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Energy efficiency Hotel case study

Figure 3: Summary of CO2 emissions and effect of improvements

Effect of improvement measures on energy use, cost, carbon emissions and assessed Rating and Grade

Electricity (kWh/yr)

Energy consumption 2009

Total effect of shorter-term measures Consumption following shorter-term measures Improvement from shorter-term measures

Total effect medium-term measures Consumption as improved after all measures in Table 1 Improvement from all measures in Table 1

Effect of longer-term measures (Table 2):

Review of power factor correction Voltage optimisation Consumption as improved including longer-term measures Improvement from all measures including longer-term

Supporting data

Floor area for DEC calculation Benchmarks as published (kWh/ sq m)

Unit cost (p/kWh) Annual standing charges excluded from costs above CO2 intensities (kg/kWh) for this report generally CO2 intensities (kg/kWh) for DEC certification only

available from the staff engagement initiative, and there would be an opportunity to get agreement on updated time scheduling which allows a review of time schedules and set points. The energy savings assessed for the BMS review measures alone is eight per cent of electricity and gas, providing 186,000 kWh of electricity savings and 350,000 kWh of gas. Payback period: 1.3 years. Meter-reading management: this measure supports

the above by providing managed evidence of electricity and gas savings. A half-hourly meter is to be installed with associated data reporting and analysis for the kitchen gas supply. Energy performance objectives can be set for the kitchen operation and monitored on a regular basis for adherence to energy performance

2,335,206

303,000

2,032,206

-13%

155,000

1,877,206

-20%

20,000 30,000

1,827,206

-22%

105

9.80 £640 0.537 0.550

Gas (kWh/yr)

4,379,283

450,000

3,929,283

-10%

0

3,929,283

-10%

CO2 (te CO2/yr)

2,064

246

1,818

-12%

83

1,735

-16%

11 16

3,929,283

-10%

330

2.50 £640 0.185 0.195

objectives. Any fluctuations above expected performance can be checked to determine any relevant reasons such as failure of controls, longer operating hours. Costs for automated meter reading (AMR) installation

are assessed at £1,000 for the kitchen gas meter. A cost of £1,500 is allowed for set-up and software costs, to give a total budget cost of £2,500. Payback period: one year. Variable speed drives: operating a fan at 50 per cent volume flow at times of low occupancy saves virtually nothing with conventional drives, but typically 75 per cent of energy use with variable speed drives. On this basis, and with low occupancy for six hours out of 24, the average energy use of the fans would reduce by 25 per cent. Variable speed drives are proposed for the foyer,

Figure 4: Cost savings and payback from measures

Measure

Electricity

savings estimate (kWh/yr)

Shorter term payback measures: Staff engagement initiative Building Management System scheduling and control review Set up half-hourly meter based management procedures

Sub Total

Medium term payback measures Install variable speed drives on selected fans Lighting control upgrade

Sub Total

Total

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47,000 186,000 70,000

303,000

51,000 104,000

155,000

458,000

0

450,000

1,708

-17%

Cost (£/yr)

338,300

40,900

297,400

-12%

15,200

282,200

-17%

2,000 2,900

277,300

-18%

16,050 sq m 122.1

Emissions (kg CO2/sq m)

128.6

15.3

113.3

-12%

5.2

108.1

-16%

0.7 1.0

106.4

-17%

76/D 67/C 78/D 70/C

95/D 82/D

78/D 74/C

Guide ratings / Grades DEC EPC

>

Gas savings estimate (kWh/yr)

350,000 100,000

450,000

Carbon

dioxide saving (te CO2/yr)

25

165 56

27 56

Cost

saving (£/yr)

4,600 27,000 9,400

5,000 10,200

Guide price (£)

2,500 35,000 2,000

246 41,000 39,500

21,000 40,000

83 15,200 61,000

329 56,200 100,500

June 2010 CIBSE Journal

Simple payback

period (yrs)

0.5 1.3 2.0

1.0

4.2 3.9

4.0

1.8

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