buildingPhysics.py

buildingPhysics.py contains the thermodynamic model which calculates the energy demand and temperatures of the building. It is based on the ISO-13790 standard. Here we will explain the main methods and classes

buildingPhysics.Building(args*)

Initialises a building to be studied

The arguments here are

window_area: Area of the Glazed Surface in contact with the outside [m2]
walls_area: Area of all non glazed (opaque) surfaces, with contact to the exterior. Including roofs [m2]
floor_area: floor area of zone [m2]
room_vol: volume of interior zone [m3]
total_internal_area: area of all surfaces facing the room. A_t [m2][m2]
lighting_load: Lighting Load [W/m2]
lighting_control: Lux threshold at which the lights turn on [Lx]
lighting_utilisation_factor: A factor that is determines how much natural solar lumminace is effectively utilised in the space. Environmental Science Handbook, SV Szokolay, Section 2.2.1.3 [1- full utilisation, 0 - no utilisation]
lighting_maintenance_facotor: A factor based on how dirty the windows are. Environmental Science Handbook, SV Szokolay, Section 2.2.1.3 [1- full transmission, 0 - no transmission]
U_walls: average U value of opaque surfaces [W/m2K]
U_windows: U value of glazed surfaces [W/m2K]
ACH_vent: Air changes per hour through ventilation [Air Changes Per Hour]
ACH_infl: Air changes per hour through infiltration [Air Changes Per Hour]
ventilation_efficiency: The efficiency of the heat recovery system for ventilation. Set to 0 if there is no heat recovery []
thermal_capacitance_per_floor_area: Thermal capacitance of the room per floor area [J/m2K]
**T_set_heating **: Thermal heating set point [C]
T_set_cooling: Thermal cooling set point [C]
max_cooling_energy_per_floor_area: Maximum cooling load. Set to -np.inf for unresctricted cooling [C]
max_heating_energy_per_floor_area: Maximum heating load per floor area. Set to no.inf for unrestricted heating [C]
heatingSupplySystem: The type of heating system. Choices are DirectHeater, ResistiveHeater, HeatPumpHeater. Direct heater has no changes to the heating demand load, a resistive heater takes an efficiency into account, and a HeatPumpHeater calculates a COP based on the outdoor and indoor temperature
coolingSupplySystem: The type of cooling system. Choices are DirectCooler HeatPumpCooler. DirectCooler has no changes to the cooling demand load, a HeatPumpCooler calculates a COP based on the outdoor and indoor temperature
heatingEmissionSystem: How the heat is distrubuted to the building
coolingEmissionSystem: How the cooling energy is distributed to the building

The default settings are

	window_area=4.0,
	walls_area=11.0,
	floor_area=35.0,
        room_vol=105,
        total_internal_area=142.0,
	lighting_load=11.7,
	lighting_control = 300.0,
	lighting_utilisation_factor=0.45,
	lighting_maintenance_factor=0.9,
	U_walls = 0.2,
	U_windows = 1.1,
	ACH_vent=1.5,
	ACH_infl=0.5,
	ventilation_efficiency=0.6,
	thermal_capacitance_per_floor_area = 165000,
	T_set_heating = 20.0,
	T_set_cooling = 26.0,
	max_cooling_energy_per_floor_area=-np.inf,
	max_heating_energy_per_floor_area=np.inf,
	heatingSupplySystem=supplySystem.OilBoilerMed,
	coolingSupplySystem=supplySystem.HeatPumpAir,
	heatingEmissionSystem=emissionSystem.NewRadiators,
	coolingEmissionSystem=emissionSystem.AirConditioning,

Supply Systems

The following SupplySystems can be selected. For more informaiton see the wiki page supplySystem.py or the supplySystem.py script

OilBoilderOld: A boiler with a fuel efficiency of 63%
OilBoilerMed: A boiler with a fuel effiiency of 82%
OilBoilerNew: A boiler with a fuel efficiency of 98%
HeatPumpAir: An air heat pump
HeatPumpWater: A water heat pump
Electric heating: A 100% efficient electric resistive heater
CHP: Combined heat and power unit with a 60% conversion to heat, and 33% conversion to electricity
DirectHeater: A default unit with a 100% thermal to electricity conversion for testing
DirectCooler: A default unit with a 100% thermal to electricity conversion for testing

Emission Systems

The following emission systems can be selected. For more information about each system see the wiki page emissionSystem.py or the emssionSystem.py script

OldRadiators
** NewRadiators **
** ChilledBeams**
** AirConditioning**
** FloorHeating**
** TABS: Thermally Activated Building System**

solve_lighting(illuminance, occupancy)

Calculates the lighting demand for a set timestep

Inputs

illuminance: illuminance transfered into the building [lumens]
Occupancy: probability of full occupancy [%]

Return

my_building.lighting_demand: lighting demand of the office space in Watts

solve_energy(internal_gains, solar_gains, T_out, T_m_prev)

Calculates the heating and cooling consumption of a building for a set timestep

Inputs

internal_gains: internal heat gains from people and appliances [W]
solar_gains: solar heat gains [W]
T_out: Outdoor air temperature [C]
T_m_prev: Prevous air temperature [C]

Return

my_building.heatingDemand: space heating demand of the building
my_building.heatingSysElectricity: heating electricity consumption
my_building.heatingSysFossils: heating fossil fuel consumption
my_building.coolingDemand: space cooling demand of the building
my_building.coolingSysElectricity: electricity consumption from cooling
my_building.coolingSysFossils: fossil fuel consumption from cooling
my_building.electricityOut: electricty produced from combined heat pump systems
my_building.sysTotalEnergy: total exergy consumed (electricity + fossils) for heating and cooling
my_building.heatingEnergy: total exergy consumed (electricity + fossils) for heating
my_building.coolingEnergy: total exergy consumed (electricity + fossils) for cooling
my_building.COP: COP of the heating or cooling system
my_building.has_heating_demand: Boolean
my_building.has_cooling_demand: Boolean