The Bord Gáis Energy index saw a 2% decrease in October as oil prices fell slightly on the back of falls in US equity markets due to growth concerns.
Despite the fall last month, the energy index is still 8% higher than the same time last year and stood at 148 in October.
The oil element of the index fell by 4% last month as several factors put downward pressure on oil prices.
These included concerns for the prospects for global economic growth, announcements from OPEC that oil supplies were ''comfortable'' and caution from the IEA that only a serious supply disruption would merit any release of strategic oil stocks.
October saw the natural gas element of the index rise by 6%. Bord Gáis said that gas supply concerns supported prices during the first month of the ''gas winter' of 2012/2013. These concerns were driven by mechanical failures which disrupted Norwegian supplies and the arrival of only three LNG cargoes to the UK in October compared to 11 the same time last year. Colder weather and rising demand also boosted prices.
The coal element of the index saw the third monthly fall in a row in October, and dropped by 5% last month. Bord Gáis said the coal market in Europe remains subdued due to ample supplies from Colombia, which is one of the world's top five thermal coal exporters. It also noted that coal demand continues to weaken due to a slowdown in the Chinese economy.
The electricity element of the index was up 1% in October due to higher prices for gas - gas imported from the UK is a key component in the production of electricity in Ireland. As a result of the colder weather, peak demand is starting to slowly increased, which in turn puts more pressure on wholesale prices, Bord Gáis noted.
John Heffernan, a power trader at Bord Gáis, said that as we enter the winter months, weather will influence wholesale gas prices.
''The US-based Weather Services International has forecast that temperatures in the UK will be below average in November. Colder weather coupled with supply issues has the potential to increase wholesale prices as Britain is becoming increasingly dependent on imported gas from Norway and the Middle East to meet its winter gas demand,'' he added.