Monitoring Energy Use & Setting Targets Session 2

Transcription

1 Monitoring Energy Use & Setting Targets Session 2 1

2 Why is energy wasted? Energy waste is virtually invisible and easy to ignore Nothing to see No dripping tap No clear link between energy wasted and money wasted Unless you have a coin meter 2

3 Energy measurement culture The only way to understand energy use and trap waste: Assess by measurement Improve Compare Assess again 3

4 Energy measurement - practicality TOTAL USE e.g. electricity, gas, oil etc Boiler Space heater Pumps Lighting 4

5 More detailed metering Utility metering Covers the whole site too coarse to pick up small changes Consider sub-metering The only way to monitor changing energy use at an equipment / building level Use cheap kwh meters or hours-run meters Use clip-on profile meters 5

6 Electricity and gas metering Learn to read your meter Don t rely on supplier reads many estimates can give a false picture Your electricity meter might be read by telephone in which case your data will be accessible over the net Build up a record of energy use Use a spreadsheet solution for recording Enter units of energy not money 6

7 For bulk fuels Record deliveries Record stock levels Dipping tanks Assessing coal heaps Reading gas tank meters Use in period is: Opening stock Closing stock + Deliveries e.g litres 5000 litres + 12,000 litres = 9,000 litres 7

8 Oil tanks Mark sight glasses with volumes Make sure you can see levels Use a dip stick if no sight glass Use flow meters best solution 8

9 Assessing coal stocks Tonnes with measurement in metres Diam 2 x H/4.65 L x B x H/1.22 L x B x H/2.44 9

10 Record Use a spreadsheet solution Copy on CD Subscribe to FEC s ERBIS product 10

11 Use Smart profile metering Record and store energy on a ½ hourly basis Some electricity meters already do this 11

12 Profile monitoring Shows what s really happening 12

13 Profile monitoring 13

14 Boiler profile from climate control computer 14

15 Measuring and monitoring The only way to truly gauge the effectiveness of efficiency activities is to measure use before and after implementation 15

16 Energy efficiency using less Assess efficiency using benchmarks Specific Energy Consumption (SEC) The ratio of energy use to output kwh/m 2, kwh/kg So you must monitor energy use related to area or throughput Real energy efficiency is price proof 16

17 Adjust for changing circumstances Link usage to throughput or other influencing factors Greenhouse temperature Ambient temperature Output 17

18 How do you account for changing weather? Heating degree days The sum of the average daily temperature each day below your glasshouse target temperature Divide heating energy by degree days Gives a measure of heating efficiency which is independent of outside temperature 18

19 Example of degree days Heat use in the last 5 days was 11,000 kwh If the average temperature for the last 5 days was 5 o C,6 o C, 10 o C, 11 o C and 8 o C, with target greenhouse temperature of 15 o C. (15-5) + (15-6) + (15-10) + (15-11) + (15-8) = 35 degree days heat used per degree day would be: 11,000 kwh / 35 = 314 kwh / DD Divide by area cropped to get a specific figure This figure can be compared with any other period to give an indication of system efficiency 19

20 A real example - peppers DD Requirement 2006 kw h delivered Degree days kwh (energy) Week Number

21 Exercise Thermal screens installed for 2006 season Have thermal screens improved energy efficiency? Degree days Areas cropped Energy used ,200m 2 2,837, ,500m 2 3,192,462 21

22 Answer 1 Using specific energy consumption ratio of kwh/m 2 2,837,744 / 5200 = kwh / m 2 (2005) 3,192,462 / 6500 = kwh / m 2 (2006) ((491.15/545.72) x 100) = 10% saving So thermal screens saved 10%?? 22

23 Answer 2 Energy efficiency ratio in 2005 = 2,837,744 = kwh / DD / m x 5,200 Energy efficiency ratio in 2006 = 3,192,462 = kwh / DD / m x 6500 The site used ( ) / x 100% = 15% less in 2006 Thermal screens actually saved 15% 23

24 Compare performance Compare with other time periods Last October consumption was 30 kwh / m 2 This year it is 40 kwh / m 2 WHY??? Weather, equipment, management??? Compare with other sites Site A uses 350 kwh / m 2 Site B uses 400 kwh / m 2 WHY??? 24

25 Session 2 summary Take care to understand where energy is going Use sub-metering MONITOR, RECORD & BENCHMARK 25