Lyn Corum 2016-04-20 18:33:35
Imagine that your company management has told you they are planning to design and build a new headquarters, or retrofit the current building to be Leadership in Energy and Environmental Design (LEED) certified Platinum and net zero energy . . . and they want you to make it happen. If you face that major challenge, you now have a book to turn to. The Continental Association of Buildings Automation (CABA) has provided a blueprint in its report, “Zero Net Energy Building Controls,” published in November 2015. The report takes the reader from the design stage, to beyond the building’s commissioning stage. It describes the problems that can arise and how to deal with them. The report’s bottom line: in today’s buildings, with extensive plug loads and changing work and occupancy patterns, the occupant is now an operator. “Controls are at the nexus of energy performance,” conclude the authors. CABA hired The New Buildings Institute to research and interview a sample of the designers and occupants of the 191 net zero energy buildings now in operation in the US. One of the major conclusions they drew from the responses: integrate the engineer in charge of controls, or the controls sub-contractor, to be a primary team member from design through occupancy. Why is this? “Zero net energy buildings have more high-performance systems and integrated energy production. And they tend toward greater system integration, metering, monitoring, and feedback as their standard practice,” says the report. What is a net zero energy building? Simply put, it uses less energy than it produces over the period of a year. In virtually all cases, it does this with a rooftop solar system, daylighting, passive building design to limit mechanical heating and cooling, automated controls and occupant involvement in operating windows and blinds, controlling plug loads, and creating energy awareness campaigns or displays. The LEED certification process has become the standard in energy-efficient building design and the highest certification—platinum—provides the rules that allow a design team and building engineer to get to net zero energy. Getting to net zero energy is not required for LEED platinum designation. Three organizations are profiled here that were chosen at random from the list of 191 listed in the CABA study, which had designed and built net zero energy buildings. None were familiar with the study. The major CABA recommendations form the sections in which the three organization representatives related their experiences. Bridging the Design to Operations Gap “The zero net energy building is driven by good design, high-performance systems, and shading” (CABA 2015). The General Services Administration (GSA) modernized its 41,562-square-foot Wayne E. Aspinall Federal Building and US Courthouse in Grand Junction, CO, thanks to funding from the American Recovery and Reinvestment Act. The work was completed in January 2013 at a cost of $15 million. It is the GSA’s first major net zero energy building on the National Register of Historic Places. The original prospectus called for a LEED Silver goal, but GSA decided to go for the higher platinum goal and net zero energy at the site. The renovation restores historic volumes and finishes. It also modernizes design to include wireless lighting, allows prominent spaces to be preserved and showcased, and drastically reduces energy consumption. The building was originally constructed in 1918 as a US Post Office and Courthouse. A major addition was completed in 1938. A variety of federal tenants, including the Internal Revenue Service, work in the building, along with the US Courts, the Army Corps of Engineers, the FBI, and other federal law enforcement agencies. Roger Chang is director of sustainability and engineering at Westlake Reed Leskosky, and was the lead engineer on this project. WRL partnered with the Beck Group. Chang says he had the benefit of five years of involvement from the start of the design phase in 2010 through two years after commissioning and occupancy in 2013. In the 2014 issue of High Performing Buildings magazine, Chang reports the design-build procurement approach followed the federal government’s goal to be carbon-neutral by 2030. It provided a “green proving ground demonstrating how to potentially make an existing historic building perform at zero net energy.” The renovation of the GSA building helped shape GSA’s perspective on performance strategies with historic buildings, he says. The design team evaluated five different building heating and cooling schemes and chose a variable refrigerant flow (VRF) system because it had the most favorable 40-year life cycle cost. The decision was based on a combination of energy savings, ability to deliver a high-quality indoor environment, and constructability in a historic building. Chang was able to provide feedback to the team during the design phase, which offered higher design performance than the building had previously had. Historically, this included a central-station rooftop air handler system with boilers and small chillers. There was only one zone for heating and cooling controls for four floors. The building engineer who had been on the job for 30 years and who was invited to participate in the design evaluation was resistant to the new ideas, but toward the end of construction began to understand, says Chang. That building engineer has since retired and the current building engineering staff is almost entirely new. Sustainability Motivates Design The David and Lucille Packard Foundation in Los Altos, CA, spent six years in the process of designing and constructing its LEED Platinum, net zero energy building. One year of that involved a halt due to the 2008 financial crisis. It was completed in 2012 at an estimated cost of $37.5 million. A history of the development of 343 Second Street, as the building is known, is related in a comprehensive report, “Sustainability in Practice—Building and Running 343 Second Street,” available on the Packard Foundation website. Some of the material discussed here was extracted from that report. The 