Schedules

90.1-2016 BM

Cooling Schedule

Applicability

All cooling systems

Definition

A schedule that represents the availability of cooling

Units

Data structure: schedule, on/off

Input Restrictions

Schedules should be typical of the proposed building type or as assumed for the building design. The schedules in Appendix C can be used as a default for cooling availability. The cooling availability schedule shall be consistent with the supply fan schedule and thermostat schedules to reduce the likelihood of unmet load hours.

Baseline Rules

Same as the proposed design

 

Heating Schedule

Applicability

All systems

Definition

A schedule that represents the availability of heating

Units

Data structure: schedule, on/off

Input Restrictions

Schedules should be typical of the proposed building type or as assumed for the building design. The schedules in Appendix C can be used as a default. The heating availability schedule shall be consistent with the supply fan schedule.

Baseline Rules

Same as the proposed design

 

Air-Handler Schedule

Applicability

All systems that do not cycle with loads

Definition

A schedule that indicates when the air handler operates continuously

Units

Data structure: schedule, on/off

Input Restrictions

Schedules should be typical of the proposed building type or as assumed for the building design. The schedules in Appendix C can be used as a default.

When a fan system serves several occupancies, the fan schedule must remain ON to serve the operating hours of each occupancy.

Baseline Rules

Same as the proposed design

 

Air Handler Fan Cycling

Applicability

All fan systems

Definition

This building descriptor indicates whether the system supply fan operates continuously or cycles with building loads. The fan systems in most commercial buildings operate continuously.

Units

List: continuous or cycles with loads

Input Restrictions

Schedules for HVAC fans that provide outdoor air for ventilation shall run continuously whenever spaces are occupied and shall be cycled on and off to meet heating and cooling loads during unoccupied hours.

Exceptions:     

  • Where no heating and/or cooling system is to be installed and a heating or cooling system is being simulated only to meet the requirements described in the 90.1 PRM, heating and/or cooling system fans shall not be simulated as running continuously during occupied hours but shall be cycled on and off to meet heating and cooling loads during all hours.
  • HVAC fans shall remain on during occupied and unoccupied hours in spaces that have health and safety mandated minimum ventilation requirements during unoccupied hours.

For hotel guest rooms and high-rise residential, continuous operation is the default, however, the option to let the fan cycle with loads may be used when the following conditions are met and documented:

  • The spaces served by the system are located within 25 ft of an operable window.
  • The openable window area is at least 4% of the floor space.
  • Other requirements for natural ventilation specified in ASHRAE Standard 62.1-2016 are satisfied. 

Baseline Rules

Same as proposed design, except if the proposed building has natural ventilation, in which case the baseline building fans  will operate continuously when the space is occupied and cycle to meet the loads duing unoccupied periods.

HVAC fans shall remain on during occupied and unoccupied hours in spaces that have health and safety mandated minimum ventilation requirements during unoccupied hours.

 

Optimal Start Control

Applicability

Systems with the control capability for flexible scheduling of system start time based on building loads.

Definition

Optimal start control adjusts the start time of the HVAC unit such that the space is brought to setpoint just prior to occupancy. This control strategy modifies the heating, cooling, and fan schedules.

Units

Boolean (Yes/No)

Input Restrictions

As designed

Baseline Rules

The baseline building shall have optimum start controls when the baseline building design supply airflow is greater than 10,000 cfm.

 

Night-Cycle HVAC Fan Control

Applicability

All systems

Definition

The control of an HVAC system that is triggered by the heating or cooling temperature setpoint for thermal blocks during periods when the heating, cooling and fan systems are scheduled to be off. Night cycle control is required for both baseline and proposed building in accordance to 90.1 2010 Section 6.4.3.3.2. For this control, the space is controlled to the setback or setup temperature only; this control is not equivalent to a night purge control. The choices are:

  • Cycle on call from any zone
  • Cycle on call from the primary control zone
  • Stay off
  • Cycle zone fans only (for systems with fan-powered boxes) for cooling. Cycle AHU fans for cooling Restart fans below given ambient temperature.

Units

None

Input Restrictions

Schedules for HVAC fans that provide outdoor air for ventilation shall run continuously whenever spaces are occupied and shall be cycled on and off to meet heating and cooling loads during unoccupied hours

Exceptions:

  • Where no heating and/or cooling system is to be installed and a heating or cooling system is being simulated only to meet the requirements described 90.1 2010 PRM, heating and/or cooling system fans shall not be simulated as running continuously during occupied hours but shall be cycled on and off to meet heating and cooling loads during all hours.
  • HVAC fans shall remain on during occupied and unoccupied hours in spaces that have health and safety mandated minimum ventilation requirements during unoccupied hours.

Baseline Rules

 Same as proposed design except if the proposed building has  natural ventilation in which case the baseline building fans will operate continuously when the space is occupied and cycle to meet loads during unoccupied periods.

HVAC fans shall remain on during occupied and unoccupied hours in spaces that have health and safety mandated minimum ventilation requirements during unoccupied hours.