Assess Current energy demand Energy audit Analyse Energy requirements Advise On technical improvements Advertise Ways to save energy Account For energy consumption

1. Energy Conservation
Energy
Management

2. Role of an energy manager
 Assess
 Current energy demand
 Energy audit
 Analyse
 Energy requirements
 Advise
 On technical improvements
 Advertise
 Ways to save energy
 Account
 For energy consumption

3. Assess energy demand
 Keep records
 Consumption
 Time of readings
 Temperature
 Other factors affecting demand
 Weekday/weekend
 Special events
 Frequency of readings
 Weekly
 Daily

4. Energy Audit
 Feasibility study
 Establish and quantify energy flows into and within a
building or organisation
 Aim
 Identify viable and cost effective energy saving
measures
 Enhance operating efficiency and reduce
maintenance costs
 Establish a baseline energy consumption
 Process
 Collect data from energy invoices and meters
 Surveys of plant, equipment and buildings
 Collect information from managers and other staff

5. Auditing process
 Identify energy management
opportunities
 Can be ‘no cost’ or ‘low cost’ measures
 Change an energy tariff
 Change an energy supplier
 Reschedule production activities
• Preferential tariffs
 Adjust existing controls to match requirements
 Implement ‘good housekeeping’ policies
 Invest in small capital items
• Thermostats & time switches

6. Who does energy audits?
 Can be undertaken internally – energy manager
 Specialist energy consultants
 Energy service companies
 Performance contracts
 Guarantee organisations energy cost savings in
return for a fee
 Main interest is in installing and managing their
recommended plant
 May arrange finance of projects
 Vested interest

7. Why is energy wasted?
 Poorly designed buildings and
installations
 Insufficient insulation
 Undersized ventilation ducts
 Inadequate control systems
 Poor control settings
 Inefficient plant operation
 Out of date technology
 Poor maintenance
 Poor operating and working
practices

8. Different types of energy audit
 According to level of detail and depth of
analysis
 Preliminary
 Targeted
 Comprehensive

9. Preliminary audit
 How much energy is being consumed
 What type of energy
 Performance of facility compared with
similar facilities
 Characteristic performance of building

10. Preliminary energy audit
 Identification of potential areas of energy
saving
 Financial energy audits
 Collect data
 Establish quantity and cost of each form of
energy
 Data from energy invoices and meters for
previous year
 Analyse data
 Present data
 Establish priorities
 Make recommendations

11. Targeted energy audit
 Provide data and analysis on specific
targeted projects
 e.g. heating of one building or lighting
 Detailed survey of target area
 Analysis of energy flows and costs
 Recommendations for action

12. Comprehensive energy audits
 Similar to preliminary audits but in far
more detail
 Detailed data on energy flows into
and within organisation or facility
 Often requires use of sub-metering to
accurately determine component energy
flows
 Or estimate energy use
 (Plant power output (kWh)/efficiency of
plant) *operating hours per year
 Use of thermal imaging
 May use complex energy simulation
software
 Detailed energy survey
 Energy project implementation plans

14. Collect data
 Build up picture of pattern of energy consumption and
cost from energy invoices
 All invoices for relevant time period
 Delivery notes for oil, solid fuel, LPG
 Identify estimated meter readings – check with previous years
 Inadequate/unavailable invoices – contact utility company/fuel
supplier
 Collect geographic data
 Location, altitude, orientation
 Weather data, degree day data
 Manufacturing data (if appropriate)
 Production output
 Check data for anomalies
 Small building using more energy than larger one
 High energy use at night when unoccupied

15. Understanding invoices: electricity
 Date of meter reading
 Monthly standing charge
 Present and previous meter reading
 Daytime – peak rate
 Night time – off-peak rate
 Charges for each rate
 Some tariffs have a higher unit charge for first 1000 kWh
 Monthly maximum demand charge
 For every kW of the peak power demand during the month
 Penalise users make heavy demands during peak periods
 Supply capacity – annual maximum demand
 Monthly charge
 Total cost + VAT

16. Gas invoices
 Much less complicated than electricity
 Date of meter reading or estimate
 Calorific value of gas
 Present and previous meter readings
 Amount of gas used
 ft3, kWh or therms
 Unit price per kWh
 Standing charge
 Monthly or quarterly
 Total cost + VAT

