Is it possible to achieve a net zero energy building, or NZEB, at scale?
It’s often inherently harder to do so, often due to increased occupant density, intensity of operations within or simply less project footprint on which to harvest renewables. By far, the best approach is to undertake drastic reduction in energy demand of the project before serving these reduced energy requirements with simple renewable systems.
Nearly-zero energy building approaches or those that seek to drive down demand before applying renewable energy generation, for example the Passivhaus standard, give a great base for NZEB. The Passivhaus realises drastic reductions (up to 90 per cent) for both HVAC and whole building energy consumption.
There are many, many built examples around the globe of the net zero energy buildings, though with most in the small scale or residential sector, it’s hard to find inspiration on super-size scale. Here are a few of the highest achievers:
Pearl River Tower, Guangzhou (China)
“[Redefining] what is possible in sustainable design”, the 214,000 square metre, 71-storey tower in Guangzhou was completed in 2010 and incorporates building integrated wind turbines to generate much of the building’s energy. The aerodynamic form of the tower drives wind through openings, enhancing energy harvest. The building’s double skin façade contributes to energy efficiency and the form is conducive to extensive daylighting and views. Further attributes include solar PV, chilled ceilings and under floor ventilation.
NREL RSF, Golden, Colorado (USA)
The US National Renewable Energy Laboratory Research Support Facility (RSF) is a stunning example of high-efficiency design. Located in Colorado, the 33,000 square metre facility utilises extensive daylighting (at 100 per cent of workstations), natural ventilation, high efficiency façade with triple glazing, under-floor ventilation, plug load management and a state-of-the-art high efficiency data centre. Solar PV and wind provide energy, while the radiant heating system operates from a district system fed by a wood-fired boiler and ground source heat pumps. The building is also rated LEED Platinum.
Bullitt Centre, Seattle (USA)
While just a modest six storeys, this project is both significant for its holistic approach to sustainable design and a visual standout. Designed to meet the Living Building Challenge, which requires a project to generate in excess of 105 per cent of the net energy requirements, the building has, to date, outperformed the targets set during the design by a whopping 33 per cent. An ultra-efficient façade coupled with an unmissable array of solar PV (244kWp) distinguish the building and work to hit the net zero mark, while supplementary passive design measures, a geothermal heat exchanger, exhaust air heat recovery, night purge and radiant heating all help. But a key factor to the project’s success, despite being a speculative development, has been the education process for the occupants, helping to engage users and reduce plug loads. The project also targets net zero water (within regulatory restrictions) and is free of Red List toxins.
Honourable Mention: RHW2 tower, Vienna (Austria)
Housing 900 staff for the RHW Group, as well as a kindergarten, conference centre, garages and catering facilities, the RHW2 Tower is located adjacent to the Danube Canal in Vienna. At 21 storeys and 24,140 square metres of occupied area, the tower leads the way in energy efficient high-rise commercial design. The tower is certified to the Passive House standard and utilises innovative systems such as a biogas-fuelled trigeneration system and canal heat rejection in order to realise first-year electricity savings of between 75 and 84 per cent savings on heating energy (compared to a typical UK office building). These figures are expected to improve with building tuning.
In the works: The Bloomberg Centre, Roosevelt Island, NY (USA)
The Bloomberg Centre is a four-storey, 15,000 square metre academic building, currently in construction at Cornell Tech’s Roosevelt Island campus. Designed by the architecture firm Morphosis, the building successfully melds architecture with performance, with the net zero energy target to be complemented by a LEED Platinum rating. The centre is dedicated to both art and academia and makes reference to the “push and pull between nature and human endeavour.” A sculptural array of photovoltaic panels sits atop the structure, and efficient HVAC includes geothermal heating and cooling. Construction is anticipated to be completed in mid-2017.
Other projects on the sustainable campus site include the world’s tallest Passive House building, which will also be the first high-rise residential Passive House project. This building will house 350 staff and students as part of the 200,000 square metre technology campus and is projected to save around 882 tons of CO2 per annum.
In the works: Pertamina Energy Tower, Jakarta (Indonesia)
At 99 storeys, this aspirational tower will house 20,000 workers when it is completed in 2019. Wind energy will provide electricity to meet 25 per cent of the building’s demand and a campus solar PV installation will top up supply. The brainchild of architecture firm Skidmore, Owings and Merrill, the tower will “be a symbol of Indonesia’s commitment to sustainable development.” The 540,000 square metre building is curved to mitigate heat gains and utilises geothermal systems and radiant cooling.
In the works: Tesla’s Gigafactory, Nevada (USA)
Elon Musk isn’t one to do things by halves. The Gigafactory, currently under construction in Nevada, was a project born of necessity. As Tesla ramps up production to 500,000 cars per year, competing issues of limited worldwide battery supply and price point for their cars demanded Musk and Tesla to look for alternatives. It’s entirely fitting that a project intended to “accelerate the world’s transition to sustainable transportation” would be, in itself, net zero energy as well as net-zero emissions. Rooftop solar combined with local wind turbines will deliver the energy required for operation, and the intent is that the whole operation will be electric.
What’s next for net zero? Many organisations around the world are considering or moving toward the target. The world needs to achieve net zero by mid-century. At a period in time where it has never been more critical to achieve significant advances in energy efficiency and reductions in carbon emissions, the focus will move from single building projects to community and district solutions.
As the global community (slowly) starts to take action following COP21 and amid a growing climate crisis, targets like net zero will provide aspiration for more inclusive developments. Communities such as the Kapuni Village (Hawaii) and UC Davis show how modern living can be achieved with lower impact. Seacombe West, planned for Gippsland in Victoria, will demonstrate how it can be achieved locally and with a regenerative spin.