A leading building society has announced the launch of a new Home Energy Efficiency mortgage product to assist its existing customers in going green. The product will help homeowners who want implement environmentally-friendly measures in their homes, with a 5.65 per cent rate on a Home Energy Efficiency Additional Loan for five years. This represents a discount of 1.5 per cent on the society's standard variable rate of 7.15 per cent, and applied to a minimum loan of £1,000 and a maximum of £15,000.