How well will you want your utility bills reduced?
Not well enough to buy any magic devices to add anywhere in my house. Only well enough to replace what has worn out with more efficient appliances. Perhaps also by being smart enough to switch off what is not in use, including unneeded lights fans, heaters or heat outlets. Cut down on unneeded ventilation through cracks. I also have added insulation and made sure that there are no uninsulated spots in my walls. I found them with a borrowed heat-camera.