The US government has a Weatherization Assistance Program. The program provides weatherization improvements free of charge for people of low income.
The average improvement is $2800 and they say: "On average, weatherization reduces heating bills by 32% and overall energy bills by $358 per year at current prices"
So this could be a lot of savings for a low income family and its free to those who qualify.
The system is funded by the federal government but handled locally at each state level.
They discuss application at this page. If you are on Supplemental Security Income or Aid to Families with Dependent Children then you're automatically eligible. Otherwise states give precedent to people who are over 60 years of age, families with one or more members with a disability and families with children (in most states). Low income is a main factor in application. Depending on what state you are in you can be eligible if your income is below 125% or 150% of the poverty level or 60% of median income.
If you or someone you know would qualify for this plan then it can't hurt to apply and it might result in saving hundreds of dollars a year in energy costs.