Energy efficiency Fire station case study
years, based on the installation cost of £2,900 (which was also subsidised by a 50% Energy Efficiency Loan). Staff engagement: The London Fire Brigade recognised
that the co-operation of staff at all levels was vital in order to maximise the full potential of the energy efficiency initiative through actions such as correct operation of equipment, reporting of faults and providing suggestions for further energy saving measures. It therefore developed a formal Green Champions training course covering the broad theme of saving energy. This staff- engagement initiative is estimated to make potential energy savings of about 2.5% of electricity consumption per year. No gas savings are attributed to this measure because gas savings are associated with improved boiler control and scheduling which is not in the control of the occupant. Variable speed drives: The LFB’s site refurbishment
overview confirmed that the primary heating pumps were not fully loaded and spent a significant amount of time running part-load. This was avoided by installing variable speed drives that would match pumping with demand. Operating a fan at 50% volume flow at time of low occupancy saves virtually nothing with conventional drives but typically 75% of energy use with variable speed drives – on this basis, and with low occupancy occurring for six hours out of 24, the average energy use of the fans would reduce by 25%. Achieving a 25% reduction results in a saving of 950 kWh of electricity a year, which would save an estimated £95 a year. The measure would also cut annual CO2 emissions by 0.5 tonnes. Lighting: This was largely provided by ceiling mounted fluorescent lamps, which used older switch start control gear. On the advice of the lighting designers, it was decided to completely rewire the site’s lighting installation and fit new modern efficient fluorescent fittings (T5) with automatic movement detection. The new installation provides considerable energy savings compared to switch start units, which also reduces replacement costs as lamp life is extended. The changes have saved about 11,800 kWh per year and the associated saving in carbon dioxide emissions is 6.3 tonnes per year. Energy use by the new lighting installation for the Wembley site is assessed at 118,000 kWh per year. Consequently the lighting upgrade together with motion detection has delivered a saving of around 20%.
Recommendations The following two measures were recommended by Power Efficiency as additional improvements that could be undertaken in the longer term (see Figure 2). • Ground source heat pump: GSHPs are used to extract heat from the ground to provide space and water heating to both individual houses and any type of non-domestic building. The potential savings from a GSHP are strictly associated with its coefficiency of performance (COP); assuming a COP of 3.2 for a GSHP, the potential savings could be estimated at 40% of the fuel consumption. A change from gas boilers to a GSHP at the Wembley site would result in an increase in the annual electricity consumption
www.cibsejournal.com
by about 42,250 kWh. However, annual savings in gas usage would total 176,000 kWh, saving £5,280 a year. With installation costs of £50,000, the payback period would run to 10 years. Estimated CO2 emissions cuts would be 34 tonnes a year.
• Voltage power optimisation: VOP is managed reduction in the supplied voltage at the recipient site, to reduce energy use, power demand and reactive power demand. The potential savings at Wembley fire station are
strictly associated with the current site voltage and the scope for reduction. Consequently, assuming a potential saving of 5% was available, this could produce an overall annual saving of 9,000 kWh, or £900 a year. The estimated £9,000 cost of the system would have a payback period of 10 years. There would also be a cut in annual CO2 emissions of 4.8 tonnes.
Conclusion The energy and carbon-saving measures adopted at the Wembley fire station site since 2008 have clearly had a major impact. For CIBSE, the lessons learnt from these findings will provide key insights for both energy assessors and the wider engineering community involved with such green-building developments. In 2009, the fire station achieved a Display Energy
Certificate grade of D. Power Efficiency has found that additional improvements would also help to reduce cost and emissions further – albeit with considerably longer payback periods. The installation of a ground- source heat pump would produce substantial extra savings from reduced gas consumption. A second new measure, voltage power optimisation, would notably cut the electricity bill. The findings and recommendations will, hopefully,
provide engineering professionals and low carbon building assessors with insights that will help them to provide effective energy efficient solutions in future. l
John Field and Alexandros Balaskas work for Power Efficiency, which gratefully acknowledges the valuable support of Niel Roake, energy consultant, and the helpful co-operation of Ian Shaw of London Fire Brigade and the Wembley Fire station staff.
A range of energy saving measures at the fire station site have produced a number of projected savings
Get the full report
For the full survey report, go to the digital version of the February 2010 CIBSE Journal at
www.cibsejournal.com Previous survey reports can be found with the June and October 2010 digital editions. To obtain a copy of CIBSE’s TM22: Energy Assessment and Reporting Methodology, visit
www.cibse.org/ bookshop
February 2011 CIBSE Journal
37
Power Efficiency
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72