If you are a system 8 (Electric Heat), then the only pumps would be for chilled water. If your total cooling capacity is greater than 300 tons then the baseline must have variable speed drives. Even if you are less than 300 tons it is a primary/secondary loop with pumps riding their curves so it's less efficient but not straight constant volume. Also, with heat recovery it is important to look at how many hours you would expect that it would run in your climate. For example, you would not want to run a ERU when a economizer would be available. There are obliviously other ways to get to 10% but it can be hard with district systems because by not being able to take credit for having a chiller you are losing out on opportunity to gain efficiency. Good luck.
Is the central utility plant serving other buildings other than LEED
candidate building? If it is, then the energy modeler should use the
guidelines for district cooling / heating which will require him to add
chilled water meter on both models then I believe the pump type including
the chiller specifications would not matter in the energy model anymore.
You may search in the archive about modeling system with district cooling /
heating and "Treatment of District or Campus Thermal Energy in LEED V2 and
LEED 2009 - Design & Construction."
Hope that helps.
If you are a system 8 (Electric Heat), then the only pumps would be for chilled water. If your total cooling capacity is greater than 300 tons then the baseline must have variable speed drives. Even if you are less than 300 tons it is a primary/secondary loop with pumps riding their curves so it's less efficient but not straight constant volume. Also, with heat recovery it is important to look at how many hours you would expect that it would run in your climate. For example, you would not want to run a ERU when a economizer would be available. There are obliviously other ways to get to 10% but it can be hard with district systems because by not being able to take credit for having a chiller you are losing out on opportunity to gain efficiency. Good luck.
Brendan Hall
D
Is the central utility plant serving other buildings other than LEED
candidate building? If it is, then the energy modeler should use the
guidelines for district cooling / heating which will require him to add
chilled water meter on both models then I believe the pump type including
the chiller specifications would not matter in the energy model anymore.
You may search in the archive about modeling system with district cooling /
heating and "Treatment of District or Campus Thermal Energy in LEED V2 and
LEED 2009 - Design & Construction."
Hope that helps.
-Bob
You may disregard my email. Sorry I did not see your response to Yazan.
-Bob
DD