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A trip to Iona in the Inner Hebrides is a lengthy affair. Once reaching Oban on the west coast of Scotland, two ferry rides lie ahead – these a 90 minute drive apart – making the pilgrimage to this historic setting a complex task. The remoteness also created complications for what elsewhere may have been a relatively simple refurbishment project.

Iona Abbey is one of the most sacred sites in Scotland and dominates the horizon on the approach to this tiny island, which measures just three by 1·5 miles. Originally founded in AD563 by St Columba, the structure on the current site dates from 1203, with the majority of the building fabric being from the early 13th and the 15th centuries. Major restoration work has taken place at various times, most recently in the 1950s.

Historic Scotland took over ownership of the Abbey in 1999 from the Iona Community, an ecumenical Christian group that resides here. This move begun the latest maintenance thrust, which is focusing on the m&e services.

  Scheduling of maintenance is crucial as the abbey cannot be closed during the peak summer season. However, this also means work has to be carried out in the most adverse weather conditions of the year. For the latest work it also meant splitting the programme into three phases: lightning protection; updating the services in the accommodation areas and attached buildings; abbey services. Ellis Dudley of m&e consultant TGA Consulting Engineers explains: "The only time you can work is from September to mid-March. Because of the amount of work to be done and the location you couldn't have done all three phases in six months."

TGA has been involved on the scheme since August 2001, having won the contract by competitive tender. TGA's first task was a three month survey, before four months were spent on the design. It deemed lightning protection of the Abbey as phase one, which was carried out over the winter of 2001-02.

Phase two was completed between October 2002 and February 2003. The Edinburgh office of Hills Electrical & Mechanical acted as principal and m&e contractor for this phase after winning the contract by competitive tender.

Cabling in cloisters
The main abbey complex is formed around a central cloister, with the abbey running the length of one side. Facilities such as a shop and chapter house fill the remainder of the ground floor; these are topped by a two-storey accommodation block, with library, kitchen and refectory.

The scheme involved the complete rewiring of the accommodation blocks and rooms surrounding the cloister; installing an emergency lighting system and an addressable fire alarm system; and replacing the 1940s switchgear.

The complex is powered by its own substation, which is fed via an 11 kV supply from Mull. Armoured cable takes the supply into the complex for distribution, which needed careful handling. "One of [Historic Scotland's] main concerns is protection of the fabric of the building," explains Ellis. No holes could be created and attachment to the brickwork was forbidden, so use was made of existing service runs. However, direct replacement was not possible as the Abbey and shop were still open so power could not be lost. Another consideration was safety. "We didn't just go in and take the whole area apart, we did areas one at a time," explains Gary Daniel, senior project manager for Hills, "we didn't want it to be plunged into darkness."

After consultation the existing entrance hole for the sub-main supply cables could be made slightly larger to accommodate old and new cables together. A new main switchboard and sub-switchboard were installed: one to feed each half of the complex. The latter one is in preparation for phase 3. "The idea was when we come to the next phase we don't have to work in an area that we've already completed," explains Daniel. These feed localised distribution boards fitted with surge suppressors to cope with the intermittent electricity supplies from which the island suffers.

The cabling is distributed around the cloisters at high level behind wooden beams that cover the courtyard. These are carried on black pvc coated cable tray that was chosen to blend into the scene.

Fittings were installed in the existing locations as far as possible on the ground floor so existing cabling routes could be followed. On the upper floors these could be hidden under floorboards and in the ceilings, as the internal structure here dates only from around the 1950s.

Low energy lighting has been used throughout to reduce electricity use and in line with the policies that have seen the abbey win a gold award under the Green Tourism Business Scheme.

The mechanical works were small in comparison to the electrical. They involved updating the heating system, including all associated insulation, installation of showers, and ventilation.

Options considered for the heating system renovation included using a redundant heat pump system fed from pumps on the sea bed, converting the existing four electric boilers to oil or upgrading them. The latter option was chosen as maintenance may have been a problem with the heat pump and there was nowhere suitable to put an oil tank.

The three 50 kW and one 30 kW boilers switch on in stages to suit demand. These were renovated and pumps and controls added to improve efficiency. Heat is fed from these through a pipe network that passes through and directly heats each room in turn. Again, rerouting and replacing the pipes was not possible if the building fabric was to be protected so the existing pipes have been checked, cleaned and reused.

Getting to site
One of the biggest obstacles to overcome was location. The question of how to access Iona was of vital importance for two main reasons: the delivery of materials and available working hours.

In volume terms there were about sixteen transit van loads of materials needed for phase two – thirteen for the electrical and three for the mechanical. There were also around four skiploads of waste material to be removed. With no suppliers on Iona or the nearest island Mull, these all had to be shipped to and from the mainland. Added to this journey there was the question of how to transport the materials the quarter mile uphill from the Iona ferry port to the site as vehicle access onto the island is strictly limited.

"Some firms were pricing helicopters," Daniel reports, reinforcing the complications of the journey, but Hills opted to gain special permits from Argyll and Bute Council to enable its team to use a car and a small van for the 6·5 h journey from their Edinburgh homes and the transportation of materials.

The Community moved to alternative accommodation during the works, taking all possessions with them. This enabled Hills to use empty rooms for materials storage. Deliveries had to be carefully planned for the entire phase as getting them to site was complex and could take several days. "Even a wholesaler in Oban has still got two ferries to take – you're not going to get anything urgently," stresses Daniel.

The firm's preferred suppliers delivered materials to the Glasgow office of carrier Oban Express who transported them to the Oban Ferry port. From here a local firm took them to Iona. Extra materials were transported by Daniel when he attended fortnightly site meetings with the client and consultant. As his car could not be taken onto Iona the workforce van met him on Mull, where it was filled with the materials in the car before being ferried back to site. "The materials that we were getting were well in advance of when we needed them," explains Daniel.

With the materials deliveries in place, another decision to be taken regarded the staffing. Local labour was looked at due to the distance from Hills' office, but the required skills were unavailable so its direct labour completed the job. "The only logistical way of completing the programme within the timescale was for the workforce to stay on Iona," explains Daniel. "You couldn't hire accommodation on Mull because it would have restricted the hours of work," he adds. The last ferry leaves Iona at 4.30 pm – giving a maximum of around 6.5 h/day on site – and is weather dependent, so workers were faced with not being able to reach the abbey or being stranded there. The island's hotel and B&Bs close for the winter so the most cost-effective solution was to rent two properties.

The third phase of the project involving the lighting within the Abbey and around the cloisters is currently scheduled to begin in September 2003.