Commercial User Guide

Using the Office

Default Office

The "default office" is an incomplete construct. The minimum definition for an office object includes:

object office{
   floor_height 6 ft;
   floor_area 4000 sf;
   interior_mass 2000;
   interior_UA 2.0;
   exterior_UA 2.0;
   hvac.cooling.capacity -4500; // must be negative
   hvac.heating.capacity 4500;
}

Office

Single-zone commercial office building with rooftop package unit

Synopsis

class office {
    double floor_area[sf];
    double floor_height[ft];
    double exterior_ua[Btu/degF/h];
    double interior_ua[Btu/degF/h];
    double interior_mass[Btu/degF];
    double glazing[sf];
    double glazing.north[sf];
    double glazing.northeast[sf];
    double glazing.east[sf];
    double glazing.southeast[sf];
    double glazing.south[sf];
    double glazing.southwest[sf];
    double glazing.west[sf];
    double glazing.northwest[sf];
    double glazing.horizontal[sf];
    double glazing.coefficient[pu];
    double occupancy;
    double occupants;
    char256 schedule;
    double air_temperature[degF];
    double mass_temperature[degF];
    double temperature_change[degF/h];
    double outdoor_temperature[degF];
    double Qh[Btu/h];
    double Qs[Btu/h];
    double Qi[Btu/h];
    double Qz[Btu/h];
    enumeration {OFF=0, VENT=5, ECON=4, COOL=3, AUX=2, HEAT=1} hvac_mode;
    double hvac.cooling.balance_temperature[degF];
    double hvac.cooling.capacity[Btu/h];
    double hvac.cooling.capacity_perF[Btu/degF/h];
    double hvac.cooling.design_temperature[degF];
    double hvac.cooling.efficiency[pu];
    double hvac.cooling.cop[pu];
    double hvac.heating.balance_temperature[degF];
    double hvac.heating.capacity[Btu/h];
    double hvac.heating.capacity_perF[Btu/degF/h];
    double hvac.heating.design_temperature[degF];
    double hvac.heating.efficiency[pu];
    double hvac.heating.cop[pu];
    double lights.capacity[kW];
    double lights.fraction[pu];
    double plugs.capacity[kW];
    double plugs.fraction[pu];
    complex demand[kW];
    complex total_load[kW];
    complex energykWh;
    double power_factor;
    complex power[kW];
    complex current[A];
    complex admittance[1/Ohm];
    complex hvac.demand[kW];
    complex hvac.load[kW];
    complex hvac.energykWh;
    double hvac.power_factor;
    complex lights.demand[kW];
    complex lights.load[kW];
    complex lights.energykWh;
    double lights.power_factor;
    double lights.heatgain_fraction;
    double lights.heatgain[Units|kW];
    complex plugs.demand[Units|kW];
    complex plugs.load[Units|kW];
    complex plugs.energy[Units|kWh];
    double plugs.power_factor;
    double plugs.heatgain_fraction;
    double plugs.heatgain[kW];
    double cooling_setpoint[degF];
    double heating_setpoint[degF];
    double thermostat_deadband[degF];
    double control.ventilation_fraction;
    double control.lighting_fraction;
    double ACH;
}

Office Schedule

The office has a built-in occupancy schedule subsystem that is used to determine the minimum air change coefficient. This subsystem parses a string and constructs a bitfield for the hours of each day that the building should be occupied. By default, office buildings are occupied from 8am to 5pm local time, Monday through Friday.

The format for the office schedule consists of two parts, the day and the hours, in a semicolon delimited list. The default string is 1-5 8-17. The first part is the range for the days of the week, with 0 being Sunday, 1 for Monday, etc. The hours are numbered 0-23 and reflect a 24 hour clock. Multiple schedule elements can be aggregated with an OR operation by seperating them with semicolons. For example, 1-4 8-17; 5 8-20; 6 8-23; 0 8-20 would define an 8-5 schedule Mon-Thur, 8-8 on Friday, 8am-11pm on Saturday, and 8-8 on Sunday.

