An easy DIY project is to add foam insulation to all the water piping. Insulation on hot water piping reduces heat lost to the environs. Insulation on cold water piping prevents condensation. The water from even a small condensation drip can damage carpet, wood framing, and any other building material.
The foam insulation is pre-formed to fit the outside diameter of the pipe. Some brands have integral glue ~ just peel off the tape where the foam pipe splits open, fit the sleeve around the pipe, then tighten the pipe against the glue for a proper seal. Duct tape around the joints between foam pipe seams.
Any piping inside a crawl space needs to be insulated against freezing. Likewise piping in the attic, if the attic ever gets below freezing (heat rises from the house, which helps – unless the power goes out or you’re away from home on vacation).
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Excerpted from Going Green, available as an eBook at this list of eBook retailers online.