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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.

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 [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
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 [bookref id="hvac-mapping"] and [bookref id="sat-cooling-setpoint-reset-based-on-outdoor-air-temperature-oat-for-dry-b-and-marine-c-climates"].
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. 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.

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 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
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:

(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.

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.

 

90.1-2019

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, 6, 7, and 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

· Refrigerant (for VRF)
Units List (see above)
Input Restrictions As designed
Baseline Building  Table 38 shows the terminal heat type for each baseline building system

Table 38. 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 PVAV 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 None
System 12 SZ-CV-HW None
System 13 SZ-CV-ER None

 

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 UMLH exceed 300, the energy analyst and design team may have to increase the size of the equipment so that the UMLH are less than 300. See

Figure 3 and Section 2.7.1.
Baseline Building Sizing would be carried out at zone level where the oversizing parameters would be applied to the zone design loads. The software shall automatically size the terminal heating capacity to be 25% greater than the design loads. Refer to Section 2.7.2 of this document for more details.

 

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:
Units Degrees Fahrenheit (°F)
Input Restrictions

As designed, but may need to be increased if UMLH are greater than 300
Baseline Building Same as proposed. If the proposed building doesn’t have a reheat system, then the reheat delta T shall be based on a supply-air-to-room-air temperature difference of 20°F and shall be no more than 40°F

 

 

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.
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.
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
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.
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.
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