49,000-square-foot building was designed in two long, relatively narrow, two-story wings and two short, perpendicular wings, which bridge the gap and define a generous internal courtyard. The design allows daylight to flow into offices and conference rooms. The roofs of the long wings are mostly covered with the solar photovoltaic (PV) panels, which provide the building’s energy. Sustainability was one of the major drivers of the design. The Packard Foundation Board of Directors and staff were widely engaged in pursuing in-house sustainability. Their desire was that the building be transparent, with nearly complete concealment of building services; more vertical proportions to be reminiscent of residential rather than commercial buildings; and materials with warmer, less technological textures. Craig Heyman, the chief financial officer, was a member of the “Sustainability Task Force” of Packard staff that advised EHDD Architecture, the firm selected to design the building. The goal of the task force was to engage the staff in the integrity and effectiveness of organizational sustainability. It probed work styles to reduce energy use such as sharing printers, converting to 100% recycled paper, converting paperwork to digital form, and to reduce electricity demands to 30% of their 2007 levels. Plug loads added up to one-third of total energy use and were targeted. A plug load study was conducted by the Sustainability Task Force and concluded that plug loads could come down by 58%. Results are covered below. This work overlapped with EHDD’s design team investigations and the task force continued working through the year even though the design team’s work was halted due to the financial crisis. Heyman says that it was important that the building make few, if any, demands on occupants. A Tiger Team was created in 2011 to coordinate the move into the new building and the first year of occupancy. It created an internal Internet site that described elements of the building. And it devised a system for communicating with staff about comfort. Biweekly meetings identified small items such as signage for electric car charging stations, timing of training videos, and nonfunctioning occupancy sensors that were dealt with. Heyman says the building was certified net zero energy at the end of the first year by International Living Futures Institute. Its solar system produced 351 MWh during that first year and exported over 60 MWh to the grid and over 80 MWh the second year. Exports increased during the third year, but final numbers are not yet known. The building’s energy use is 24 kBTU per square foot. Teaching Building Drove Design Lane Community College in Eugene, OR, began planning to build two connected buildings in downtown Eugene in December 2009. One building would be for student housing, and the second would be an academic building providing instructional service programs. An architectural firm, Robertson Sherwood Architects in association with SRG Partnership, was selected and began designing the project in August 2010. The decision was to build the academic building to LEED Platinum certification standards and to work toward net zero energy consumption. The student housing building was designed to LEED Gold specifications and is not a net zero energy building. A project management firm, Gerding Edlen, and construction manager/general contractor, Lease Crutcher Lewis, were soon hired and construction began in March 2011. Titan Court, the student housing building opened in September 2012 and the Academic Building was completed in December 2012. The buildings have been in use now for three years. Roger Ebbage is Director of the Energy Management Program, which offers two-year degrees in energy management in the downtown center. He was a member of the design team advising the architectural firm during the design process. Since it would be a teaching building for students coming through its courses, the design firm needed to know what the teaching staff wanted. Ebbage’s contribution was to identify the teaching elements the design had to accommodate. For example, geothermal wells provided a ground source heating system. The pipe headers located beneath the floor level are exposed, covered with clear plexiglass, and equipped with monitors as a teaching tool for students. The system is described in greater detail below. The Academic Building did not achieve net zero energy, but is instead designated “net energy ready” because they did not install enough solar panels for budgetary reasons. A 12-kV PV system on the roof supplies electricity to the building and none is exported. It is also used for training purposes. Prioritize Passive Strategies “Passive strategies should be prioritized during design so that controls can be layered in, thereby optimizing the whole building outcome” (CABA 2015). The GSA building already consisted of high thermal mass construction. It was augmented with interior insulation systems to increase thermal stability. The thermal stability of the building also allowed the HVAC systems to react more quickly during morning warm-up and cool-down. Chang wrote in High Performance Buildings magazine that the design team maintained the historic appearance of existing fenestration systems while reducing solar gain and thermal conductance. Windows are not operable because of law enforcement security concerns. However, storm windows were installed inside the original windows to preserve them. High-performance solar control film was then applied to the new windows, which reduced solar gain by 50%, contributing to the maintenance of the building’s interior thermal stability. The daylighting in the most regularly occupied spaces allows for continued use of office areas during a power outage. A restored skylight was installed over the main tenant space on the first floor to allow deeper daylight penetration in the largest open office area. On the second and third floors, perimeter-ceiling zones are kept free of building services to allow maximum daylight penetration. Some occupancy sensor control signals were connected to the central control system to shut off