Cold Weather and Energy Use
SEDAC has many long-term clients. For one such client, all of the gains they had made in efficiency where wiped out in one winter! In 2008, SEDAC performed an energy audit that recommended that they install high efficiency chillers, condensing boilers, and new lighting. In addition, the client changed single-pane glazing systems to double-pane with low-e, performed air sealing, and more. This work was completed by 2009 and remarkable savings were realized. However, sometimes things go awry.
SEDAC has tracked this client’s energy usage over the years, and we noted that after implementation, gas use significantly decreased until the winter of 2013-14. This client has several other facilities that also experienced high energy use during that winter. The 2013-14 winter was colder than usual, but the cold temperatures alone don’t explain the magnitude of increase in energy consumption. The following graph illustrates this client’s gas usage over six years: prior to implementation through last winter.
This analysis shows two years of approximately 30% gas savings per year, then reveals a dramatic rise in gas use this last winter. This troubling phenomenon piqued our interest at SEDAC. What happened, why, and what can be done to avoid reoccurrence? Conversations with the client disclosed that, due to the extremely cold weather, thermostat setbacks were disabled due to concern that sprinkler systems and hydronic systems might freeze. The client’s approach to avoid their prior experiences of burst pipes during very cold weather was to run the heating system 24 hours a day. And the 24-hour operation apparently was left in place well into the spring. Their approach worked and the troubling experience of burst pipes did not occur. But, at what cost?
SEDAC calculations estimate the facility used 16,994 more therms than expected, at an additional cost of $14,355 at this single facility. And this was at just one of several facilities experiencing the same phenomena. Other SEDAC clients have reported similar experiences.
What does SEDAC recommend?
Disabling setbacks could have been done only when very cold weather was anticipated, and then promptly reset after the cold weather passed. However, is this task reasonable to require of facility operators—when they already have a very full plate of responsibilities?
Addressing potential vulnerable areas (where piping could freeze) with increased insulation or heat tape would be an optimum solution. However, depending on accessibility, this solution may prove difficult. For hydronic systems, using glycol solutions would increase the resiliency of the system. Note that older unit ventilators may have fixed fresh air intakes, which could expose coils to vulnerable conditions.
Regrettably, SEDAC does not have a one-size-fits-all recommendation. SEDAC recognizes the facility operator’s desire to reduce the potential for disasters, nevertheless, we are concerned about our client’s energy bills. One response may be to pay someone extra to monitor and adjust thermostat settings during extreme weather conditions. This approach has the possibility to deliver rapid paybacks and mitigate the potential for disaster. Regardless, careful monitoring of weather conditions as well as the building systems is critical to reducing vulnerability to unexpected high utility costs!