4.0. Building Performance Tracking: A Process of Continuous Improvement
Buildings are investments with significant profit potential. In today’s commercial building market, buildings need to be comfortable for occupants and must operate efficiently to remain competitive. Building owners who achieve this balance benefit from deep cost savings and market leadership. Building performance tracking is a long-term strategy for supporting the continuous improvement of building systems. It is fueled by the hardware, software, people, and processes that make optimization a regular part of building management. Building performance tracking is a process of continuous improvement. The four steps in Figure 5 show the fundamental process for tracking, analyzing, diagnosing, and resolving issues with heating, ventilation, and air conditioning (HVAC) and lighting systems. Building performance is tracked on an ongoing basis and incorporated as part of standard processes (https://www.cacx.org/PIER/documents/bpt-handbook.pdf).
At its core, building performance tracking is a process that monitors how efficiently a building meets its occupants’ needs, which includes maintaining:
- Comfortable temperatures and humidity
- Ventilation requirements
- Lighting requirements
Modern building HVAC and lighting systems are interactive and complex. Over time, many building systems begin to operate inefficiently and may require frequent attention to ensure they are optimized. For example, sensors may drift out of calibration, building use could change, and adjustments in control sequences might affect how well systems work together. This can result in occupant complaints and increased energy costs. Building performance tracking is a proactive strategy for achieving occupant comfort without jeopardizing energy performance.
Today’s building systems also generate huge amounts of data. This data is highly valuable, as system faults are often invisible to building operators without it. Building performance tracking helps operators gather and analyze data to diagnose problems and identify solutions.
Lastly, to become an industry leader in today’s market, owners of income-producing properties must attract and retain tenants by boosting building performance. Building performance tracking is a strategy to help owners enhance property value and net operating income (NOI) through lower investment and higher returns on investment. The goal of building operation is to achieve optimal occupant comfort with the least amount of energy consumption. Buildings that achieve this balance do so by addressing the two main elements of building performance: 1) System Tracking for HVAC and lighting systems, and 2) Energy Tracking for the whole building and wherever sub-meters are in place.
Building owners should address both sides of the coin to reap the full rewards of tracking building performance, since each side can answer different questions about building operation. Figure 6 shows how meters and controls gather data on system or energy performance for HVAC, lighting, and plug load systems (https://www.cacx.org/PIER/documents/bpt-handbook.pdf).
4.1. Builing Performance Tracking and Commissioning
Building performance tracking can serve as an ideal complement to existing building commissioning (EBCx) – also referred to as retro commissioning (RCx) or recommissioning (ReCx). Building performance tracking helps verify the energy savings achieved through EBCx and ensures that occupant comfort and financial benefits last. EBCx is a systematic process for investigating, analyzing, and optimizing the performance of building systems by improving their operation and maintenance. EBCx helps ensure that building systems are well-integrated and meet current facility requirements. In practice, EBCx has been shown to reduce energy costs by an average of 16 percent, and provide non-energy benefits such as improved occupant comfort and reduced maintenance costs. Ongoing commissioning extends the EBCx process by incorporating building performance tracking, training, and updated documentation so that energy savings persist (https://www1.eere.energy.gov/femp/pdfs/OM_7.pdf).
4.2. Building Standards
A standard is a set of guidelines and criteria against which a product can be judged. Common standards related to building practices are created through consensus processes by organizations such as ANSI, ASTM, or ASHRAE. Supporting the governance of standards and certifications is the International Standards Organization (ISO), which defines and develops worldwide standards that frequently become law or form the basis of industry norms. ISO defines a standard as: “a document, established by consensus, approved by a recognized body that provides for common and repeated use as rules, guidelines, or characteristics for activities or their results (https://www.wbdg.org/resources/green-building-standards-and-certification-systems).”
Requirements found in standards may either be prescriptive (identifying methods of achievement) or performance based (stating expectations of end results). Consensus based standards, those developed through a formal, voluntary consensus process that is exemplified by an open and due process have immediate buy-in, government support, and international influence. According to the National Technology Transfer and Advancement Act (NTTAA) federal agencies are required by law to adopt existing private-sector voluntary consensus standards instead of creating proprietary, non-consensus standards. Standards frequently serve as incentives for improved performance. Many of the green product standards available today are proprietary or regulatory standards that have been developed outside of the formal ANSI and ISO consensus process. These types of standards may be more or less stringent than consensus standards and can include some level of transparency and public comment. However, many of these types of standards are trusted because they are associated with a group that has strong environmental credentials.
