Cinderella is no longer just a fairy tale about rags to riches, but has become a sustainability story too — as the clock nears midnight on carbon emissions around the globe.

In an effort to shine light on the greenhouse gas emissions problem, Disney decided to dim theirs — specifically those that illuminate Cinderella’s Castle and other park attractions at Disneyland during the overnight hours.

This is just one of the many tactics that the theme park’s engineers instituted in 2009 to reduce its carbon footprint. If not, they’d be taxed — not by the government, but by their own bosses. Disney was among the first wave of companies (along with Shell and Microsoft) to implement internal carbon pricing on corporate activities. At the time, a self-imposed carbon emissions tax was considered a novel idea, but over the last few years, many other global corporations have followed suit.

According to a survey conducted by the Carbon Disclosure Project (CDP), 435 companies worldwide reported using an internal price on carbon in 2015 with another 583 indicating they plan to do so in the next two years. Companies use this internal price to incentivize business units and divisions to meet corporate sustainability goals, to help fund investments in clean energy and to prepare for future carbon taxes and regulation.

These corporations are being proactive, assessing carbon taxes as if laws were already in place while most governments have yet to put a price on emissions. As one executive from Shell told The Guardian in a 2013 interview, these corporate sustainability leaders are “internally mimicking the system we’d like to see.”

To reduce their carbon emissions, and therefore avoid the internal tax, participating companies have made many changes around their facilities. These include adjusting thermostat settings, increasing the efficiency of chillers, heat exchangers and pumps and installing LED lighting. But, there’s another step that many are overlooking that could significantly help the cause.

Analyzing the energy efficiency of the electrical infrastructure, particularly the uninterruptible power supply (UPS) systems, and replacing the units if necessary, is a big step towards achieving long-term goals of net zero. UPS systems vary widely in their carbon intensity during manufacturing and their energy efficiency during operation.  And since most of the power in a mission critical facility flows through a UPS, a more efficient UPS will reduce monthly utility bills and potential carbon emissions taxes — making your company the belle of the ball when it comes to sustainability.