color-coded wall outlets when occupants left rooms. Transparency Important At the Packard Foundation, the design goals created in the planning stage were to have natural lighting and ventilation, operable windows, solar shading, and narrow building wings. These elements were achieved with design and sophisticated building controls. The directors and staff wanted an aesthetically pleasing and transparent building and chose to have the wall facing the street be 47% glass. To cut down on heat transmission, this glass wall consists of two sheets of glass separated by a gap in which a sheet of very thin plastic is stretched. All surfaces have heat-reflecting coatings and the inner gap is filled on both sides of the plastic with argon gas, which transmits heat much more slowly than air. Ventilation Is Passive Lane’s Academic Building features passive ventilation. The building is designed to take advantage of natural airflow and the natural property of concrete mass to warm up or cool down. Outside air enters and leaves the building through windows, rooftop openings, and air shafts. In the process, the concrete floor masses become cooler and discharge cool temperature to the surrounding air. Ceiling fans are controlled by occupants. Wireless and Adaptive Controls “As the built environment continues to move toward lower energy use, controls become a more critical and nuanced aspect of achieving and maintaining energy and operational expectations. It also brings controls training and improved hand-off documentation to the operators and provides ongoing connectivity with the design team and controls sub-contractor” (CABA 2015). Reports from two of the buildings commented on the tradition of building systems being unobtrusive, almost invisible, and operating silently while delivering comfort. This tradition often flew in the face of a net zero energy building’s need for sophisticated controls of all equipment and measurement. The Tridium Niagara 4 open-source control system with a JACE wireless controller was chosen for installation in the GSA building. Chang says it can communicate with all building systems except for lighting, which has its own control system. The Tridium control system features low-voltage electronic valves, pumps, and sensors that control the air temperature, ventilation, and lighting in rooms. The system allows the temperature, ventilation, and lights in each room to be controlled by preset programs. Chang recommends that establishing thermal seasonal zone set point thermostat temperatures set before tenants move in. When settings were changed, some tenants were concerned about having less control. The Magnum wireless lighting control system was chosen for offices because the design team did not want to channel new wiring in the historic walls. Unfortunately, says Chang, the company had no experience with GSA, and it had a limited support network. It took six months of troubleshooting to wring the bugs out of the system. He says the control system as designed was intended for new construction and most installations had been in hotels and hospitals. The Magnum light switches are operated with a piezoelectric current where a static charge signal is sent to a ceiling-mounted solar cell sensor. Many switches would get confused about whether they were on or off. The problems were solved, says Chang, by installing more sensors in every room, which usually has only one wall switch. There are now 100 solar sensors in the building, with two or three every 300 feet. Daylight sensors automatically dim ambient lighting to achieve 30 foot-candles in most workspaces. Occupancy sensors are used throughout the building and have a 15-minute delay before turning off. The fan coils will also go to setback mode. Roller shades are available to further control daylight and solar gain when staff is working. Lighting in hallways was upgraded to higher-efficiency fluorescent and LED technology while replicating historical fixtures. A new heating, ventilating, and air-conditioning system was installed after natural ventilation was considered. The need for increased building security nixed that idea. The heating and cooling plant is made up of six twinned, ground-source variable refrigerant flow heat pump units, tied to a 32-well geoexchange loop. An evaporative fluid cooler allows energy balance of the loop, given the relatively high ground temperature of 62°F. Variable frequency drives vary the geoexchange loop flow rates in response to unit needs. Later, Chang wrote that it is better to use a greater number of single-unit heat pump units instead of the twinned units installed, to maximize the full load range of equipment. The Mitsubishi system’s cooling cycle has its own control system, and this was the first time the company was asked to verify the energy performance of their system, says Chang. The system had no methodology to measure how much heating and cooling the building was using, so staff depended on the electric meters to calculate building energy use. The GSA’s 123-kW PV array was placed atop an elevated canopy on the roof with a very thin profile to protect the historic significance of the building’s exterior. The PV was finished with a white reflective material to support daylighting within the original light well. The system was designed to allow for future upgrades as technology improves. Smart panel boards allowed every circuit to be metered. Chang says, “It is important for the design team to know what measurement data is wanted by the engineering staff to monitor electricity use.” SkySpark analytics software automatically analyzes building energy and equipment data and provides daily measures and overlies Tridium, the building automation system, he adds. SkySpark is necessary because Tridium is not sophisticated and needs better graphics, Chang says. He says the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) is working on a next-generation standard for high-performance sequences of information, so this would help to improve Tridium. Controls Engineer Important The Packard Foundation staff hired an experienced controls engineer as staff