We are partnering with our local energy company for an energy model as this service will provide anlaysis and incenteive back to the Owner. The project is using several low speed high volume fans in a large warehouse type space. However when reviewing the model and potential energy cost savings bundles we were told the use of these fans is actually a penalty to the model. Both the Mech Engineer and the Architect were suprised by this as we have always been told this should be an energy cost savings. How do we convince the modeler that this is not a penalty and it actually provides energy cost savings? How should they be modeling these fans?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5915 thumbs up
November 16, 2021 - 11:05 am
What function do the fans serve? Are they exhaust fans, ventilation fans, ceiling fans?
Donald Green
Sr Project Manager / Operations ManagerProgressive AE
35 thumbs up
November 16, 2021 - 11:51 am
They are large ceiling fans; i.e. big ass fans, we have 3 of them in the space each is 24' wide.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5915 thumbs up
November 16, 2021 - 12:30 pm
Such fans are not regulated by 90.1 so they are considered a process load. As such they should be modeled identically in both models. So no penalty but no savings either. If you wish to claim savings then you must follow the exceptional calculation method. Be sure to firmly establish the baseline for any savings you are claiming. The baseline should be based on typical industry proactice in your area. So if ceiling fans are not typically installed in such facilities you will need to document that. Maybe big ass fans can help you with the documentation.
In my experience ceiling fans can be an energy saver is spaces that are cooled. The movement of air will have a cooling effect and allows temperature setting to be a bit higher for the same level of comfort. On the heating side they generally do not save energy. You will typically need at least a 20 degree temperature differential to overcome the air movement effect and that level of temperature stratification rarely exists in high ceiling facilities in my expereince measuring ceiling temperature in hundreds of facilities. Slow air movement can help a bit but again you need significant temperature stratification.
Donald Green
Sr Project Manager / Operations ManagerProgressive AE
35 thumbs up
November 16, 2021 - 2:29 pm
thank you!