Klondyke Building, Cromac Avenue, Gasworks Building Park, Lower Ormeau Road, Belfast, BT7 2JQ

The Klondyke Building is a large, attached three-storey former Retort House, now converted to offices, built around 1891 to designs by Belfast-based architect Robert Watt. It forms part of Belfast Corporation's Ormeau Road Gasworks complex and sits at the south-west corner of the Gasworks Building Park, with its west gable facing onto Ormeau Road. The listing extends to the former Retort House itself, its chimney, and the boundary walling. The building has group value with the nearby Meter House and Gas Office, the latter also designed by Robert Watt.

ARCHITECTURAL CHARACTER

This is a utilitarian red brick building of considerable scale, oriented on an east-west axis. Its character is enriched by granite and sandstone dressings and the use of contrasting coloured brick. The main eastern block originally housed the coal-gas retorts, while the slightly narrower section at its east end contained the water gas plant. The pitched roof is covered in natural slate with raised dressed sandstone verges. Box and ogee-section cast-iron rainwater gutters run along the eaves.

EXTERIOR

The walls are of red brick with external pilasters along the side walls and at the corners. There is an advanced base course with a chamfered granite coping. Below the eaves, a corbelled brick course runs continuously, beneath which a series of diamond-shaped openings are trimmed with stepped purple brick; modern aluminium-framed fixed windows have been inserted into these openings. A chamfered sandstone and brick string course runs beneath these openings, level with the chamfered sandstone copings to the pilasters. Between the string courses and pilasters are large blank rectangular recesses, many of which have been fitted with large modern aluminium-framed glazed units to bring light into the interior.

The north elevation is partly abutted on the right by a lower single-storey building, formerly a workshop and now used as an industrial unit. The south (rear) elevation is almost entirely abutted by a modern flat-roofed office block that rises to eaves level.

The exposed section of the east gable of the main block has three high-level cast-iron brackets that once supported a shaft, now long removed. Its apex contains five semicircular-headed openings, all now infilled. A number of infilled segmental-headed openings trimmed with purple brick are located below the ridge duct pipe. Similar detailing appears along the south elevation of the water gas section. The east gable of the water gas section has a blank pedimented gable trimmed with brick, with two small and two larger blank panels below, into which modern glazed units have been inserted.

The west gable is of particular architectural note. It has an advanced base course of quarry-faced granite blocks laid to regular courses and coped with chamfered granite. Above this rise four shallow brick pilasters defining four panels, two of which are blank, with the other two fitted with modern glazed units; all four panels are framed with moulded sandstone dressings. An ornately detailed terracotta frieze runs across the top of the gable, above which is a pedimented gable trimmed with moulded sandstone dressings. The tympanum at the apex carries three panels framed with moulded sandstone. The central panel bears a dressed sandstone plaque carrying the Belfast coat of arms and the city motto — Pro tanto quid retribuamus (For so much, what shall we repay). This is flanked by bas-relief sandstone panels bearing the numerals '18' and '91' (forming the date 1891) set against a herringbone-brick background. The size and quality of the stonework in this tympanum is of particular note.

ROOF STRUCTURE AND RIDGE DUCT

The metal truss roof is an excellent example of this type of roof construction. A tubular metal duct runs along the ridge; this was originally designed to vent fumes from the interior, working on the venturi principle. Although now defunct, a pipe still runs from the east end of the duct across to the chimney. The west end of the duct is covered with a radial screen and is surmounted by an ornately fretted cast-iron standard.

CHIMNEY

The chimney stands just beyond the east gable of the main section of the building. It is full height, slightly tapered, and has an off-octagonal cross-section. It is built of red brick with purple brick quoins. Tie bars secure the lower section, and a lightning conductor runs down its side. The juxtaposition of the chimney with the main building serves as a visible reminder of the building's former role in gas production.

SETTING

The building stands at the south-west corner of the park, with the west gable facing Ormeau Road. An original red brick boundary wall runs along its south side, acting as a buffer between the building and the nearby railway line. An office block abuts the building, with parking located at the eastern entrance.

HISTORICAL CONTEXT

The Ormeau Road Gasworks site dates from 1821 and, while not the first gasworks in Ireland, it eventually became the largest in the country by the mid-19th century. The Retort House was completed in 1891, three years after the Gas Office on the same site had opened. During this period, James Stelfox served as General Manager of the works and oversaw the expansion programme.

According to a 1910 map of the Gasworks, the building was then captioned as 'Retort House' and contained 288 retorts capable of producing 2.16 million cubic feet of gas per day. A retort is a horizontally-mounted, earthenware, D-shaped tube in which coal was heated in the absence of air; the gas content was driven off, leaving coke as a by-product. A smaller building on the east gable was marked 'Water Gas No. 1', with a capacity of 1.5 million cubic feet of water gas per day. Water gas was made by heating coke and then passing steam over it. Unlike coal gas, water gas has little luminosity, so oil was injected into it to make it suitable for gas lighting and to allow it to be blended with coal gas. This oil was imported and piped to the gasworks all the way from Alexandra Wharf. The water gas apparatus came on stream at the end of 1893. In an interview in 1894, Stelfox noted that this section had originally been intended as a conventional retort house, but that water gas was adopted instead.

The 1910 map also shows a Boiler House abutting the north side of the water gas building, where steam for the process would have been generated, and a Blower House along the east side of the Boiler House, containing fans to blow steam onto the coke in the water gas apparatus. Two chimneys also stood at the east end of this block.

Water gas production was invented in America, and Belfast was the second city in the British Isles after London to use it. Aside from Carrickfergus Gasworks, this is the only retort house remaining in the province, and the only surviving one in Ireland associated with a water gas plant, giving it considerable rarity value.

The building's popular name — the Klondyke Building — is clearly a later addition, since the Klondike gold rush in the Yukon did not begin until 1897, six years after the building was completed. The name may have been adopted in acknowledgement of the American origins of the water gas process and/or the use of imported oil to enrich the gas.

The Gasworks closed in the 1980s. By that time, the interior was an empty shell, the retorts having been removed long before — coal gas production having ceased in the 1960s. Over the following two decades the entire gasworks site was redeveloped, and the Klondyke Building was converted to offices for the Northern Ireland Environment Agency, with a number of modern interventions including the insertion of aluminium-framed glazed units throughout the exterior.