Rammed-earth walls and innovative rock-bed thermal storage make the high-functioning Hillside clinic a stellar example of form and function working together


From the outside, it doesn’t seem too out of place… Located at the end of Plein Street in Beaufort West, the single-storey public day clinic boasts earth-toned walls, white corrugated roofs, and ventilation stacks with cheery concave cowls. Closer inspection, however, reveals that the building – somewhat unexpectedly – includes sustainable design elements such as rammed-earth walls, solar-water heating and cleverly positioned rock-bed thermal storage beneath the concrete floors.

Hillside Clinic in the heart of the Great Karoo is, in fact, a pretty clear example of how the Western Cape government is testing out alternative technologies for their healthcare facilities.

The brief from the Western Cape Government Transport and Public Works (WCGTPW) department was for a day clinic with waiting areas as well as treatment and consulting rooms for Chronic and Acute Care; Infectious Diseases; Preventative Care (Woman and Child Health, Oral Health and Rehabilitation); and staff facilities and common areas for the reception, record-keeping and pharmacy.

The well-being of the patients, staff and environment had to be prioritised in a passive, vernacular design with a low carbon footprint, and reduced energy consumption and running costs. Interiors had to be healthy, with natural lighting and ventilation. The building also had to be easy to maintain and made to accommodate possible future extensions.

In addition to the specifications that are standard when designing a health facility, the remote location brought other obvious challenges, such as high material haulage costs and comfort issues related to extreme temperature variations.

The department explored sustainable design solutions together with the project team. ‘We were surprised and encouraged by the request from the department to investigate using eco-friendly solutions for the clinic,’ says lead architect John Wilson-Harris, of Gabriël Fagan Architects. ‘The department was just as enthusiastic as we were with implementing various passive technologies.’

The architects approached Greenplan Consultants to advise on general green aspects. MD and founder Francois Joubert says: ‘For us, this was one of the most exciting and rewarding projects incorporating passive design elements to date.’ First up, Greenplan conducted a thermal-comfort study to determine the best orientation for the clinic’s waiting and sub-waiting areas, located in the wings.

They assessed two concept building types designed by the architects, using the adaptive comfort standard ASHRAE Standard 55-2010. Option A had the sub-waiting passages on the (colder) southern side of the building wings, while the clinical and consulting rooms were on the (warmer) northern side.

In Option B, this was the other way around. The study showed that the non-conditioned areas in the first design would experience too many cold days during winter, while Option B (waiting areas facing the north facade) offered a better balance between too cold and too hot, making it the best choice for the average of 110 patients visiting per day.

These passageway waiting areas are open, light-filled areas, and benches built into the walkway glazing system outside the consulting rooms catch the winter sun beautifully. In summer, large overhangs shade the glass.

At this stage, the project team aren’t necessarily chasing Green Star status. Accolades were never the aim. ‘Bear in mind that it’s an experimental building, so the features used will be monitored for possible use in future clinics,’ says Wilson-Harris.

The WCGTPW is currently using an energy monitoring system to compare the facility with other, more conventional ones of the same scale. But as it stands, they’re already pleased with the end result. The department’s chief architect, Ulrike Kuschke, and architectural technologist, Jehan Bhikoo, say the design serves as a good example of future approaches to low-cost, sustainable healthcare facilities in SA.

Joubert concurs. ‘[It’s] an outstanding example that green buildings can be beautiful, comfortable and energy efficient. It represents a facility that proudly serves the whole of Beaufort West and shows respect [for] the inhabitants of the town.’

A central aspect of the design intervention was the rammed-earth walls. Globally, there’s been a revival of the use of these walls, which date back to at least 5000 BC in China. The construction technique uses raw materials sourced locally and generates little waste, so it’s more sustainable and cost-effective than transporting kiln-fired bricks to site. Building rammed-earth walls is also fairly labour intensive, contributing to employment.

