COMMENTARY The Proof Is Performance How Does 4 Times Square Measure Up? B Y A D A M W. HINGE, P. E . , M EM B E R A S H R A E , A N D D ON A LD J. WINSTON, P. E . , M EM B E R A S H R A E he road to high per- From this perspective, we’ve experi- T enced firsthand the all-too-common forming buildings is paved frustration of a building’s energy per- formance not meeting design expec- with high expectations— tations, particularly a new building’s energy savings projection that over- but, ultimately, it is mea- states actual performance. Across sured performance that the high performing building indus- try, these unrealistic energy perfor- shows how energy efficient mance goals have come from (among other things) inadequate modeling a building really is. As own- practices, failure to include opera- tions staff in goal setting or accu- ers and managers of more rately communicate the design intent to the staff and lack of adequate than 8 million ft² of Class budgets for commissioning, evalua- tion and ongoing benchmarking. A office space in midtown As more actual energy perfor- mance data become available on Manhattan, including the high performing buildings, clearer Condé Nast Building at and more realistic expectations will help to establish confidence within 4 Times Square, The Durst the building design and construc- tion industry about costs and sav- Organization understands ings. By providing some of our data, observations and experience working this concept well. through design, construction and operation of high performing build- ings, specifically using the 4 Times Square building as an example, we hope to encourage others to share actual energy performance operating results and lessons learned earlier, Condé Nast Building at 4 Times Square. 3 0 HIG H PERFORMING BUILDINGS Winter 2008 The Times Square redevelopment district requires a specified amount of exterior signage and lighting. rather than later; this helps everyone avoid making the same mistakes as the high performing building move- ment gains momentum. Defining and Measuring Energy Performance Energy performance in buildings can mean many different things. Energy intensity, or energy use per unit of floor area, is one common measure of building energy performance. The U.S. Environmental Protection Agency (EPA) ENERGY STAR® building pro- gram, with its Portfolio Manager rat- ing system, measures and compares building energy performance through adjusted energy intensity. However, energy intensity must be balanced against other performance criteria and project requirements—for example, a building with no lights, air- conditioning or mechanical ventilation will have extremely low energy inten- sity, but will not adequately serve the needs of building occupants. Building energy performance can also be measured as compared to a threshold, usually with respect to an energy code or standard. While this is the most common metric used for new building energy performance, a build- cess other than conditioning spaces end users in new buildings, such as ing that has been designed to perform and maintaining comfort and ameni- server rooms, lab equipment, cook- at a significant reduction below the ties for the occupants of a building.” ing or restaurant equipment, security energy code may not compare well to For example, many design teams systems, building control systems, a similar building where performance will gather energy performance fire safety systems, computers, print- is measured by energy intensity. data for energy-efficient buildings ers, copiers and some plug loads. In addition, many earlier codes and by comparing only the systems that Many of these excluded loads oper- rating schemes did not take process the design team controls—such as ate 24/7; so while an energy savings energy into consideration, defined envelope insulation value, percent- calculation will state significant in ANSI/ASHRAE/IESNA Standard age glazing, solar shading, chiller energy savings, the real energy use 90.1-1999, Energy Standard and boiler efficiency, fan and pump of a new building may be much for Buildings Except Low-Rise motor efficiency, installed lighting higher. These details need to be Residential Buildings, as “energy power density, and system selec- considered when setting goals and consumed in support of a manufac- tions. This excludes the process reporting both projected and actual turing, industrial, or commercial pro- energy elements, some of the biggest energy performance. Winter 2008 HIG H PERFORMING BUILDINGS 3 1 C A S E S T U D Y The Condé Nast Building at 4 Times Square An early, high-profile building that cally over the last several years, we calculates to be the annual site is often cited as being one of the reviewed energy use at 4 Times energy intensity for an average- pioneers in the high performing Square and compared it to other rated building (50th percentile) with building movement is our Condé buildings