High-Performance Tower in Australia

HIGH-PERFORMANCE TOWER IN AUSTRALIA Double row panel N E N W PV panel on horizontal facade shelf Single row panel Triple row panel Architecture with performance The office tower is organized as seven discrete but interconnected habitats. Each four-level habitat is a freestanding mass-timber constructionsupportedwithin the steel exoskeleton. Thenaturally ventilated protected Park zone is located at the northwest side of each habitat. These spaces are key to the tower’s exceptional environmental innovation and diminished ecological footprint. A single facade expression wraps the tower and creates its iconic appearance. The staggered panels of the facade may accept glass louvers, single glazing, IGUs, and operable vents to address the environmental needs of each location of the tower interior. In response to site and orientation, the facade is designed a single thermal envelope or as a double facade. The facade interplay with climate and sun The performance of the tower’s faceted and operable facade system is essential achieving its high levels of environmental excellence. The innovative facade enables the project to leverage Sydney’s climate at all times of the year in a choreographed play of natural and mechanical ventilation that results in tremendous savings on energy and a reduced carbon footprint while increasing the wellness and comfort of the building’s occupants. Optimized solar gain mitigation The facade structure with frames, beams, exoskeleton, horizontal opaque shelves and high selective glazing tiled 18° outwards creates a complex filter for solar radiation and daylight. To inform the design the hourly reduction of solar radiation was evaluated with Radiance and Grasshopper scripts, considering the different wall types for the major facade orientations. The proposed facade specs have been tested with detailed simulation with TRNSYS 18, a leading software for dynamical hourly system analysis. The results were further considered for the thermal, comfort and energy simulations. Internal loads Assumptions for internal loads and design density have been mindfully reduced and coordinated to meet the requirements of high efficient future tech industry work spaces. Active system performance The radiant panels can be efficiently operated most of the year directly with cooling water from cooling towers with supply water temperatures dynamically ranging up to 21 °C. Only during conditions with high wet bulb or very hot ambient air temperatures chillers will kick in to lower supply temperature to 18°C. In heating mode heat pumps will provide warm water on a low temperature level. Both, the high cooling water and the low heating water temperatures allow for a very efficient operation of the supply systems. The mechanical supply air system is supplying fresh air tempered to 18 °C. Avoiding low supply air temperatures and dewpoints in summer is creating significant energy savings. The return air from the spaces is spilled over to the parks. There is no energy advantage in using heat recovery. Consideration is given to optimize pressure drops in the air ducts and shafts to significantly reduce auxiliary energy demand. Energy modeling The thermal energy modeling includes space heating and cooling, heating and cooling for temperedmechanical supply air and DHW. All energies are converted to electrical energies. The electrical energies include electrical energy for: office equipment, lap top and appliances, artificial light, energy for mechanical air supply, BMS and auxiliary energies, elevators and the kitchen in YHA. It is anticipated that the heating and hot water will be supplied by heat pumps. Given the high ratio of hot water (in the YHA) only a moderate COP of 2 was considered fore conversion into electrical energy. For chillers, a COP of 4 is anticipated, for the cooling tower of 20. Simulated zones of tower building The building comprises a total GFA of about < 77,000 m² on 32 above ground floor levels. Letable areas, NLA, are about 7,000 m² in the YHA, about 52,000 m² in the office tower, about 2,700 m² in the Crown terrace areas and Shed Roof, and about 1,000 m² Retail. The color code indicates the assigned thermal zones for the energy modeling. _______ Solar gain control Solar incident radiation on NW facade, solar radiation passing facade structure and solar radiation reduced by structure and glazing. Top for a typical summer day, bottom hourly data for the full year. The combined solar gain reduction is about 85% in summer and 70% in winter. Operation -50% Construction -50% Renewables 100% _______ YHA level 1 to 5 _______ Habitat Level 7 to 14 _______ Habitat Level 15 to 22 _______ Habitat Level 23 to 30 _______ Habitat Level 31 to 34 and crown Level 35 to 37 _______ Electrical energy for base building and tenant Energy results of the detailed comfort and energy for 19 major thermal zones of the tower. _______ Daylight autonomy The design creates a high spatial daylight autonomy (sDA) in average of 60% across all working areas in the habitats (example for L1 and L2 only). Level 1 DA=90% sDA=94% Level 2 DA=68% sDA=70% Thermal envelope with double glazing Structural shade by horizontal shelves with PV Structural shade by frame and horizontal beams 18° tilted single glazing with high selective foil, SHGC of 41%, daylight transmittance 70% Shading by exoskeleton The diagram is illustrating the combined strategy for low-carbon construction