In three months alone 49 residential towers were approved in the Melbourne CBD. But why is the Victorian state government, which controls approval for the biggest towers, ignoring the City of Melbourne’s Green Star minimum standards? Especially when so much can be done to make these tall buildings as sustainable as their commercial neighbours.
According to Tony Arnel, global head of sustainability for Norman Disney & Young, Melbourne’s new crop of tall buildings could be in a race to the bottom.
“All these buildings are being built to minimum code standards, and those aren’t very high,” Arnel says. “The building code only eliminates worst practice. When you only do the minimum you are delivering a project that is going to be at the bottom of the market.”
Currently, multi-residential projects are required to meet the basic Building Code of Australia Section J requirements for natural ventilation, daylighting and heating and cooling demand. New residential development projects are required to achieve a total average of six stars under the National House Energy Rating Scheme, and each dwelling must achieve a minimum five star standard.
But Arnel says that a disconcerting aspect of the current approval process is that while the City of Melbourne’s Metropolitan Planning Scheme has a clear policy around 5 Star Green Star as a baseline for all buildings, the council is not responsible for approving developments over 25,000 square metres. Instead, these are approved by the Minister for Planning, who requires projects meet only the Building Code requirements instead of achieving best practice.
“It is disappointing the City of Melbourne policy is being avoided. The reality is that what is in the code is a long way away from 5 Star Green Star,” Arnel says.
And while Docklands has the nation’s highest concentration of Green Star commercial projects, there are no Green Star residential towers in the CBD, Southbank or Docklands. This, Arnel says, indicates a problem.
“Tall buildings can be sustainable, if you simply apply the fundamentals of energy, water, waste and materials,” Arnel says. “At the end of the day, what you need to do is not that complicated.”
Sustainable design consultant and GIW Environmental Solutions director Gary Wertheimer says that because Section J requirements are the absolute minimum requirement, there is a risk that a development that meets those benchmarks but goes no further could find itself outdated if market demand shifts further towards sustainability.
He also says there may be a compliance issue in terms of projects meeting even those basic standards.
“Enforcement of the regulations has been an ongoing issue. It is unclear how vigilant the industry is in ensuring the compliance with Section J on site. This is a major issue which demands more work by the industry,” Wertheimer says.
Where green is cool… and a marketing tool
That’s quite a contrast to inner city areas such as Fitzroy, Collingwood and Richmond, where buyers are actively looking for green residential product that aligns with their ideology and vision for the future, and where developers are incorporating quite progressive ESD features, he says.
An example is a development on Queens Parade at Clifton Hill, which is in the planning stage and aims to deliver a 4 Star Green Star rating.
In these kinds of areas a Green Star rating is a “great marketing tool” for clients, Wertheimer says. “It is about market differentiation, responding to market and showing true leadership.”
Green is not so hard
High rise residential buildings can also produce quite strong environmental outcomes, Wertheimer says.
This can include exceeding the 6 Star standard for building energy efficiency, solar panels feeding back into building common areas, rainwater tanks for toilet flushing or irrigation, high efficiency hot water systems and dedicated bicycle facilities designed above the minimum number prescribed under current planning schemes.
Other ESD measures can include optimising the use of low VOC finishes and floor coverings, ample natural daylight to habitable areas, natural cross-ventilation, and waste management strategies for ease of recycling such as appropriate sorting within apartments and dedicated bin chutes.
Parking spaces on the wane
Parking is often a highly contentious issue but some inner city councils are starting accept lower car parking ratios. Green Star also rewards minimised car parking.
Wertheimer says it makes sense where a lot of tall buildings are going up close to public transport nodes and car share locations.
“People are starting the transition towards a high density inner city lifestyle akin to New York, Tokyo and London,” he says.
“At present developments seeking to attract the overseas investor market will consider no parking, largely because those occupying these buildings are university students or live and work in the same local.”
Local buyers still cling to the notion that independent vehicle ownership is an essential, he says.
“I would say that it is only a matter of time before the economics and impracticality of this model begins to waver.”
High performance facades are increasingly important to comfortable indoor environments and good daylight. Wind load in very tall buildings may preclude having balconies, however wintergardens might be a good alternative.
Wertheimer suggests that a north facade is best. Here they can aid with passive heating during winter by compartmentalising heat from the facade. In summer the space can be used as an internal living area that can be opened up completely when the outside conditions are comfortable.
“The way the space is to be used will dictate the external glazing. Louvres are definitely a good option but given that these are generally single glazed we tend to also suggest other types of window systems which can be delivered as a double glazed unit.
“Building envelope design is a fine art. On the one hand we seek to maximise views with large expanses of glass, while on the other hand we require thermally efficient glazing solutions to maintain comfort. We then balance passive solar gains, natural daylight, shading, privacy and aesthetics.”
In terms of ventilation, as buildings continue to become more airtight designers need to pay close attention to providing adequate natural ventilation. This is particularly relevant to saddleback apartment configurations and south facing apartments, Wertheimer says.
Making density achieve its potential
Sarah Reid, sustainability group manager for NDY Melbourne agrees that there are many opportunities to embed sustainability into tall tower projects, building on the innate sustainability that comes from high density living.
