Figure 1: Annual energy performance compared with benchmarks
Metered energy
Electricity kWh/sq m Non-electricity kWh/sq m
Carbon emissions kgCO2/sq m
Cost £/sq m
>
Actual Adjusted Good practice
145 273 129
206 228 153
£21.18 £26.03
140 360 142
£22.83
Benchmarks Typical
240 550 231
£37.45
Metering and recording
The hotel has two half-hourly electricity meters, one half- hourly gas meter, plus a non-half-hourly gas meter for the kitchen area. Half-hourly meter data are uploaded to the energy supplier’s web portal and can be checked remotely by hotel staff. The non-half hourly gas meter is billed by manual reading of the meter. The hotel’s CHP system, which is operated by
a third party, is metered remotely. Energy data are transferred to the operator monthly. The CHP system’s gas consumption, which is not metered separately, is calculated on the system’s operating hours and design consumption. Total CHP energy consumption and generation is recorded on a spreadsheet each month.
Energy consumption
When looking at energy supplied to the hotel, the unadjusted emissions figure of 129 kg/sq m is used (see Table 1). This is eight per cent better (lower) than the ‘good practice’ benchmark (142 kg/sq m) and includes the effect of a 16 per cent reduction in emissions from the CHP system. However, removing the impact of the CHP so as to
show how the building performs, we find that overall carbon emissions, at 153 kg/sq m, are eight per cent
Figure 2: Systems’ energy usage
Electricity
Unit cost 9p/kWh 9.849
Heating Hot water Refrigeration
Fans
Pumps Control systems Humidification
Lighting Office equipment Other normal e.g. vending lifts Catering
Pool, leisure Process Other special
kWh/ year
kWh/ sq m
The combined heat and power unit links to three gas boilers.
worse (higher) than ‘good practice’ but 34 per cent better than ‘typical’. This result arises from electricity being 14 per cent and gas 59 per cent better than typical – reflecting the use of electricity for heating (via the heat pumps) with an underlying good electrical performance. Energy costs for the hotel in 2009 were £340,000
(£230,000 for electricity and £110,000 for natural gas). Energy supplies were 2,335,000 kWh of electricity and 4,379,000 kWh of gas.
Energy saving solutions
Power Efficiency’s review of the hotel’s operations produced the following list of recommended actions, each of which would provide on the cost of the respective improvement proposed.
Building management system (BMS): to review the
schedules and settings of the BMS and update these to provide lean operation without reduction in service levels when the building is occupied. Information on customer and staff requirement and feedback would be
Annual energy use Annual cost £/
% of total
0 0
1,005,383
739,532 521,974 0 0
758,577 0
48,048 137,592
20,966 0
63,773
0.0 0.0 62.6
46.1 32.5 0.0 0.0
47.3 0.0 3.0 8.6
1.3 0.0 4.0
0% 0% 31%
22% 16% 0% 0%
23% 0% 1% 4%
1% 0% 2%
sq m
0.00 0.00 0.00
0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00
0.00 0.00 0.00
£ Full load Full load Op hours
£0 £0 £0
£0 £0 £0 £0
£0 £0 £0 £0
£0 £0 £0
0.00 0.00 16.14
5.87 4.71 0.00 0.00
8.99 0.00 0.34 2.80
0.19 0.00 0.59
TOTAL 3,295,844 205.3 100% 0.00 £0 39.64
40
CIBSE Journal June 2010
- -
3,881
7,847 6,910 - -
5,255 -
System hours
W/sq m hrs/yr hrs/yr
0 0
7,454
6,993 6,909 0 0
7,224 0
8,736 6,552
6,552 0
6,552
System indices Utilisation
%
- -
52%
112% 100% - -
73% -
0% 0%
0% -
0%
5,181 7,169 72%
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