Properties

Table 1: Office Properties

Property name	Type	Unit	Description
floor_area	double	ft^2	Floor area of the office (presuming one floor).
floor_height	double	ft	Ceiling height within the office interior
exterior_ua	double	BTU/degF/hr	Exterior thermal resistance
interior_ua	double	BTU/degF/hr	Interior thermal resistance
interior_mass	double	BTU/degF	The thermal mass of the interior finishing and building materials
glazing	double	ft^2	The external glazing area (total area)
glazing.north	double	ft^2	The external glazing area facing north
glazing.northeast	double	ft^2	The external glazing area facing north-east
glazing.east	double	ft^2	The external glazing area facing east
glazing.southeast	double	ft^2	The external glazing area facing south-east
glazing.south	double	ft^2	The external glazing area facing south
glazing.southwest	double	ft^2	The external glazing area facing south-west
glazing.west	double	ft^2	The external glazing area facing west
glazing.northwest	double	ft^2	The external glazing area facing north-west
glazing.horizontal	double	ft^2	The external glazing area facing up (skyward)
glazing.coefficient	double	per unit	The fraction of solar radiation that is transmitted by the glazing.
occupancy	double	-	Current occupancy ratio
occupants	double	people	Total occupants for the office
schedule	char256	-	Schedule string. Semicolon delimited cron-style schedule definition.
air_temperature	double	degF	Office interior air temperature
mass_temperature	double	degF	Office interior mass temperature
temperature_change	double	degF/hr	The rate of change of temperature since the last update
Qh	double	BTU/hr	The HVAC gain/loss since the last update
Qs	double	BTU/hr	The solar heat gain since the last update
Qi	double	BTU/hr	The internal heat gains since the last update
Qz	double	BTU/hr	The inter-zonal heat gain/loss since the last update
hvac_mode	enumeration	-	Current mode of the HVAC system. HEAT, AUX, COOL, ECON, VENT, or OFF.
hvac.cooling.balance_temperature	double	degF	The balance temperature of the HVAC cooler
hvac.cooling.capacity	double	BTU/hr	The constant heat output capacity of the HVAC cooler (should be negative)
hvac.cooling.capacity_perF	double	BTU/degF/hr	The temperature-dependent heat output capacity of the HVAC cooler (should be negative)
hvac.cooling.design_temperature	double	degF	The design temperature of the HVAC cooler
hvac.cooling.efficiency	double	-	The cooling efficiency of the HVAC cooler
hvac.cooling.cop	double	-	Coefficient of performance of the HVAC cooler
hvac.heating.balance_temperature	double	degF	The balance temperature of the HVAC heater
hvac.heating.capacity	double	BTU/hr	The constant heat output capacity of the HVAC heater
hvac.heating.capacity_perF	double	BTU/degF/hr	The temperature-dependent heat output capacity of the HVAC heater
hvac.heating.design_temperature	double	degF	The design temperature of the HVAC heater
hvac.heating.efficiency	double	BTU/W	The heating efficiency of the HVAC heater
hvac.heating.cop	double	-	Coefficient of performance of the HVAC heater
lights.capacity	double	kW	Total power of the lights installed in the office
lights.fraction	double	pu	The fraction of the installed lights that are turned on
plugs.capacity	double	kW	Total power of the devices plugged into wall sockets
plugs.fraction	double	pu	The current fraction of the total power draw from the various devices
demand	complex	kW	Aggregate peak power draw from the office
total_load	complex	kW	Current aggregate power draw from the office
energy	complex	kWh	Accumulated energy consumed by the office
power_factor	complex	-	The power factor of the house load
power	complex	kW	Constant power component of the office load
current	complex	A	Constant current component of the office load
admittance	complex	1/Ohm	Constant resistance component of the office load
hvac.demand[kW]	complex	kW	The HVAC load
hvac.load[kW]	complex	kW	The HVAC load
hvac.energy	double	kWh	The HVAC energy use
hvac.power_factor	complex	-	The HVAC power factor
lights.demand[kW]	complex	kW	The lighting load
lights.load	complex	kW	The lighting load
lights.energy	complex	kWh	The lighting energy use
lights.power_factor	double	-	The lighting power factor
plugs.demand	complex	kW	The plug load
plugs.load	complex	kW	The plug load
plugs.energy	complex	kWh	The plug energy use
plugs.power_factor	double	-	The plug power factor
cooling_setpoint	double	degF	The cooling thermostat set-point
heating_setpoint	double	degF	The heating thermostat set-point
thermostat_deadband	double	degF	The thermostat deadband (hysteresis)
control.ventilation_fraction	double	pu	The current outside air fraction for ventilation
control.lighting_fraction	double	pu	The current lighting fraction in effect

Commercial - Commercial building developer's guide

Building

The building class implements that abstract class used to solve all linearized multizone building models. All multizone commercial building classes are derived from this class.