17. Other fuels
 Fuel oil
 Measured by volume
• Varies with temperature corrected to standard condition of
15.50C
 Date of delivery
 Unit cost per standard litre
 Calorific value (?)
 Total cost + VAT
 Solid fuel
 Weight delivered
 Date of delivery
 Total cost + VAT
 No calorific value

18. Analysing energy records
 Key variables
 Heating
 External temperature - dominant
 Wind speed )
 Humidity ) <=10% variation
 Solar gain )
 Lighting
 Hours of darkness

19. Data analysis
Many different ways of analysing data
 Annual energy consumption
 Analysis of heating requirements
 Degree day method
 Mean temperature method
 Cumulative deviation method
 (Details in Keith’s lecture notes)
 Normalised performance indicators (NPI)
(Beggs, 2002)
 Time dependent energy analysis
 Linear regression analysis
 CUSUM – cumulative sum deviation method

20. Annual energy consumption
 Simplest analysis
 Assess overall energy performance of building
 Produces a percentage breakdown of annual energy
consumption and cost data
 Convert all energy consumption data into standard units (kWh)
• Standard conversion factors & gross calorific values
 Percentage breakdowns of total consumption and cost of each
energy type
 Present data
• Total annual energy consumption
• Cost
• Percentage breakdown of each fuel type
• Historical trends

21. Analysis of heating requirements
 Degree day method
 Quicker
 Oil & coal heating difficult – general estimates
of consumption
 Mean temperature method
 More accurate
 Plot mean consumption against mean
external temperature

22. Degree day method
Two component parts
 Temperature related
 Independent of temperature
• Hot water & cooking if by gas
 E = W + H*degree days*86400
• Where E is total energy consumed
• W energy for hot water + cooking (gas)
 W approx constant for given house – 7-10 GJ/quarter
• H is heat loss rate for the home
 Two unknowns W & H,
 Know degree days & energy consumption
 Estimate heat loss & steady energy requirement

23. Degree day method - example
Energy consumption 2 successive quarters
 31.76 & 18.80 GJ
Corresponding degree days
 1100 and 500
E = W + H * degree days*86400
1100 * H * 86400 + W = 31.76 (1)
500 * H * 86400 + W = 18.80 (2)
Simultaneous equations (subtract 2 from 1)
H = (31.76 – 18.80) * 109 = 250 Watts
(1100-500)*86400
Substitute for H in either equation to get W
W = 31.76 * 109 - 1100 * 250 * 86400
= 8 * 109 = 8GJ
H - heat loss
W - hot water

24. Degree day method
Once H & W have been calculated
 Performance for subsequent quarters can
be estimated
 If degree days for 3rd quarter = 400
 Consumption predicted to be
 400 * 250 * 86400 + 8 * 109 = 16.64 GJ
 If actual consumption is 17.5 GJ then
energy has been wasted

25. Mean temperature method
(non electrical heating)
 Plot the mean consumption over a specific period
against mean external temperature
 For 1 week or 1 day - less time than previous method

26. Analysis of lighting
(non-electrically heated house)
 Lighting varies throughout
the year with hours of
darkness
 Need to assess a realistic
time for lighting
 There is constant load (A)
from appliances and
refrigeration use and an
increasing amount from
lighting.
 Increase in lighting hours
is used to obtain L & A in
same way for H & W in
heating example

27. Analysis of heating & lighting in an
electrically heated house
 More complex as both H & L are unknown
 Combine A & W to give overall appliance + hot water
load (A)
 E = (degree days * H + lighting hours * L) * 86400 + A
 Where E = energy consumption
 H = heat loss rate
 L = lighting (units of L are Watts per hour)
 A = appliance + hot water
 3 unknowns – H, L & A
 If we have data for 3 quarters
 Estimate values for H, L & A by solving 3 simultaneous equations
 If appliance load is known calculation is easier

28. Cumulative deviation method
1. No energy conservation
– horizontal line
2. Winter following
improved insulation
3. Summer – no savings –
heat conservation only
4. Winter – parallel to 2
5. Summer - improved
management of hot
water
6. Should be (4) + (5) but
less - energy
conservation
performance is reduced

