Since 1970, Earth Day has been celebrated worldwide to demonstrate support for environmental protection. Across the globe, the Earth Day Network coordinates celebrations on April 22 in 193 countries.This Earth Day, it might seem like there are more challenges than ever facing the planet. Between the disappearance of the Great Barrier Reef, alarming signs of climate change, and declining biodiversity, it is hard to feel encouraged.However, commercial real estate professionals are in a unique position to have a direct impact on the environment.Buildings use about 40 percent of the energy produced in the U.S., and they contribute a roughly equivalent portion of the country's carbon footprint. A significant portion of that footprint can be cut down with energy efficiency measures, and what better day to start than Earth Day? (It doesn't hurt that these investments are often beneficial to a building's long-term bottom line, either.)Here are 5 energy-savingprojects that you can start this Earth Day.1. Implement Nighttime HVAC Setbacks

With a modern building automation system, nothing could be easier than enacting nighttime setbacks. Under this energy-saving strategy, heating or cooling is reduced overnight, allowing the building to drift out of the normal comfort range for occupants.An hour or two before people start coming into work in the morning, heating or cooling is turned back on to bring the space back into the comfort zone. The energy saved overnight cuts carbon emissions and saves on energy bills.Setbacks aren't right for every building. Buildings that run overnight, on irregular schedules, or that can't be quickly heated or cooled are generally not good options for this strategy. An energy management system can help you to measure and verify results from experiments with HVAC setbacks.2. Plant a Green Roof

Green roofing is one of the single best energy-saving projects that a commercial building can undertake from both an environmental and economic perspective. Not only does it significantly reduce energy bills, it doubles the lifetime of the roof, provides a home for city wildlife, helps with rainwater management, and combats urban heat island effect.Green roofs come with a high up-front cost, but they are virtually always worth the money over the lifetime of the investment. Many cities also offer generous incentives because of the way that green roofs soak up rainwater and reduce the strain on drainage systems during storms. Interestingly, while the reduced heating and cooling costs are a clear appeal, the lengthened lifetime of the roof itself is generally the best fiscal argument for this project.3. Install Water-Efficient ToiletsThey aren't all that popular in America yet, but much of the world has migrated to dual flush toilets. These toilets have a modified flush valve that can send a low water flush and a full flush depending on what's needed.A standard toilet uses about 1.6 gallons of water per flush. In dual flush toilets, this is the amount used for the solid waste option. For the liquid waste option, a dual flush toilet only uses about 0.9 gallons of water, potentially yielding significant savings.According to the Sierra Club, switching to a dual flush toilet saves about 1,750 gallons of water per user per year. That makes the investment in dual flush mechanisms - generally one of the more affordable retrofits on the market - one of the most cost effective.4. Pursue LEED or Energy Star Certification

Building efficiency certificationsdemonstrate a building's commitment to conserving energy and water and generally encourage teams to work hard to make their building an efficient space. The two most common, LEED and Energy Star, also give clear signals to environmentally conscious tenants that property managers' priorities are in line with their own.The road to LEED and Energy Star certification isn't a short one, but it is rewarding. Studies have shown that employees are more productive and healthy in LEED certified spaces, and consumers are increasingly taking stock of which businesses are putting in the time and effort to conserve energy.5. Involve Tenants in Conservation Efforts

Finally, one of the best things to do on Earth Day is to reach out to your tenants and involve them in efforts to cut water and energy consumption. Not only will you conserve valuable resources and save money, but you will also most likely improve tenant engagement. Tenants that feel involved in their building, especially when its values correlate with their own, are more likely to renew their leases.Gently remind tenants to do simple things, like turn off lights in rooms that aren't being used, turn off computers when they go home for the day, and avoid leaving devices constantly drain energy plugged in, like phone chargers. In some cases, Earth Day events might help to bring a building together as a community.Earth Day celebrates our connection to the planet and its precious resources. Do your part by making use of your unique position tohelp it out!