This article was published in High Performing Buildings, Summer 2010. Copyright 2010 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Posted at www.hpbmagazine.org. This article may not be copied C A S E S T U D Y EAST and/or distributed electronically or in paper form without permission of ASHRAE. For more information about High Performing Buildings, visit www.hpbmagazine.org.

A Positive ’s Latitude East ranks among Australia’s five most efficient buildings. Latitude East’s performance stems from relatively standard building systems that are designed, implemented and controlled for maximum energy savings rather than green bells and whistles such as trigeneration, wind power or solar photovoltaics. LatitudeBY SCOTT WALKDEN-BROWN AND GODFREY FREDERICK

he National Australian BUILDING AT A GLANCE Built Environment Rating System (NABERS) gave Name Latitude East Latitude East its top rat- Location Ting, five out of five stars. Its energy- 52 , Sydney, Australia saving strategies have led to a build- Owner Brookfield/Credit Suisse Real ing that emits 40% less carbon diox- Estate Fund International (CSREFI) ide than the benchmark required for Principal Use Commercial Office the top NABERS rating. Employees/Occupants 1,400 (approx.) Latitude East is the final building Conditioned Space 247,578 ft2 built at near the heart Substantial Completion/Occupancy of Sydney’s commercial business 2007 district. World Square is a city block Occupancy 100% bounded by George Street, Liverpool Street, and Goulburn Street. The site consists of a large multilevel underground parking operational efficiency requirements area, a shopping center, restaurants, to receive a 4.5 NABERS rating. cafes, hotels, office buildings and Waterman designed the mechani- residential apartment towers. cal, electrical, plumbing and fire Latitude East has nine levels of protection services. We were com- commercial office space with a missioned by Brookfield for these central atrium and approximately consulting services and worked 247,578 ft² of air-conditioned space. closely with them and the rest of the It is built on top of a large common design team. basement and two retail levels. The Energy modeling firm AECOM plant room is located on the top floor. conducted energy simulations The building team sought to build using IES Virtual Environment a high quality, energy-efficient software according to the NABERS office building that would meet the Energy Commitment Agreement for predicting the energy use of the building. IES software is compli-

Latitude East’s central atrium with glass ant with ANSI/ASHRAE Standard elevators, exposed elevator structure and 140–2001, Standard Method of Test Drew glass-enclosed stairs results in a dramatic for Evaluation of Building Energy central space and helps unify the nine floors Analysis Computer Programs.

Richard of commercial office space.

6 HIGH P ERFORMING B UILDINGS S ummer 2 0 1 0 S u m m e r 2 0 1 0 HIGH P ERFORMING B UILDINGS 7 Energy-Efficient Design The key design elements that con- tribute to the energy efficiency of the building fall into two categories: • The building form, including a central atrium and the façade and • The air conditioning, ventilation, building management control sys- tem (BMCS) and lighting design.

Waterman worked together with Brookfield, the architect, façade engineer and energy modeling con- sultant to: • Maximize natural light via the external façade and via the

central atrium; Drew

• Provide adequate shading to

reduce solar loads and glare; and Richard The central atrium of Latitude East • Reduce heat transmission. provides natural light to the lobby and building. The shade from the exist- surrounding offices. The building team checked dif- ing buildings adjacent to Latitude ferent shading configurations and East prompted the team to mini- façades. The architectural concept glazing options for their effect on mize external shading elements, design also strongly influenced the the cooling and heating loads of the particularly on the north and west shading decision. The team selected glazing that offers a reasonable shading fac- tor, but does not reduce daylight- ing (see Lighting Design, p. 20). Double glazing improves the glazing R-value and reduces heat transmission.

Air-Conditioning Systems Central chillers, an air-handling plant located in the roof plant room, and boilers serve the building. The system includes: • Two high-efficiency water-cooled screw chillers with variable-speed drives (VSDs);

A lighting control system uses photo- electric cells to adjust high-efficiency T5 fluorescent lights based on the amount HPB.hotims.com/30305-2 Drew

of available daylight. The building team selected glazing that provides some shad-

Richard ing, but does not reduce daylighting.

