Although summer traditionally begins on June 21, most Americans begin to feel the heat long before then. But ever-increasing energy costs and concerns over environmental pollution have left some reluctant to crank up the A/C, leaving their homes stifling and uncomfortable. As home builders forge ahead into the construction season, it’s a good time to think about what energy-efficient air conditioning and green cooling options are available for the homes they are building. There are four good alternatives to central air conditioners.

Perhaps the most conventional is the whole-house fan, or the “attic fan” as my dad calls his. Whole-house fans use 90% less energy than an a/c unit, and can be run instead of the a/c during the evening, when the outside air is cooler.

Another alternative is the ductless mini-split system, which pairs an external, wall-mounted condenser connected to a series of wall- or ceiling-mounted indoor evaporators via refrigerant lines. Each room can be cooled separately, and the system eliminates wiring, noise, and cumbersome energy-inefficient attic duct work while offering at least 30% in energy savings.

Perfect for warmer climates with low humidity, central evaporative coolers (also called “swamp coolers”) are a good option. Costing about 50% less than conventional air conditioners and consuming about 75% less energy, the evaporative cooler exploits the science fact that evaporating water cools the surrounding air.

Geothermal “heat pump” systems can also be used for wintertime home heating and heating your water year-round. They use about 30%-60% less energy than a typical air conditioner. Geothermal systems rely on the circulation of fluid to transfer heat from your home into the ground beneath, and US homeowners can get a 30% tax credit on geothermal systems thorough 2016.

If budget constraints make these options unpractical for your clients’ home, there are still ways to make conventional climate control more energy efficient and environmentally friendly. One strategy is to install tinted windows to reduce the amount of light and heat that get into the house. Adding extra insulation to the attic will reduce the amount of heat that gets in and keep temperatures inside the house lower. When paired with classic a/c, the humble ceiling fan boosts the circulation of cool air, meaning that the air conditioner can run for shorter periods of time and at higher thermostat settings, saving at least $30 per month on the electric bill.