Astute Edinburgh residents may notice something different to the Edinburgh skyline this week.

Many are used to the familiar yellow glow of the floodlit Edinburgh Castle [4] towering above the city, but from tonight this magnificent attraction will look just that bit different as Historic Scotland makes a change to the 90 plus lamps which illuminate the fortress. As well as being more aesthetically pleasing, effectively lighting the castle in a more natural white light, it is anticipated the change will cut energy consumption levels in half.

David Storrar, Regional Architect for Edinburgh at Historic Scotland said: "Our in-house mechanical and electrical team are taking just one day to manually change the 93 lamps which floodlight the Castle. This sounds like a challenge in itself but if you take into account the positioning of some of the bulbs, then it really is a mission, but not an impossible one. Rope squad trained staff will have to abseil down the rock to get to some of those hard to reach places but it will be worth it once they are all replaced.

The new lights will have the same brightness but use less power. They will bring a lot more definition to the castle, highlighting the stonework and architectural detail. We are looking forward to seeing the results this evening."

Edinburgh Castle was first lit up using ex-army search lights just after the Second World War. The present system has been in place since the 1970s, with the original idea being to make the Castle look as if it was floating on air. There are seventy floodlights around the Castle and twenty three fluorescent reflector lamps, which give the contrasting colour on the roof of the Scottish National War Memorial, Gatehouse and Argyle Tower. The floodlights are switched on every evening at dusk and are turned off at 1.00am.

The old sodium flood lights will be replaced by lower wattage ceramic metal halide lamps which will be more energy efficient. The lights were trialled successfully earlier in the year on the Castle frontage for several of weeks. The Historic Scotland team will replace all the lamps manually today.

Barbara Smith, Executive Manager of Edinburgh Castle said: "Edinburgh Castle is such a breathtaking and iconic sight, we have to make sure it is presented perfectly both day and night, so it receives the full attention it deserves. The fantastic thing about these new lights is that they are energy saving too, which is very important. We hope the trial is a success."

• Edinburgh Castle is open 7 days a week from 9.30am - 6.00pm (Apr-Sept). Admission: Adult £11.00, Child £5.50, Concession £9.00.
• A majestic landmark which dominates the capital city's skyline just as it has dominated Scotland's long and colourful history Edinburgh Castle is the best known and most visited of our historic buildings. Perched on an extinct volcano and offering stunning views, this instantly recognisable fortress is a powerful national symbol, and part of Edinburgh's World Heritage site.