ENERGY MANAGEMENT

ENERGY MANAGEMENT

A combined design and management function which embraces the disciplines of engineering mathematics accounting operations research software engineering environmental management

THE ENERGY MANAGEMENT FUNCTION

THE ENERGY MANAGEMENT FUNCTION Measure

THE ENERGY MANAGEMENT FUNCTION Measure Analyse

THE ENERGY MANAGEMENT FUNCTION Measure Analyse Criticise

THE ENERGY MANAGEMENT FUNCTION Measure Analyse Criticise Generate Options

THE ENERGY MANAGEMENT FUNCTION Measure Analyse Criticise Generate Options Evaluate Options

THE ENERGY MANAGEMENT FUNCTION Measure Analyse Criticise Generate Options Evaluate Options Optimise

THE ENERGY MANAGEMENT FUNCTION Measure Analyse Criticise Generate Options Evaluate Options Modify Optimise

THE ENERGY MANAGEMENT FUNCTION Measure Analyse Criticise Control Generate Options Evaluate Options Modify Optimise

THE ENERGY MANAGEMENT FUNCTION Measure Analyse Criticise REVIEW Control Generate Options Evaluate Options Modify Optimise

ENERGY ACCOUNT A balance sheet of energy INPUTS OUTPUTS THROUGHPUTS flowing through a site boundary

The INPUT side An analysis of FUEL and ELECTRICITY bills for a representative annual period

The OUTPUT side details the ultimate energy rejection to the external environment via heat transmission through the building fabric heat lost to ventilating air flue gas losses

The THROUGHPUTS What happens inside the building may require microaudits or energy balances over individual items of plant and equipment: furnaces, boilers, refrigerators, compressors, etc. to ascertain efficiencies and to quantify sundry gains

Energy Audit

Fuel Energy Audit

Stack Loss Fuel Combustion Energy Audit

Stack Loss Fuel Combustion Boiler Energy Audit

Stack Loss Fuel Combustion Distribution Loss Boiler Distribution Energy Audit

Stack Loss Fuel People Combustion Distribution Loss Boiler Distribution EnergyAudit

Stack Loss Fuel Lights People Combustion Distribution Loss Boiler Distribution Energy Audit

Stack Loss Fuel Lights Power People Combustion Distribution Loss Boiler Distribution Energy Audit

Stack Loss Fuel Lights Power People Processes Combustion Distribution Loss Boiler Distribution Energy Audit

Electricity Stack Loss Fuel Lights Power People Processes Combustion Distribution Loss Boiler Distribution Energy Audit

Fuel Electricity Stack Loss Fuel Lights Power Food People Processes Fuels Combustion Distribution Loss Boiler Distribution Energy Audit

Fuel Electricity Stack Loss Fuel Lights Power Food People Processes Fuels Combustion Sundry Gains Distribution Loss Boiler Distribution Energy Audit

Fuel Electricity Stack Loss Fuel Lights Power Food People Processes Fuels Combustion Sundry Gains Distribution Loss Boiler Direct Reject Distribution Space Heat Delivered Energy Audit

Fuel Electricity Stack Loss Fuel Lights Power Food People Processes Fuels Combustion Sundry Gains Distribution Loss Boiler Direct Reject Distribution Space Heat Delivered Energy Audit Ventilation Fabric Transmission

Energy Audit Equation

Fuel Energy Input = Energy losses during combustion + Energy losses during conversion + Energy losses during distribution + Energy losses during utilisation + Energy losses from utilisation

For a heated building, INPUT side Heating fuel energy input + Sundry gains from electricity + Sundry gains from people + Sundry gains from directly-fired process plant and equipment - Sundry losses to cold plant

For a heated building, OUTPUT side =Energy losses in flue gases + Energy losses during conversion + Energy losses from external distribution pipelines + Energy losses via fabric transmission + Energy losses in ventilating air + Energy losses in process materials directly rejected to the external environment

Heat Loss = Fabric Transmission Losses +Ventilation Losses

Heat Loss (W) = U A DT + m cp DT U = Overall U-value (W/m2K) A = Area for heat loss (m2) m = Ventilating Air (kg/s) cp= specific heat of air (J/kg K) DT= Temperature difference between inside and outside (oC)

Mean Annual Heat Loss (W) = U A DT + m cp DT m = Ventilating Air (kg/s) = number of air changes per second (1/s) x building volume, V (m3) x density of air, r (kg/m3)

Mean Annual Heat Loss (W) = U A DT + m cp DT m = Ventilating Air (kg/s) = number of air changes per hour, n (1/hr) x hours/second (1/3600) x building volume,V (m3) x density of air, r (1.2 kg/m3)

Heat Loss (W) = U A DT + m cp DT cp= specific heat of air (= 1000 J/kg K))

Heat Loss (W) = U A DT + m cp DT = U A DT + (r V n/3600) cp DT = U A DT + (1.2 V n/3600) x 1000 DT = U A DT + (V n/3) DT = (U A + nV/3) DT

Fuel Burnt by Boiler (W) = ((U A + nV/3) DT) / h where h is the boiler efficiency (%) expressed as a fraction

Annual Heat Loss (kWh/annum) = (U A + nV/3) DT x heating hours per annum/1000 where DT = mean annual temperature difference between inside and outside (oC)

Monthly Heat Loss (kWh/month) = (U A + nV/3) DT x heating hours per month/1000 where DT = mean monthly temperature difference between inside and outside (oC)

FLOW CHART FOR AN ENERGY AUDIT Internal Data Fuel Data External Data OBTAIN DESCRIPTION OF PREMISES purpose and function number of occupants occupational patterms environmental temperatures environmental humidities lighting levels ventilation requirements plans and details of construction heating and cooling system details OBTAIN ENERGY ACCOUNTS COLLATE ACCOUNTS AND CONVERT TO COMMON UNITS COMPILE ENVIRONMENTAL PARAMETERS degree-day data outside air temperatures and humidities wind speeds solar data building orientation TRACE ENERGY RELEASE SYSTEMS AND ESTIMATE OR MEASURE EFFICIENCIES ASCERTAIN SUNDRY GAINS DETERMINE DISTRIBUTION LOSSES CARRY OUT SITE SURVEY ESTIMATE U-VALUES AND AREAS VENTILATION RATES EXHAUST AIR TEMPERATURES EXAMINE PROCESS LOSSES OR GAINS ENERGY IN ENERGY OUT ENERGY AUDIT

ENERGY MANAGEMENT