Lessons learned about zero-net-energy buildings

by Katie Daniel | October 12, 2016 10:00 am

By William L. Maiman
Zero-energy, zero-net-energy (ZNE) building, net-zero energy buildings (NZEB)—no matter which buzzword is used, the concept is inextricably linked to sustainability and, more specifically, efficiency. It involves minimizing energy consumption and reducing carbon footprints while being sensitive to ‘human factors.’ Buildings should serve their occupants, instead of the other way around.

While there are many Canadian design/construction professionals familiar with ZNE projects, questions remain. For instance, is energy consumption zero or minimized? Are all building types and sizes suitable for the concept? Are occupants happy to live or work in these spaces?

Fortunately, the Continental Automated Buildings Association (CABA), working with the New Buildings Institute (NBI) and many leading manufacturers in the controls/intelligent building/automation sector, has designed a rigorous, scientific-based research project to answer these questions. A steering committee, comprising 18 companies and organizations active in the field, provided technical assistance in deciding on the scope and focus of the study, along with feedback and financial support.

The resulting report[1], released late last year is titled, “Zero Net Energy Building Controls: Characteristics, Energy Impacts and Lessons.” It focuses on three areas from the specifier and occupant (user) perspective. According to CABA, the study reviews “how existing and emerging monitoring and control technologies help designers, building owners, operators, and occupants achieve and maintain ZNE performance.” What should design/construction professionals know in this regard, and how do controls for shading assemblies enter the picture?

The CABA study
This wide-ranging study was geographically diverse, featuring 23 ZNE buildings located throughout North America, and in four American Society for Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) climate zones (i.e. 3, 4, 5, and 6) that incorporate most of the continent’s population. Thirteen of the subjects were office buildings, five were institutional-type, and the remainder miscellaneous. Buildings were located within six states and Canadian provinces with moderate climates. Diversity, building type represented, and size were selected with the goal 
of achieving a thorough and credible report. There 
were interviews with the design teams of the 23 buildings, operators at six of those buildings, and 130 occupant surveys from seven.

One of the buildings where enough data was obtained to be included in the report was the Van
Dusen Botanical Garden’s Visitor Centre in Vancouver, which fell under the category of assembly buildings of approximately 930 to 2325 m² (10,000 to 25,000 sf). (For more on this project, see the July 2013 
issue of Construction Canada for the article, “Waterproofing Shotcrete at VanDusen Botanical Gardens,” by Jeff Bowman, BSc. It can be read online at www.constructioncanada.net/waterproofing-shotcrete-at-vandusen-botanical-gardens[2].) Another B.C. project was Burnaby’s UniverCity Childcare Centre at Simon Fraser University, which 
was representative of an education facility in the 465 to 930 m² (5000 to 10,000-sf) category.

Examples of U.S. projects in the study range from the Cornell NYC Tech First Academic Building in New York City and the Seattle’s Bullitt Foundation Cascadia Center for Sustainable Design and Construction to the Wayne Aspinall Courthouse and Federal Building in Grand Junction, Colorado.

“Building and system-level controls can be a cornerstone that secures performance, or a weak link that creates challenges for design teams and operators,” said Ronald J. Zimmer, CABA president/CEO. “ZNE buildings are now moving to the forefront of energy-efficient design and operations, but little is known about the energy-related control systems in these projects. This study focuses on answering questions around control aspects in ZNE buildings.”

As noted, NBI conducted the study and reviewed building performance with every project design firm and concluded controls and early energy targets are of vital importance in reaching the ZNE goal. However, the study also found most ZNE projects “have some controls problems.” The reasons were not based on any specific product, but rather on the process to ‘get it right’ and installation issues. While some firms suggested simplifying processes and avoiding points of failure, the majority said system integration, extensive metering, automation, granular levels of data, and feedback are “here to stay” and are “beneficial to the process.”

“The findings of this study will help manufacturers target improvements, design teams to better integrate controls and work with contractors more effectively, and utilities to identify program priorities leading to a next generation of buildings that can be on the path to zero,” said NBI CEO Ralph DiNola.

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Understanding building controls
Definitions abound in the use of terms within any discussion of the built environment. The CABA/NBI study manuscript cites the zero-net-energy building as having “greatly reduced energy loads such that, over a year, 100 per cent of the building’s annual energy use can be met with onsite renewable energy.” Especially in Canada, where winters require heating and summers often requiring cooling, this can be difficult to achieve, given the country’s desire for glass surfaces that are frequently thermally inefficient. Fortunately, operable building controls can help.

