“Add more greenery…”
When architectural renderers receive feedback, this seems to be the line that’s most in vogue internationally right now. And fair enough. The intention of a greened city is admirable; we all know well-placed greenery can humanise and soften even the most imposing of structures, not to mention the sustainable living it implies. Unfortunately, the majority of the world’s cities lack the sort of climate where year-round green, open, inside-outside living is a habitable reality. No doubt there have been many French or Danish architectural renderers who have received that aforementioned feedback, only to gaze out on another frigid winter’s day and wish for a more forgiving climate. The sort of climate you get in the subtropics.
The subtropical climate zone, from a latitudinal perspective, is considered to be between 25 and 40 degrees, both north and south of the equator. More than 50 percent of Australia, including Brisbane, Sydney, Adelaide and Perth lies within this band, but from a climatic perspective, local geography reduces the true subtropical zones predominately to southeast Queensland and northeast NSW. The geographical good fortune of cities like Brisbane and Sydney, with their hot, humid summers and mild, dry winters, frequently lands them in the top rankings for most liveable climates in the world. Not only are subtropical cities comfortable, they also have huge potential for low-energy sustainable buildings. It is, therefore, our opportunity and obligation to design buildings and spaces that celebrate this liveable climate as much as possible.
Historically, understanding the climate has been a cornerstone of vernacular design, with ‘The Queenslander’ representing a quintessential Australian response to a subtropical climate. Shade spaces around the full perimeter of the building protected the walls from direct sun and rain, while also creating space to dwell totally externally; the buildings were also oriented to the landscape to make the most of aspect, light and connection to nature, and to capture prevailing breeze. This breeze could then effectively cross-ventilate the building through a logical floor plan, with high ceilings, vented door architraves and stilt construction. While materials were mainly chosen for simplicity and availability, they also lent themselves to a flexibility and openness, which arguably has helped shape the culture and identity of Queensland.
A phrase that has been developed to encompass the typology of buildings that respond well to a subtropical climate is “buildings that breathe”. It’s a concept embraced by Brisbane City Council in its recent Buildings That Breathe Design Guide. This handbook breaks down the elements of good subtropical design (and all design, for that matter) into eight main criteria.
1. Orientate yourself
More than just facing the building north, orientation demands analysis of views, breeze, public space, layout and neighbouring structures. Sun falling on different facades and materials can warm or protect internal spaces at different times of the year. Consideration of local conditions and use of the public realm can create street activation. Extension of passive design beyond the building envelope, by maintaining sightlines, breezes and the natural landscape, enhances the breathability of the site and neighbouring sites alike.
2. Occupy outdoor spaces
Brisbane has more than 300 days a year that are considered ‘comfortable’, in which activities need not be confined to enclosed structures. Incorporation of city rooms, sky terraces, balconies and laneways as integral design elements mean the concept of a room is an enclosed box can be dissolved and blurred. Use of these spaces reduces the heating, cooling and lighting load on the building, while also proven to boost wellbeing, productivity and happiness.
3. Illuminate with daylight
The quality and frequency of brilliant blue-sky days in Brisbane mean well-placed windows, light wells, atriums and reflective finishes can provide sufficient light penetration into a building to drastically reduce the demand for artificial lighting. As a general rule, the effective light penetration at the perimeter of a building is approximately two-and-a-half times the height of the window.
4. Natural air and ventilation
Orientating a building to capture the prevailing breeze is only one step in effective natural ventilation. Building layouts should have a logical format, with circulation elements positioned to encourage air movement through spaces. Creative use of glazing, shading and voids can encourage stack-effect solutions, creating currents that draw air through. HVAC systems account for 20 to 30 percent of a building’s energy consumption, so HVAC technology, which can supplement and enhance natural ventilation, can have a substantial cost and pollution savings.
5. Shade and protect
While Brisbane is generally extremely liveable, there is no denying that summer can bring brutal conditions. Be it to protect against the harsh summer sun or torrential storms, incorporation of deep eaves, awnings and other shading structures are vital to the subtropics. Protection is also required from other elements of a prolifically green ecosystem, such as mosquitoes, spiders and snakes. Understanding and working around nature, be it bush turkeys or mozzies, is all part of an effective subtropical design.
6. Living greenery
Arguably the most visible and enviable subtropical trait is plants that thrive year-round. Potentially, almost all surfaces and facades can play host to living greenery, through green roofs, walls, balconies or sky gardens. Design consideration of root ball requirements, drainage, maintenance and access are all paramount to successful urban greening, the numerous benefits of which include biodiversity, reduced heat loads, stormwater mitigation, and psychological and visual relief.
7. Identity matters
Identity and culture are intrinsic to place and climate. The subtropics have shaped Brisbane into a relaxed, friendly, open culture proud of its traditional timber-and-tin vernacular. Modern choices of materials still favour local availability, simplicity, and permeability. Brisbane is aware of (though under-engaged with) traditional owners of the land, and through public art, urban space, and design response is striving to celebrate the past while racing forward as a new-world city.
8. Reduce energy and waste
With cities consuming 78 percent of the world’s energy and producing 60 percent of all carbon dioxide, reducing energy and waste in the built environment is an economic, social and moral imperative. As well as all the passive design solutions listed above, subtropical climates have enormous potential to use the latest technology, certifications and processes to make substantial contributions to a more sustainable future.
The design principles above were crafted for Brisbane’s subtropics in particular, but many of them apply to design universally. The blessing of a subtropical climate should not be squandered, and the ability to construct successful green, sustainable buildings that are the envy of the world is an exciting, vital, and inspiring opportunity.