‘When the clinic project began we thought that rammed earth, with its high thermal mass and as a labour-intensive construction technique, might be appropriate,’ says Wilson-Harris. The material was mostly sourced from the empty Beaufort West dam, and tested by Outeniqua Laboratories. ‘This process is imperative to confirm the constituents of the soil in order to confirm the eventual mix,’ he adds.

Given that this ancient technique was fairly new to those involved, the prototyping and building process involved trial and error. ‘We tested blocks of wall on site until the appropriate finish and stability was achieved. The contractor is now an expert,’ says Wilson-Harris.

He isn’t the only one. Chris Denny, from Edge to Edge Construction, says they trained about 15 labourers on site, ‘who could probably do it themselves now’. He advises those considering using this technique to pay attention to the shuttering. ‘The compacting of the earth puts pressure on it, so you really need a skilled shutterer.’

A major challenge was reducing the clinic’s reliance on air conditioning, while still maintaining the strict air-quality standards needed. Reducing the risk of airborne infection requires more than six air changes per hour.

‘The normal way to save energy is to recycle some of the conditioned air, so you’re not constantly cooling hot air,’ says Wilson-Harris. In a clinic, however, recycling air is a no-no, and having to condition air for the six changes per hour simply wasn’t feasible. Rock stores – in which fans and packed rock beds help temper air before it enters the artificial heating and cooling system − turned out to be the right low-tech solution.

Rock-bed thermal storage is when hot or cold air from the environment is circulated through beds of loosely packed rocks, helping store ambient temperatures and thus support air conditioning or heating systems, lessening the need for them to be on all the time. While rock-bed thermal storage can be used on a larger scale for lower-cost storage for concentrated solar power plants, they’re equally suitable for smaller sites too.

On their website, Greenplan (which specialises in rock-bed thermal storage) explains: ‘A packed bed used for cooling a building is “charged” with cold air at night when the external ambient temperature around the building is low… During the day, when the temperature rises and the building needs cooling, the low temperature stored in the packed bed can be used to cool air for the building until the packed bed is discharged by reversing the air-flow direction. Packed beds can be used for heating a building at night if it is possible to charge them with hot air during the day.’

The site was ideal for a rock-bed system, as they work best in dry climates with large diurnal temperature differences (a minimum 8°C to 10°C). What’s more, the right type of rocks was found nearby – ‘almost perfectly spherical, having the correct size and physical properties … the ideal type for use in a thermal rock store,’ says Joubert.

The rocks were carefully cleaned with water to remove sediment, fungi spores and other potential health hazards, and placed in six separate rock stores − beneath the concrete floors and between perforated plenum walls − serving different parts of the clinic. This is where the ventilation stacks come into play. ‘The stacks are actually air intakes at a high level to have them above any dust,’ says Wilson-Harris.

In summer, hot air enters via the inlet and through a plenum on one side of the bed. It’s circulated through the packed rocks. As it passes through the rocks, the air is cooled and exits the outlet plenum on the other side of the bed, then through the outlet duct to become part of the tempered air system.

When the outdoor temperature is lower than 22°C, air isn’t circulated through the rock store unless the rock store is warmer than 22°C. ‘In cold winter conditions, ambient outdoor air goes down the chimney and is supplied directly to the occupied spaces, and the building is heated with split air conditioner units,’ according to Wilson-Harris.

Rock beds won’t work in all situations, but when they do, they do so well. At the clinic, the system has a moderating effect of about 4°C. Together with the HVAC cooling, on a 33ºC day the air temperature in the clinic can be 22ºC to 26ºC.

Hillside is more than a small-scale experiment in making public healthcare facilities more eco-friendly – it’s a great example of a building sensitive to both context and community.

Western Cape Department
of Transport and Public Works

Henry Fagan
and Partners

Western Cape Department of Health

Edge to Edge Construction

Gabriël Fagan Architects
[email protected]


Mbatha Walters and Simpson


By Deidre Donnelly
Images: Gabriel Fagan Architects

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