Manual controls
Certainly, manual controls are the simplest and most economical to implement. Their effectiveness would depend on the design, including how much of their operations is intuitive and present without a user intervention. Switches would need to be accessible and convenient for occupants to use. A motivated user base would have a higher level of success.

Drawbacks are manual-based systems are subject to actions of individuals based on their proximity and personal preferences versus actual need. Manual systems are also difficult to model in energy-usage programs and to assign values for use in analysis for green building rating systems.

Automated controls
Automated systems are reliable, repeatable, and effective. At its simplest, a basic thermostat adjusts heating and cooling based on the desired setting and a sensor determining the need to activate the system. There are many different systems and their strategies differ. Building management or automation systems (BMS or BAS) are, as their name implies, for the whole building. Typically, schedules provide information on expected usage and pre-determined settings provide information on heating, cooling, elevator usage, security, and lighting. The scope of control is determined by a building design team, informed by meeting codes and standards being followed.

Specialized systems can also be employed, such as automated shading control systems for operation of shades and window treatments to manage glare and reduce heat gain, as well as to preserve a view to outside by bringing shades up when direct sunlight is not on one elevation. Automated lighting control systems can respond to daylight being present in a space by turning off or dimming lighting nearest the window.

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Comprehensive systems can:

• turn off HVAC units or change temperature levels;
• turn off lighting or reduce fan motors in response to time-of-day conditions; and
• fluctuate electrical power rates or provide demand response to meet needs of utilities to reduce 
power consumption.

Therefore, computers tracking the information then activate the appropriate system. Computerized operations also allow for recording of events and energy consumption—both of which are useful for later detailed analysis of loads and for providing information for the energy consumption dashboards frequently seen with large buildings.

The design of any automated system should include careful matching of zones with the building elements and the space’s architectural program. Both an adequate number and type of sensors to be used will provide actionable information to a system. As critical to a control system as is the calendar, sensors can be hard-wired or wireless, utilizing one of the many different communications platforms available.

In the lighting arena, sensors are offered for occupancy as well as vacancy. Careful analysis is required for optimal performance. The design strategy should be thoroughly explained to users so operation is understood by all as essential to meeting sustainability goals.

Major takeaways
The CABA study notes daylighting controls are an integral part of high-performance buildings, but glare control and shading must be done properly to realize the benefits of daylighting. Most designers used fixed elements (e.g. overhands or louvres) or manual shades. Interior shades or blinds were used in more than half the projects (i.e. 12 of the CABA buildings) toward their energy reduction and occupant comfort goals, and 34 per cent (i.e. four projects) applied automation to the shades or blinds.

These buildings are designed to energy-use levels 
50 per cent less than most new buildings today and over 75 per cent less than the average existing buildings, with renewables making up the small balance of energy needs. The majority of design firms attributed HVAC, lighting, and plug loads each having a greater than 15 per cent impact on the energy savings—therefore, the success of the control of these systems means the success of the energy goals.

From both the design team and the operators’ perspective, the solutions lie in an increased need for the controls contractor and the building operator to be more actively engaged with the design early, during commissioning, and after occupancy.

The study also suggests the role of occupants on energy outcomes has never been greater. Seventy-four per cent of the buildings rely on the occupant for some part of the controls success, from roles with operable windows and blinds to plug load controls and energy awareness campaigns.

Health and economy
When properly specified, building controls like shading assemblies also have positive impacts on aspects beyond energy efficiency. Much is now known about the health importance of maintaining circadian rhythm, day/night cycles, and having a view to the outside. Research has confirmed people have evolved to a 24-hour cycle that includes a sleep (rest) time and an alert time, with light providing the catalyst for the body to respond accordingly. Combatting Seasonal Affective Disorder (SAD) is primarily done by light, too. Exposure to light at the right intensity is critical. Restful sleep is best done with a darkened environment as light stimulates the body into its wake/alert cycle. Besides the circadian maintenance aspect, access to daylight offers psychological benefits resulting in less absenteeism, improved job satisfaction, attentiveness, and faster recovery time/need for less medicine in healthcare settings.

Roger S. Ulrich, PhD, EDAC, is one of the pioneering researchers of evidence-based design. He specifically researched the effect of window views on recovery time, reduced stress, and reduced healthcare costs of patients in hospitals and the effect of visual surroundings of patients in intensive care units (ICUs) and psychiatric facilities. He was co-founding director of the Center for Health Systems and Design at Texas A&M University and is now an architecture professor at the Center for Healthcare Building Research at Chalmers University of Technology in Sweden. His work frequently notes the preference for views encompassing natural scenes and the sky in contrast to other buildings.

