Dr Beatrice M. Bodart-Bailey
Honorary Professor, ANU College of Asia & the Pacific
Professor emerita, Otsuma Women’s University, Tokyo
10. The Urban Heat Island Effect.
In August 2021, the UN’s Intergovernmental Panel on Climate Change (IPCC) delivered a report described by The Economist as “its starkest warning yet about climate change.”[1] Most relevant for Canberra’s development is the warning against the threat of extreme temperatures caused by high density urban development known as the Urban Heat Island (UHI) effect. The large amounts of concrete used for buildings, pavements and other non-vegetated surfaces absorb the heat of the sun and, acting like a radiator, emit these high temperatures to the environment. This results in the need for air conditioning with the cooling process emitting additional heat to the outside, starting a vicious cycle.
The impact of the UHI effect on our Bush Capital even some five years ago is documented in a CSIRO heat mapping report for the summer of 2016-17. This showed that “on the morning of February 9th, 2017, a day that reached a maximum of 36oC, land surface temperatures varied by as much as 10oC in suburban areas”.[2] The report requested by the ACT Greens has, unfortunately, not been updated. Constant surveillance of the UHI effect should now be the basis of all city planning, as unprecedented heat waves are threatening the world. Towards the end of 2020, Sydney’s Penrith achieved the dubious distinction of being the hottest place on earth with temperatures close to 50oC. Such temperatures can be fatal for those who cannot afford air conditioning or must labour outside. A recent study of the University of Sussex, UK, concludes that the UHI effect could double climate change costs for the world’s cities.[3] For the newer suburbs of Western Sydney there is the prediction that in 20 to 30 years’ time they might have to be abandoned as they will have become too hot to be habitable.[4]
The CSIRO report Our Future World: Global megatrends impacting the way we live over coming decades of July 2022points out that the Australian, American and British Medical Association as well as the World Health Organization have all declared climate change as a health emergency. The report warns:
“Heat‑related deaths are predicted to grow by 60.5% or more across major Australian capital cities from 2020–50, but this is likely to be a conservative estimate. Recent research suggests that official records of deaths attributed to excessive heat in Australia are underestimated by at least 50 fold.” [5]
When Walter Burley Griffin designed Canberra at the beginning of the 20th century, hot temperatures were not an issue. But illness in the cramped quarters occupied by the poor in large cities was, and Griffin planned the capital so that city children could enjoy some of the advantages of the large open spaces of the country and not “grow weedy, stunted and deformed.”[6] These large open spaces between suburbs, wide tree-lined avenues, parks, playgrounds and playing fields and the one house per plot ruling in residential zones have so far mitigated the disastrous UHI effects observed in large cities like Sydney. However, there is already a marked difference in temperature between Canberra’s older and newer suburbs where larger houses occupy smaller blocks, leaving less room for vegetation. For instance, in the suburb of Wright, this has already caused land surface temperature up to 11oC above the city mean.[7] The ACT government’s 70% urban infill policy, mostly in the form of so-called urban renewal with high-density high-rise clusters around stops of the light rail extension to Woden will mean that Canberra’s older suburbs will similarly be affected.
11. The Canopy Cover, Urban Forest Strategy and the elusive “Territory Plan Variation 369.”
The ACT’s government response to the Urban Heat Island effect relies much on a 30% canopy cover across residential Canberra by 2045. Considering that Melbourne aims at a canopy cover of 40% by 2040, the Bush Capital’s aim is less than ambitious, especially as Canberra can build on W.B. Griffin’s legacy of large green spaces. Further, while planning 23 years ahead might be useful in some respects, there need to be annual targets to ensure progress is made. The greatest problem in combatting the heat island effect merely by increasing and measuring the canopy cover is, however, that some of the new suburbs, like Wright, where the tree canopy cover at present is a mere 2.2 per cent, no longer have sufficient space available between built-up structures to create the necessary percentage of green cover. [8]
Moreover, the calculation of canopy cover ignores that higher temperatures are produced by high-rise buildings. When such massive amounts of concrete heat up during the day, they retain the heat during the cool of the night and act like radiators both inside and outside the building. Thus, as I personally experienced living in Tokyo, even when the outside temperature is low during the night, the radiator effect of the walls requires strong air conditioning to make rooms liveable, burdening the power supply and increasing the emission of C02.
