A new multipurpose agricultural barn, known as the Power Barn, which has an array of solar PV panels on its roof, was recently built on a smallholding in Noordhoek, and is a reflection of the client’s passion for holistic sustainable living.

Retired general practitioner, Dr Caryl Richmond, bought a smallholding in the De Goede Hoop Estate in 2005 and has transformed the land into an agricultural gem that showcases sustainable living. An olive grove of 212 trees spans 1.5acres of the 10acre property. Closer to the homestead, figs, citrus and other fruit, and nut trees, as well as a vegetable garden are interspersed with indigenous fynbos. A natural wetland covers a large part of the property.

Recently, Richmond added a multipurpose barn to the property, adjacent to the existing house, with the aim of housing her olive press, propagating fynbos and perhaps most noticeably, using the roof as a platform for harvesting the sun’s energy.

Sustainable philosophy

Richmond’s passion for the environment and sustainability was initiated by her pre-medical school studies in zoology and entomology, and has now found its expression in retirement.

When Richmond bought the smallholding, the existing alien blue gum, pine and poplar trees as well as smaller alien species on the site were felled and removed to rehabilitate the land and provide a habitat for local indigenous biodiversity – fynbos and wetland biome and the creatures they support.

In 2009/10, the new olive trees were planted, partly due to their high nutritional (and medicinal) value, which fitted in with Richmond’s ethos of eating healthily, as well as their ability to survive the effects of climate change.

At the time, the small existing labourers’ cottage was converted into a house that was later extended to accommodate her large family. The felled trees provided ample timber for the floors, roof trusses, lintels, and joinery.

THE POWER BARN

The next chapter in Richmond’s sustainable story was constructing a new multipurpose farm building, completed in early 2017, to make space for various farm-related activities: olive pressing; fynbos propagation; preparing of honey (from the farm’s three bee hives) and preserves; and more. In parallel to this need for space, Richmond started monitoring her electricity usage to use less, and the idea arose to make the roof of the new farm building a renewable energy receptacle that would generate clean electricity. Coupled with its agricultural barn aesthetic, it’s no surprise that the new building is referred to as the “Power Barn”.

Andre Harms, sustainability engineer at Ecolution Consulting, who was involved in the project from early on, helped guide the sustainable design of the barn.

The roof faces due north with a pitch of 45 degrees, and accommodates 24 solar photovoltaic (PV) panels that each produce 305W peak power, producing a total of 7.3kW, explains Dave Liddell from Solarex, the system installer. This amounts to 12 700kWh per year while the farm currently uses around 13 000kWh per year. The panels provide around 40% of the farm’s power needs, the other 60% being drawn from the city’s grid for usage at night, as there is no battery storage. Due to the panels feeding electricity back into the grid during the day, the net import is only 30% of the total.

AN AGRICULTURAL BUILDING

“Sustainability is honesty – honesty of materials and honesty of building techniques,” says Power Barn architect, Mark Thomas. The natural response to designing this farm building was to follow an agricultural barn concept, he explains. The barn has a steel frame that creates the core structural skeleton. The insulation comes in the form of bagged brickwork infill panels and timber cladding reclaimed from the site, which is also used for the ceilings and beams. The timber provides natural aesthetic warmth to the interior spaces, which are lit up by the sun when six metres of sliding timber doors are opened on the northern side, bringing the outside spaces in.

The building’s form was partially constrained by the design guidelines provided by the De Goede Hoop Estate. These defined the pitch and height of the corrugated roof – the barn is built into the slope of the mountain so it is double-storey at the front and single-storey at the back.

Two unpainted, battered concrete walls flank the sides at the front end of the building, where there is a “Zen room” – a yoga studio/exercise gym/music room – upstairs. Instead of rammed earth, which would have been the first choice for Richmond, a very weak concrete mix was combined with local koffie klip stones and sand found on site.

The thickness and heavy mass of these walls also helps to provide insulation.

Solar also powers a specially designed underfloor heating system. Liddell says it is divided into four zones: the Zen room and office (suspended timber floors); bathroom; staff room; and kitchen (concrete slabs). Specialised plastic PEX  piping with no joints – to avoid the possibility of leaks – is concealed in the floors in a continuous loop. A 7.2kW heat pump uses the energy from the solar PV panels on the roof to heat water stored in two standard 150litre geysers on ground level.

Four smaller pumps draw water from the tanks, which circulates through the pipes that have aluminium insulation underneath in order to reflect the radiant heat upwards and into the rooms.

The fynbos propagation area, which is situated on the south side of the building enclosed in polycarbonate cladding, does not feature underfloor heating although Liddell says in future flexible pipes will be led underneath the seedbeds to heat the growing media at the required height.

To maintain the industrial look of the building, all the equipment for the heating, pumps and piping is exposed. This also extends to the electrical fittings, which are surface-mounted to maintain flexibility of the use of the spaces. A power track runs below the ridge of the ceiling. From here smaller power conduits can run to wherever they are required.

OPEN SPACE

A key element of the design was flexibility of the interior spaces, which was enabled by the steel frame. A timber bridge that connects the office area to the Zen room allows the central space to be double volume, and the timber staircase can be lifted by a winch to completely free up the ground floor space for activities.

The project will leave a long-lasting sustainable legacy as an example of encouraging symbiosis between water and the land, and harnessing renewable energy. It’s been a learning process for everyone, Thomas adds, but a positive one. And the learning will continue as the farm evolves.

Written by Mary Anne Constable

See earthworks magazine issue 40 October-November 2017 for the full feature.