“More and more projects are also using Green Star Multi-Unit Residential as a benchmark, raising sustainability standards across the industry. And there are a lot of easy wins to enable residents to reduce their personal environmental footprints – in particular using new smart technology,” Reid says.
In relation to Building Code requirements, the challenge of achieving the benchmarks for natural lighting, natural ventilation and passive heating and cooling may require a rethink of how apartments are laid out, with Reid pointing out that internal rooms with no facade access are generally underperformers in terms of sustainability.
According to Reid some solutions work well for mid-rise projects but not necessarily for a very tall building context.
Solar power is one, with the roof area of a very tall building simply too small in relation to the number of apartments for traditional photovoltaic systems to produce enough power to make a major contribution to overall building energy needs.
Lower rise high density projects such as the 5 Star Green Star Briggs and Jackomos Hall student residential building at Monash for which NDY was consulting engineer can incorporate rooftop solar more effectively, with that particular project achieving such a high level of solar energy generation and energy efficiency in the building systems that it almost halves the base building greenhouse gas emissions.
“However there is significant potential for building-integrated PV systems to be integrated into facades or shading elements on tall buildings, avoiding the overshadowing issues on lower rise projects,” Reid says.
“Cogeneration can work well to supply low carbon electricity to central services at the same time as meeting domestic hot water demand, and building integrated PV has a lot of future potential.”
Other innovations work extremely well in commercial buildings or medium-density residential setting, but are hard to apply to high-rise.
Motion sensors for common area lighting for example might not work so well in residential more often than not there will be people moving about, Reid says.
According to Weirtheimer PV installation connected to the common areas is typically a matter of course. It is however hard for it to entirely balance out building energy demand in the larger buildings.
Wertheimer suggests alternative technologies such as LED lighting and control systems, and CO2 detection systems as part of HVAC systems, to control fresh air requirements, thereby providing ventilation only when it is actually required to maintain indoor air quality.
High-end technological solutions such as C-Bus automation systems might deliver a benefit in sustainability terms, but they add an unnecessary level of complexity and are seen as a luxury, he says.
What people can see, they can change
Another option is to help inform residents about energy use and to embed energy efficiency into their lifestyles.
Real-time meter readouts to in-house displays or mobile devices will be a game changer, Wertheimer says. Studies show that when people can directly see how much their activities are costing, energy consumption drops, he says.
Reid agrees and her company is keen to install visual energy monitors in each apartment.
A dramatic price drop – from around $1000 each to around $100 each – helps. As do shut down switches, similar to hotel key cards that can power all lighting, heating and cooling on or off.
“It is a challenge trying to persuade occupants to think about their behaviour,” Reid says.
Lifts are essential in the tall building context, however all systems are not created equal in terms of energy use.
Reid says that in terms of reducing the energy use from tall buildings’ vertical transportation, regenerative braking systems are becoming standard. However, some buildings may not be appropriate for destination controlled lifts as the number of residents would mean this type of system could result in lifts frequently making trips with only one or two passengers, using more energy overall.
“Our goal is to try and take up less space and have fewer lifts, and utliise sky lobbies. People may have to get out and change lifts as part of the solution, but that is a key opportunity to reduce the energy used,” Reid says.
Use of natural light
Central atriums to bring light down into the centre of the building is another concept that works for mid-rise, with Common Ground in Melbourne, for example, having a full-length void space in the centre for increased natural light to apartments. Reid says that in a very tall building the quality of light in the lower levels simply would not be adequate to reduce the need for artificial lighting.
There is also a conflict between setting aside the space for a void and the developer imperative to maximise useable floor area in apartments in order to achieve a good return.
The design of floorplates in the very tall buildings also generally means artificial lighting is required for corridors, as access to natural light from the facade is more important as amenity for the apartments themselves. Again, the use of daylighting for common areas is something it is often easier to achieve in a medium density design.
Rainwater harvesting is an option for residential tall towers. However, due to the small roof area, this is generally used for irrigation, swimming pool top ups and common amenities flushing only, as it will not be possible to collect sufficient amounts to meet demand for toilet flushing in every apartment, as is often done in much smaller multi-residential projects and also in detached dwellings. In Victoria detached dwellings are required under the code to either install solar hot water or harvest rainwater that is plumbed for toilet flushing.
“Blackwater plants are also something I would avoid for a very tall residential tower,” Reid says. “It is a big ask of an owners corporation to operate and maintain the plant, and the blackwater plants are also very energy-intensive. I think they are a much better solution for precinct-wide availability of recycled water.”
Ultimately, it comes down to developer priorities
The main impediment to better sustainability outcomes generally for many very tall towers is the overriding concern for investor yield on the part of many developers. Reid says that design that needs to maximise returns from the site is not always the type of design that works well for sustainability outcomes.
“There is a need for compromise there,” she says.
“Where residential clients have a longer term interest in the building, such as Common Ground or Briggs and Jackomos, it is much easier to make the business case for sustainability initiatives. It is much harder in the investor led multi-residential sector, there’s more structural and institutional barriers to overcome there than technical ones.”
Wertheimer says the key message is that it is one thing to go high, but with it there is is also the need for responsibility.
“Iconic skyscrapers which dominate the skyline are now required to act as beacons for a sustainable future.”