# 3.6.3 Terminal Heating

This group of building descriptors applies to proposed design systems that have reheat coils at the zone level. The building descriptors are applicable for baseline building systems 5 through 8.

Applicability Terminal Heat Type Systems that have reheat coils at the zone level The heating source for the terminal unit. This includes: Electric resistance Gas furnace Oil furnace Hot water Steam List (see above) As designed. [bookref id="baseline-building-terminal-heat-type"] shows the terminal heat type for each baseline building system.

[table title="Baseline Building Terminal Heat Type" id="baseline-building-terminal-heat-type"]

 Baseline building System Terminal Heat Type System 1 – PTAC None System 2 – PTHP None System 3 – PSZ-AC None System 4 – PSZ-HP None System 5 – Packaged VAV with Reheat Hot Water System 6 – Packaged VAV with PFP boxes Electric Resistance System 7 – VAV with Reheat Hot Water System 8 – VAV with PFP boxes Electric Resistance
Applicability Terminal Heat Capacity Systems that have reheat coils at the zone level The heating capacity of the terminal heating source Btu/h As designed. However, if the unmet load hours exceed 300, the energy analyst and design team may have to increase the size of the equipment so that the unmet load hours are less than 300. See [bookref id="hvac-mapping"] and [bookref id="sat-cooling-setpoint-reset-based-on-outdoor-air-temperature-oat-for-dry-b-and-marine-c-climates"]. The software shall automatically size the terminal heating capacity to be 25% greater than the design loads. However, the equipment may need to be reduced in size such that the unmet load hours of the proposed design does not exceed the baseline building by more than 50. See [bookref id="sat-cooling-setpoint-reset-based-on-outdoor-air-temperature-oat-for-dry-b-and-marine-c-climates"].
Reheat Delta T
Applicability Systems that have reheat coils at the zone level
Definition

This is an alternate method to enter the terminal heat capacity. It can be calculated as follows:

(6.6.3-1)

$$\Delta T_{reheat} = T_{reheat} - T_{cool\_supply}$$

$$\Delta T_{reheat} = Q_{coil} / \left ( 1.1 * C\!F\!M \right )$$where

 $\Delta$Treheat heat rise across the terminal unit heating coil (°F) Treheat heating air temperature at design (°F) Tcool_supply supply air temperature at the heating coil (°F) Qcoil heating coil load (Btu/h) CFM airflow (cfm)
Units Degrees Fahrenheit (°F)
Input Restrictions As designed, but may need to be increased if unmet load hours are greater than 300
Baseline Rules Method not used for baseline building. See Heat Capacity above.
90.1-2010

This group of building descriptors applies to proposed design systems that have reheat coils at the zone level. The building descriptors are applicable for baseline building systems 5 through 8.

Applicability Terminal Heat Type Systems that have reheat coils at the zone level The heating source for the terminal unit. This includes: Electric resistance Gas furnace Oil furnace Hot water Steam List (see above) As designed. Table 6.6.3-1 shows the terminal heat type for each baseline building system.

Table 6.6.3-1: Baseline Building Terminal Heat Type

 Baseline building System Terminal Heat Type System 1 – PTAC None System 2 – PTHP None System 3 – PSZ-AC None System 4 – PSZ-HP None System 5 – Packaged VAV with Reheat Hot Water System 6 – Packaged VAV with PFP boxes Electric Resistance System 7 – VAV with Reheat Hot Water System 8 – VAV with PFP boxes Electric Resistance System 9 – Heating and Ventilation None System 10 – Heating and Ventilation None
Applicability Terminal Heat Capacity Systems that have reheat coils at the zone level The heating capacity of the terminal heating source Btu/h As designed. However, if the unmet load hours exceed 300, the energy analyst and design team may have to increase the size of the equipment so that the unmet load hours are less than 300. See Figure 2.4-1 The software shall automatically size the terminal heating capacity to be 25% greater than the design loads. However, the equipment may need to be reduced in size such that the unmet load hours of the proposed design does not exceed the baseline building by more than 50.
Reheat Delta T
Applicability Systems that have reheat coils at the zone level
Definition

This is an alternate method to enter the terminal heat capacity. It can be calculated as follows:

(6.6.3-1)

$$\Delta T_{reheat} = T_{reheat} - T_{cool\_supply}$$

$$\Delta T_{reheat} = Q_{coil} / \left ( 1.1 * C\!F\!M \right )$$where

 $\Delta$Treheat heat rise across the terminal unit heating coil (°F) Treheat heating air temperature at design (°F) Tcool_supply supply air temperature at the heating coil (°F) Qcoil heating coil load (Btu/h) CFM airflow (cfm)
Units Degrees Fahrenheit (°F)
Input Restrictions As designed, but may need to be increased if unmet load hours are greater than 300
Baseline Rules Method not used for baseline building. See Heat Capacity above.
90.1-2016 BM

This group of building descriptors applies to proposed design systems that have reheat coils at the zone level. The building descriptors are applicable for baseline building systems 5 through 8.

