Design Temperatures

Overview

Design temperatures is a card that appears in the Space Use tab.

The card lets you instruct the model what temperatures the spaces are trying to maintain, both for heating and cooling.

This section outlines:

  • What the controls do
  • How they work with natural ventilation
  • How to make your own "unconditioned" space

The controls look a bit like this:

Setpoint Temperature

The Setpoint temperature range defines the temperature range the heating, cooling and natural ventilation systems will be trying to maintain during occupied hours.

EnergyPlus will control HVAC systems and / or windows to keep the space within this temperature range.

If you are using Natural Ventilation, do not adjust the cooling setpoint to be outside the temperature range you expect to be maintained in the zone. The Natural Ventilation controls will switch off the mechanical HVAC system, you don't need to do it here.

The basic templates have default Setpoint Temperatures and these are provided in the table below. 

Setback Temperature

Setback temperature defines the minimum and maximum temperatures that the building is allowed to float to during unoccupied hours. 

If the space temperatures end up outside of these ranges when the building systems are off, the heating and cooling systems in the building will come on to try and keep the space within these ranges.

The basic templates have default Setback Temperatures and these are provided in the table below. 

Making an unconditioned space

You can adjust the setpoint and ventilation values to create an "unconditioned" space. You might want to do this for a space that has lighting (eg an atrium void) but no heating, cooling or ventilation.

To do this, extend the heating setpoint to the lowest possible value and the cooling setpoint to the highest possible value. 

Ventilation cannot be set to zero, so set it to a very low value (eg 0.1l/s/person).

Things to be aware of with radiant floor system type

The radiant floor system lets you control the setpoint basis in the zone settings. The default is Operative Temperature.

This setpoint range will be the temperature control type you choose in this dropdown when you have a radiant floor. So if you have set "Radiant Floor" with "Operative Temperature" control then the setpoint and setback ranges will be working towards operative temperature targets.

Things to be aware of with Natural Ventilation Comfort outputs

If you're using natural ventilation, the setpoints will control how the windows operate. By default they control windows to maintain a dry bulb setpoint and they work in tandem with heating and cooling systems.

This is done to minimise windows being open to hit one comfort condition while heating and/or cooling systems are running to hit a different comfort condition.

The important thing to note is that if you do a PMV study or Operative Temperature study, the windows are controling to hit dry-bulb setpoints, not operative or comfort setpoint ranges.

Values that are used in the default space uses

Typical Values

  Setpoint Temperatures Setback Temperatures
 

Heating

°C / °F

Cooling

°C / °F

Heating

°C / °F

Cooling

°C / °F

Office (Plugin defaults) 21 / 70 24 / 75 12 / 54  28 / 82
Residential (Plugin defaults) 20 / 68 25 / 77 18 / 64 28 / 82
School (Plugin defaults) 20 / 68 25 / 77 12 / 54 28 / 82
Healthcare (Plugin defaults) 21 / 70 24 / 75 19 / 65 28 / 82
Laboratory (Plugin defaults) 21 / 70 24 / 75 12 / 54 28 / 82
Retail (Plugin defaults) 21 / 70 24 / 75 12 / 54 28 / 82

 

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