Consequently, building regulations calculated merely on the area of canopy cover are highly inequitable. Multi-storey buildings must be accompanied by large “carbon sinks” that is, be surrounded by suitably large areas of “living infrastructure” (vegetation) to make up for the hotter air they emit. Moreover, if canopy cover is calculated by districts rather than individual plots, it permits covering a whole plot with heat-reflecting material with the argument that a sufficient area of canopy cover is provided by trees on the verge or other near-by public land. In this fashion the re-development of blocks in older suburbs impacts on neighbourhoods with increasing temperatures in summer.
Below are two examples from Narrabundah. From 1946 pre fabs were built in this suburb for the workers: small houses on good-sized plots.[9] Many are occupied by elderly residents but
have become unaffordable for these long-time occupants with constantly rising rates and are sold to developers. The houses are demolished, and the plots are razed of all vegetation, including mature trees, and covered nearly in their entirety by buildings and concrete.
The author’s photo at left illustrates one of two adjacent identical developments where three connected townhouses have replaced a single dwelling. Virtually the rest of the property is covered by a wide drive running the full length of the block. The neighbours’ garden has mature trees, but their single dwelling will be much affected by the heat created by the massive amount of concrete across the fence. This is likely to cause the residents of the townhouses as well as the single house next door to rely heavily on air-conditioning in summer, emitting copious amounts of hot air affecting an increasingly larger area of the neighbourhood.
Barely a hundred paces away, another developer purchased four single small houses with mature gardens, and then flattened the whole area to cover close to 90% with concrete to provide underground parking and storage for ten townhouses.
The author’s photo upper left shows the back of the development where concrete extends virtually to the back fence with only relatively small plots of soil every two houses close to the fence available for vegetation. The rest of the backyard area is covered by concrete the whole width of the four blocks, down to the narrow space between each pair of townhouses. The rails of the sliding doors facing the concreted area at the back of the house are some 10cm above the level of the concrete, indicating that the area will not be covered with soil deep enough for planting trees and shrubs.
In front, the small area between the entrance and public footpath (the grey strip in the lower author’s photo) will no doubt be filled with paving to the front doors and courtyards for privacy. Large, mature oak trees on the public verge shade the road and footpass. This might bring the calculation of the canopy cover close to the required 30%, even though this massive area of concrete will very negatively affect the neighbourhood.
The problem is even worse in the new suburbs where, as mentioned above, one developer is permitted to construct 243 apartments, 87 townhouses plus commercial spaces on merely two blocks in Gungahlin.[10] At present the area on the other side of the road is still green with a few trees, but since this plot is next to a tram stop, it seems unlikely that it will be turned into a park. Even if it were, one needs to ask: Is it fair to have the public purse (namely all of us) pay for green spaces so that developers can achieve maximum profits by covering plots with excessive amounts of concrete?
The decline of vegetation and canopy cover in Canberra’s suburbs is not new. The percentage of building to open space on plots has always been regulated, but with new developments it has become obvious that the required open space is increasingly concreted for wide drives and paved courtyards or to be covered with pebbles and artificial grass. In response, community groups have for years now pleaded for a requirement of at least 30% of permeable soil, soil deep enough for the roots of sizable trees, before a development application is approved. If this rule were applied without exception, it would be easy to understand and easy to enforce with satellite imagery to ensure that the area continues to be covered by vegetation. However, for developers it would decrease the size of structures they at present place on the land they purchase, as illustrated by the above examples. Consequently, the variation to the Territory Plan known as 369 has been watered down by clauses permitting a host of exemptions and requires review if it is to prevent increasing extreme temperatures also in Canberra’s older so-called “leafy” suburbs.
In brief, the ACT government has produced a host of material describing what should be done to mitigate the Urban Heat Island effect, but the outcome remains elusive to the public. The document with the promising name “Canberra’s Living Infrastructure Plan: Cooling the City” contains a long list of actions which the EPSDD (Environment, Planning and Sustainable Development Directorate) has begun to carry out from 2020, such as a “Microclimate Assessment Guide” and “Microclimate Assessment Program”, a “Climate-wise Landscape Guide” and “Climate Plans.” When approvals for large new apartment and commercial buildings covering the greater part of a block are announced, simultaneous publication by the EPSDD of the required microclimate assessments and climate plans would assure those living in the neighbourhood that they will not have to suffer increased summer temperatures due to the new development. Moreover, the outdated CSIRO temperature map of the ACT must be updated after every summer to assure the public that the actions the EPSDD has committed to are effective and sufficient to maintain the Bush Capital as one living up to its name, and a place safe to visit even in the heat of summer.