8 HIGH P ERFORMING B UILDINGS S ummer 2 0 1 0 • Variable-speed chilled water, Chillers. Cooling load calculations heating water and condenser indicated that the building load at T A B L E 1 water pumps; Latitude East was in the vicinity of Load % COP • Three cooling towers with 3,000 kW, prompting a design using variable-speed fans; two chillers at 1,500 kW cooling 100 6.2 90 6.8 • Two gas-fired hot water heaters; capacity each. 80 7.8 Higher chiller set- • • Central air-handing units (AHUs) The team based its chiller selec- point improved effi- 70 8.7 for each perimeter zone and the tion on the following energy-effi- ciency at all loads. 60 9.6 center zone with VSDs; and ciency specifications: It also reduced 50 10.8 pump motor power. • Return/relief air fans with VSDs. • A chilled water operating setpoint of 59°F to 45°F; 40 10.2 30 9.1 • A condenser water temperature of 85°F; and 20 7.6 10 5.7 Latitude East is part of Sydney’s World • A minimum coefficient of perfor- Square, a city block that includes retail mance (COP) at various load The higher chiller setpoint rep- stores, restaurants, office buildings, apart- ments and hotels. The site was previously conditions from 100% to 10% resents a slight shift from tradi- home to the Anthony Hornden & Sons (Table 1). tional practice in Australia where department store, which opened in 1905 and was called The Palace Emporium. Richard Drew

1 0 HIGH P ERFORMING B UILDINGS S ummer 2 0 1 0 HPB.hotims.com/30305-27 chilled water design temperatures Second, using a higher chilled BUILDING ENVELOPE are typically 54°F to 43°F. The water ΔT makes it possible to Roof higher chilled water temperatures reduce the flow rate for the chilled Type Concrete, air gap, insulation improved energy efficiency in water pumps. The team determined Overall R-value R-11 Reflectivity 0.5 two areas. that the 46°F split was a good solu- First, the higher chilled water sup- tion for chiller and AHU coil opera- Walls ply temperature directly increases tion allows for a reduction in the Type Concrete, air gap, insulation, plasterboard the efficiency of the refrigeration chilled water pump motor power by Overall R-value R-11 cycle and chiller COP. The building approximately one-third. Glazing percentage 98 team selected the highest possible Windows chilled water supply setpoint that Air Distribution. Ductwork ris- U-value 0.35 (average) did not adversely affect the dehu- ers deliver air to each floor from Solar Heat Gain Coefficient (SHGC) 0.4 (average) midification ability of the air-han- the central air-handling units. dling unit cooling coils or the over- Latitude 33°55' South all cooling coil selection including Three electrical submeters track energy Outdoor Design Conditions air and water pressure drop. used by the building’s elevators and escala- 90°F dry bulb, 73°F wet bulb tors. Additional submeters track building systems’ energy consumption, providing data that helps building managers identify and resolve problems. Richard Drew

1 2 HIGH P ERFORMING B UILDINGS S ummer 2 0 1 0

HPB.hotims.com/30305-33 ENERGY AT A GLANCE

Energy Use Intensity (Site) 24 kBtu/ft2 Natural Gas 10 kBtu/ft2 Electricity 14 kBtu/ft2 Annual Source Energy 58 kBtu/ft2 NABERS Energy Rating f five out o five stars (valid through May 2011)

Latitude East uses standard light air boot/troffer type air dif- fusers. Laboratory testing and the calculation of the Air Diffusion Performance Index (ADPI) helped determine the optimum diffuser performance in accordance with Drew ASHRAE Standard 113-2005. Richard Some areas were designed to suit ten- ant requirements, such as the ceiling in this area. ELECTRICITY USE 2 0 0 7 – 2 0 0 8 ( CUMULATIVE)

Multiple variable air volume ter- minal boxes (VAVs) on each floor then modulate the airflow to con- trol zone temperatures. In Australia, VAV systems are generally designed for a minimum airflow rate of approximately 0.98 cfm/ft2 with the VAV boxes at full capacity. This design aims to ensure reasonable air movement when the VAV boxes are at minimum turndown (airflow). However, often this practice G A S U S E 2 0 0 7 – 2 0 0 8 ( CUMULATIVE) allows for a minimum VAV turn- down of only approximately 70%. The turndown rate could vary based on diffuser manufacturer, selection, spacing and layout. Unfortunately, this typically means that the VAV boxes do not always have enough modulation range to control temper- ature unless the VAV boxes are also fitted with electric zone reheat.

