North-west of Port Elizabeth city’s edge, 3000 hectares of once unproductive and neglected land is about to be transformed into a nature reserve with approved housing. The Hopewell Conservation Estate will be a green lung for the Nelson Mandela Bay metro. A visitor’s centre is Hopewell’s first completed building and offers a glimpse of the conservation spirit and design of the estate.
This multi-functional pavilion-style building was awarded a 2013 Regional Architectural Award by the Eastern Cape Institute of Architects.
Hopewell director Brian Corrigan says they’ve adopted a pragmatic approach to conservation. Their development goal to provide for environmentally sensitive housing within the nature reserve is balanced by the estate’s near-city location.
When it came to choosing a suitable site for the visitor’s centre, the team was guided by a number of factors. On such a vast property, “the visitor’s centre acts like our sentinel. This specific building had to stand out in the landscape. But that didn’t mean that it had to be ostentatious. Rather, it is how the site benefitted the building”, explains award-winning architect Richard Stretton of Koop Design.
The chosen site is a small, previously disturbed site where a derelict cottage once stood.
For Stretton, the natural landscape provided the strongest cues for the design and position of the building. In response to the unique environment, Stretton wanted to create a building that imitated the feeling of sitting under a tree on the hillside, overlooking the natural landscape.
The design philosophy was centred on multifunctionality, the use of minimal materials, and the re-use of materials and infrastructure.
Although an open, natural atmosphere was a key design principle, the building was planned on an exposed hillside where harsh south-westerly winds are common. Structural support and protection were key considerations, while at the same time utilising minimal building material.
Developing a building with two components was the solution. The northern and eastern fronts of the building make up its front and open component. A solid masonry block forms the closed southern and western fronts. The solid component provides the building with structural stability, while protecting the open fronts by putting a hard shoulder into the wind.
Structural engineer Walter Smith of BVi Consulting Engineers Eastern Cape says the development site has a slight natural slope. The team recycled stone building material from a ruined cottage to build a retaining wall.
Referring to their intention of responding to the landscape, Stretton says: “The earth rises up to create a platform. We’ve used the site’s own rock material. It is not another material that made the platform and retaining wall: it is the earth.”
For the solid masonry components, the rock continues to rise from the platform, becoming the walls. The platform and retaining wall create a link between the landscape and the building.
Timber and steel frame
A South African pine timber frame was created for the building. In addition to purposefully shielding the eastern and western fronts from the blazing sun, the timber frame supports the waterproof steel roof.
But, unlike pine originating from colder climates, the fast growing nature of local pine delivers lower-strength timber.
However, combining the use of pine with steel proved to be a solution. Lightweight steel sections were built-in between the window panels. These steel sections connect to the roof structure, which in turn, stabilises the timber. The building construct does not utilise any cross-bracing; the solid component fulfils this role.
“We needed the steel to give rigidity to the structure; the timber would not have been able to offer this on its own. The combination of South African pine and lightweight steel works nicely together and is reliable,” says Stretton.
The next challenge was to shelter the building’s open side from wind and rain while preserving the unique views overlooking the valley.
“We built a glass box around the open space, but inside of the timber structure. The glass box is there to provide shelter — it is separate from the structure that holds the roof up,” says Stretton.
Multi-functionality features once again. “The building is naturally shielded by its own structure,” he says. “There is no additional need for shutters.”
The glass box connects all the building elements. By using solar performance glass, solar gain is avoided.
Inside the landscape-inspired theme continues. Sand from the construction site was carefully cleaned, graded, mixed with cement and used as flooring aggregate. Maintaining a close link with the natural environment, this red flooring is literally “a polished version of the soil outside,” says Stretton.
It is not only the structural features that speak of detailed planning and design. The building operates independently of the municipal electrical grid. “We rely on the building’s natural light and passive solar design, and use as little energy as possible,” says Stretton.
Besides the structure itself overshadowing the windows, the building also benefits from deeply shaded windows.
Generator-operated LED lights provide light at night when needed. Gas operated fridges and water heating offer staff and visitors basic amenities.
The building design provides for photovoltaic (PV) installation and solar water heating, but the low demand does not justify these installations yet.
The glass box inside the timber frame also allows natural ventilation, and because the building is not occupied at night, creating thermal stability at night was not a priority.
Planning is key to conservation
Detailed planning ensured that each element of this building worked together, that no unnecessary material was used and that most elements demonstrate multi-functionality. Stretton believes 90% of sustainable architecture comes down to careful planning of passive design and structure mechanics, and avoiding shortcuts. This is all about basic conservation.
To the untrained eye, it may appear a simple building. But look closely and you will see the sustainability baseline built into every nut and bolt.
The full feature appears in the April-May 2014 issue on page 50.