The previous answer does not take into account the fact that this is your conclusion. Therefore, its suggestions are not valid for your particular situation. In the future, you might want to make clear that each of your posts is simply one part of a larger overall essay. A few comments:
In your second sentence, you say “By adding… it…” This is something you have done throughout the essay. The pronoun “it” needs to refer to something that has already been. Nothing has been mentioned so far that “it” can refer to. You could just make your sentence say “Adding insulation (not “insulations”)… can have a large impact…”
You do a good job here of referring back to what you have said in each paragraph (leaks, window coverings, etc).
You might improve that second sentence by not mentioning insulation twice. You could say “Adding insulation in walls and ceilings to prevent air leaks, adding window coverings, and changing window directions can have…”
In the introduction and throughout the essay, you talked about costs. You should therefore end by talking about costs. You might insert a sentence just before the last sentence. It might say “By preventing heat transfer, homeowners can greatly reduce the costs of heating and cooling their homes.”
Finally, you briefly mentioned solar panels in your previous paragraph. You should either delete that reference or add it to the list of things in this conclusion that can help lower costs.