The audit should have some information about what is going to be the most beneficial cost wise. Additional insulation is often a pretty safe win (especially if

The audit should have some information about what is going to be the most beneficial cost wise. Additional insulation is often a pretty safe win (especially if it doesn't change the moisture barrier). Of course there can be other goals. I don't expect that upgrading my 80% AFUE furnace would save me any money. High efficiency furnaces cost more, break faster and it would require more work to install one vs just replacing with an 83% unit. But it would change how air moves in the house, instead of drawing combustion air from the conditioned space, a high efficiency furnace would pull it from outside, so it would be easier to humidify the house to a more comfortable level (a medium size wick humidifier doesn't keep the house above 20% on colder days).