and operation of the new high-rise building. Embodied emissions are combined with emission of a 10-year operation (2030 scenario). Building with mass timber replacing materials with high carbon emissions in construction is targeting to reduce embodied carbon by 50%. Optimizing the building and load will reduce the carbon emissions of operation by about 50%. Given the ratio of load and available areas for energy production on roof and facade, a net zero supply of the high-rise on the site appears not to be possible. Renewable onsite production could supply about 10%. The remaining energy needs to be purchased from recently added low carbon renewable energy sources through the RE100 commitment. Electricity purchased from public grid in NSW has a high carbon emission. Depending on source, the emissions range from 750 to about 920 g CO 2 per kWh. So, strategies to reduce energy consumption need to be combined with strategies to utilize low carbon energy supply. _______ Combined low carbon strategy Thespecificandtotal electrical energydemand forbasebuildingandtenant was simulated in detail for the current design status of the tower building. To set the results in perspective, theNational Australian Built Environment Rating System, NABERS is used. Reference design is equivalent to NABERS 5 star (Good), design with AC and innovative cooling is equivalent to NABERS 5.5 star (Excellent). The aspiration for the innovative high-rise is in the range of about 100 kWh/m²a, which is equivalent to NABERS 6 star (Market Leading). There are only very few office buildings achieving this in Sydney today as this is calling for a serious reduction of the energy consumption on the client or tenant side as well as for an optimized building design and highly efficient systems and operation. The Shed with lobby and retail is aiming on specific energy consumption of less than 250 kWh/m²a. The YHA is aiming on specific energy consumption of less than 120 kWh/m²a (including DHW). The total electrical energy demand (Atlassian and YHA) is about 6800 MWh/a. Out of which the YHA is about 835 MWh. The detailed simulated results correspond well to the energy numbers estimated and documented as aspirations for the design brief. The outstanding low specific energy numbers indicate the outstanding performance of the integral design. _______ Market Leading Energy Design Options for onsite renewable electrical energy production are limited in a tower. Photovoltaic can be used on the roof and in the vertical facades. On this tower the roof areas are used for people and the solar plain does not allow PV as roof canopy. The potential for optimized solar energy production with photovoltaic panels attached to the horizontal shelves was studied. The north-east and north-west facades at the park spaces are most efficient for energy production. The range of specific production is about 850 kWh/kWp on north-east to 1150 kWh/kWp on north-west. With about 3,800 high-efficient panels, with two parallel rows of PV cells, about 500 MWh/a could be produced. _______ Evaluation of on-site renewable energy production While part of the SSDA submission, at current phase of value engineering, photovoltaic is not part of the concept because of budget and code challenges. Cost. The current cost estimation for the PV panels and facade integration is high. To identify most efficient panel sizes and performance for money, the possibilities of geometrical integration and solar yield are studied. The color code is indicating different types with single, double or triple row of PV cells. The team is further investigating into simplifying panel design to one single size for easier facade integration and lower pricing by more developed details. Code. Australian codes for fire protection in high-rise significantly limit the use of PV panels in facades. The design team is investigating into possibilities to achieve a permit. Testing of fire rating with laminated glass-glass modules are ongoing. Achieving code compliance, proving feasibility, and creating an example of facade integrated PV in Australia with this tower will help to push the boundaries of limitations of current practice for building applied photo voltaic (BAPV). _______ PV panels attached to horizontal shelves at facade _______ Performing facade design “In a lifetime, there are but a handful of projects that etch themselves into one’s career memory. Some projects even tower above the few. To me, Atlassian Central is that project. Conceived in the shadow of an ideology, designed with a vision, and executed with passion, the Atlassian SLT building will eclipse the current building stock and forge a new paradigm. This building is the culmination of my experience over a 35-year career in sustainable design”. ____ _______ _______ __________ LCI Director, Lester Partridge “Atlassian has a unique opportunity to shift the needle on how commercial/office buildings are designed. Albeit that we are designers and developers of software, not property, we’ve elected to “hold the design pen” so that sustainability outcomes are not compromised at the sake of commercial outcomes. Our aim is to not win a plethora of awards with this design, but to show what can be achieved with sensible design that reduces the carbon footprint of the built forms that we occupy.” ____ _______ _______ __________ Atlassian APAC Real Estate & Development Leader Ric Wang ENERGY AND CARBON STORY _______ View of crown