I have had the privilege to visit many chilled water plants in Dubai and surprised at how many sites are struggling with flow management. It seems that many building operators are attributing little to no value to their circulating pump operation, concentrating on large ticket items such as chillers and air handling units to seek energy improvement. Unfortunately, chiller and/or AHU upgrade are often abandoned due to high capital cost to retrofit them.
As energy supply in the UAE is becoming an intensely hot topic (as everywhere else in the world), are we overlooking “low hanging fruits” by not tackling pumping cost?
Sure, the annual pumping cost is relatively small compared to chillers, but it still accounts for 30-35% of the plant total consumption. Furthermore, cutting in half the annual pumping cost does not require changing pumps or inverter, nor it requires piping modification and can be safely implemented without plant shut-down. This energy conservation measure is simple, low cost and without any operational risks.
Considering that every building in Dubai has large pumps operating 24/7 to circulate chilled water for its air conditioning needs, a concerted effort from the local engineering community to focus on that segment would go a long way to help building’s owners reducing consumption and contribute in a big way to the country energy objectives.
WANT TO CHECK IF YOUR PUMPING COST IS IN BALANCE?
ASHRAE 90.1 suggest that power consumption of a variable speed circulating pump should be no more than 30% of its nominal Wattage at 50% of its flow. In other words, if your pump power consumption is 75kW at 100% flow, at 50% flow it should be no more than 22.5kW.
For the none techy guys, the flow is directly proportional to the cooling need, so in the summer months, more flow is needed because more cooling is needed, but during spring, fall and winter all pumps can be turned right down because less cooling is needed hence lower flow demand. This gives a very practical “yardstick” to assess plant saving opportunities.
UNBEATABLE RETURN ON INVESTMENT
If you just realize that your building pumping cost is too high, the good news is that ASHRAE laid-out all the information on how to deal with it and can be downloaded for $200 today! – www.ashrae.org – This provides the blueprint of remedial measures to improve pumping performance.
Want to save $200? – Simply send us a mail and we will share with you the common faults seen on-site that are contributing to excess pumping costs. email@example.com
NEED A HAND TO ASSESS YOUR PLANT?
Your building energy consumption drives you crazy but not sure where to start, get in touch – we will be happy to share ways for you to implement solutions in your building – firstname.lastname@example.org – www.orcivalpump.com