioIn the first penny-farthing…

This has now been superseded by an adjacent post Bikes ‘gear up’ our feet’s movement so we can travel more quickly than with feet alone. This gearing up happens in three stages. Radius gainOur feet press on pedals which turn the cranks which are typically 170 mm radius. But the bike wheels are bigger than…

The cost of storing energy in batteries is getting less as this report shows, quoting a figure of about $135/kWh for the cost of storage in 2020. That’s about £100/kWh. Nissan Leaf replacement batteryIn the US, a 30 kWh replacement battery costs about $4000, about £3000. That’s £100/kWh – about the same as the Bloomberg…

The null hypothesisOnce Covid has spread significantly among a population, normal lockdown actions have no significant effect on the spread of the disease. Definitions of significant and normalBy ‘spread significantly’ I mean the sort of spread that was observable in most countries, the UK in particular, well before there was a general awareness of the…

We are so used to seeing Covid daily death figures in the following format: In fact such figures mean nothing at all unless the figures are a) seen in the context of general death figures and b) corrected for those who would have died at similar times had Covid not been around. The only way…

Electric fuel costs per mileLooking back to this post, small family cars, Renault Megane, Ford Focus, VW Golf, etc, do about 4 miles per kWh. Electricity costs about 18p per kWh if you charge in the day, 10p per kWh for charging at night and quite a lot more if you charge away from home.…