|
Water Heating System Name |
|
|---|---|
|
Applicability |
All water heating systems |
|
Definition |
A unique descriptor for each water heating system. A system consists of one or more water heaters, a distribution system, an estimate of hot water use, and a schedule for that use. Nonresidential buildings will typically have multiple systems, perhaps a separate electric water heater for each office break room, etc. Other building types such as hotels and hospitals may have a single system serving the entire building. |
|
Units |
Text, unique |
|
Input Restrictions |
Where applicable, this should match the tags that are used on the plans such that a plan reviewer can make a connection |
|
Baseline Building |
The naming convention for the baseline building system shall be similar to the proposed design |
|
Water Heating Peak Use |
|
|---|---|
|
Applicability |
All water heating systems, required |
|
Definition |
An indication of the peak hot water usage (e.g., service to sinks, showers, and kitchen appliances). When specified per occupant, this value is multiplied by design occupancy density values and modified by service water heating schedules to obtain hourly load values that are used in the simulation. Peak consumption is commonly specified as gallons per hour per occupant, dwelling unit, hotel room, patient room, or floor area. If consumption is specified in gallons per hour, then additional inputs would be needed such as supply temperature, cold water inlet temperature, etc. It is also common to specify peak use as a thermal load in Btu/h. In the latter case, there is an implied assumption for the cold water inlet temperature, supply temperature, distribution losses, and other factors. The thermal load does not include conversion efficiencies of water heating equipment. |
|
Units |
Btu/h or gallons/h |
|
Input Restrictions |
As designed. If these values are not available, the hot water use specified in COMNET Appendix B (COMNET 2017) may be used. |
|
Baseline Building |
Hot water consumption or load in the baseline building shall be the same as the proposed design, except in cases where:
NOTE: Calculations need to be provided to support the difference in service hot water loads between the proposed and baseline model. |
|
Water Heating Schedule |
|
|---|---|
|
Applicability |
All water heating systems |
|
Definition |
A fractional schedule reflecting the time pattern of water heating use. This input modifies the water heating peak use, described above. |
|
Units |
Data structure: schedule, fractional |
|
Input Restrictions |
If known, anticipated schedules shall be used. If not known, the schedules from COMNET Appendix C (COMNET 2017) may be used. |
|
Baseline Building |
Hot water schedules for the baseline building shall be the same as the proposed design, except in cases where a specific measure is specified for the proposed design that will reduce water consumption and the impact of the measure can be best approximated through an adjustment to the schedule. In general, such measures would be addressed through an adjustment to the water heating, peak use (see above). |
|
Water Heating System Configuration |
|
|---|---|
|
Applicability |
All water heating systems |
|
Definition |
The configuration and layout of the water heating system, including the number of water heaters; the size, location, recirculation systems and pumps; and any other details about the system that would affect the energy model. Piping heat losses shall not be modeled per Standard 90.1-2019. |
|
Units |
Data structure |
|
Input Restrictions |
None |
|
Baseline Building |
The number of water heaters in the baseline building are dependent on the building area types. Section 3.9.1.2 discusses the requirements for the baseline building model. |
|
Water Mains Temperature Schedule |
||
|---|---|---|
|
Applicability |
All water heating systems |
|
|
Definition |
A monthly temperature schedule indicating the water mains temperature. This temperature and the setpoint temperature are used to convert the load into a water flow rate. |
|
|
Units |
Data structure: schedule, °F |
|
|
Input Restrictions |
Entering water temperature can be defaulted to the values in Table 95 or provided by the user |
|
|
Baseline Building |
Same as proposed |
|
Table 95. Defaults for Water Mains Temperature Based on Climate Zone
|
Monthly Average |
|||||||||||||||||
|
Water Main Supply Temp (°F) |
|||||||||||||||||
|
|
1A |
1B |
2A |
2B |
3A |
3B |
3C |
4A |
4B |
4C |
5A |
5B |
5C |
6A |
6B |
7 |
8 |
|
January |
76.5 |
70.2 |
64.6 |
65.8 |
56.5 |
59.4 |
59.7 |
50.8 |
52.3 |
52.9 |
45.5 |
48 |
50.6 |
43.1 |
43.1 |
37.6 |
32 |
|
February |
77.1 |
72.2 |
65 |
67.3 |
56.4 |
59.5 |
59.5 |
50 |
51.7 |
52.3 |
44.1 |
47 |
49.9 |
41.6 |
41.6 |
35.6 |
32 |
|
March |
79 |
77.6 |
67.9 |
72.2 |
59.5 |
62.4 |
60.1 |
52.2 |
53.8 |
53.4 |
45.8 |
48.7 |
50.7 |
42.7 |
42.5 |
36.1 |
32 |
|
April |
81.7 |
85.1 |
72.7 |
79.5 |
65 |
67.4 |
61.5 |
57 |
58.3 |
56.1 |
50.1 |
53.1 |
52.7 |
46.4 |
45.6 |
39 |
32 |
|
May |
84.6 |
92.6 |
77.9 |
87.2 |
71.6 |
73.3 |
63.2 |
63.1 |
64 |
59.5 |
56 |
58.8 |
55.5 |
51.6 |
50.2 |
43.5 |
32.9 |
|
June |
86.8 |
98.1 |
82.3 |
93.1 |
77.4 |
78.4 |
64.8 |
68.9 |
69.3 |
62.9 |
61.9 |
64.3 |
58.3 |
57 |
54.9 |
48.5 |
36.9 |
|
July |
87.7 |
100.2 |
84.6 |
95.8 |
80.8 |
81.3 |
65.9 |
72.7 |
72.8 |
65.2 |
66.2 |
68.2 |
60.4 |
61.1 |
58.6 |
52.6 |
40.7 |
|
August |
87.1 |
98.1 |
84.2 |
94.3 |
80.9 |
81.3 |
66.1 |
73.6 |
73.5 |
65.9 |
67.6 |
69.4 |
61.1 |
62.8 |
60.2 |
54.7 |
43.1 |
|
September |
85.1 |
92.6 |
81.2 |
89.2 |
77.8 |
78.3 |
65.4 |
71.3 |
71.3 |
64.7 |
65.9 |
67.6 |
60.3 |
61.6 |
59.2 |
54.2 |
43.4 |
|
October |
82.4 |
85.1 |
76.4 |
81.8 |
72.2 |
73.2 |
64 |
66.4 |
66.7 |
62 |
61.5 |
63.2 |
58.2 |
57.9 |
56 |
51.3 |
41.5 |
|
November |
79.5 |
77.6 |
71.1 |
74.2 |
65.6 |
67.3 |
62.3 |
60.3 |
61 |
58.5 |
55.6 |
57.5 |
55.4 |
52.6 |
51.4 |
46.7 |
38 |
|
December |
77.4 |
72.2 |
66.8 |
68.3 |
59.9 |
62.3 |
60.7 |
54.6 |
55.8 |
55.2 |
49.7 |
51.9 |
52.6 |
47.2 |
46.7 |
41.7 |
33.8 |