The people likely to be fuel-poor are those who have very low incomes and those who live in older dwellings, particularly houses built before 1919, or in housing that is in disrepair and has not been modernized. You get two overlapping groups: the poor in terms of income, and those who are in housing that is substandard and inadequate. That is quite a large group of households.
There are also effects.... Obviously it's warmer in the middle of a city than in the rural areas. What you tend to get is a group of people in rural small towns and villages in poor housing on the periphery of those towns, but also people living in the inner cities who are very income poor. That's particularly the case among the elderly, those over 75; large families, those with many children; and also people who are unemployed.
There are very high rates of poverty among the unemployed, and it's particularly a problem for single young women who are unemployed. This group is not recognized by governments in many of the policies. Single women in general--lone-woman households--tend to have high rates of fuel poverty. Normally the policy is targeted to elderly single women over 75, but younger single women, particularly those in the 19- to 29-year age range also suffer from very high rates of fuel poverty.