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Another frequently cited report is Windowscapes: The Role of Nature in the View from the Window, authored by Judith Heerwagen of the Pacific National Laboratory in Seattle. She thoroughly explains the role of daylight and time cures such as alertness during the day and calmness for promoting sleep at night. Co-editor of Biophilic Design: The Theory, Science, and Practice of Bringing Buildings to Life, Heerwagen discusses how research is moving very quickly on circadian rhythm and how the brain responds to light. As light-emitting diode (LED) sources replace incandescent and fluorescent lighting to reduce energy consumption, there is opportunity for light-tuning or manipulation of colour to mimic natural day/night cycles. However, additional research must be done in order to establish exact parameters of colour and intensity—a feature that dynamic daylight does from sunrise to sunset.

Certainly, Leadership in Energy and Environmental Design (LEED), the venerable green building rating system, recognizes a view to the outside and many other ratings standards note the importance of views and proximity to a window. In the LEED 2009 program, Indoor Environmental Quality (EQ) Credit 8.1, Daylight, requires daylight integration via controls for saving energy.

Another important standard is ASHRAE 189.1-2011, Standard for the Design of High Performance Green Buildings, which offers peer-reviewed definitions, guidance, clarifications, narratives, and prescriptions/rules on systems and concepts being used in 
the built environment. This standard 
can be used as a companion to green rating systems.

From an energy perspective, energy codes value daylighting—especially when used along with controls for turning off or dimming nearby electrical lighting that is made redundant by abundant daylight. In the United States, California’s Title 24 has a goal of reducing energy consumption; this state rule has spurred design changes throughout the built environment and fosters usage of control systems. A key element is use of sensors for dimming or turning-off electrical lighting when daylight is present.

Conclusion
To ensure building controls can be an effective strategy for realizing zero-net-energy goals, it is important to develop strategies early. However, it is also important to realize while automation ensures repeatability and desired responses to a situation, verification and review are critical. There are many instances in the report noting the human element—be it operations or occupant—and additional savings or the maintenance of expected savings are subject to the variability of actions other than automation.

Be it energy dashboards, reminders, or other means of user/occupant engagement, the human element must not be overlooked for continued success of a ZNE building. However, sensors get cheaper and more effective (Moore’s law at work) and connectivity options are more numerous and varied than copper wire installed point to point. Therefore, it is possible the two scenarios will converge in the future.

COMMISSIONING CONSIDERATIONS

The recent Continental Automated Buildings Association (CABA) study notes the vital role of commissioning and the involvement of the operations team in this process. Commissioning is an important concept in the systems arena and is required by the Leadership in Energy and Environmental Design (LEED) green building rating program, and numerous codes and standards (along with building owners). A commissioning program is an organized and structured process and plan that includes a thorough inspection, testing, and verification of systems in accordance with the specification relating to their procurement, the design intent, and the manufacturers’ performance specifications. At its most basic level, it seeks to answer the question, “Does the system work as promised?” American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) Guideline 0-2005, The Commissioning Process, can offer recommendations and detailed information on the intention of a commissioning program. Illuminating Engineering Society of North America (IES) DG-29-2011, The Commissioning Process Applied to Lighting and Control Systems, provides a supplement to Guideline 0-2005 specifically for lighting-related devices/systems. It is vital a plan be developed to outline: participants; methodology for testing; information to be recorded; how to record the test results; specification to be the basis of the commissioning; scheduling of system operations; and time to accomplish the tasks. After the testing is done, the commissioning process should also include operational personnel so information transfer from builder/contractor to facility/maintenance can occur. The CABA study has significant observations attesting to the benefits to building occupants and energy-saving benefits of properly functioning systems, and commissioning is part of this. It is critical there is user satisfaction of not only the systems, but also in meeting the overall sustainability goals of the building and organization. Besides a technical proficiency of operation, the users must therefore embrace the concept—methods to circumvent systems or change established parameters such as light levels or thermostat settings will defeat the purpose of the design.

 

William L. Maiman is marketing manager at MechoSystems, and has worked to inform the architectural, lighting, and interior design communities of the benefits of using daylight, preserving views of the outside, and saving energy consumed by electrical lighting. He is a member of the National Electrical Manufacturer’s Association (NEMA) Daylight Management Committee Council, has taught lighting design at the Fashion Institute of Technology (FIT), and conducts educational sessions across North America. He can be reached via e-mail at william.maiman@mechosystems.com[6].

Source URL: https://www.constructioncanada.net/lessons-learned-about-zero-net-energy-buildings/

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