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 Aim Process
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Out of date technology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 Solid fuel Measured by volume Date of delivery
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
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 & GJ
Corresponding degree days
1100 and 500
E = W + H * degree days*86400
1100 * H * W = (1)
500 * H * W = (2)
Simultaneous equations (subtract 2 from 1)
H = (31.76 – 18.80) * 109 = 250 Watts
( )*86400
Substitute for H in either equation to get W
W = * * 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 * * 109 = 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) * 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
No energy conservation – horizontal line
Winter following improved insulation
Summer – no savings – heat conservation only
Winter – parallel to 2
Summer - improved management of hot water
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. Building fabric 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