Energy Saving Opportunities During Low Office Occupancy Periods

Written by: Alex Kampf

For many building owners, the COVID-19 pandemic has disrupted tenant occupancy with vacancy rates climbing since Q1 2020. Extreme weather continues to keep HVAC systems in flux. Fortunately, though, both owners and operators have the opportunity to react to adversity together to protect their assets by implementing a few key HVAC strategies.

A tangible crossover between both parties is energy usage. According to a Commercial Building Energy Consumption Survey (CBECS) report (released by the U.S Energy Information Administration in 2016), space heating, cooling, and ventilation account for 44% of all major fuel consumption in commercial buildings. When considering the costs of owning and operating a commercial building, energy usage is a top priority.

At the onset of the pandemic, millions of square feet transitioned from occupied to empty at an unprecedented rate. During this turbulent time, owners and operators were focused on keeping employees safe and addressing building compliance with rapidly changing health and safety guidelines.

Yet, this scenario represents an excellent opportunity for energy savings. Empty spaces do not need the same level of conditioning as occupied spaces. With building managers focused elsewhere, this externality may have been overlooked. Whether the site has been upgraded with an integrated building automation system (BAS) or still relies on older technology for HVAC controls, adjusting comfort setpoints provides an instant return for energy savings.

Office vacancy rates have not returned to pre-COVID-19 pandemic levels. Luckily, there are several paths to pursue energy savings for vacant spaces. To start, building operators should routinely perform a high-level self-audit of their BAS systems. One quick change, available regardless of HVAC controls, is increasing the cooling setpoint in unoccupied spaces. Adjusting a few degrees up can result in significant savings without sacrificing comfort.

Another opportunity for buildings with more programmable BAS systems is decreasing minimum outside air requirements. Excessive ventilation can be avoided by using or commissioning demand control ventilation (DCV). DCV is a strategy used to measure indoor air quality with various sensors and provide outdoor make-up air accordingly. Using both thermostat setback and DCV to leverage energy savings in unoccupied spaces is an invaluable tool to building owners and operators.

While a qualified on-site operator likely knows their building well enough to make small adjustments and achieve savings, a more comprehensive approach is pursuing a retro-commissioning (RCx) project. The purpose of RCx is to obtain a complete assessment of a building’s energy performance and make changes to existing equipment. As operators and tenants change over long periods of time, building systems may no longer be operating as commissioned. RCx is generally classified by operational savings projects that do not carry an equipment cost but utilize external consultants to complete the full assessment.

Taking a reactive approach to energy usage can prove useful during this period of increased vacancy and implementing a more sustainable solution can provide long-term savings. A 2017 report prepared for the Department of Energy found that a properly tuned building can cut energy consumption by 29%. The following strategies can help you achieve similar savings:

  • Increase thermostat cooling setpoint on empty spaces

  • Install and commission a BAS system

  • Reduce outdoor air intake

  • Use DCV to automatically control air quality

  • Perform RCx to retune setpoints

In addition, utility customers can often receive free energy efficiency assessments to help guide them towards greater savings. Consult with your utility provider to find out about current offerings for energy efficiency assessments.

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