Seeing the Big Picture in Building Design

By Al Fullerton, Systems Leader, Trane

In commercial building design, individual pieces of heating, ventilation and air conditioning (HVAC) equipment are often selected based on their efficiency. It’s natural to want to choose the most effective solution, and many times we consider this through the performance of an individual component.

But 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 that contribute 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 building performance and efficiency — 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 your customers may have 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 and results. For building owners and managers, it can result in improved energy efficiency, lower first cost and overall cost savings. For engineers and contractors, understanding and meeting customer needs with a systems-design approach can provide a competitive edge.

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 go granular immediately — and instead taking this systems approach upfront — helps maximize efficiency of the entire building.

It starts with understanding what the building owner or facility or property manager is trying to achieve in their facility. What building outcomes are being sought? Is the driver LEED certification, a net-zero building, a corporate sustainability goal or other benchmarks or regulations?

Next, 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-load and part-load performance, which helps determine what equipment and systems are best suited for the building.

From there, move backward into what building systems best match these goals and needs. In addition, it’s important to look at how the various building systems — from plumbing, lighting, security and HVAC — interact and best work together to optimize building efficiency.

Consider this example: Many chilled water systems are designed to pump 2.4 gallons of water every minute for every ton of chilled water to be produced, and 3 gallons per minute of water for every ton of coolant to be made. If a chiller is selected based on these conditions, the end 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 a much more efficient system-level performance.

As more organizations and states enact increasingly stringent energy-efficiency goals and regulations, the industry recognizes that systems-level efficiency provides a great opportunity for improvement in this area. The Alliance to Save Energy made a case for using a systems-level approach to improve energy efficiency in a recent white paper, “Greater than the Sum of its Parts.” The white paper notes that in addition to reducing energy use and associated costs to consumers, a systems approach has the potential to achieve significant non-energy benefits, including reduced greenhouse gas emissions, improved grid reliability and resilience, water savings, extended equipment life, and increased occupant comfort and productivity. Studies have estimated that the quantifiable non-energy benefits can add 25 to 50 percent to the total monetary benefits of energy efficiency.

Key strategies for a systems-level approach

Consider these key strategies that can help in successfully implementing a systems-level approach in building design:

• Understand the utility cost structure. Don’t choose building systems and equipment without having a clear understanding of the utility rates and structure for a specific building and location. Understanding the utility rate structure — which often includes consumption charges 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 percent of the monthly utility bill. Knowing this can help in choosing the most efficient system from a utility bill perspective, such as taking advantage of the load-shifting capabilities of a thermal storage system. It’s often helpful to consult a partner who offers expertise in building systems and equipment, as well as in utility rate structures and billing.
• Consider the total budget. Selecting the building systems and equipment that will best provide optimized efficiency and performance for a specific building also hinges on the budget — both upfront and long-term for staffing and maintenance. Selecting a system that requires less long-term maintenance can help an organization save staffing costs in the long run.
• Understand the needs. Asking the right questions about how the building will be used and occupied is a critical consideration in choosing the systems and equipment that will provide the most efficient performance. For example, it typically takes several years after construction for most data center facilities to operate at full load. However, those early years of part-load operation are often not considered in building design when choosing the systems that will offer the most efficiency. It’s important to consider how systems and equipment will perform under partial loads.
• Use a modeling program. Using a building modeling or energy simulation program in building design contributes to sound decision making — and it can pay off in improved energy efficiency and performance. Modeling allows you to optimize the systems from an energy and utility bill perspective before construction even begins. It’s important to model against the potential optimized performance of the whole building and its systems, rather than modeling against performance of individual components.  

How can it pay off?

While improved energy efficiency and utility savings are significant benefits of system-level design, using this method can pay off in other ways.

Better fresh air ventilation or better 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.

It is possible 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 is it that your customers want to achieve in their building, and what is the best way to get those results? Considering these questions at the start of the design process can help in choosing the systems that are best suited for the job — and help your design stand out.

A building design process that focuses on the efficiency of the whole building — rather than on the efficiency of individual components — can improve energy efficiency and help you better meet the changing priorities of building owners.

Author Bio
Al Fullerton is Intelligent Systems Leader for Trane, a leading global provider of indoor comfort solutions and services and a brand of Ingersoll Rand. In this role, Al leads a team of engineers focused on expertly applying Trane Systems. Al has worked in the HVAC industry since graduating from the University of Cincinnati with a bachelor’s degree in Mechanical Engineering in June of 1981.