This page provides notes and information on human work and energy levels
The notes below are very simple notes identifying very approximate working and energy levels for typical UK humans.
The units used are ISO units of mechanical work. A kiloJoule is 1000 Joules and a joule defined as the energy expended (or work done)
in applying a force of one newton through a distance of one metre (1 newton metre or Nm). The dietary/nutritional energy values are
normally identified using kilogram calorie (kcal ) . ( 1 bar of dark Kit Kat has a nutritional value of 243kcal = 1013 kJ ).
The conversion factor is
1 kcal = 4,187 kJ.
the current UK normal calorie intake for a man to maintain his weight is about 2 500kcal per day = 12 217 kJ per day
BS EN ISO 8996:2004 :
Ergonomics of the thermal environment. Determination of metabolic rate
Human work and energy levels.
The normal uses energy at a standard rate when lying down with an empty stomach. The rate
is called the basal metabolism and for a 70 kg man this is about 7000kJ per 24 hours.
A person also consumes energy (leisure joules) for everyday activities not associated with
work rate required to do normal tasks. The average leisure joules for a man is about 2400kJ per day.
( A man not engaged any physical activity other than light leisure activities would use about 9400kJ )
Energy is consumed for occupational activities which differ relative to the type of occupation. The following table lists
the daily energy levels related to humans involved in different employments.
Type of Work
Normal Manual Work
Moderate bodily work
Heavy manual work
Specific activities consume energy at different rates as shown below;
Energy consumption kJ/min
Level Walking (5 km/hr)
Cycling (20 km/hr)
Jogging (10 km/hr)
The human energy efficiency in completing task is illustrated below:
Shovelling Soil (stoop)
Shovelling Soil (upright)
Turning a Handwheel
Carrying a load on back (level)- Returning without load