Table 19.

Variable set of each subsystem

Variable types	Economic subsystem	Environment subsystem	Social subsystem	Energy subsystem
State variables	Social fixed assets investment	Solid waste emergy	Population	Grain emergy
				Output resources
				Raw coal emergy
				Input emergy
Rate variables	Growth in social fixed assets investment	Reduction of solid waste emergy	Population growth	Growth in input emergy
			Population reduction	Growth in output resources
				Growth in grain emergy
				Growth in raw coal emergy
Auxiliary variables	Primary industry labor force	Production waste water emergy per unit of GDP	Birth rate	Growth rate of input emergy
	Secondary industry labor force	Production waste gas emergy per unit of GDP	Death rate	Growth rate of output resources
	Tertiary industry labor force	Domestic waste water emergy per head	Survival index	Growth rate of grain emergy
	Proportion of investment in primary industry	Domestic waste gas emergy per head	Environmental pressure index	Growth rate of raw coal emergy
	Proportion of investment in secondary industry	Production waste water emergy	Employment rates	Renewable emergy except grain
	Proportion of investment in tertiary industry	Production waste gas emergy	Employed population	Nonrenewable emergy except raw coal
	Investment in primary industry	Domestic waste water emergy	Emergy per head	Renewable emergy
	Investment in secondary industry	Domestic waste gas emergy		Nonrenewable emergy
	Investment in tertiary industry	Waste water emergy		Output emergy
	Primary industry output	Waste gas emergy		Exchange rate
	Secondary industry output	Reduction rate of solid waste emergy		Total emergy
	Tertiary industry output	Waste emergy		Emergy index for sustainable development
	Proportion of labor force in primary industry	Waste emergy to total emergy ratio		Ecological efficiency index
	Proportion of labor force in secondary industry
	Proportion of labor force in tertiary industry
	GDP
	Growth rate of social fixed asset investment
	Emergy to money ratio