also refrigerates food on its way from field to shopping basket. I’ll estimate
the power cost of the food-chain later, in Chapter 15.

Total heating and cooling

Our rough estimate of the total energy that one person might spend on
heating and cooling, including home, workplace, and cooking, is 37 kWh/d
per person
(12 for hot water, 24 for hot air, and 1 for cooling).

Evidence that this estimate is in the right ballpark, or perhaps a little
on the low side, comes from my own domestic gas consumption, which
for 12 years averaged 40 kWh per day (figure 7.10). At the time I thought I
was a fairly frugal user of heating, but I wasn’t being attentive to my actual
power consumption. Chapter 21 will reveal how much power I saved once
I started paying attention.

Since heating is a big item in our consumption stack, let’s check my
estimates against some national statistics. Nationally, the average domestic
consumption for space heating, water, and cooking in the year 2000 was
21 kWh per day per person, and consumption in the service sector for heat-
ing, cooling, catering, and hot water was 8.5 kWh/d/p. For an estimate
of workplace heating, let’s take the gas consumption of the University of
Cambridge in 2006–7: 16 kWh/d per employee.

Totting up these three numbers, a second guess for the national spend
on heating is 21 + 8.5 + 16 45 kWh/d per person, if Cambridge University
is a normal workplace. Good, that’s reassuringly close to our first
guess of 37 kWh/d.

Notes and further reading

page no.

50An oven uses 3 kW. Obviously there’s a range of powers. Many ovens have
a maximum power of 1.8 kW or 2.2 kW. Top-of-the-line ovens use as much
as 6 kW. For example, the Whirlpool AGB 487/WP 4 Hotplate Electric Oven
Range has a 5.9 kW oven, and four 2.3 kW hotplates.
www.kcmltd.com/electric oven ranges.shtml
www.1stforkitchens.co.uk/kitchenovens.html

Figure 7.10. My domestic cumulative gas consumption, in kWh, each year from 1993 to 2005. The number at the top of each year’s line is the average rate of energy consumption, in kWh per day. To find out what happened in 2007, keep reading!
Figure 7.11. Heating and cooling – about 37 units per day per person. I’ve removed the shading from this box to indicate that it represents power that could be delivered by low-grade thermal energy.