1 4 HIGH P ERFORMING B UILDINGS S ummer 2 0 1 0 HPB.hotims.com/30305-38 Left This view looking up from the atrium This enabled lower VAV turndowns, WHILE YOU WERE SLEEPING, Drew lobby shows the large skylight, which pro- resulting in two energy benefits: vides natural light to internal offices.

Richard • Electric reheats were not Below Various glazing treatments were OTHERS WERE MAKING ICE! selected based on building orientation and required in the VAV boxes for shading from other buildings. The limited temperature control. yet varied colors used in the façade help • to connect Latitude East with other World Reduced flow rates at low loads “By shifting our electrical Square buildings. decrease AHU fan energy use. demand to less expensive The lower VAV turndown has low- off-peak hours, we estimate ered energy use and has succeeded that this project will save in keeping tenants comfortable. taxpayers over $2.5 million in energy costs over the next 25 years.”

— Bill Wilson, Management Analyst, City of Encinitas Public Works Department Drew

Richard

Encinitas Civic Center is the recipient of the AEE 2009 Renewable Energy Project of the Year, the San Diego Excellence in Energy award from the California for Sustainable Energy, San Diego, CA and registered with the certification goal of LEED Silver. The building uses CALMAC energy storage systems, a technology that can save up to 40% on air-conditioning bills by making and storing ice at night for use the next day. For a partial listing of our more than 3500 installation in over 35 countries, visit www.calmac.com/installations

JXm\dfe\p%JXm\\e\i^p%:fej\im\i\jfliZ\j% NNN%:8CD8:%:FD 1 6 HIGH PERFORMING BUILDINGS S ummer 2010 HPB.hotims.com/30305-10 Left Glass-enclosed areas allow daylight- ing and views. In addition to daylighting, which reduces lighting energy consump- tion, the air-conditioning system uses energy-saving strategies such as economy cycles, night purge cooling and chilled water reset, which allows the chilled water supply temperature to rise above the design setpoint when the building load is low. Below The entrance lobby, which connects

Drew the street level to the base of the atrium,

features a large public art piece by Sarah

Richard Sibella Robson.

Other Air-Conditioning Energy • The lower on coil temperature Strategies. In addition, the fol- reduces the load on the AHU. lowing key strategies were used to improve energy efficiency: Unfortunately, this method does not • Outdoor air economy cycles based account for the latent load of air, on enthalpy; resulting in times when economy • Night purge/cooling based on mode requires more cooling than

enthalpy; normal mode. Clearly, this is not a Drew

• Minimizing air and water friction particularly energy-efficient strategy. losses by generously sizing duct- The typical solution to this prob- Richard work and pipework; lem involves the use of enthalpy • Chilled water temperature reset; and sensors. However, the enthalpy At Latitude East, the design called • Condenser water relief. sensors on the market were often for enthalpy control of economy not very accurate and/or not very cycles, but instead of enthalpy sen- Using outdoor air economy cycles is reliable. sors, the system uses temperature not a new energy-saving technique. Unfortunately, building managers sometimes disable this option after WHAT IS NABERS ENERGY? construction because of operating Formerly known as the Australian Building between buildings in different climates. problems. In normal mode, the air Greenhouse Rating System (ABGR), Two key energy criteria that affect ratings supplied to a space is a combination NABERS Energy is an Australian rat- are energy efficiency and the type ing system that accounts for all energy of energy consumed. of the required minimum airflow (for sources used in a building over a This criteria presents what some con- example, 30%) plus return air (for 12-month period. Other factors consid- sider a loophole in terms of determining example, 70%). Traditionally, the ered in determining the rating include the how green an actual building is, because rentable floor area, hours of occupancy an inefficient building can receive a five economy mode involves: and other variables. star rating if a high proportion of its • Measuring the outdoor air tem- The rating focuses on the greenhouse energy is from green power (renewable energy) sources that are accredited by the perature (dry bulb); and gas (CO2) emissions resulting from all energy sources. Ratings range from one Australian government. Green power can • Comparing it to the return air tem- to five stars in half-star increments, with be purchased through regular electricity perature (dry bulb). one star representing a poorly performing providers at a small premium. Therefore, caution should be taken when If the outdoor air is less than the building, four stars representing an excel- lent building and five stars representing interpreting a building’s NABERS energy return air temperature, then the sys- an exceptional building. rating to ensure that the building itself is energy efficient. Accordingly, NABERS tem switches to the economy cycle; All ratings account for variations in geographic location to provide normalized ratings show the amount of “normal” • The economy cycle mode con- results that enable direct comparision and “green” power used in the rating. sists of 100% outdoor air and 0% return air; and HPB.hotims.com/30305-41

1 8 HIGH P ERFORMING B UILDINGS S ummer 2 0 1 0 Drew

Richard In typical office areas, slot diffusers in the light fittings provide air supply. All and humidity sensors and a ductwork was slightly oversized to reduce LESSONS LEARNED psychrometric calculation. This friction by 20% and save energy.