12. Our Ecological Footprint.
The ACT government supports its 70% infill policy with the argument that Canberra’s ecological footprint must be restricted. However, the ecological footprint is often considered to be the area occupied by buildings and not calculated by measuring the much more harmful amount of greenhouse gases emitted by the occupants of high-rise buildings into the atmosphere.
Further, there is the general assumption that residents of high-rise apartments consume considerably less energy and hence produce less C02 than occupants of single low-rise houses. Anybody voicing doubt needs only to be referred to the US Energy Information Administration (EIA) stating that “Households living in apartment buildings with five or more units use about half as much energy as other types of homes.”[11] No doubt the ACT Government’s decision that 70% of all new buildings must be suburban infill, presumably high-rise as that along the Civic to Gungahlin light rail line, is based on this kind of information.
Rather ironically, however, a paper presented at the Annual International Conference on Tall Buildings and Urban Habitat (CTBUH) held in Sydney in 2017 dropped the bomb-shell information that a detailed study comparing energy consumption in Chicago high-rise and free-standing houses showed that energy consumption per person in the latter was lower.[12] Which of the two statements is correct?
As the EIA material readily states, apartments are generally smaller than houses and require less energy. Further, a statistically significant number of apartment dwellers in the US are of a lower economic status than single house dwellers and forced to economize on living space as well as heating and cooling costs. The Chicago study attempted to avoid such distorting facts by comparing the energy consumption of apartment and single house dwellers of comparable socio-economic status and income.[13] Since in Canberra the socio-economic status of apartment and single residence dwellers is comparable, the Chicago study is the relevant one.
The results of this study are often startling. As one would expect, the average Gross Floor Area (GFA) per household in suburbia is 53% greater than that of high-rise flats (226 m2 compared to 147 m2). But when the GFA is calculated per person, suburban homes show a greater GFA efficiency with 68.6 m2 per person, compared to 77.4 m2 per person in the high-rise setting. The same applies to cars. Calculated per household, the number of cars per household is slightly higher in suburbia, but lower when calculated per person: 0.5 versus 0.6 for high-rise occupants.
Energy use, including heating and cooling, hot water and all other appliance and equipment operations show the same trend. When calculated per square meter, high-rise living shows a 5% increase over suburban homes. Again, this is an unexpected result, for many of the single houses in this study were of an older type and expected to have higher energy consumption than the more recently built energy-efficient high-rise. The reason for higher energy consumption in high-rise is that beyond the space of individual flats, a considerable amount of common area, such as indoor pools, whirlpool spa and fitness centres with changing rooms and showers, as well as entrance halls, libraries and, of course, lifts and long corridors are part of the equation. With individual houses, savings can be made when all occupants are away, but this is not possible in the common areas of apartment buildings which are usually heated or cooled and often also lit 24/7, consuming a considerable amount of energy.[14] Often the temperature within flats is also beyond the control of individual occupants. In winter, windows are opened because the heating is excessive while in summer, the temperature of the air conditioning is adjusted in the same way.
In addition, the authors compare Home Embodied Energy cost which they define as
“the energy consumed in all activities necessary to construct the building, including the embodied energy in the materials themselves, and the direct energy used by the contractors/sub-contractors for all on-site and off-site activities to facilitate any construction, prefabrication, administration and transportation of goods. In addition, during a building’s life, embodied energy is added through goods and services used in the maintenance and refurbishment of the home.”
Calculated on a 100-year life span for all buildings in the study, this resulted in an average annual value of 0.101 GJ per square meter for high-rise living and some 30% less 0.068 GJ per square meter, for the suburban homes.[15] (To convert GJ to kWh, multiply by 277.8.) Water consumption is, of course, higher for suburban homes surrounded by gardens with 24,266 gallons p.a. per person, as compared to 17,652 gallons for high-rise occupants.