prepared to move into the 343 Second Street Building in late 2011. The actual move-in occurred in July 2012. The controls engineer maintains the complex building control system by providing observations of both the real building and its digital portrayal on control screens, a job which the foundation values to maintain the building as a net zero energy system. Packard’s building control system, which was installed and is managed by Syserco, a San Francisco energy management company, has nine distinct subsystems all connected to a corporate EtherNet network through a supervisory control and data acquisition (SCADA) server. The subsystems connect solar panels, light, heating and cooling, exterior shades, and the HVAC system, along with landscape irrigation. The building has about 15,000 monitoring and control points. Heating and cooling is organized into 29 zones. Heating is supplied by a heat pump largely during a morning warmup period after the building was allowed to cool off overnight. Once temperatures are in the comfort zone, it is reduced, allowing internal heat gains to maintain temperatures. Active chilled beams were chosen to ventilate the warmed air. Ventilation air is jetted along the sides of ceiling cavities and the high-speed flow drags the other air in the cavity along with it, which in turn draws room air up past an array of heating tubes and then back out into the room with the ventilation flow. This system was chosen primarily for architectural reasons over radiant panels, which use water to heat large flat plates in the ceiling or wall. The chilled beams have much smaller piping and flow could be kept to slow speeds with fatter pipes, to save energy. Cooling is provided during the April to October periods by chilling water at night with a cooling tower, storing it in a large insulated tank, and circulating it during the day to the occupied spaces. A compressor-based cooling system is thereby avoided, saving money and reducing energy use by 90%. A 285-kW PV array was installed on 24,000 square feet of the roofs, divided into four quadrants. The power generated is used in the building, and the excess is sold to the local utility. The Lutron lighting controls and occupancy sensors are managed room-by-room, according to occupancy and brightness of outside light, and computer servers are put on reduced activity for night and weekends. The Sustainability Task Force was able to reduce plug loads in the new building by having timers or occupancy sensors installed to turn off office and kitchen equipment when not being used. Controlling standby energy use of this equipment in this way reduced plug load use by 58%. However, the major electricity users were servers and their energy use could be cut only 15%, partly due to having already moved to higher-than-average efficiency servers and power supplies. The building was designed with 12 “neighborhoods” to include about 10 people in each one. Within each neighborhood a display was located in break rooms and automatically turned green when windows should be open for optimal comfort. However, says Heyman, they found these displays weren’t reaching people because they were working in their offices. The IT people then came up with an icon that appeared on individual computers—a green “up” arrow signals that windows could be opened and a “down” arrow signals that windows should be closed. The icon is still in use Heyman says. Geothermal Wells Heat Building The Lane Community College’s Academic Building’s automated logic control system controls the building’s geothermal, solar thermal, domestic hot water systems, windows, mechanical heating, ventilation and air conditioning equipment, and central plant boiler and chiller operation, as well as the building’s rainwater harvesting system, according to Anna Scott, an energy and indoor environmental quality analyst in Lane’s facilities department. It also controls heat wheels located in the air handles to recover heat from the exhaust air stream. The system allows the temperature and ventilation in each room to be controlled by preset programs. Scott says the standalone lighting control system controls lights in classrooms, labs, offices, meeting places, bathrooms, and halls. The fourth floor’s louvered skylight daylighting system is also part of the control system. Occupancy sensors in classrooms and offices require occupants to turn lights on. The system then turns the lights off when sensing the room is unoccupied or if daylight levels are high enough to provide appropriate lighting levels. The occupancy sensors used in bathrooms and other areas turn on when someone enters the room. Occupants can override the automatic controls with individual switches if working in the building after the lights are turned off automatically. Plug load controls were considered during the design phase, but the decision was not to use them, Ebbage says. The geothermal wells provide a ground source heating system. Pipe loops conduct water into and out of 55 wells built under the buildings. Each well is 350 feet deep. The water is warmed by the wells, and then is integrated into the building’s hydronic heating and cooling system. Ebbage says the wells, which are divided into quadrants and are buried under the first floors, come to several headers. In the Academic Building, the headers are exposed under the floor and covered with clear plexiglass. They are equipped with monitors, so the temperatures of incoming and outgoing water can be used as a teaching tool for the students. “Actual temperature differences are important so we can do calculations on the energy consumption for heating and cooling the building,” says Ebbage. A solar thermal high-performance evacuated tube system is installed on the front entrance of the building. It produces 90% of the hot water required for both buildings between May and October, says Ebbage. The geothermal wells warm up the water coming into the system with the solar thermal system giving the water a final boost of heat. It, the boiler, and geothermal wells are connected together by the building’s automatic control system. Scott says the boilers