Sherlock Holmes, Cx Agent

Sherlock Holmes, Cx Agent

In building construction, so many issues can be hidden from plain view — sometimes literally behind brick walls — and often no one even knows they’re there, until the day they become a problem. That’s where we come in. At SES, we work with a wide range of building designs and construction methods, giving us the unique ability to spot not only what’s wrong – but also what may be missing.

New Construction: Missing Damper

New Construction Commissioning (NCCx) is included in the construction process to ensure that buildings are operating efficiently and according to design. This means that effective NCCx prevents latent issues from becoming problematic after the building is turned over to the owner. Our investigative process through formal design reviews is one of the most effective methods for troubleshooting building systems before issues occur.

Design reviews and system controls submittal reviews, which focus on the building sequence of operations, can have a significant impact on building performance. Though many review comments are simply tweaks in setpoints for operational efficiency, missed control devices, or requests for warranty requirements; sometimes small omissions in design drawings are present that can have big implications in the fully operational building.

In a recent design review for a campus housing unit, our team noticed a potential airflow issue for an air handling unit. While the unit sequences were common for controlling and air handling units, the combination of building pressure control (method for maintaining a slight positive pressure in the building) and outdoor airflow (method for maintaining a minimum amount of outside air) had the potential to create a positive feedback loop where air could potentially flow backwards through the system. The backwards flow would cause the building pressure to increase, signaling the system to open a damper causing more air to flow backwards through the system. No controls or equipment were indicated to prevent the loop from continuing to increase the building pressure.

Relying on a combination of experience of both air handling systems and fluid dynamics, SES identified this hidden issue. In practice, there are several potential solutions to prevent this issue from occurring, but SES suggested installing simple gravity dampers which prevent backwards airflow and, in this case, prevents the over-pressurization of the building.

Design reviews are the first stop in identifying potential issues before they exist and reviews by experienced and knowledgeable commissioning engineers can identify not only issues in design, but omissions as well.

Retro-Commissioning: Omitted Programming

Even the most meticulously run buildings will find that their energy costs rise over time. From throttled (partially closed) isolation valves to full building renovations, there are countless reasons for building energy to gradually increase. Retro-Commissioning (RCx) helps significantly bring a building back toward baseline energy use, or in some cases, even find additional energy savings.

During a recent investigation into a campus medical facility built in 2018, it was discovered that a chilled water reset strategy (programming to adjust the chilled water temperature based on the needs of the building) had not been programmed into the system. While a fixed chilled water temperature ensures cooling is available year-round, by monitoring downstream systems and feedback the chilled water supply temperature setpoint can be reset and “optimized” to the current load of the building. Although SES recommended several other energy conservation measures, none had the potential to save more building energy than this one program modification. Through our investigative process, this simple tasks resulted in beneficial savings for the client and the project team.

Because the system was over-producing, there were no “issues” to report, no complaints of warm offices or loud equipment, virtually no reason to scrutinize if anything was amiss. Regardless, SES identified a major system inefficiency and saved our client thousands of dollars per year.

While this is just one efficiency measure discovered during the retro-commissioning process for this project, several more potential measures were discovered and brought to the attention of the Owner. Energy savings, other energy conservation measures, and retro-commissioning costs for similar-type projects can be found in case studies.

Envelope Commissioning: Voids

Something that can be detrimental to a building, and infuriating to a new owner? A brand-new leaky building.  The biggest issue with failures in building envelope is that you only have two options: remove the building façade and repair faulty areas or deal with the leaks. Neither of these are great options.

Luckily, Building Envelope Commissioning (BECx) can alleviate concerns with envelope construction and prevent future issues.  A trained third-party professional can review building envelope construction or an existing building envelope that is experiencing issues like roof leaks and drafty windows (a cause of significant energy loss).

During a site visit to a high school in Rhode Island, SES noticed two failures which may not have individually caused any significant issue but together could spell a substantial problem. A spray applied air-vapor barrier (AVB) was applied too thinly and the joints between the sheathing (exterior drywall) weren’t adequately sealed. As a result of these two flaws in AVB application, small gaps formed in the vapor barrier. Each small hole was another location where water could penetrate the building enclosure, meaning several potential locations for leaks to be discovered years down the road.

It was clear that although all the parts of the envelope system were installed there was one key element that was missing, coordination. SES met with the contractor, construction team, AVB material manufacturer, and the owner collaboratively to find an answer.  The team agreed that the best solution was to seal all the joints and re-apply a proper thickness of air-vapor barrier before the issues were concealed by a brick façade.

As building systems become more complex and programming more advanced, it’s essential to have the right commissioning agent on your team – specialists who can identify hidden issues before they arise and bridge the gaps between design and construction. Much like making a pizza, it’s easy to recognize when the cheese is missing, but requires a little detective work when you forget the sauce!