Download interval energy data. This comes from your utility company, in which most of them supply the customer with interval data, which means the meter keeps track of energy use at a given interval (15 mins, 1 hour, 1 day, 1 month, etc.). This is extremely helpful and quite honestly, necessary when conducting a retro-commissioning effort. This tells you how a building operates, when the chillers come on, how high your base load is, what your peak demands are and on which days they occur. The list goes on. So make sure to ask your customer or energy provider, if they can supply you with that information. This may also give you insight into which rate and tariff they’re on, and could be a possible situation for additional energy savings.
Walk the facility. Keep your eyes open for anything that sticks out to you, broken items, equipment noises and comfort levels in the building. This is simply a high level walk through to make sure everything is in order. (See step 4 for a more thorough search of the facility.
Develop a system diagram if the As-Built drawings aren’t clear enough as to what the HVAC and controls layout is, then we highly recommend making your own system diagram from scratch, as it not only serves as a maintenance and system troubleshooting map, but also allows the engineer to double check if the As-Builts are the same as what was actually installed currently. Sometimes the contractor won’t supply the customer with As-Builts after construction, which can make things very confusing in the field. So an accurate system diagram can easily simplify even the most complex of systems. See our blog post on that for more information.
Conduct a conditional assessment of all building mechanical systems involved:
Which includes walking the facility – climbing in the overheads of office spaces to find VAV boxes, terminal boxes, reheat equipment, temperature sensors, fire dampers, differential pressure switches, etc. You want to mark all of this up on either your As-Built drawings or on a system diagram. These components are key when troubleshooting a large building mechanical system, but may not be necessary on smaller (residential) systems.
Check all dampers (especially outside air dampers) for rust, proper operation of actuators and damper blades,
Check for hunting of outside air (OA) and return air (RA) dampers. This is when the economizer tries to adjust the amount of outside air the dampers bring in, if the controls/building systems aren’t set up correctly, they tend to swing all the way open and closed constantly, in order to maintain temperature in the space.
Check all piping for proper labeling (HW supply, HW return, etc.). You want to make sure that if you plan to renovate a unit, that the piping is properly marked, as to avoid confusions during troubleshooting/construction. As well as any damage done to the units, associated piping systems and valves, to ensure that they are free of rust, cosmetic damage and even operational/internal damage.
Check space temperatures and thermostat placements, to ensure the space is being properly heated. Pay attention to doors being left open, or if the tenants purposely have the doors open because they either need fresh air or its too hot in the space. Talk to the tenants or building staff to see if you can get a grasp on how the building operates. Is it cold in the mornings? Is there too much air being supplied, and can you feel a draft? Are the thermostats in the right place and not blocked or placed directly above a supply grille?
Locate all of the supply/return diffusers. Are they blocked? Are the fans running right now? Is there hot or cold air coming/returning from them? Take a temperature gun and point it up at the grille. How hot is the air? This helps when developing a system diagram as well, because sometime it’s not clear whether a grille is supply air, return air or even exhaust air.
Take a look at the controls side of things, and wires, cables or gages that might affect the air handling unit, would be helpful to place on your system diagrams. Again, refer to our blog post about how to write a system diagram here.
Build an equipment inventory list. It’s always good to have a master list of currently installed equipment. You should capture data such as: name of system (if applicable), equipment name, location, make/model, output capacity, input capacity, electrical information, and any notes you want to put. It’s good to make this a table in excel or word, that way you can manipulate it later if need be.
Build a Picture Sheet or List. You don’t have to do this part, but it can simplify complex situations, by taking photos of each component and where they tie into the system. You can refer back to these as the project progresses, and is helpful to refer back to when explaining configurations of components and such to co-workers and other staff.
This is a general overview of how to listen to a building. You can’t “fix” a building until you’ve completely walked, operated and listened to how it performs. Again, the easiest way to learn how a building is acting is to talk to building staff that use it everyday, and then conduct a conditional assessment (sometimes adding in a few troubleshooting tests), and the rest is implementing those changes you find along the way.
Next Post:
Interpreting your interval data (provided by local municipality)
Using a pivot table to recognize energy use trends
How to look for energy reduction items
Energy rebates offered by PG&E
Thanks for reading, and tune in for the next post coming soon! Now get working on those system diagrams!
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