If you’re in the market for a greener home, here are some factors to consider:

●Ask the seller of an existing home for a year’s worth of utility bills. By dividing annual electricity and gas costs by square footage, you can come up with cost-per-square-feet figures for easy house-to-house comparison.

●Check if the home has storm windows or double-paned ones, which do even better at keeping the outdoor climate outdoors.

●Look for insulation in the attic. If there isn’t much insulation up there, it’s likely the rest of the house is poorly insulated as well.

●Inquire about the home’s ventilation system. It should go beyond a few bathroom fans. Good ventilation is key to air quality, especially in tightly insulated homes.

●Understand the green building certification systems. Energy Star focuses solely on energy efficiency. The Leadership in Energy and Environmental Design program (LEED) takes into account other factors so that the more green features a home includes — such as solar panels or low-flush toilets — the more points it earns. Other systems include a German standard called Passive House, the National Green Building Standard and Green Globes.

— Christine MacDonald