Engineering Fruit Salad: Finding the Low-Hanging Fruit

Inefficiencies are, unavoidably, built into buildings. There are many reasons for this to occur, including:

1. Value engineering

2. Imperfect construction

3. Ineffective or non-existent initial commissioning

While some of these inefficiencies are now mitigated by modern energy and water use codes, odds are, if a building is older (15+ years), some inefficiencies are still present. 

Other inefficiencies occur when a building is allowed to drift from the original design intent, or when a building has suffered from neglect. For instance, if ventilation rates aren’t defined or managed, or if there are poor maintenance practices implemented, the building could encounter underperforming heat exchangers, variable air volume (VAV) systems out of calibration, unattended automation overrides, V-belts slipping, and more. 

So, how does one resolve such issues? According to Joe Sorbet, Director of Engineering at Collaborative Real Estate, “The path to efficiency always starts with data and benchmarking. However, an operator cannot perform in the dark. Gathering utility usage information, at a minimum, on a monthly basis, is essential.” He continues, “Energy Star Portfolio Manager is an excellent and free interactive resource management tool that allows you to effectively monitor energy usage. At the end of the day, developing real-time data capabilities is vital, and provides an operator with yet another powerful tool.”

And when it comes to the actual task of improving a building’s performance, in regards to utilities, there are seemingly several starting points. Within a building lies thousands of energy-consuming devices and it is up to the operator to determine which of those are causing inefficiencies. These can be categorized in two ways:

1. Fixed components, such as curtain wall and roof systems

2. Dynamic components, systems that are potentially out of compliance with the original design intent

With so many points of entry, which would you consider to be the low-hanging fruit? The option with the fastest payback? The upgrade that would have a more permanent, positive impact? A modification to the sequence of operation? Or the implementation of a computerized maintenance system? 

To the unimaginative operator, the path of least resistance to energy reduction, i.e., the low-hanging fruit, may be a quick upgrade, like a lighting retrofit. It tends to be as simple as replacing luminaires with ones that use some fraction of the initial watts. The reduction is then permanent and a typical payback time for this may be as little as two years. However, there are potential pitfalls:

•  Are the lighting levels reduced? 

• Did the design intent of the building rely on the lighting watts for winter heating? 

• Did the color temperature change?

The sequence of operation on an older building may present energy saving opportunities through a variety of processes. Applying variable frequency drive (VFD) technology to superannuated systems typically has a quick payback. A VAV system that utilizes inlet guide vanes is primed for a VFD upgrade, for instance. And this type of project may have a payback time as short as 18 months.

Imperfect construction inefficiencies are typically more difficult to define and mitigate. They are also often overlooked in the process of defining energy-reduction strategies. An infrared image produced by a thermal imaging camera of the exterior of the building may show where conditioned air is escaping due to failed caulking or leaking window seals. Infrared imaging may also define where the insulation values are not being met. This is often noted when there have been roof leaks and the insulation is wet. Replacing a roof or re-caulking the exterior of the building are larger undertakings and definitely not low-hanging fruit. The good news is that if a building leaks, the leaks can be stopped and energy consumption can also be reduced with a properly-designed and executed project. While a payback may not be the driving force of this type of project, they do exist, but they may be protracted to the life expectancy of the project (±25 years).

So, what’s the best choice when it comes to achieving smaller wins first? The real low-hanging fruit is actually effective maintenance management. Ensuring heat exchangers are clean and the media flow rates are correct (check the equipment schedules in the construction drawings) are basic best practices. Confirming the VAV systems are calibrated and performing to the original design intent (check the HVAC sheet metal drawings). Ventilation rates represent the amount of unconditioned outside air being brought in the building, a necessary but intensive use of energy. At a minimum, operators should ensure that the ventilation rate matches the original design intent. There are strategies, demand ventilation for one, that are effective and approved. Good preventive maintenance is a proven strategy for managing utility costs. Cleaning coils, punching tubes, and greasing bearings, to name a few fundamental tasks, all have a direct impact on energy consumption. And perhaps most importantly, the time to payback on good maintenance management is zero years. 

Well-defined and vetted utility reduction projects are a worthy use of time and money. But step one should always be employing the best maintenance and operational practices. At Collaborative Real Estate, we employ a team of experts to continuously and routinely oversee the maintenance and management of all of our buildings’ operating systems. From HVAC systems to utility management, you can rest assured that our highly-qualified engineers are equipped to keep your building running at optimum efficiency.

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