In most family budgets, the biggest monthly "operational" expenses are costs for automobiles (fuel/maintenance), groceries, and utilities.

Auto expenses are the most difficult to rein in (especially with sharply rising gas prices), while grocery costs are the easiest to control (you can always eat rice and beans). Utility expenditures fall in the middle—not as flexible as grocery spending, but certainly not as inflexible as auto-related costs.

Here are several ideas for holding down your monthly utility expenses.

ELECTRICITY

In many sections of the country, it won't be long before air conditioners come out of their winter hibernation. If you have a central heating and air system, now is an excellent time of year to make sure it's operating at peak efficiency — reduced efficiency translates into higher cost. Leaky ductwork, for example, can reduce efficiency up to 20%, according to the Alliance to Save Energy. An inspection by a certified technician may cost $50 to $100, but those could be dollars well spent if the inspection results in lower AC bills throughout the summer.

Depending on where you live you may be able to get an inspection at no cost. Many power companies offer efficiency inspections as part of a free or low cost "energy audit." Such audits not only check for leaky ducts, but also for leaks around windows, doors, electrical outlets, chimneys, etc. Call your power company or check its website to find out if such a service is offered in your area.

The audit may show that some caulking and weather-stripping will significantly reduce air loss. Audit recommendations will likely include adding extra insulation in the attic (a total of 12-15 inches is recommended by the Department of Energy). Cost? Expect to pay 50¢-$2 a square foot, depending on local climate and type of materials. But you can recover up to $500 by means of a 2011 federal tax credit.

Here are two other low-cost things you can do to save on heating/cooling costs. First, change your air filters regularly. Most filters used in heating and AC systems, especially older systems, are designed for only 30 days of use. After a few weeks, collected dust and dirt significantly reduce efficiency. So develop a reminder system (phone app, "task" reminder on your computer, or just an old-fashioned wall calendar with a circle around a date) that prompts you to change your filters.

Second, update your thermostat. If you have a non-programmable thermostat, you're wasting electricity. Used properly, a programmable thermostat (cost: $25-$100) can cut energy consumption at night and when you're away from home. (For recommended settings, see www.energysavers.gov, a site of the U.S. Dept. of Energy.) Don't have central heat and air? Get a temperature-based programmable outlet (about $30) for use with a window AC unit or space heater.

Adding an insulating blanket to your water heater (cost: $25-$35) also can be a big money saver (more so with electric heaters but also with gas). According to the Department of Energy, unless your water heater's storage tank already has an insulation value of "R-24," adding an insulation blanket will likely save you 4%–9% in water heating costs.

More low- and no-cost ways to save on electricity are shown in the table below.

Of course, there are other strategies that will yield significant savings but are more costly on the front end, such as replacing older appliances with newer energy-efficient models.