Standard for the Design of High Performance Green Buildings except Low-Rise Residential Buildings provides minimum requirements for site, design, construction and operations in mandatory, code-enforceable language. This standard is comprehensive and includes chapters for site, water, energy efficiency, indoor environmental quality, and materials. For a detailed description on many other building codes and standards that address sustainability goals and requirements, see the Relevant Codes and Standards section below and Energy Codes and Standards (https://www.wbdg.org/resources/green-building-standards-and-certification-systems).
4.3. Green Codes
Green building codes continue to be developed and adopted in the U.S. and abroad that seek to push the standard of building design and construction to new levels of sustainability and performance. Codes come in two basic formats: prescriptive and performance, with outcome-based becoming a developing third option. A Prescriptive path is a fast, definitive, and conservative approach to code compliance. Materials and equipment must meet a certain levels of stringency, which are quantified in tables. Performance-based codes are designed to achieve particular results, rather than meeting prescribed requirements for individual building components (https://en.wikipedia.org/wiki/Performance-based_building_design). Outcome-based codes for example, establish a target energy use level and provide for measurement and reporting of energy use to assure that the completed building performs at the established level. The unique difference between codes and building rating systems is that codes are mandatory. If green codes become adopted on a wide spread basis, their impact can change the building environment rapidly and extensively. When undertaking a project, whether it is new construction or a renovation, check to see if there is a state or local green code that will dictate the direction and scope your project must take.
The International Green Construction Code (IgCC) provides a comprehensive set of requirements intended to reduce the negative impact of buildings on the natural environment (http://c.ymcdn.com/sites/www.linkme.qa/resource/resmgr/Presentations/The_International_Green_Cons.pdf). It is a document which can be readily used by manufacturers, design professionals and contractors; but what sets it apart in the world of green building is that it was created with the intent to be administered by code officials and adopted by governmental units at any level as a tool to drive green building beyond the market segment that has been transformed by voluntary rating systems.
4.4. Green Product Certifications
A certification is a confirmation that a product meets defined criteria of a standard. ISO defines certification as: “any activity concerned with determining directly or indirectly that relevant requirements are fulfilled.” Green product certifications are intended to outline and confirm that a product meets a particular standard and offers an environmental benefit. Many product labels and certification programs certify products based on life-cycle parameters, making them multi-attribute programs. These parameters include energy use, recycled content, and air and water emissions from manufacturing, disposal, and use. Others focus on a single attribute, such as water, energy, or chemical emissions that directly impact IEQ.
A green product certification is considered most respected when an independent third party is responsible for conducting the product testing and awarding the certification (https://www.wbdg.org/resources/green-building-standards-and-certification-systems). Third-party means they are independent of the product manufacturer, contractor, designer, and specifier. Third-party labels and green product certification programs can be helpful in evaluating the attributes of green products because they validate that the product meets certain industry-independent standards. They can also offer greater assurance to consumers, designers, specifiers, and others that a product’s marketing claims accurately reflect its green attributes. Many product certifications are also recognized within comprehensive green building rating systems such as LEED, Green Globes, and the National Green Building Standard. As a result, green product certifications are on the rise as market conditions change and the demand for greener products continues to increase. It is important to note that green-washing, which is defined as the use of green claims that are not true or are unverifiable but used to sell products or a corporate image, has become commonplace as companies try to stay competitive in the green marketplace.
To fully understand what a green certification represents and the quality of information it provides, the details of its requirements need to be reviewed carefully. The ISO defines different types of labels that can be used for products. Below is an outline of the ISO-defined labels and what is being claimed. Product certifications available in the U.S. are mostly Type I and Type II labels while Type III labels are now required in France and becoming more common in Europe and for those U.S. manufacturers with an international focus (Table 1).
Summary of Green Product Certifications
The following Table (2), and the expanded information directly below it, outlines some of the most commonly used and respected green product certifications in the marketplace.
