President Trump, center, displays a signed executive order during an event at the International Union of Operating Engineers Training and Education Center in Crosby, Texas, April 10, 2019. Loren Elliott | Bloomberg | Getty Images

President Donald Trump has called for a sweeping look at regulation of the energy industry — and that includes investments in retirement plans. In an executive order issued last week, Trump called for the Department of Labor to complete a review of energy investment trends and the fiduciary responsibilities tied to proxy voting to determine whether "guidance should be rescinded, replaced or modified." That will likely mean greater scrutiny for environmental, social and governance, or ESG, funds that have become available in retirement plans for some workers.

The Department of Labor has 180 days to complete its analysis, per Trump's executive order. DOL officials did not respond to CNBC's request for comment. "The fiduciary duty is the hallmark of ERISA," or the Employment Retirement Income Security Act of 1974, a senior administration official said last week ahead of the executive order. "We believe it's an essential protection for beneficiaries so that they do have adequate retirement savings, and that the focus of an ERISA plan is on retirement savings, and not other social and political goals," the official said.

Guidance released by the Department of Labor last year called for all funds, regardless of their strategy, to be evaluated equally by performance when deciding whether or not to include them in retirement plans. That marked a change from President Barack Obama's administration, which mostly encouraged the inclusion of ESG funds in retirement plans. "What I suspect the Department of Labor will find is that ESG considerations absolutely do affect bottom lines, and considering ESG factors is important," said Danielle Fugere, president of As You Sow, a non-profit foundation focused on environmental and social corporate responsibility. Research from Morningstar found that sustainable funds largely outperformed their benchmarks in 2018, with 63% of those funds making it to the top half of their categories. The appetite for these kinds of funds in 401(k)s and other retirement plans is strong, according to a recent survey from Natixis Investment Managers. It found that 61% of workers would increase their retirement savings if socially conscious investments were available to them. Yet only 13% of workers surveyed had access to such investments in their plans.