Image via WikipediaMr Ditchfield said sustainable investment differed from ethical investment as it seeks to actively address environmental problems.
He said: "We all agree we are depleting the world's resources and sustainable investing aims to support companies trying to prevent and even reverse this.
"With social impact investing, investors not only want good financial returns but for their investments to have a positive social impact, for example microfinancing."
Mr Ditchfield said green investing was not an alternative to giving to charity.
He said: "Not at all, many individuals are keen to tie their money and their views together in how they invest but they are still looking for good returns.
"This will undoubtedly become a growth area.
"Currently, the majority of the population do not invest in environmental funds as they think the market is too small to put in serious amounts of money, such as company pension funds.
"Our challenge is to change that perception."
Clare Brook, the fund manager of Wheb Asset Management, said her fund provided investments with a good return while making a social impact.
She said: "Wheb quite specifically only has funds in companies whose major business derives from activities working with climate change, water shortage, ageing population solutions.
"Our companies are at the sharp edge of environmental protection such as smart grid or providing water to people who currently have no access to clean water."
A push for sustainable investment rather than ethical investment was revealed at National Ethical Investment Week (NEIW).