4.5. High Performance Buildings: Energy Policy Benchmark and Energy Targets
Benchmarking is the practice of comparing the measured performance of a single building over time, to similar-use buildings, or established norms such as an energy code. The goal of benchmarking is to provide the informed data required from which to establish performance improvement. Typical factors that can be used to establish a benchmark for energy use:
- Establish a target that would be a percentage improvement over code minimum.
- Identify the proven performance of Non-Dartmouth buildings with similar use, size and climate and target a percentage better.
- Identify the proven performance of existing Dartmouth buildings with a similar use, size and climate and target a percentage better.
- Set an energy target utilizing a combination of all the above.
The most commonly used index today is the Energy Use Intensity (EUI), which adds up all of the building energy used in a year (including lighting, elevators, heat, cooling, auxiliary use, etc.) and divides it by the total of square feet in the building and provides you with the British Thermal Units that have been used per square foot, per year (Btu/sq ft-yr). Based on information provided and assembled by the Dartmouth FO&M Energy Management team, the chart below assembles existing Dartmouth buildings into broad categories, averages their actual energy use per category and provides an obtainable goal for improvement.
4.5.1. Energy Modeling
It is very important that energy modeling is done comprehensively and often during the design process to ensure that the design process is on the right track and that the energy model results are used to inform decisions about systems. Energy modeling shall begin in the conceptual phase and shall continue through the construction document phase so it can inform design decisions. Energy modeling may be done by the design team or a hired third party. Dartmouth shall be informed of who will do the energy modeling. The energy modeler can use industry accepted packages such as eQuest, DOE-2, Energy Plus, Trane Trace or Carrier HAP. The files shall be made available to Dartmouth for their use.
The final energy model shall be based on the 100% construction documents. At a minimum, energy modeling shall be conducted during early design conceptual phase, schematic design phase, design development phase and for final design. All energy models shall summarize annual energy consumption and peak demand for:
- Heating energy
- Cooling energy
- Major HVAC units organized in logical categories
- Domestic hot water
- Interior lighting
- Exterior lighting
- Miscellaneous loads
Cost benefit analysis shall be conducted, starting in the SD phase, to assist the team in making informed design decisions. Cost benefit analysis shall also be done to inform the team in value engineering decisions effecting energy use and CO2 emissions associated with the project. The cost benefit analysis shall calculate simple payback and net present value of relative design options and the analysis shall account for operating and maintenance costs for the life of the system. Dartmouth College will provide information for energy costs and energy cost escalation rates. After one year of operation for projects greater than $10 million, the design team shall perform a calibrated energy model for the project where they use actual weather and usage data and compare it to what the real energy use is. If the discrepancies’ are larger than 10%, the design team shall assist Dartmouth and the commissioning agent investigating what may be causing this.
4.5.2. Energy Saving Strategies
The design team is encouraged to think outside the box to evaluate suitable systems for the project. As a minimum, the design team shall (http://www.dartmouth.edu/~opdc/pdfs/high_perf_bldg_energy_policy.pdf):
- Achieve the EUI as directed by the Dartmouth project team.
- Minimize ventilation by using demand control ventilation (DCV) strategies and use of dedicated outside air (DOA) units.
- Recover as much energy as possible by using the best energy recovery strategy for the project.
- Reduce lighting power densities (LPD) and use lighting control systems that will further minimize the energy used by the lighting system
- Reduce plug loads by specifying energy efficient equipment.
- Reduce water use to 50% or less of what a conventional building uses.
- Evaluate what renewable energy use systems can be used on the project
- Use energy modeling extensively to evaluate different system types for the project.
- Consider natural ventilation as energy efficiency strategy.
4.6. Air Quality Improvement
Air quality scenario demands formulation of comprehensive action plans for improvement in the non-attainment cities and towns. These Action Plans need to be realistic, technically feasible & economically viable to deliver the intended benefits. The steps and activities required for formulating a sound action plan necessarily include the following: (i) appropriate air quality monitoring networks & data generation; (ii) identification of emission sources; (iii) estimation of pollution load; (iv) assessment of contribution of these sources on ambient air concentrations and prioritization of the prominent sources that need to be tackled; (v) techno-economic evaluation of the control options and intervention analysis; and (vi) selection/introduction of the best practical mitigation measures for short and long term city-specific Action Plans (http://www.cpcb.nic.in/sourceapportionmentstudies.pdf).
