June 12, 2018
By Al Fullerton
Commercial buildings are among the biggest consumers of energy, with much of it being wasted. According to Energy Star, the average commercial building wastes 30 per cent of its energy. (This statistic is derived from www.energystar.gov/buildings/about-us/how-can-we-help-you/improve-building-and-plant-performance/improve-energy-use-commercial.) In other words, the buildings sector represents a great opportunity for improving energy efficiency. To address this, many businesses are setting increasingly stringent climate and environmental goals to lower emissions and drive efficiency. As a result, there is growing pressure to provide more efficient designs that not only perform when they are first installed, but are also sustainable over the life of the building.
In commercial building design, individual pieces of HVAC equipment are often selected based on their efficiency. It is natural to want to choose the most effective solution, and this tends to be determined by considering the performance of an individual component. However, is this really the best way to achieve the most efficient building performance?
It may seem counterintuitive, but the most efficient piece of equipment may not always result in the most efficient building or system performance. There are many variables contributing to optimized building performance—it depends on how the building is being used and occupied, how the various pieces of equipment in the building interact and work together, and what the goals are for the facility.
This makes it important to look beyond the efficiency of a single piece of equipment and instead consider overall building performance, seeing the whole as greater than the sum of its parts. Taking this approach can result in improved energy efficiency and operational cost savings, and play a role in meeting goals for sustainability, energy consumption, and efficiency.
Why is whole-building design a better approach?
“The whole is greater than the sum of its parts” is a common concept. Applying it to building design can provide significant value. For building owners and managers, it can result in improved energy efficiency, lower initial costs, and overall cost savings. For engineers and contractors, understanding and meeting customer needs with a systems-level approach can provide a competitive edge.
As more organizations and provinces enact increasingly strict energy efficiency goals and regulations, systems-level consideration provides a great opportunity for improvement in this area. For instance, the 2030 Challenge, endorsed by the Royal Architectural Institute of Canada (RAIC)/Architecture Canada, calls on design professionals to become actively engaged in reducing fossil fuel use in building construction and operation. Whole-building design can help in achieving this.
Natural Resources Canada (NRCan) defines the whole-building design method as a holistic approach to building design and construction. It requires every member of the project team to share a vision of environmental responsibility and work collaboratively to implement sustainability goals.
This process enables the team to optimize systems, reduce operation and maintenance costs, and minimize the need for incremental capital, which refers to costs associated with acquiring additional debt or equity for a future project. Taking a whole-building design approach has been shown to produce more significant results than investing in capital equipment upgrades at later stages. (For more information, visit www.cmhc-schl.gc.ca/odpub/pdf/67868.pdf?lang=en.)
How to begin
Rather than asking which individual pieces of equipment are the most efficient, the question becomes how to make the entire system more efficient. Resisting the urge to immediately go granular—and instead taking this systems approach upfront—helps maximize efficiency of the entire building.
It starts with understanding what the building owner or facility/property manager is trying to achieve within the facility. What building outcomes are being sought? Is the driver Leadership in Energy and Environmental Design (LEED) certification, a net-zero building, a corporate sustainability goal, or other benchmarks or regulations?
Next, one should consider how the building will be run and when it will be occupied. The needs of a commercial property differ greatly from the needs of a hospital, for example. Knowing how the building will be used provides a better understanding of full- and part-load performance, which helps determine what equipment and systems are best suited for the building. Additionally, it is important to look at how the various building systems—from plumbing to lighting to security to HVAC—best work together to optimize building efficiency.
For example, many chilled water systems are designed to pump 9 L (2.4 gal) of water every minute for every ton of chilled water to be produced, and 11 L (3 gal) of water per minute for every ton of coolant to be made. If a chiller is selected based on these conditions, the result is a lot of water being pumped around a building. By contrast, using a whole-system approach can save significantly in the amount of water and energy used. While in this option the chiller may initially look less efficient, it actually uses much less pumping energy—especially at part-load conditions—and results in much more efficient systems-level performance.
Strategies for a systems-level approach
Various strategies can help in successfully implementing a systems-level approach in building design.
Understanding the utility cost structure
One should not choose building systems and equipment without having a clear understanding of the utility rates for a specific building and location. Understanding the utility rate structure—which often includes consumption and demand charges—allows for a more accurate analysis of building performance based on how the building will be occupied and used.
In some areas, demand charges can comprise up to 75 per cent of the monthly utility bill. Knowing this can facilitate choosing the most efficient system from a utility bill perspective—for instance, one might take advantage of the load-shifting capabilities of a thermal storage system. It is often helpful to consult a partner offering expertise in building systems and equipment, as well as in utility rate structures and billing.
Considering the total budget
Selecting the building systems and equipment that will provide optimized efficiency and performance for a specific building also hinges on the budget—both upfront and long-term (i.e. for staffing and maintenance). Selecting a system that requires less long-term maintenance can help an organization save staffing costs in the long run.
Understanding the needs
Asking the right questions about how the building will be used and occupied is critical. For example, it typically takes several years after construction for most data centre facilities to operate at full load. However, those early years of part-load operation are rarely considered when choosing systems. It is important to consider how systems and equipment will perform under partial loads.
Using a modelling program
Taking advantage of a building modelling or energy simulation program contributes to sound decision-making—and it can pay off in improved energy efficiency and performance. Modelling allows optimization of systems from an energy and utility bill perspective before construction even begins. One should model against the potential optimized performance of the whole building and its systems, rather than against performance of individual components.
How can it pay off?
While improved energy efficiency and utility savings are significant benefits of systems-level design, using this method can also pay off in other ways. Better fresh air ventilation or acoustic levels in the building are examples of secondary benefits that can result from proper system design. These features can result in fewer complaints, as well as in more productive occupants. Some systems also offer benefits for ease of maintenance and reduced risk down the road.
As mentioned, one option is to use a single provider with expertise in equipment and system design and building optimization. This can help reduce risk and ensure a more efficient design and planning process. A knowledgeable partner can also help assess the best opportunities for efficiency.
Seeing the sum instead of the parts
What do owners want to achieve in their buildings, and what is the best way to get those results? Considering these questions at the start of the design process can aid in determining the systems suited for the job, and can enable designs to stand out.
Looking holistically at the entire system helps ensure the most energy-efficient building performance to allow building owners and managers to meet their sustainability and environmental goals. HVAC equipment and system components must operate together to achieve optimal results. This requires a method focused on total system efficiency rather than equipment-only optimization.
Every building is different, so there is no easy answer. Careful analysis is required to determine real payback, expected costs, and efficiency savings.
Al Fullerton is the systems leader for Trane, a provider of indoor comfort solutions and services and a brand of Ingersoll Rand. He leads a team of engineers focused on expertly applying Trane systems. Fullerton has worked in the HVAC industry since graduating from the University of Cincinnati with a bachelor’s degree in mechanical engineering in 1981. He can be reached via e-mail at firstname.lastname@example.org.
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