UK commercial business owners are urged by home and business energy comparison website Love Energy Savings to take greater control.
The site's managing director Phil Foster was reported to have said several renters might be paying significantly more for gas and electricity as it is not clear in the terms of their tenancy who provides energy requirements.
A report from the British Chambers of Commerce (BCC) and British Gas has revealed that 27% of business owners who rent a commercial area believe they have no influence over power-efficiency enhancements in their buildings.
Phil Foster said: "With commercial property rents rising again, it's crucial that businesses find ways to trim their outgoings.
"Communication is key. Talk to your landlord, building manager and energy supplier at the earliest opportunity and make sure you're not getting a raw deal.
"Ask them if you can make energy-efficiency changes, and if they say no, find out why."
He advises business owners to familiarise themselves thoroughly with the terms and conditions of their tenancy.
Foster added: "If the tenant is responsible for the meter they can dictate the supplier. However, in a serviced office environment the landlord agrees the contracts and recharges the cost to the tenants.
"The landlord would be responsible for any unoccupied space and therefore it would be in everybody's interest for them to obtain the best possible rates. As a rule, the agreed lease says who's doing what with energy."