The design shall meet rigorous comfort standards to ensure all occupants achieve the highest level of productivity and comfort. Elimination of volatile organic compounds (VOC), chlorine, and formaldehyde supports healthy, indoor environmental conditions.
The following key objectives shall inform the design of the project in terms of the scope of Air Quality Improvements (http://www.cpcb.nic.in/sourceapportionmentstudies.pdf):
- Manage the design and construction process to achieve good IAQ.
- Control moisture in building assemblies.
- Limit entry of outdoor contaminants.
- Limit contaminants from indoor sources.
- Capture and exhaust contaminants from building equipment and activities.
- Reduce contaminant concentrations through ventilation, filtration, and air cleaning.
4.7. Temperature, Humidity, Ventilation, Filtration
Space temperature, humidity and ventilation levels are paramount to meeting the OPR for indoor environmental quality and energy efficiency. The following tables highlight the typical indoor thermal comfort and ventilation requirements for occupied conditions. Temperature setbacks will be utilized when feasible. Set points may be adjusted based upon specific space requirements.
4.8. Acoustics Standards
As a target, all MEP systems shall conform to ANSI standards, with maximum permissible background noise of 40 dBA in all spaces. The following NC levels shall be the basis for maximum total equipment noise permitted in the areas noted (Table 4):
It is not easy to establish a reliable number of the existing high performance buildings in the various countries. The answers given by the national experts regarding the details, as well as the period, differ. Some have stated, for example, that low energy houses are nowadays standard buildings, which does suggest that the definition was not updated with new national requirements. Others stated that about 10% of all new buildings are energy saving houses, while a third group gave an estimation of all existing buildings in their country that follow the relevant definition. If low energy houses are not taken into account, the number of realised high performance buildings seems to be rather low (< 200 in total) in most countries, with the exception of Austria, Germany, Czech Republic, and Slovenia.
5.0. Performance Attribute: What to Consider and Measure
While EISA develops a set of attributes for high performance and green high performance, qualitative terms like “integrates, optimizes and outperforms” are subjective and relative measures that yield no concise metrics for evaluation. The National Institute of Building Sciences (NIBS) is one of the organizations working to define these needed metrics, baselines, benchmarks and verification strategies, specifically with respect to the building envelope. The building envelope is the nexus of many, often conflicting, functional demands, or as NIBS states: “many high-performance attributes interact at the envelope” (National Institute of Building Sciences). NIBS have leveraged EISA 2007 to define a set of performance attributes relevant to the building envelope, with an emphasis on enhanced security. The following attributes are similarly derived (http://blog.worldarchitecturenews.com/?p=3831).
5.1. Attributes for Determining Performance of the Building Facade
Building energy performance is significantly impacted by various attributes of the facade. The building skin provides thermal insulation, mitigates air infiltration and controls solar energy radiation, providing day-lighting opportunities to reduce electricity consumption and heating loads resulting from artificial lighting. Solar energy harvesting technologies will one day contribute to net-zero and net-plus energy buildings. Natural ventilation through the facade can play a significant role in building energy efficiency (http://www.enclos.com/site-info/news/high-performance-facades-part-four-getting-there-metrics-best-practices).
ENVIRONMENTAL IMPACTS of the building facade include energy consumption and resulting emissions over the operations phase of the building lifecycle, as well as larger, more lasting impacts. The lifecycle context requires that embodied energy, disassembly and end-of-life impacts also be considered. Waste generation through the building lifecycle is another important consideration.
SAFETY and SECURITY are provided to the building occupant by the facade systems (at the most fundamental level, keeping bugs and burglars out, and babies in). Protection from weather extremes includes impact resistant design practices. Blast loading criteria is now commonplace in facade design. NIB’s references ballistic, chemical, biological and radiological protection.
