Housing conditions and energy efficiency Households according to whether they have made improvements to thermal insulation or the heating system, by size of the household. Unidades: Horizontal percentages. ;Has made improvements to thermal insulation or the heating system;No improvements have been made and it is warm enough during the cold months;No improvements have been made and it is not warm enough during the cold months; Total;14,1;60,8;25,1; 1 member;12,5;59,2;28,3; 2 members;14,5;61,3;24,1; 3 members;14,9;61,3;23,8; 4 members;15,2;62,7;22,1; 5 members or more;14,5;58;27,5; Notas: Fuente: Instituto Nacional de Estadística