Conduct a quick straw poll of pension investors, such as the one conducted at the National Association of Pension Funds (NAPF) annual conference, on whether they are sold on the idea of sustainable investing offering returns above that of the regular portfolio, and you will often be met with a wave of scepticism.

The scepticism comes despite outspoken support for sustainable, or impact, or targeted environmental, social and governance (ESG) investing, to name but three nom de plumes bestowed to an approach that, essentially, asks if the investment is as beneficial to the here and now as it is to the future.

Mainstream support for a sustainable approach to investing has been growing steadily ever since the UN published its Principles for Responsible Investment in 2005, and it has attracted support from a number of large pension investors over the years.

PGGM’s corporate strategy and innovations manager Wouter Koelewijn recently said any such investment should be viewed as part of the “same game” as any other commitment, and was backed by a counterpart at the Norwegian local government pension fund KLP.

“The only difference for a targeted ESG investment is that I want to know what is your impact strategy and how are you going to reach those goals,” Koelewijn said. “What problems are you solving?”

His view is seemingly shared by royalty. In a pre-recorded speech at the NAPF in Manchester, Prince Charles once again waded into the debate.

The Prince of Wales insisted that, in light of growing pension liabilities, the focus on “quarterly capitalism” – a problem highlighted by John Kay in his recent review of long-term investing – was becoming “increasingly unfit for purpose”.

“Now, I know old habits die hard and that it is difficult to make the first move,” the heir to the British throne told delegates, “but is there not a case for ensuring your portfolios are resilient in the long term? Could you do so by incorporating sustainability into your mainstream strategy, rather than having it sit in a subordinate silo?”

In the ongoing debate on ESG investing and its place in the investment universe of pension funds, it is questionable if this seemingly artificial divide should remain. Others point that the divide in place could also be a danger to sustainable investment taking hold.

Addressing the PRI in Person conference in South Africa earlier in the month, Erika Karp of Cornerstone Capital insisted that the surrounding debate should no longer be about ideals, but rather pragmatism.

“The language of sustainability – whether it is SRI, sustainable investment, the double or triple bottom line, impact investing, values-based investing – they all are good, […] and the opposite is implied to be bad,” she said.

“This is where it gets divisive,” she added, countering that the debate was not one of values, but creating value.

All this would point to the idea of a separate but equal portfolio for long-term, sustainable investment being a concept no longer fit for purpose. Investors must abolish the silo, and begin viewing sustainable investing as part and parcel of everyday activities.