Module: BrighterPlanet::Meeting::CarbonModel

Defined in:
lib/meeting/carbon_model.rb

Class Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/meeting/carbon_model.rb', line 10

def self.included(base)
  base.decide :emission, :with => :characteristics do
    committee :emission do # returns kg CO2e
      quorum 'from duration, area, and emission factor', :needs => [:duration, :area, :emission_factor] do |characteristics|
        characteristics[:duration] * characteristics[:area] * characteristics[:emission_factor]
      end
      
      quorum 'default' do
        raise "The emission committee's default quorum should never be called"
      end
    end
    
    committee :emission_factor do # returns kg CO2e / square metre hour
      quorum 'from eGRID subregion and fuel intensities', :needs => [:egrid_subregion, :natural_gas_intensity, :fuel_oil_intensity, :electricity_intensity, :district_heat_intensity] do |characteristics|
        natural_gas = FuelType.find_by_name "Commercial Natural Gas"
        fuel_oil = FuelType.find_by_name "Distillate Fuel Oil 2"
        
        # FIXME TODO won't need this once we convert emission factors to co2 / unit energy
        #   kg / J                           kg / cubic m     J / cubic m
        natural_gas_energy_ef = natural_gas.emission_factor / 38_339_000
        
        # FIXME TODO won't need this once we convert emission factors to co2 / unit energy
        #   kg / J                        kg / l           J / l
        fuel_oil_energy_ef = fuel_oil.emission_factor / 38_655_000
        
        # based on CA-CP calculator
        # assume district heat is 50% natural gas 50% distillate fuel
        # assume natural gas boilers 81.7% efficient; fuel oil boilers 84.6% efficient
        # assume 5% transmission loss
        district_heat_emission_factor = (((natural_gas_energy_ef / 0.817) / 2) + ((fuel_oil_energy_ef / 0.846) / 2)) / 0.95
        
        (characteristics[:natural_gas_intensity] * natural_gas.emission_factor) +
          (characteristics[:fuel_oil_intensity] * fuel_oil.emission_factor) +
          (characteristics[:electricity_intensity] * characteristics[:egrid_subregion].electricity_emission_factor) +
          (characteristics[:district_heat_intensity] * district_heat_emission_factor)
      end
    end
    
    committee :natural_gas_intensity do # returns cubic metres per square metre hour
      quorum 'from census division', :needs => :census_division do |characteristics|
        characteristics[:census_division].meeting_building_natural_gas_intensity
      end
      
      quorum 'default' do
        CensusDivision.fallback.meeting_building_natural_gas_intensity
      end
    end
    
    committee :fuel_oil_intensity do # returns litres per square metre hour
      quorum 'from census division', :needs => :census_division do |characteristics|
        characteristics[:census_division].meeting_building_fuel_oil_intensity
      end
      
      quorum 'default' do
        CensusDivision.fallback.meeting_building_fuel_oil_intensity
      end
    end
    
    committee :electricity_intensity do # returns kilowatt hours per square metre hour
      quorum 'from eGRID region and census division', :needs => [:egrid_region, :census_division] do |characteristics|
        characteristics[:census_division].meeting_building_electricity_intensity / (1 - characteristics[:egrid_region].loss_factor)
      end
      
      quorum 'from eGRID region', :needs => :egrid_region do |characteristics|
        CensusDivision.fallback.meeting_building_electricity_intensity / (1 - characteristics[:egrid_region].loss_factor)
      end
    end
    
    committee :district_heat_intensity do # returns joules per square metre hour
      quorum 'from census division', :needs => :census_division do |characteristics|
        characteristics[:census_division].meeting_building_district_heat_intensity
      end
      
      quorum 'default' do
        CensusDivision.fallback.meeting_building_district_heat_intensity
      end
    end
    
    committee :egrid_region do # returns eGRID region
      quorum 'from eGRID subregion', :needs => :egrid_subregion do |characteristics|
        characteristics[:egrid_subregion].egrid_region
      end
    end
    
    committee :egrid_subregion do # returns eGRID subregion
      quorum 'from zip code', :needs => :zip_code do |characteristics|
        characteristics[:zip_code].egrid_subregion
      end
      
      quorum 'default' do
        EgridSubregion.find_by_abbreviation 'US'
      end
    end
    
    committee :census_division do # returns census division
      quorum 'from state', :needs => :state do |characteristics|
        characteristics[:state].census_division
      end
    end
    
    committee :state do # returns state
      quorum 'from zip code', :needs => :zip_code do |characteristics|
        characteristics[:zip_code].state
      end
    end
    
    committee :area do # returns square meters
      quorum 'default' do
        base.fallback.area
      end
    end
    
    committee :duration do # returns hours
      quorum 'default' do
        base.fallback.duration
      end
    end
  end
end