Baseline Building Summary. Hot water pumping in the baseline building (systems 1, 5, and 7) shall be modeled as a variable flow primary only system. When the spaces served by the hot water system are greater than or equal to 120,000 ft², the pump shall have a variable speed drive, otherwise, the pump “rides the curve”. Pumping energy shall be assumed to be 19 W/gpm. Two-way valves are assumed at the heating coils with a modulating bypass valve at the end of the loop. The bypass valve shall open as necessary to maintain minimum flow through the boiler when the system is activated. This will establish the minimum flow through the system.
Chilled water pumping in the baseline building (systems 7 and 8) is a primary/secondary system. Each chiller has its own primary and condenser water pumps that operate when the chiller is activated. All primary and secondary pumps shall be assumed to be 22 W/gpm and the condenser water pump is assumed to be 19 W/gpm. For plants less than or equal to 300 tons, the secondary pump “rides the curve” for larger plants, the pump has a variable speed drive.
General Notes. The building descriptors in this section are repeated for each pumping system. See the Pump Service building descriptor for a list of common pump services.
| Pump Name |
| Applicability |
All pumps |
| Definition |
A unique descriptor for each pump |
| Units |
Text, unique |
| Input Restrictions |
User entry. Where applicable, this should match the tags that are used on the plans. |
| Baseline Rules |
Same as the proposed design. If there is no equivalent in the proposed design, assign a sequential tag to each piece of equipment. The sequential tags should indicate the pump service as part of the descriptor (e.g. CW for condenser water, CHW for chilled water, or HHW for heating hot water).
|
| Pump Service |
| Applicability |
All pumps |
| Definition |
The service for each pump. Choices include:
- Chilled water
- Chilled water (primary)
- Chilled water (secondary)
- Heating water
- Heating water (primary)
- Heating water (secondary)
- Service hot water
- Condenser water
- Loop water (for hydronic heat pumps)
|
| Units |
List (see above) |
| Input Restrictions |
As designed
|
| Baseline Rules |
As needed by the baseline building system
|
Number of Pumps
|
| Applicability |
All pumps |
| Definition |
The number of identical pumps in service in a particular loop, e.g. the heating hot water loop, chilled water loop, or condenser water loop
|
| Units |
Numeric: integer |
| Input Restrictions |
As designed |
| Baseline Rules |
There will be one heating hot water pump for each boiler, one chilled water pump, and one condenser water pump for each chiller. |
Water Loop Design
|
| Applicability |
All pumps |
| Definition |
The heating and cooling delivery systems can consist of a simple primary loop system, or more complicated primary/secondary loops or primary/secondary/tertiary loops. |
| Units |
List (see above) |
| Input Restrictions |
As designed |
| Baseline Rules |
Assume primary loops only for heating hot water. For chilled water loops, a primary-secondary loop design is assumed.
|
| Pump Motor Modeling Method |
| Applicability |
All pumps |
| Definition |
Software commonly models fans in one of two ways: The simple method is for the user to enter the electric power per unit of flow (W/gpm). This method is commonly used for smaller systems. A more detailed method requires a specification of the pumping head, impeller efficiency, motor efficiency, and other inputs. |
| Units |
List: Power-Per-Unit-Flow or Detailed |
| Input Restrictions |
Either method may be used, as appropriate. |
| Baseline Rules |
Power-Per-Unit-Flow |
| Pump Motor Power-Per-Unit-Flow |
| Applicability |
All baseline building pumps and proposed design pumps that use the Power-Per-Unit-Flow method. |
| Definition |
The electric power of the pump divided by the flow at design conditions. |
| Units |
W/gpm |
| Input Restrictions |
As designed |
| Baseline Rules |
Prescribed to be 19 W/gpm for condenser and heating hot water pumps and 22 W/gpm for primary and secondary chilled water pumps. |
| Impeller Efficiency |
| Applicability |
All pumps in proposed design that use the detailed modeling method |
| Definition |
The full load efficiency of the impeller |
| Units |
Ratio |
| Input Restrictions |
As designed |
| Baseline Rules |
Not applicable |
| Motor Efficiency |
| Applicability |
All pumps in proposed design that use the detailed modeling method |
| Definition |
The full load efficiency of the pump motor |
| Units |
Ratio |
| Input Restrictions |
As designed |
| Baseline Rules |
Not applicable |
| Pump Design Head |
| Applicability |
All pumps in proposed design that use the detailed modeling method |
| Definition |
The design pressure for the pump |
| Units |
Feet of water (or feet of head) |
| Input Restrictions |
As designed |
| Baseline Rules |
Not applicable |
| Pump Minimum Speed |
| Applicability |
All two-speed or variable-speed pumps |
| Definition |
The minimum pump speed for a two-speed for variable-speed pump. For two-speed pumps this is typically 0.67 or 0.5. Note that the pump minimum speed is not necessarily the same as the minimum flow ratio, since the system head may change. |
| Units |
Ratio |
| Input Restrictions |
As designed |
| Baseline Rules |
The secondary chilled water pumps for baseline building systems 7 and 8 have variable speed drives when the size of the cooling plant is greater than 300 tons. In these cases the Pump Minimum Speed shall be 0.10.