in our portfolio as well as the use characteristics of 4 Times Nast Building at 4 Times Square in the broader population of peer build- Square. Source energy includes the New York City. In response to grow- ings in New York. energy consumed at the building ing interest in the measured energy Table 1 shows how the 4 Times itself—or the site energy—plus the performance of green buildings, as Square energy intensity, in kBtu/ft² energy used to generate, transmit well as increased interest from ten- per year, compared with other Durst and distribute the site energy. ants about relative energy use/costs buildings, and with what the EPA as energy prices have risen dramati- ENERGY STAR® Portfolio Manager T A B L E 1 COM P ARISON OF 4 T I M E S S Q U A R E E NERGY PERFORMAN C E T O B EN C HMARKS kBtu/ft per year The table demonstrates that 4 Times Square • The principal tenants of the building, a pub- is significantly more energy efficient than the lishing house and a law firm, both have signifi- Source Site median New York City office building, but that cant after-hours operations, often until 1 a.m. Energy Energy it is not the lowest in energy intensity among The building is available for tenants 24/7. the Durst portfolio. Some of the reasons for • A broadcast antenna atop the building with 4 Times Square 244 120 higher energy intensity at 4 Times Square transmitter facilities for radio and television relative to other Durst buildings include: stations uses significant process energy. • Significantly higher amounts of outside air Some of these facilities operate 24/7 and Best Durst Building 213 76 (twice the prior New York City industry stan- require continuous operation of the building dard practice) are delivered to the tenant cooling plant. floors by a dedicated outside air system. Durst Fleet Average 239 107 • Two corporate cafeterias with commercial This additional outside air requires additional kitchen facilities use significant amounts of fan and chiller energy use to deliver and process energy. 50th percentile per condition the air. In addition, the outside air • Finally, direct gas-fired absorption chillers, ENERGY STAR ® (with the is filtered to a higher level (85%) than older 366 180 selected by the design team primarily for use characteristics buildings with the additional filter resistance, of 4 Times Square) adding to fan energy consumption. their lack of impact on the electrical grid, favorable operating costs, and lack of harm- • The Times Square redevelopment district ful refrigerants, are not the most efficient requires a specified amount of exterior sig- choice with respect to overall net site or nage and lighting as the minimum, process source energy use. If the building had been energy that was not taken into consideration built with electric chilling, the site energy while setting performance goals. This lighting intensity would be substantially lower. consumes substantial additional energy. 3 2 HIG H PERFORMING BUILDINGS Winter 2008 info.hotims.com/15939-12 B UIL D I N G A T A G LAN C E Building Name Condé Nast Building Location 4 Times Square, New York City Size 1.6 million ft² Managing Energy energy modeling tools are very Started 1996 Performance Expectations good at modeling standard HVAC Completed 1999 In any rapidly growing industry, systems, but it can be more of a Use Office space performance expectations are challenge for less experienced Cost $270 million reported at a rate that outpaces modelers to predict the energy use Distinctions The first green high-rise publication of actual results, and of advanced green building compo- in the United States. are often inflated. In the case nents such as natural ventilation, of green buildings and actual atria, displacement ventilation, operating performance, potential chilled beams, and double façades, B UIL D I N G T EAM savings are being oversold in some among others. instances. Another element that can result Owner The Durst Organization Modeling can be one major issue in low building performance is a Architect Fox & Fowle Architects in understanding why energy disconnect between design and Mechanical Designer Cosentini Associates expectations are not being met. operation—at the time of design Other Key Players Tishman Construction Potential inaccuracies of energy and modeling predicted energy modeling are well known, nonethe- performance, optimal control less common errors persist. Most strategies and schedules often 3 4 HIG H PERFORMING BUILDINGS Winter 2008 4 Times Square was the nation’s first green high-rise. are assumed that do not occur in operation. For example, day- lighting strategies might assume that artificial lighting is dimmed or turned off, while operators or occupants often do not understand the control systems and so do not use them as intended. Also, lack of commissioning can result in systems that are not operating as designed, frustrating operators and occupants.