The performance of Latitude East has approach provides a more energy- reminded us as engineers that energy efficient solution with more accurate 45°F design at times when the efficiency does not necessarily require and reliable results. building load is low. Allowing the the use of the latest green trends such as trigeneration, underfloor displace- Night purge works on a similar prin- chilled water supply temperature ment air distribution or chilled beams. ciple to the economy cycle. It involves to rise improves the chiller com- Rather, we have found that even rela- tively standard building façades and running the AHUs at night without pressor efficiency, reducing chiller air-conditioning systems can potentially the use of chillers when the enthalpy energy consumption. perform very well if all aspects are opti- conditions are favorable outdoors. Condenser water relief allows mized to suit the local climate and to work with the whole building. The ductwork and pipework sys- the condenser water temperature tems in a typical building can add to drop at times when the outdoor This approach has resulted in: a) Significant savings in capital cost; significant resistance and increase ambient wet-bulb temperature is b) Minimized risk of systems not per- the power used by fans, AHUs and low. The lower condenser water forming because the systems used pumps. This resistance, or pressure temperature improves the chiller are more “tried and tested”; and c) Simpler operation and control sys- loss, is wasted energy. compressor efficiency, reducing tems that building managers can At Latitude East, all ductwork chiller energy use. understand without having to learn new technologies. and pipework systems are slightly oversized, reducing friction by 20%, Lighting Design This does not mean that we will not which saves energy. The building team maximized continue using the latest green trends if and where appropriate. However, we The chilled water system design natural light to enhance the indoor will be more diligent in considering the incorporates chilled water reset. environment and connect occupants relatively standard alternatives, which could provide significant benefits. This allows the chilled water sup- to the outdoors. Photoelectric cells ply temperature to rise above the linked to a lighting control system HPB.hotims.com/30305-45

2 0 HIGH P ERFORMING B UILDINGS S ummer 2 0 1 0

D60145asjl_1006551.indd 1 5/13/10 9:56:51 AM adjust the high efficiency T5 fluores- • One electrical submeter for chill- • Air-handling unit fans using more 6HH

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'KSEBLQGG 30 This metering system has helped density and hours, plant operation BUILDING TEAM building management fine-tune the and operating hours. building after construction. Mostly To qualify for the top NABERS Building Owner/Representative small incremental improvements Energy rating of five stars, buildings Brookfield have reduced the building’s energy must meet maximum emissions cri- Architect 2 Crone Partners Architecture Studios use by more than 10% compared to teria, which is 15 lbCO2/ft per year energy use at the end of construc- for Sydney. General Contractor Brookfield 2 Mechanical, Electrical Engineer; tion and commissioning. Latitude East emits 8 lbCO2/ft per year, 40% less than the five star Lighting Design Waterman AHW Energy Target Versus Actual greenhouse gas emissions bench- Hydraulic and Fire Services Engineer Waterman AHW The building team set out to obtain mark. This is achieved without the a 4.5 star NABERS Energy rat- use of green power. (Emissions fig- Energy Modeler AECOM ing (What is NABERS Energy?, p. ures are normalized to account for Structural Engineer Taylor Thomson Whitting 18) without the use of green power various Australian climates and to sources such as on-site or pur- allow for realistic comparisons.) chased solar or wind power. The As of March 8, 2010, Latitude’s ABOUT THE AUTHORS energy model indicated that the energy performance placed the Scott Walkden-Brown is a director at building would qualify for either 4.5 building in the top five performing Waterman Group in Sydney, Australia. or five stars, depending on a num- NABERS-rated base buildings that Godfrey Frederick is the business devel- ber of factors, including occupant do not use or purchase green power. opment manager for the Waterman • Group in Australia.

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