|
| Pump Design Flow (GPM) |
| Applicability |
All pumps
|
| Definition |
The flow rate of the pump at design conditions. This is derived from the load, and the design supply and return temperatures. |
| Units |
gpm or gpm/ton for condenser and primary chilled water pumps |
| Input Restrictions |
Not a user input |
| Baseline Rules |
The temperature change on the evaporator side of the chillers is 12 F (56 F less 44 F) and this equates to a flow of 2 gpm/ton. The temperature change on the condenser side of the chillers is 10 F, which equates to a flow of 2.5 gpm/ton. The flow for secondary chilled water pumps varies with cooling demand, since there are two-way valves at the coils. The flow for primary only heating varies with demand down to the minimum required for flow through the boiler. A VSD is required for heating pumps when the service area is greater than or equal to 120,000 ft². |
| Pump Control Type |
| Applicability |
All pumps |
| Definition |
The type of control for the pump. Choices are:
- Fixed speed, fixed flow
- Fixed speed, variable flow (the default, with flow control via a valve)
- Two-speed
- Variable speed, variable flow
|
| Units |
None |
| Input Restrictions |
As designed. The default is “Fixed Speed, Variable Flow” which models the action of a constant speed pump riding the curve against 2-way control valves. |
| Baseline Rules |
The hot water and condenser water loops shall be primary loops only. When the hot water system serves less than 120,000 ft², the hot water pump shall be modeled as a fixed speed, variable flow pump (riding the pump curve). When the hot water system serves more than 120,000 ft², the hot water pump shall be modeled as a variable speed pump on a primary loop. The chilled water pumping for systems 7 and 8 is primary/secondary with variable flow. When the chilled water system has a capacity of less than 300 tons, the secondary system pumps shall ride the pump curve. When the chilled water system has a capacity of more than 300 tons, the secondary chilled water pumps shall be variable speed. Chilled water pumps used in the primary loop shall be fixed speed, fixed flow. Condenser water pumps shall be modeled as fixed speed, fixed flow. |
Pump Operation
|
| Applicability |
All pumps |
| Definition |
The type of pump operation can be either On-Demand, Standby or Scheduled. On-Demand operation means the pumps are only pumping when their associated equipment is cycling, so chiller and condenser pumps are on when the chiller is on and the heating hot water pump operates when its associated boiler is cycling. Standby operation allows hot or chilled water to circulate through the primary loop of a primary/secondary loop system or through a reduced portion of a primary-only system, assuming the system has appropriate 3-way valves. Scheduled operation means that the pumps and their associated equipment are turned completely off according to occupancy schedules, time of year, or outside conditions. Under scheduled operation, when the systems are on they are assumed to be in On-Demand mode. |
| Units |
List (see above) |
| Input Restrictions |
As designed |
| Baseline Rules |
The baseline system pumps are assumed to operate in On-Demand mode. The chilled water and condenser pumps are tied to the chiller operation, cycling on and off with the chiller, and the heating hot water pumps are tied to the boiler operation. |
| Pump Part Load Curve |
| Applicability |
All pumps |
| Definition |
A part-load power curve for the pump
(6.8.5-1)
(6.8.5-2)
where
| PLR |
Part load ratio (the ratio of operating flow rate in gpm to design flow rate in gpm) |
| Ppump |
Pump power draw at part-load conditions (W) |
| Pdesign |
Pump power draw at design conditions (W) |
Table 6.8.5-1: "Default Part-Load CIRC-PUMP-FPLR Coefficients – VSD on Circulation Pump"
| Coefficient |
CIRC-PUMP-FPLR |
| a |
0.0015303 |
| b |
0.0052081 |
| c |
1.1086242 |
| d |
-0.1163556 |
|
| Units |
Data structure |
| Input Restrictions |
As designed. Default is curve above. |
| Baseline Rules |
Use the defaults described above. |
