With increasing national concern about environmental issues, landlords have a huge opportunity to appeal to renters who care about energy efficiency by cutting down on energy waste and reducing utility costs.

At the same time, landlords can save money by making their properties more energy efficient and feel good about helping the environment.

While there are numerous low investment, low-tech ways to make a difference, you can also get a lot of bang for your buck with technology.

Here are five upgrades to help you go green.

1. Efficient heating and cooling

Heating and cooling play a significant role in the comfort and cost of a rental unit, especially in locations that experience temperature extremes. A more efficient system has the potential to improve your tenants’ quality of living and lower both energy consumption and costs.

Domenick Tiziano, a landlord in Springfield, New Jersey, outfitted the basement of his rental with a zoned, ductless heat and air conditioning system rather than a window AC unit and space heater—an upgrade that added more year-round liveable space and allowed him to charge more in rent while keeping utility costs low. Wall-mounted ductless systems deliver air directly to a specific space, which helps tenants heat and cool only the areas that are occupied and therefore use less power to achieve a comfortable temperature.

“This unit is ultra-efficient and very quiet,” Tiziano says. “My new tenants really appreciate that the unit saves them money and makes the space usable all year.”

Ductless systems do require cleaning and upkeep, but with ENERGY STAR rated equipment—which can cut cooling costs by 30% compared to conventional units—and local utility incentives, the investment can actually save you and your tenants on your monthly bills.

Smart learning thermostats are another step toward efficient temperature control. These devices connect to central HVAC systems, can be controlled remotely via a smartphone app, and best of all, pick up on occupants’ habits to create optimized heating and cooling routines. Tiziano says he plans to install a Nest device as a way to attract quality tenants, which he believes will be “well worth the extra few hundred dollars investment.”

2. Low-energy lights

In 2016, lighting accounted for 10% of all residential electricity use. Newer, more efficient lightbulbs use up to 80% less energy and last longer than standard hardware store alternatives. The Department of Energy estimates that replacing your five most-used lights with better bulbs could save at least $75 each year.

Upgrade from regular bulbs to halogen incandescents, compact fluorescent lamps (CFLs), or light emitting diodes (LEDs). Another high-tech option: smart bulbs. These lights, which come in white and color options, can be set to routines—to turn on at a specific time in the evening or to fade out slowly at bedtime, for example—and controlled via smartphone app and voice-activated smart home hubs.

If tenants forget to turn their smart lights off when they leave, they can do so from afar. This helps reduce already minimal energy consumption. An added security bonus: lights can also be scheduled to mimic comings and going, even when tenants are out of town, to discourage would-be burglars.

3. Smart electricity

You can’t manage whether your tenants turn off their lights when they’re not in use or unplug fully-charged electronics, but you can install smart devices that help minimize unnecessary waste. Vampire energy occurs when devices such as TVs and phone chargers go into standby mode but continue to draw small amounts of power. This may account for 10% or more of monthly electricity bills.

Smart power strips can help address this problem. These devices shut off current to plugged-in electronics in response to a switch to low power mode, a set timer, or a lack of movement nearby. Install smart outlets, which allow occupants to cut power to devices remotely using their smartphones. Educate your tenants on how to use power strips and outlets to reduce waste and costs.

4. ENERGY STAR appliances

If the washer, dryer, dishwasher, and refrigerator in your rental haven’t been replaced in more than a decade, chances are these items are wasting energy and costing you money. You may also be missing out on prospective tenants who value more modern features. Consider replacing outdated appliances with ENERGY STAR-certified models.

For example, a newer refrigerator is 9% more energy efficientthan minimum federal standards and can save you $270 over five years. Certified washers use 25% less energy and 45% less water than regular models—those over 10 years old cost an average of $210 more per year.

5. Solar power

Switching to solar can turn into a costly project, but it doesn’t have to. Solar panels harness sunshine, which is free, to power specific appliances and even entire homes. As one of the cleanest, most sustainable and renewable energy resources available, solar has the potential to decrease electricity costs as well as toxic emissions and pollution.

Even with a 30% federal tax credit, the initial investment for a full solar array is high—from $10,000 to more than $30,000 depending on the size and state of your property. Additional discounts and subsidies may be available depending on the solar company, however, and residents in some cities are seeing positive returns in just six years.

If a full array is out of reach, or if you’re not planning to hang onto your property long-term, consider taking a smaller step with a solar water heater. These devices cost significantly less upfront and are also eligible for the 30% tax credit, which means they may be profitable immediately. Caleb Backe says that a solar water heater at his rental property in Coral Springs, Florida has lowered electricity bills, especially in hotter months when sunshine is plentiful.

Of course, you don’t have to implement every one of these upgrades to make a difference. Small steps can have a big impact on reducing energy waste and lowering utility costs for you and your tenants.