Ishioka No. 2 Power Station Main Building

A generating hall set parallel to the river

The Ishioka No. 2 Power Station Main Building is a single-storey reinforced concrete generating hall at 69-1 Ishioka, Nakagocho, Kitaibaraki City, Ibaraki Prefecture, built in 1913 (Taisho 2) and listed as a Registered Tangible Cultural Property on 3 August 2006 (Heisei 18).

It stands on a plot facing the Okitagawa, its long axis running parallel to the water: 18 meters along the ridge, 10 meters across, with a floor area of 175 square meters. The roof is Kirizuma-zukuri, gabled and covered in iron sheet, and the trusses carrying it are of the Fink type, a steel or timber frame whose diagonal members fan out from the centre so that a wide span can be crossed with light sections.

Reinforced concrete was barely a generation old in Japanese practice when this hall was poured. The Ishioka No. 2 Power Station Main Building is counted among the country's early works in the material, and it was built as a smaller counterpart to the main building of the Ishioka No. 1 Power Station upstream, whose composition it repeats at reduced size.

Windows doing the work of ornament

Along the eaves side of the Ishioka No. 2 Power Station Main Building runs a row of tall windows, each closed at the top by a segmental arch, a shallow curve cut from a circle rather than a full semicircle. Repeated down the wall they set up a steady rhythm that carries the whole elevation, and there is almost nothing else on the facade to compete with them.

The reason is practical. A generating hall needs daylight on the machine floor and it needs it evenly, since a technician reading a gauge at nine in the morning should see as well as one reading it at four. Big openings in a load-bearing wall demand an arched head, and the flatter segmental form gains headroom without pushing the wall higher.

Then the gable ends do something different. Each carries a round window, a shape with no structural excuse at all, set high where the truss meets the wall. It is the one gesture in the building that was made because someone wanted it there.

Why the hall is on the register

The Ishioka No. 2 Power Station Main Building holds registration number 08-0218 from the 51st round, entered under the criterion of contributing to the historic landscape of the country. Six structures of the plant went onto the register on the same day in 2006, from the intake weir at the top of the water route to this hall at the bottom.

Registering the whole sequence rather than the building alone was the right call. A power house on its own is a shed with machines in it; what gives this one meaning is the 750 meters of channel, the settling basin, the tank and the pipe that deliver water to its door. Protection as a Registered Tangible Cultural Property also allows the hall to remain what it was designed to be, a working building, unstaffed now and run by remote control.

Seeing the Ishioka No. 2 Power Station Main Building

Of the six registered structures here, the Ishioka No. 2 Power Station Main Building is the easiest to see. It sits beside a prefectural road, so the gable end and part of the window wall can be taken in from public ground without difficulty. The interior is not open, the plot is owned by Tokyo Dengen Co., Ltd., and there is no parking bay, no explanatory board and no staff on site.

The nearest station, Minaminakago on the JR Joban Line, is about 5 kilometers away, some 15 minutes by car, and no bus serves the Ishioka district. Photographs from the roadside are fine. The road is narrow with little verge, so stopping a vehicle safely matters more here than at most heritage sites, and the light on the window wall is best in the first half of the day.

Kitaibaraki City opens a selection of cultural properties each autumn, and the upstream Ishioka No. 1 Power Station has been included by advance application in past years, with numbers drawn by lot. The Ishioka No. 2 Power Station Main Building has not appeared in that programme, so the interior should not be counted on; the city's Lifelong Learning Division publishes the current year's list.