29. Normalised Performance Indicators (NPIs)
 Provides an indication of the energy performance of a building
 Compares actual annual energy consumption and costs with those
achieved by buildings of a similar type and function
 Problems
 Buildings may be different sizes
 Locations may have different climates
 Locations may have different levels of exposure
 Maybe different operating hours
 Correct the building energy consumption data
 allow for variables such as occupancy and weather.
 NPIs developed to address these problems. Used to
 compare with other buildings of a similar type and function
 compare with standard energy benchmark for different building types
 Benchmarks
 Many countries have national energy benchmarks for different types of
buildings
 Usually kWh/m2 of floor area (volume)
 Provide guidance, not absolute values to achieve

30. How to calculate NPIs
 Establish total building energy use in standard units
 Calculate the annual energy use for space heating
 Sub-metering, or analytical techniques
 Correct space heating energy data for climate & exposure
 Weather coefficient = std annual heating degree days/ annual heating
degree days experienced by building
 Exposure coefficients
• Sheltered (city centre) = 1.1
• Normal (urban/rural) = 1.0
• Exposed (coastal/hilly site) = 0.9
 Non-heating energy consumption + corrected space heating = non-
time corrected energy consumption
 To calculate normalised annual energy consumption need to correct
for ‘hours of use’
 non-time corrected energy consumption * coefficient
 Hours of use coefficient = std annual hours of use/actual annual hours
of use
 NPI = normalised annual energy consumption/building floor area

31. Energy Surveys
 Integral part of energy audit
 Helps to understand energy flows within a
facility/building
 Helps to identify energy wastage
 Can be comprehensive or targeted
 Objectives
 Determine energy performance of facility/building or specific
plant/equipment
 Identify and quantify the principal energy flows & energy cost
savings
 Produce costed recommendations to achieve energy cost
savings
 Make recommendations on future energy management of
facility

32. What to include in an energy survey
 Management and operation characteristics
of a facility or organisation
 Energy supply to an organisations various
facilities
 Energy use within an organisations
facilities
 The plant and equipment within a facility
 The fabric of the organisation’s buildings

33. Management and operating characteristics
 Management culture
 Can have considerable influence on energy
consumption
 Determine management structure and
practices relating to energy procurement
and consumption
 Identify cost centres
• Are the managers accountable for operating
costs also responsible for energy consumption?
 Maintenance procedures
• Frequency and quality
• Identify new maintenance measures to improve
energy efficiency

34. Operating practices: data collection
 Use of particular space or building
 Mechanical/electrical services in building
 Number & type of occupants e.g. stationary or
active
 Occupancy patterns
 Environmental conditions
 Air temp, humidity, lighting
 Operating practices of plant/equipment
 Identify where actual practices deviate from that
stated by management
 Overheated rooms, open windows, computers left on

35. Energy Supply
 Identify tariffs and supply contracts of organisation
 Ensure organisation is using correct electricity tariff
to suite its load profile
 Calculate load profile
 Regular meter readings – include daytime, night time &
weekends
 For large electrical loads
• Need to be more accurate
• Measure every 30 mins, use portable meters if necessary
 Investigate large peaks in load

36. Plant and equipment
 Survey major items of plant and equipment to determine their
operating efficiency
 Include pipe distribution networks
 Boilers
 ‘tune’ to minimise flue gas heat loss
 Identify if flue gas heat recovery is feasible
 Refrigeration
 Check efficiency
 Opening practices
 Is heat recovery feasible
 Pipework
 Insulation & leaks
 Planned replacement of old plant
Building fabric
 Identify using U values areas of greatest heat loss
 Thermal imaging
 Excess ventilation – open doors

37. Energy management: recommendations
 Recommendations will relate to cost of fuel – more interested in
saving money than energy/carbon
 Technical
 Insulation, draft exclusion, thermostatic radiator valves, heating control
 Low energy lighting, efficient refrigeration
 Power factor corrections
 Relocation of switches, movement sensors
 Energy management
 Checking performance
 Record keeping
 Financial
 Make sub-sections responsible for their own energy budget
 ‘Carrots’ for those who save energy
 Other factors
 Change patterns of working
 Working practices
 Use of space