The above study shows how generally accepted statistics can be misleading. The Chicago study indicates that when the energy consumption of people of the same socio-economic background is compared, that of flat dwellers is not lower, as expected, but higher than that of residents in single houses. Moreover, when one adapts the Chicago study to best-practice Canberra conditions, the consumption of energy and water of free-standing houses is further reduced. For instance, if single homes have rainwater tanks connected to toilets, washing machines and all outside tabs as mandated for new buildings in the ACT, water consumption is likely to be equal if not lower for single homes than for flats, even when gardens are watered. Solar panels and batteries will much reduce electricity consumption in the case of free-standing houses, while the roofs of multi-story buildings frequently become entertainment areas and have little or no space for solar panels. Similarly, saving energy by means of solar-passive design is problematic with apartment buildings. In the case of free-standing houses, overhanging eaves and deciduous trees can protect the structure and its inhabitants from the heat of the summer sun while the low rays in winter can enter, warming the dwelling.
13. Where is Canberra’s rapidly increasing population supposed to live?
At the beginning of the 20th century, the area allotted to the Australian Capital Territory was considered ample. Taking into account that after 50 years the US capital of Washington had a population of 35,000 for a national population of 17 million, Australia’s population of just over 4.4 million was expected to result in a capital of some 2,000, growing in proportion with the increase of the nation’s population.[16] Nevertheless, a population of 25,000 was specified in the Australian Capital Competition.[17] What could not be foreseen is the rapid growth of the population of Australia as a whole and, perhaps even more significant, the global trend of rapid urbanization. One may add to this that the living space per person has dramatically increased, while the number of people in the same home has decreased, resulting in even more homes required.
Canberra’s population is increasing at a fast rate, and the fact that the government’s land release programs often have more than fifty times the number of registered applicants than available plots indicates that there is a large number of people who don’t want to live in flats.[18] Lots as small as 350 sqm in the new suburb of Macnamara in the Ginninderry development suggest that even if the requirement of 30% deep soil and the planting of trees were strictly enforced, this suburb too will in future be plagued by the Urban Heat Island effect. If climate change and the resulting rise in temperatures make both the proposed infill of population in old suburbs as well as the new suburbs with their small plots and large houses unsuitable for healthy living, where is the rapidly increasing population supposed to go?
Cities all over the world have faced the problem of overcrowding and one solution has been satellite towns. Working in Japan, I was fortunate to live in a satellite town within Greater Tokyo, teaching at a satellite university campus. The thirty minutes’ walk to my office was shaded by plane trees, with azalea bushes along a low fence separating pedestrians and cars. Accounting centres and other offices of large companies were housed in architecturally interesting buildings no higher than three storeys on large plots planted with trees, covered with fields of lavender or other decorative vegetation. Good-sized sections of the original forest were preserved and linked so that animals could migrate. Most importantly, in summer temperatures were considerably lower than in down-town Tokyo.
An example from the other side of the world is the Waldparksiedlung (forest park development) Boxberg in the photo left, overlooking the Rhine valley, built in the 1970s to relieve population and housing pressure on the old university town of Heidelberg, Germany. [19]
If Walter Burley Griffin could be asked the question of where the increasing population of his low-density city should live, he might well refer to Oak Park, the satellite town outside Chicago where he grew up and worked in the office of Frank Lloyd Wright. It had large plots, filled with trees and was easy to reach from Chicago since it was situated along the railway line.[20]
Griffin’s ‘temporary’ railway station at Kingston is still there and the line to Sydney operating. Since it runs mainly through open country, partially wooded, it would be well suited for satellite towns carefully placed into the natural environment like Griffin endeavoured to create with Canberra and the Sydney suburb of Castlecrag. These could become examples of ecological planning with regulations to prevent the clearing of land beyond what is essential (as in the photo above), incentives to use materials mitigating the Urban Heat Island effect such as rammed earth and strawbale instead of concrete, combined with solar passive design, efficient surface and roof top rainwater harvesting, grey water for irrigation, shared batteries for the storage of solar power, etc.
At present the train from the Kingston railway station to Sydney operates too infrequently and is too slow to be of use for commuting to the already existing neighbouring towns. The Federal Government investigated a high-speed train running at hourly intervals between Canberra and Sydney in 1996/97, but issues such as land acquisition, noise, safety and environmental concerns as well as the lack of finance led to failure.[21] However, now that a reduction of C02 emissions has become a question of survival for future generations, the pollution produced by the steadily increasing number of buses and planes between Canberra and Sydney might finally tip the scales in favour of a fast electric train or at least the more affordable medium-speed rail operating in countries like Canada, the U.S., Sweden and Switzerland.
