Sheep have long been drawn to the warmth stored up by roads

The Road Energy System (RES) uses heat absorbed by tarmac to warm water piped through the mid-layer of a road. It is hoped it could be used to heat houses.

Wester Ross firm Invisible Heating Systems had hoped to install it under a section of its car park on Wednesday - Midsummer's Day.

However, torrential rain has delayed the construction work.

Henk Verweijmeren, of IHS, said he was hoping for a dry spell later this week so that the pipes and a layer of grit could be stuck down.

We have done substantial trials of the system in Holland and it is being used in fly-overs and airports Henk Verweijmeren of IHS

He said: "It is more like autumn. We've got horizontal rain."

Once installed, the RES will be a permanent feature of the firm's car park in Ullapool.

Mr Verweijmeren said: "We have done substantial trials of the system in Holland and it is being used in fly-overs and airports."

He said there has been interest from Ireland in the system and hopes it will become a feature in roads across Scotland the rest of the UK.

The method of warming up water by piping it under roads, which naturally store up heat from the sun, was pioneered in Holland.

IHS saw the potential for using the system in Scotland after noting that sheep, which roam freely in many parts of the Highlands, often warm themselves by lying on a road.

Level of maintenance

Environmental benefits include cutting CO2 emissions and lowering the amount of salt needed to keep roads ice-free in winter.

In summer, cold water can be pumped through the pipes to cool it and reduce the level of maintenance the road requires.

Mr Verweijmeren and Liz Stewart launched IHS in 1995 and started out by buying under-floor heating systems from Holland and then adapting them for use in UK homes.

They were awarded a �125,000 grant from Highlands and Islands Enterprise Skye and Wester Ross to help with the construction of the Road Energy System.

IHS has helped to develop similar road systems in Holland.

Ms Stewart said: "We are delighted to be installing the first ever heating system of its kind here in Wester Ross."