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Energy efficiency in commercial buildings

JonesInvesting in energy efficiency on commercial building projects is a trend in Idaho. And with the advent of more stringent energy codes and the city of Boise’s voluntary Green Building Code, the market will continue to move in this direction.

Code requirements aside, energy efficiency can pay off in the form of utility bill reduction, and in reduced operating and maintenance costs. So how can you be sure that your investment will pay off? How can you be sure that the design as drawn will get you the savings and payback promised? Lastly, how do you know that your as-built condition is performing to specifications? Many things can go wrong in the complicated design and construction of your building and with the “Green” and “High Performance” building getting more popular, design and construction will not be getting simpler.

Building commissioning is the third party verification of the owner’s project requirements. The commissioning agent’s job is to be the owner’s technical representative from concept to occupancy. A good commissioning agent should be a licensed engineer or architect within Idaho, and should have experience with every phase of building, from design to construction. For projects seeking payback on energy efficiency, the commissioning agent should also have a background in building science and energy.

Involving a commissioning agent costs money. However, of the handful of projects I’ve been involved with in Idaho, simple paybacks on the service have ranged between three and seven years. This payback is generally realized in avoided utility cost by suggesting more efficient design characteristics, or addressing issues during construction that have an energy impact. Typically, more complex design or construction projects pay back the service more quickly. Items or issues are tracked by the commissioning agent throughout the design and construction process, with followup to ensure the items are resolved.

Other items or issues without a direct cost or energy impact are also tracked and typically offer other benefits, like increased thermal comfort or reduced contractor callbacks. Every project has its own unique set of design opportunities and installation issues, so it is difficult to say to the investor: “look out for this.”

A couple of examples taken from actual Treasure Valley projects may paint a better picture.

1. The owner of a combination office/data center included requirements for stringent energy reduction goals, but the goals were deemed unreachable by the local design team. Their recommendation for energy efficiency only partly addressed the owner’s energy goals. In an effort to help fully address the original requirement, the commissioning agent presented equipment options that exceeded the original energy reduction goals, with a lower cost.  In a dry climate where it is typically less than 62° F for 70 percent of the year, constant heat loads such as server or data center equipment are efficiently addressed by using outdoor air to cool as opposed to running costly mechanical equipment. That would have been an option here.

2. Another example concerns a medical facility.  A high performance design, as drawn by a local design team, included provisions for a motorized modulating valve responsible for regulating temperature on a chilled water loop that supplied cooling for patient rooms. During construction, this valve was not installed by the contractor. Without the valve, water was bypassing the patient rooms while tripping equipment alarms repeatedly. After testing performed by the commissioning agent that proved cooling was not operating to design specifications, the contractor installed the valve. Cooling performance was restored before occupants moved in.

On about 90 percent of projects, airside economizers have been found by the commissioning agent to be not working properly. Economizers are used to cool spaces by bringing in outside air when it is less than 70° out. If they are stuck open, they will significantly raise heating and cooling energy costs while possibly not effectively cooling the space during the hottest and coldest days of the year. Fixing economizers typically has energy cost paybacks of less than a year.

Michael S. Jones is a licensed professional engineer in Idaho.  He runs SEEDIdaho P.C., a Boise-based mechanical engineering and building commissioning consulting firm dedicated to sustainable design and building operation.

About Michael S. Jones