Carmarthenshire businesses and public sector organisations have been asked by the council to switch off lights overnight.
More than 1,100 lights have been turned off by the authority to cut its carbon footprint and energy costs.
The council now wants others to look at cutting back on outside lighting overnight.
Road agencies are being asked if they have any energy-saving lighting initiatives planned.
Carmarthenshire is one of several counties across Wales switching off lights during the early hours.
Altogether 6,000 lights there are being targeted to cut its carbon emissions by about 1.4% a year and to cut energy cuts by about 13% a year.
One in three street lights are being switched off in Carmarthenshire's residential areas and up to two in three on highway routes.
So far Burry Port, Kidwelly and Pontyberem have seen the lights extinguished between the hours of 0030 BST and 0530 BST, and the measure will be introduced throughout Llanelli this month.
A meeting of the council's environment scrutiny committee heard that there have been a few queries, but no major complaints from the public.
Richard Workman, director of technical services, said: "This kind of scheme could be considered by private businesses and other public sector bodies where it is feasible that lighting levels in car parks and other external areas of premises could be reduced for specific periods during the hours of darkness, as the initiative is relatively easy to implement.
"There are also alternatives available other than part-night, such as dimmable lighting, or LED lighting that can be considered depending on the nature of existing installations
Mr Workman added: "The council would therefore encourage other public sector bodies and private sector businesses to think about introducing similar initiatives and consider new energy efficient technologies for any new installations that are planned."
The scrutiny committee has asked for representatives from trunk road agencies for mid and south Wales to attend a future meeting to discuss if they have any energy-saving lighting initiatives planned.