Sometimes you need to spend money to save money, like investing in energy-efficient changes that would lower heating costs. But if you're spending too much on energy bills you may never save enough to pay for cost-cutting improvements.

To combat this problem, Constellation Energy Group is donating $1 million over three years to replace old furnaces for low- or limited-income Baltimore residents, some of whom might not qualify for other state or federal aid.

City weatherization auditors who will be assessing the need for energy-efficient options such as water heater blankets, attic insulation and caulking and other weatherproofing for windows will determine who needs for a replacement paid for by the Baltimore Gas and Electric Co. Heating System Fund, city officials said.

Right now, only homeowners who earn no more than 200 percent of the federal poverty level would qualify for the furnace replacement program. However, a spokeswoman for Baltimore's Department of Housing and Community Development said they are waiting for U.S. Department of Energy approval to expand the program to include people who make up to 60 percent of the median income for the Baltimore metro area. Right now HUD says the median is $82,100 for a family of four, so 60 percent would be $49,260.

For more information about the program, including what kind of information applicants will need to provide, check out the Weatherization Assistance Program page at baltimorehousing.org.

Don't forget that energy assistance is also available to help Marylanders who meet income eligibility standards pay their utility bills. Here's the breakdown for this year, according to the Maryland Office of Home Energy Programs: