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It’s Getting Hot in Here…



Set your HVAC system up for success—and savings.

 

By Myrna Traylor


With summer on its way, it is a good time to make sure that your facilities’ HVAC systems are ready to provide the proper level of cooling. There are ways to make sure that you can get what you need out of your air conditioning systems without breaking the bank.

Ron Prager, Brinco Mechanical Management Services, Inc.
Ron Prager, Brinco Mechanical Management Services, Inc.

Connexus spoke with Ron Prager, Executive VP and COO of Brinco Mechanical Management Services, Inc., to get a crash course on keeping costs down while keeping facilities cool.

 

Connexus: Why does the summer season place such a strain on HVAC systems?

 

Ron Prager: Air conditioning units are equipped with multiple stages of capacity control. The first cooling stage is maybe 50% of the unit’s capacity, while the second stage brings you up to 100%. In moderate temperatures, you might use one compressor out of two, but when it gets hot outside, you will operate two stages of capacity, putting more strain on the unit.

 

Also, during cooling operation, units work harder at higher outdoor temperatures because the internal refrigerant pressures are proportionately higher based upon the temperature you're operating at. There's a linear relationship between temperature and pressure. A higher temperature yields higher pressure, which means the machine must do more work to produce the same level of cooling, which requires increased energy usage.

 

Connexus: Are there ways that facilities managers can reduce their costs or their energy consumption during summer months?

 

Prager: Yes. First, you can buy equipment that is rated as standard efficiency or high efficiency. When you use higher-efficiency equipment, it costs you less each year to operate that equipment. Of course, you're paying more for the high-efficiency equipment up front, but if the higher efficiency equipment is 20% more efficient, you will save 20% of the utility costs each year.

 

There are also options that you can add to your equipment, such as variable frequency drives—they vary the blower speed with the required capacity, which will save a significant amount of energy. You can choose a machine with low-leakage economizers, which allow you to use outdoor air for cooling rather than running the compressors in the machine.

 

There's also a control strategy called demand-controlled ventilation, or DCV. Normally, a system must bring in a certain amount of outdoor air for ventilation purposes as required by code. However, if you put a carbon dioxide (not carbon monoxide) detector in the space, it will sense how far you need to open your dampers to dilute the products of respiration that people in the space are producing. You can then reduce the amount of code-required outside air you bring in. Think of what it takes to cool outside air in Arizona from 110 degrees outside to 74 degrees inside versus just cooling the air in the store from 77 or 78 degrees back down to 74. If you cut down on the amount of outside air, you can cut down on your energy expenses.

 

Connexus: How far in advance should FMs plan to make these accommodations for summer savings?

 

Prager: There are maintenance tasks that are going to save you energy and they should be performed as soon as the outdoor temperatures rise above 60 degrees. You need a thorough cooling preventive maintenance (PM) startup before each cooling season. That should be performed on any commercial system and includes replacing air filters because dirty filters restrict the airflow. Replace the drive belt because a slipping drive belt will prevent you from moving the correct amount of air. Your contractor should inspect the indoor coils (evaporator coils) and the outdoor coils (condenser coils) to determine whether they need to be cleaned. Correct refrigerant charge should also be confirmed. These are not all the recommended PM tasks, but these are the simplest tasks that affect energy usage and cost.

 

Connexus: Can FMs use historical data to anticipate their HVAC needs for an upcoming season?

 

Prager: FMs should look at their assets based on age, geographic location and historical breakdown of the number of repairs and cost. In addition, a facilities manager can see which facilities are their energy hogs by reviewing energy usage during the prior cooling season on a per square foot basis and then normalizing that by the number of cooling degree days in that geographic area. This can help you plan for a proactive system replacement program or help determine why a site is consuming excessive energy. For example, while reviewing the data, one might discover a site with 23-year-old equipment, an extremely high annual repair spend, and a high call count. Depending on lease life and store performance, replacement would be a better option than continuing to throw money into a black hole.

 

Connexus: How can an FM be sure that their HVAC supplier is performing the correct preventive maintenance?

 

Prager: Use a supplier with a good reputation in the business or get a recommendation from another facilities manager. You will be relying on the HVAC tech to follow the procedures checklist. Also, expect to pay a fair price based on the amount of labor and materials that go into performing this work.


Learn more about how to make sound HVAC repair vs. replace decisions.

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