Substation No.175

Substation No.175

Hill Thalis Architecture + Urban Projects Pty Ltd
Surry Hills, Australia | View Map
Année du projet

Substation No.175

Hill Thalis Architecture + Urban Projects Pty Ltd en tant que Architectes.

"Size is not scale and some time small projects can say big things" - Manuel de Sola-Morales

Originally completed in 1925, Substation No. 175 was a small face brick building housing oil filled transformers for the City of Sydney’s power supply until its decommissioning in 1996.

Situated on a 44sqm plot at the southern edge of the city, the substation sat mutely within an eclectic urban context of low scale row housing to the east, a fifteen-storey commercial slab tower to the north and pocket park to the west.

A lightweight, zinc clad addition is grafted onto the substation building, transforming the redundant industrial shell into a miniature city tower. The 4.8m x 9m site now holds a street level café and 2 residential apartments over 6 storeys.

The habitable rooms within the tower have dual orientation, addressing both the park and street frontages while maximising light and ventilation to the interiors. A carefully calibrated pattern of windows presents a reinvigorated urban façade to the adjacent pocket park.

The building attempts, in microcosm, to intensify the urbanity of the site, and suggests a positive dialogue between architecture and the city.

Relationship Of Project To Site

The site is located in the suburb of Surry Hills, on the north side of Devonshire Street between the intersections with Elizabeth and Holt Streets. The site is within 200 metres of the Devonshire Street entrance to Central Railway Station, and is convenient to most parts of Surry Hills.

The immediate context of the substation site is dominated by a 15 storey 1960’s slab office block, which runs from Elizabeth to Holt Streets parallel with Devonshire Street. The associated widening of Devonshire Street did not eventuate, creating a de-facto pocket park in front of this building.

As a result of the above site history, the substation presented a blank party wall to the pocket park. The project addresses these shortcomings by orienting a new cafe and all new residential floors to the park. This new facade helps to potentially transform a left over area into a positive and activated urban space. The substation's Devonshire Street entrance is retained as the residential address.

Architectural expression of the concept

The adopted strategy retains most of the existing structure, and builds above a new structure of equivalent volume. This is clearly seen in the massing of the Devonshire Street facade, where the solidity of the existing brickwork is counterbalanced by the openness of the balconies above. To the pocket park, the blank party wall is replaced by the new activated new facade of juliette balconies and bay windows.

Both facades combine elements derived from the size of the individual room with a larger compositional order that relates to the urban setting. Despite its tiny site and footprint, the building responds robustly to the scale of its neighbours.

The mix of cafe and two different apartments intensifies the use of the site, showing that no lot need be too small to be used efficiently. This is counter to the profligate land use characteristic of Australian cities. Therefore the project is a model for appropriately scaled infill development, serving as a demonstration of the benefits of compact city planning principles. Cost effectiveness

The project cost was managed throughout the design and construction process by the builder / developer, in collaboration with the architect.

The smallness of the site, access restrictions, fire and acoustic requirements and structural constraints all presented acute challenges. The structure comprises a three storey concrete frame, supporting a three storey steel frame. This arrangement satisfied the earthquake code, and provided an efficient structure in terms of erection times and weight.

The budget is concentrated on the most visible and durable parts of the project; the zinc cladding and Capral aluminium door system. All interior components, such as the stairs and kitchens, were realised by contractors interpreting the architectural drawings and sketches.


The project employs a number of environmentally sustainable design principles;

- The project transforms a redundant industrial site into a viable mixed use development. - The project serves as a demonstration of the virtues of compact city planning principles, as it is an intensive use of an extremely small lot. This is a realised model for improved land use in Sydney, as an alternative to continued sprawl. - The project retains much of the original fabric of the substation. - All internal spaces have openable windows to provide daylight and fresh air. Most habitable rooms enjoy two orientations, and both apartments benefit from stack effect ventilation. The occupants will have the choice of 38 openable panes, allowing great flexibility in controlling cross ventilation. - Operable external blinds are provided for the large west facing living doors. - The building is fully insulated. - No lift is provided. The stairs will encourage housing for the fit! - No car parking is provided, as the site is extremely convenient to public transport and within easy walk of the city centre and many facilities.

Organisation of spaces inside and out

The project vertically extends the existing building footprint. The increases in floor space and height are within the standards set in the City of Sydney's LEP.

The proposal comprises six levels of accommodation.

On the ground floor, the existing opening to Devonshire Street is adapted as the residential entry and common stair. The remainder of the ground floor will serve as a café, with new openings on the west façade to the public open space. Works in the public domain associated with the construction of the ground floor Café are carried out under a separate Development Application.

The common stair rises to the first floor, and gives access to the two new sole occupancy residential units. Apartment 1, which has its own internal stair, occupies the first and second floors. A private internal stair to Apartment 2 commences at the first floor and rises to third and fourth floors, which contain a bedroom and living areas respectively. A further flight gives access to a second living space and roof terrace. The efficiency of the stairs was a key element of the planning. Each room can be interpreted from the fenestration pattern of the facades, while the type of opening is tailored to the function and relative privacy of each room.

Structure, construction, materials, services

The key structural challenge was dealing with the slenderness ratio of the building while satisfying the earthquake code. In order to provide sufficient stiffness to the structure, the lower three floors are a reinforced concrete frame. The frame is fireproof and stabilises the retained brick perimeter walls. For lightness and speed of erection, the upper three floors are a steel frame. Promat products are used extensively for fire protection of the steel structure and the perimeter walls.

The new work is clad in zinc sheeting, selected for its long life and low maintenance. The windows and sliding doors are anodised aluminium, again selected for durability.

Stairs are alternatively concrete, steel mesh or timber, while floor finishes include sealed steel trowel concrete, carpet, Pirelli rubber and timber. The stair and floor finishes have each been selected to relate to the character of specific rooms, and to elaborate spatial sequences. Except where the concrete frame is left exposed, the internal walls and ceilings are all painted plasterboard.

Given the tightness of the site, all services are stacked and risers concealed within the apartment 2 stair.

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