have run rarely, and then only when outdoor temperatures fall below 20–25°F. They temper the geothermal well loop water if it drops below 45°F, and quickly raises the loop temperature to about 60°F. The boilers take about 10 to 15 minutes to complete their work. The heat recovery chillers run both during the heating and cooling season, Scott explains, to temper the geothermal well loop water with the assistance of a heat exchanger. The chiller’s heating mode typically runs between 4 a.m. and 11 a.m. and for its cooling mode, between 11 a.m. and 6 p.m. While a conventional commercial building control system may cost $2.50 per square foot, Ebbage explains that this building control system ran around $7 per square foot due to the extra cost to meet curriculum needs. “We wanted to access as much of the building systems as we can,” he says. Increase Operator Training and Support “Occupants are operators but default settings need to be the backup. Provide occupants with energy use engagement and control access with a ‘hybrid’ system that returns controls to default settings and ‘off’” (CABA 2015). Chang says that, at the GSA building, “We created a tenant manual for agency heads that provides a list of preferred equipment. It is based on the LEED framework for organizing information. The equipment included laptops and Energy Star-labeled devices. Plug load energy use is further controlled with smart plug strips tied into lighting occupancy sensor systems, and scheduled receptacles. Reports of energy use for each tenant allow feedback on use of equipment. The most difficult to integrate into the central control system was the energy dashboard where it would draw the data it needed to display, “but we never got it to 100%,” Chang says. The Tridium control system is hosted in the data center in Kansas City and linking the dashboard to it ran into conflict with the GSA security system. The building continued to be occupied by all but one tenant during construction, which required dynamic scheduling. A building information model was developed by the team to graphically communicate and document phasing and sequencing of temporary tenant moves and build-out, demolition, historic preservation, construction, and final occupancy. Once the building was occupied every tenant received a weekly energy performance report, overlaid with the past performance, and they could see their highs and lows. Chang says each tenant has its own culture and some cared about their performance, while others didn’t care. The Army Corps of Engineers and the IRS have cultures that used measurement and accepted the reports. They used less energy than other tenants as a result. Chang says the IRS, in particular, used laptops, which kept their energy use down. On the other hand, a major law enforcement agency (Chang wouldn’t name it) had two people in one office, which used as much energy as everyone else in the building. It had specialized equipment that was never turned off and had no interest in any modifications. Chang says the building experienced a power blip in 2014, and it fried a lot of the law enforcement electronic equipment. The measurement report for that week saw the dip in energy use until their equipment was repaired. At the lower scale of energy use, a 10% reduction may seem small, but it makes a difference, says Chang. After two years, the building was operating at 20 kBTU per square foot without solar. With solar, it was less than 10 kBTU per square foot. The design goal without renewables was 17 kBTU per square foot. He says the average office in the US operates at 70 kBTU per square foot. Inhouse Staff Educates Occupants At the Packard Foundation the in-house Tiger Team worked with the communication staff to identify the right channels to present key information to the occupants on energy consumption in the building and keep them motivated about avoiding energy waste. Creating a building dashboard was found to be difficult. As the Packard Foundation report says, “Having Packard staff participate directly in reducing energy use is vital to achieving the [zero] net energy goal. Active cooperation, direct contributions to the effort, however small, is far more satisfying and effective than passive cooperation.” Video Aids Training Staff training at the Lane Community College academic building consisted of bringing in college staff that would occupy the building during the design phase to explain how the building would operate. The building facilities staff received training on its technical operations, says Ebbage. Occupants received no further formal training after commissioning. Scott says, in looking back on the three years the building has been in operation, the most important lesson from her perspective is having a trained and dedicated staff available to monitor the building’s performance on a daily basis and maintain the outcomes of a high-performance building. A video documentation of the training produced by the staff and contractor, and edited by the school’s Media Arts students is allowing the college to implement a continuous training program for the operations staff, says Scott. “Our facilities management group is trying to incorporate the video training into the operations staff’s annual training plans,” she reports. Closing Thoughts The two documents referenced earlier: “Zero Net Energy Building Controls” and “Landmark Resurrection” will provide further insights into the design, construction, and operation of net zero energy buildings. Several additional case studies, including those of the GSA’s Wayne E. Aspinall Federal Building and the David & Lucile Packard Foundation Headquarters can be found under case studies at www.hpbmagazine.org. References Chang, Roger 2014. “Landmark Resurrection: Wayne Aspinall Federal Building.” High-Performance Buildings, ASHRAE, June 2014. Continental Association of Buildings Automation (CABA) 2015. “Zero Net Energy Building Controls,” November 2015. www.caba.org/CABA/Research/Zero-Net-Energy-Buildings.aspx. BE Lyn Corum is a technical writer specializing in energy topics.
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