DURABILITY is an often neglected but fundamental aspect of performance and sustainability for all building systems, with special significance for the facade in its protective role of separating inside from out. In the majority of cases, a predicted service life for a building and its facade system goes undefined. Most damage and deterioration in a building can be traced to moisture penetration and migration through the building skin. Weathering is a particular concern for the exposed elements of the facade. Renovation requirements should be anticipated and planned for over the full building lifespan.
COST-BENEFIT, or ECONOMIC EFFICIENCY, is yet another important performance consideration, which takes into account at what cost performance attributes are being amplified, verses the benefit the improvement provides. As discussed in Part One of this ongoing series, high performance and green programs are often motivated by promotional and image interests (green-washing) and may ignore simpler and less costly solutions capable of providing equal or greater benefit at less cost, solely because they do not provide a high-profile green “wow” factor.
HUMAN COMFORT, HEALTH, and PRODUCTIVITY are profoundly affected by the facade system. The facade provides thermal and acoustical comfort, daylight, visual comfort and glare control, as well as connection to the natural environment. Natural ventilation through the facade can greatly enhance indoor air quality. Favorable biophilic facade attributes are well documented in providing a more productive and healthier indoor environment). Even small improvements in productivity can quickly trivialize related first costs.
SUSTAINABILITY criteria are included by the EISA in evaluation of high-performance systems. This opens the evaluation to the wide and varied considerations – and the inexact science – of sustainability. Many of the issues discussed here are fundamental sustainability issues. These considerations also include emergent issues like resilience, or the ability of a system to withstand extreme and unanticipated future conditions. Sustainability considerations will drive future development of facade technology. Water harvesting, for example, will become an increasingly important function of the facade in many geographic areas as supplies of potable water diminish. Lifecycle Assessment (LCA) will become the framework for the sustainability metrics that will drive future development of facade technology.
OPERATIONAL CONSIDERATIONS for the building facade include its integration with other building systems, the user interface, and maintenance and renovation requirements over the operational phase of the building lifecycle. Provisions must be considered to keep a building operational during planned renovation cycles, including disruptions to fuel and water supply, extreme weather conditions, and political insta¬bility.
Using the EISA definition then, a high-performance facade would be one that integrates and optimizes the above attributes on a lifecycle basis. A high-performance green facade is a high-performance facade that outperforms similar buildings with respect to key sustainability metrics as described above, again, on a lifecycle basis. Context, however, will determine the attribute set and the priority of those attributes as represented by the project specific criteria adopted for each attribute.
The EISA definition effectively leaves no perfor¬mance attribute off the table when it comes to evaluating high-performance systems. If a facade design employs high-performance materials and technology in an application where near equivalent performance could have been achieved with a simpler and less costly strategy (i.e., an expensive double-skin system where triple-glazed IGUs would have sufficed), is the system still deserving of the high performance designation? One begins to recognize how easily the term high performance may be applied with inadequate discrimination.
High performance and green are terms that should be protected from dilution of meaning by clear definition and standards of practice. While helpful to have some relevant performance attributes identified, related metrics are still lacking. The evaluation of some of these attributes may be inherently subjective, while others lend themselves to quantitative measure. In either case, appropriate evaluation criteria must be developed.
5.2. Compliance of Metrics and Best Practices
Slow economic growth, high competition, and construction industry restructuring have put a strong pressure on construction companies to continually improve their productivity and performance. Many studies on performance measurement have been carried out at the project level. However, recently, the demand for performance evaluation and management at the company level has increased (http://www.sciencedirect.com/science/article/pii/S1018363912000074).
The path to a high-performance facade is simple in concept. In addition to the facade fundamentals – weather barrier, air and water seal, condensation resistance, safety and comfort – the high-performance facade must succeed in doing the following (http://www.enclos.com/site-info/news/high-performance-facades-part-four-getting-there-metrics-best-practices):
- Optimize daylight to reduce energy consumption and cooling load from electrical lighting
- Optimize view to provide a connection to nature
- Minimize glare
- Control solar heat gain
- Minimize heat loss in cold climates
- Provide natural ventilation to the greatest possible extent
- Optimize performance and minimize environmental impact over the lifecycle of the facade system
The complexity comes in the implementation of these provisions, a delicate balancing of often contradictory considerations. And that’s just the beginning.