Either of the above would put satellite towns between Canberra and Goulburn in the reach of Kingston Railway station within minutes. But even a train running just somewhat faster than the present one, offering frequent services especially at the beginning and end of the working day, would mean that these satellite townships would take no more time to reach than outlying suburbs of the ACT.
With Canberra Railway Station being part of the East Lake renewal project, there is the opportunity to turn the station into a commercial hub for both the new residents of East Lake and those arriving by train from satellite townships. The government’s flexible work hubs (Flexi hubs), which the Chief Minister announced for all parts of the ACT, would accommodate those coming in by train to spend their one-day-a week in a communal office networking with their colleagues. Moreover, with the station being within walking distance from residential East Lake, the new suburb would be a convenient locality for those frequently commuting to Sydney, especially if the fast or medium-speed rail between Canberra and Sydney should finally materialize. In this age of climate change and Urban Heat Island effect, what better environment could attract the talent the Chief Minister wants to draw to Canberra, than being able to live surrounded by nature, yet within easy commuting distance to Australia’s capital and the metropole of Sydney?
14. In Conclusion: Is Canberra the ideal City for the future?
“In planning Canberra, every detail of the natural conditions were (sic) studied … to preserve them … so that the city could be a living healthy and growing thing. The continent of Australia will do well to learn this lesson from its capital. Such reverence for the earth is acutely necessary now, for the rate of destruction is increasing rapidly, even in a century or two the Earth may not be capable of supporting life.”[22]
These words could well have been spoken today, but they were part of a 1938 radio broadcast by Marion Mahony Griffin, the collaborator and wife of Walter Burley Griffin.
The British urban planner Peter Hall (1932-2014) suggested that Canberra “will soon rank with Washington as one of the world’s great monumental capitals.”[23] However, for Mahony Griffin it was not the monumental aspect of the capital city she planned with her husband which was of importance. For her, the natural conditions, the geographic environment and flora which, in tune with the philosophy of the Prairie School, the Griffins carefully integrated into the city plan, rank first and must be preserved. Second comes the health of the city dwellers, a result of nature preserved. For in the Griffin’s thinking both physical and mental health depended on the natural environment that shaped their design. Thirdly comes the growth of the city. For Mahony Griffin there is no question that this must take place respecting the first two principles if life as we know it is to continue.
Mahony Griffin is striking a prophetic note. In the 110 years since the Griffins submitted their design for Canberra, urban planning has come full cycle and public health has again become the issue. For science tells us that unless we provide sufficient space for urban forests in our environment, increasingly extreme temperatures will make living in this frequently parched land impossible. Canberra has arrived at a turning point. The fundamentals of the Griffin’s design have well prepared the city for the future. Relevant now are the words which Edmund Bacon (1910-2005), the American urban planner of modern Philadelphia, expressed when he visited Canberra in 1966:
“The great accomplishment of Walter Burley Griffin, and of the Australian nation which selected, and up to now has supported the Griffin plan, was the capacity to conceive space itself as the basic design issue … Now that you have produced such a masterwork, the great issue is that you don’t wreck it.”[24]
Many people claim that parts of Canberra have been wrecked already when areas in the North of this garden city were turned into a light rail corridor with high-density, high-rise housing. Here the Urban Heat Island effect will be acutely felt when the next parched summer arrives. The question is, will the ACT government continue to encroach on the open spaces central to the Griffin design by bringing the tram line to Canberra’s South with patterns of housing similar to the North, making it look more like Sydney and Melbourne, and less like the capital the Griffins designed?