Class members

General Properties

Property| Unit | Constraints | Default | Description | Remarks
--|--|--|--|--|--| T | degF | N×1 ∈ R | Ø | Node temperatures N | (int16) | ∈ N + | 1 | Number of nodes in model
U | Btu/degF/h | N×N symmetric ∈ R 2 | Ø | Node conductances
C | Btu/degF | N×1 ∈ R * | Ø | Node capacitance | NaN indicates outdoor node
Q | Btu/h | N×1 ∈ R | Ø | Node heat flows \(Q_s\) | Btu/h | N×1 ∈ R *** | Ø | Node solar heat gain \(Q_i\) | Btu/h | N×1 ∈ *R *** | Ø | Node internal heat gain

Default HVAC properties

Property| Unit | Constraints | Default | Description | Remarks
--|--|--|--|--|--| \(Q_{fl}\) | Btu/h | N×1 ∈ R *** | NaN | Node fan heat gain at low power \(Q_{fh}\) | Btu/h | N×1 ∈ R *** | NaN | Node fan heat gain at high power \(Q_f\) | Btu/h | N×1 ∈ R *** | NaN | Node heat gain from fans \(Q_{hc}\) | Btu/h | N×1 ∈ R *** | NaN | Node heating capacity \(Q_h\) | Btu/h | N×1 ∈ R *** | NaN | Node heat gain from heating \(Q_{cc}\) | Btu/h | N×1 ∈ R *** | NaN | Node cooling capacity \(Q_c\) | Btu/h | N×1 ∈ **R *** | NaN | Node heat loss from cooling

Default controller properties

Property| Unit | Constraints | Default | Description | Remarks
--|--|--|--|--|--| \(T_s\) | (double) | N×1 ∈ {0,1,2,3,4,5} | NaN | HVAC state | 0=OFF, 1=VENT, 2=HEAT, 3=COOL, 4=AUX, 5=ECON
\(V_m\) | pu/h | N×1 ∈ R *** | NaN | Minimum ventilation required |
\(T_h\) | degF | N×1 ∈ R + | NaN | Heating set-point | Must be less than \(Tc-2Td\)
\(T_c\) | degF | N×1 ∈ R + | NaN | Cooling set-point | Must be greater than \(Th+2Td\)
\(T_d\) | degF | N×1 ∈ R + | NaN | Set-point deadband |
\(t_l\) | s | N×1 ∈ N** + | 300 | Control lockout time | Must be less than or equal to maximum_timestep

Other members

autosize	(bool)	∈	FALSE	Enables automatic sizing of arrays
load	(end use)			Electric end use load composition

Default HVAC Controller

The default controller implements a simple single zone vent/heat/cool/aux control. To override the default controller you must implement the plc() function is the derived class.

The default control strategy for node n is as follows:

if mode == OFF || mode == VENT
  if T < Th-2*Td
    mode = AUX
  else if T < Th - Td/2
    mode = HEAT
  else if T > Tc + Td/2
    mode = COOL
  else if Vm > 0 
    mode = VENT
  else
    mode = OFF

else if mode == HEAT
  if T < Th-2*Td
    mode = AUX
  else if T > Th+Td/2
    if Vm > 0
      mode = VENT
    else
      mode = OFF

else if mode == COOL
  if T < Tc - Td/2
    if Vm > 0
      mode = VENT
    else
      mode = OFF

else if mode == AUX
  if T > Th - Td/2
    if Vm > 0
      mode = VENT
    else
      mode = OFF

Options

Warn Control

Determines whether air temperature control in commercial buildings is monitored.

module commercial {
warn_control TRUE
}

Warn High Temp

Determines the commercial building indoor air temperature above which a warning is produced.

module commercial {
warn_high_temp 90 degF;
}

Warn Low Temp

Determines the commercial building indoor air temperature below which a warning is produced.

module commercial {
warn_low_temp 50 degF;
}