High-performance buildings and systems yield from high-performance processes: design, material procurement, fabrication, installation, commissioning and maintenance. High-performance design encompasses optimization of the attributes identified in Part Three over the building lifecycle, but high-performance attributes developed in design can easily be compromised during manufacturing and installation phases. A commissioning process helps assure that systems are operating as designed and maintenance procedures are required to sustain performance levels over the lifetime of the building systems and assemblies. The following concluding section breaks down the various components and considerations that should be addressed at each stage of the design.
5.3. A Foundation to Measure Performance
Generally speaking, high-performance organizations are superior to their low-performance counterparts in the following areas:
- Their strategies are more consistent, are clearer, and are well thought out. They are more likely than other companies to say that their philosophies are consistent with their strategies.
- They are more likely to go above and beyond for their customers. They strive to be world-class in providing customer value, think hard about customers’ future and long-term needs, and exceed customer expectations. And they are more likely to see customer information as the most important factor for developing new products and services.
- They are more likely to adhere to high ethical standards throughout the organization.
- Their leaders are relatively clear, fair, and talent-oriented. They are more likely to promote the best people for a job, make sure performance expectations are clear, and convince employees that their behaviors affect the success of the organization.
- They are superior in terms of clarifying performance measures, training people to do their jobs, and enabling employees to work well together. They also make customer needs a high priority.
- Their employees are more likely to think the organization is a good place to work. They also emphasize a readiness to meet new challenges and are committed to innovation.
- Their employees use their skills, knowledge, and experience to create unique solutions for customers.
High-performance companies are the role models of the organizational world. They represent real-world versions of a modern managerial ideal: the organization that is so excellent in so many areas that it consistently outperforms most of its competitors for extended periods of time. Managers want to know more about high-performance organizations so they can apply the lessons learned to their own companies. Of course, the goal is to ensure that their own organizations excel in the marketplace (http://www.amajapan.co.jp/e/pdf/HRI_HIGH-PERFORMANCE_Organization.pdf). The Foundation/Organisation so conceived should, inter alia, look into these in specifics:
Basis of Design (BOD): This narrative becomes the roadmap to attaining building performance goals. Establish key performance benchmarks early as part of the BOD, including relevant green standards and rating systems (Energy Star, LEED, Green Globes, and Living Building Challenge). Identify where code, standards and rating system requirements will be met or exceeded. Address how the facade systems will contribute to achieving these benchmarks as part of an integrated whole building design. These benchmarks become the building and system’s performance goals.
Project Delivery Strategy: Adopt a project delivery strategy suited to the goals of a high-performance building project. The conventional design-bid-build strategy is generally inappropriate for this project type. Rather, consider design-assist, integrated project delivery, or other collaborative processes that facilitate the involvement of appropriate constituents early in the design process.
Service Life: Define a design service life for the building and the facade system. Assure that the estimated service life of the building, facade system, materials and sub-assemblies of the facade system are commensurate with the standard: ISO 15686, CSA S478-95.
Durability & Maintenance Plan: Adopt or develop a durability and maintenance plan for the facade system that supports the design service life. In addition to maintenance requirements, the durability plan should define major renovation cycles over the building lifespan. The Canadian version of LEED provides a point for durability planning.
Operating Manual: The operation of a high-performance building is often a complex affair placing demands on the facility’s engineering team and building occupants. Operational procedures should be developed simultaneous of design development. Training strategies should be included.
Customer-centered approach to drive building performance achieved through (http://www.trane.com/HighPerformanceBuildings/pdf/LarryWash.pdf):
- Conducting audits and making performance improvements
- Validating system performance within set standards
- Providing periodic energy audits and identifying improvements
- Upgrading control systems with intelligent technology
- Using analytics to improve efficiency and self-sufficiency
- Continuously monitoring and analyzing data against operating benchmarks
Leveraging an existing facility’s investments by using technology to access operational data and optimize building performance through (http://www.trane.com/HighPerformanceBuildings/pdf/LarryWash.pdf):
- Benchmarking current building performance
- Using custom analytics to provide performance improvement recommendations
- Performing recommended actions to meet business needs
- Continuously monitoring and analyzing data against operating benchmarks
- Documenting progress toward high performance building status