Gough Whitlam (1916-2014), Australia’s only prime minister who experienced Canberra as a schoolboy, praised it as a city Australians could justly be proud of, and felt that there could be no better tribute to Walter Burley Griffin than having the design “applied throughout Australia, raising up new regional centres to surpass the beauty and the efficiency of Canberra itself.”[25]
Unfortunately, Whitlam’s decentralisation policy fell victim to “rational economics” and was reversed.[26] This left Sydney and Melbourne with ever more high-rise, high-density areas, in the years to come increasingly affected by the Urban Heat Island effect. London did the opposite. The centre of this great metropole has become reachable within a 30-minute train ride from a large choice of regional satellite towns.[27]
Now that Australia has another Labor prime minister, there is hope that he might follow Whitlam’s advocacy of decentralization. The creation of well-planned regional satellite towns along the railway line to Sydney would not only provide families with the plots for the detached homes they are seeking surrounded by nature mitigating the Urban Heat Island effect. It would also eliminate the need for “wrecking” the accomplishment of Griffin and that of the Australian nation which 110 years ago selected and continued to build on his vision of the ideal city of the future.
TO READ PART ONE CLICK HERE
TO READ PART TWO CLICK HERE
Footnotes: [1] The IPCC delivers its starkest warning yet about climate change | The Economist. Consulted August 2021. [2] Jacqui Meyers, environmental analyst, CSIRO and lead author of Mapping Surface Urban Heat in Canberra, Strategies for turning down the heat - Ginninderra (ginninderraproject.com.au) Consulted May 2022. [3] ‘Heat island’ effect could double climate change costs for world’s cities: Broadcast: News items: University of Sussex (Consulted May 2022). [4] Daniel Sandford, Suburban Heat: An examination of the urban heat island effect in Canberra, through an in-depth analysis of the suburb of Wright and a review of ACT Government policy, Alastair Swayne Internship, 2021, p. 3. James Purtill, “Heatwaves May Render Parts of Sydney Unliveable in Decades,” ABC News 25.1.21, https://www.abc.net.au/news/science/2021-01-24/heatwaves-sydney-uninhabitable-climatechange-urban-planning/12993580 [5] CSIRO, Our Future World - CSIRO, “Our Future World: Global megatrends impacting the way we live over coming decades”, July 2022, p. 10. [6] Progress, 1913, as cited in The Griffin Legacy, p. 40. [7] Daniel Sandford, Suburban Heat: p. 6. [8] Nearmap names Aranda ACT's leafiest suburb for most trees while new developments fall behind | The Canberra Times | Canberra, ACT. (Consulted June 2022). Daniel Sandford, Suburban Heat: p. 9. [9] Alan Foskett, Homes for the Workers: The History of the Narrabundah Pre Fabs, The Narrabundah Pre Fabs History Group, 2011. [10] See NUE Camilleri Way GUNGAHLIN, ACT 2912 is for Sale on Zango | Zango. Consulted July 2022. [11] U.S. Energy Information Administration - EIA - Independent Statistics and Analysis. Consulted May 2022. [12] Antony Wood, & Peng Du, “Dense Downtown vs. Suburban Dispersed: A Pilot Study on Urban Sustainability”, International Journal of High-Rise Buildings, Vol. 6/2, 2017. [13] Antony Wood, & Peng Du, p. 119. [14] Antony Wood, & Peng Du, pp. 120-121. [15] Antony Wood, & Peng Du, pp. 121-122. [16] Paul Reid, p. 28. [17] John W. Reps, Canberra 1912, p. 69. [18] Suburban Land Agency defends supply of residential land in ACT as tight market drives price boom | The Canberra Times | Canberra, ACT. Consulted July 2022. [19] heidelberg.de - Boxberg. Consulted May 2022. [20] The well-known British town planner Peter Hall outlines Britain’s strategies past and present to cope with the lack of housing at Town planning: Sir Peter Hall, UCL - YouTube. Consulted June 2022. [21] High Speed Trains between Canberra and Sydney – Parliament of Australia (aph.gov.au) Consulted July 2022. [22] The Griffin Legacy, p. 40 [23] Peter Hall, cited in The Griffin Legacy, p. 24. [24] Edmund Bacon, cited in Peter Harrison, p. 96. [25] Gough Whitlam in 1969 cited in Peter Harrison, p. 96. [26] Stephen Bargwanna, Is decentralisation worth keeping on the policy agenda? | The Canberra Times | Canberra, ACT. Consulted May 2022. [27] A good summary of Britain’s planning of satellite towns can be found at Town planning: Sir Peter Hall, UCL - YouTube. Consulted June 2022. For towns within commuting distance of London see London’s Best Commuter Towns - TotallyMoney.com. Consulted June 2022.