By Sonya M. Pouncy, CEM, CMVP, LEED-AP. Sonya is a senior engineering consultant with Energy Sciences. The firm helps clients meet energy challenges with practical solutions that reduce waste and increase net operating income.
The median age of all U. S. commercial buildings is about 39 years. Some buildings are over 100 years old. Many of these structures will likely be active for another 25, even 50 years. For these facilities to continue delivering acceptable building performance, they must be properly maintained. Actions must be taken to preserve the condition of each building and its internal systems to ensure that they continue delivering the intended thermal comfort, indoor environmental quality, and energy performance required by their owners and occupants.
Specific actions taken in any facility maintenance program will depend on several factors including building operation and complexity as well as reliability and availability criteria. However, one thing that is consistent across all buildings is the need for regular performance assessments. Just like our bodies require regular visits to the doctor, dentist, and optician to ensure all systems are functioning properly, our buildings require regular check-ups by a team of specialists, too. We can’t take them to the clinic, but we can conduct in situbuilding assessments. We can have in-house staff or outside contractors observe how the building systems—envelope, HVAC, lighting, hot water, conveyance, etc.—operate. We can take measurements of key performance indicators (KPIs). We can evaluate what those indicator values mean, what they tell us about how our buildings operate now and how, or even whether, they are likely to operate in the future. And, we can take prescribed actions to help ensure that each building continues to provide beneficial use throughout its expected life cycle.
Our bodies have generalized targets for KPIs such as blood pressure and cholesterol. Buildings also have performance targets. Guidance for how your building should be performing can be obtained from ASHRAE Standard 100-2018: Energy Efficiency in Existing Buildings. The Standard provides site and source level energy use targets for most building types by climate zone in units of annual overall energy use, annual electric energy use, and annual heating fuel use. For example, the ASHRAE Standard 100 site level energy use targets for a southeast Michigan office building operating 60 hours per week are shown in the table below.
If your office building is performing at or better than these recommended target levels, then you’ll want to keep doing what you’re already doing. But, if your building is consuming more energy, you’ll want to investigate why and take corrective actions, such as replacing worn components, adjusting setpoints, re/retro-commissioning, or upgrading aged systems.
As with our bodies, the general opinion is that building performance should be examined at least annually. This way, the variations due to seasonality can be viewed in proper context. However, if operating tolerances are critical or building systems are exposed to extreme conditions, it may be advantageous to review the data more frequently. Building data should be evaluated often enough to identify performance drift before it becomes too costly or impossible to repair; but not so often that the reviews are meaningless or divert time and resources that could be better used elsewhere.
Once you begin regularly assessing your building’s performance, you’ll need a place to store all your data and a tool to help interpret what it means. ENERGY STAR Portfolio Manager is perfect for that. This free tool from the U.S. EPA can be used to track energy consumption as well as water consumption and greenhouse gas emissions. Plus, it summarizes all your data and provides you with an ENERGY STAR Score, a benchmark indicator of how your facility’s performance compares to that of similar facilities across the country. Where your ENERGY STAR score lands within the national distribution can guide your next steps to, perhaps, invest in major upgrades, tweak your O&M practices, or continue doing what you’re doing.
Regularly assessing, reviewing, and tracking your building energy performance is an important first step toward preserving building longevity. If you’re interested in learning more about how your building is performing, contact Energy Sciences to discuss how a facility assessment can help inform your next steps in building performance management.