Terminal Heat Type

Applicability

Systems that have reheat coils at the zone level

Definition

The heating source for the terminal unit. This includes:

• Electric resistance
• Gas furnace
• Oil furnace
• Hot water
• Steam

Units

List (see above)

Input Restrictions

As designed.

Baseline Rules

Table 3.6.3-1 shows the terminal heat type for each baseline building system.

#### Table 3.6.3-1: Baseline Building Terminal Heat Type

 Baseline building System Terminal Heat Type System 1 – PTAC None System 2 – PTHP None System 3 – PSZ-AC None System 4 – PSZ-HP None System 5 – Packaged VAV with Reheat Hot Water System 6 – Packaged VAV with PFP boxes Electric Resistance System 7 – VAV with Reheat Hot Water System 8 – VAV with PFP boxes Electric Resistance System 9 – Heating and Ventilation None System 10 – Heating and Ventilation None System 11 SZ–VAV Depends on proposed design System 12 SZ-CV-HW Hot Water System 13 SZ-CV-ER Electric Resistance

Terminal Heat Capacity

Applicability

Systems that have reheat coils at the zone level

Definition

The heating capacity of the terminal heating source

Units

Btu/h

Input Restrictions

As designed. However, if the unmet load hours exceed 300, the energy analyst and design team may have to increase the size of the equipment so that the unmet load hours are less than 300. See Figure 2.4-1

Baseline Rules

The software shall automatically size the terminal heating capacity to be 25% greater than the design loads. However, the equipment may need to be reduced in size such that the unmet load hours of the proposed design does not exceed the baseline building by more than 50.

Reheat Delta T

Applicability

Systems that have reheat coils at the zone level

Definition

This is an alternate method to enter the terminal heat capacity. It can be calculated as follows:

(Equation 3.6.3-1)

DTreheat = Treheat - Tcool_supply

DTreheat = Qcoil / (1.1* CFM

where

 DTreheat heat rise across the terminal unit heating coil (°F) Treheat heating air temperature at design (°F) Tcool_supply supply air temperature at the heating coil (°F) Qcoil heating coil load (Btu/h) CFM airflow (cfm)

Units

Degrees Fahrenheit (°F)

Input Restrictions

As designed, but may need to be increased if unmet load hours are greater than 300

Baseline Rules

Method not used for baseline building. (The temperature difference shall be no more than 40F.) See Heat Capacity above.

Building EQ
Applicability Terminal Heat Type Systems that have reheat coils at the zone level The heating source for the terminal unit. This includes: Electric resistance Gas furnace Oil furnace Hot water Steam List (see above) As designed.
Applicability Terminal Heat Capacity Systems that have reheat coils at the zone level The heating capacity of the terminal heating source Btu/h As designed. However, if the unmet load hours exceed 300, the energy analyst and design team may have to increase the size of the equipment so that the unmet load hours are less than 300.
Reheat Delta T
Applicability Systems that have reheat coils at the zone level
Definition

This is an alternate method to enter the terminal heat capacity. It can be calculated as follows:

(6.6.3-1)

$$\Delta T_{reheat} = T_{reheat} - T_{cool\_supply}$$

$$\Delta T_{reheat} = Q_{coil} / \left ( 1.1 * C\!F\!M \right )$$where

 $\Delta$Treheat heat rise across the terminal unit heating coil (°F) Treheat heating air temperature at design (°F) Tcool_supply supply air temperature at the heating coil (°F) Qcoil heating coil load (Btu/h) CFM airflow (cfm)
Units Degrees Fahrenheit (°F)
Input Restrictions As designed, but may need to be increased if unmet load hours are greater than 300
Energy Star
Applicability Terminal Heat Type Systems that have reheat coils at the zone level The heating source for the terminal unit. This includes: Electric resistance Gas furnace Oil furnace Hot water Steam List (see above) As designed.
Applicability Terminal Heat Capacity Systems that have reheat coils at the zone level The heating capacity of the terminal heating source Btu/h As designed. However, if the unmet load hours exceed 300, the energy analyst and design team may have to increase the size of the equipment so that the unmet load hours are less than 300.
Reheat Delta T
Applicability Systems that have reheat coils at the zone level
Definition

This is an alternate method to enter the terminal heat capacity. It can be calculated as follows:

(6.6.3-1)

$$\Delta T_{reheat} = T_{reheat} - T_{cool\_supply}$$

$$\Delta T_{reheat} = Q_{coil} / \left ( 1.1 * C\!F\!M \right )$$where

 $\Delta$Treheat heat rise across the terminal unit heating coil (°F) Treheat heating air temperature at design (°F) Tcool_supply supply air temperature at the heating coil (°F) Qcoil heating coil load (Btu/h) CFM airflow (cfm)
Units Degrees Fahrenheit (°F)
Input Restrictions As designed, but may need to be increased if unmet load hours are greater than 300