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Energy Saving Heating & Ventilation

Mini-CHP Lowers Running Costs For London Fire Brigade


Baxi-SenerTec UK, part of Baxi Commercial, has played a major role in enabling the London Fire Brigade (LFB), the world’s third largest fire fighting organisation, to reduce its carbon footprint by 28% in six years. This dramatic cut in carbon emissions, which has also helped drive down running costs, has involved a variety of renewable and sustainable solutions, with Combined Heat and Power (CHP) as the ‘lead’ technology. There are Baxi-SenerTec MINI-CHP installations, comprising a CHP unit, condenser and buffer vessel, installed in over 35% of the LFB’s 112 premises. This proportion is expected to eventually reach 50%, excepting only those buildings without suitable space.

The LFB is committed to an ambitious programme of energy upgrades, combining CHP with other compatible energy efficient/LZC solutions, including improved building management systems, LED lighting and upgraded window glazing. “CHP is our core technology for reducing the carbon impact of electricity and hot water across our estate,” said LFB Energy and Compliance Manager, Lloyd Bentley.

Dachs mini-CHP engines are designed to operate for thousands of hours, delivering up to 440 MWh of electricity and 1,200 MWh of usable heat at a combined energy efficiency of over 90%. They will also reduce carbon emissions by over 100 tonnes during their operating life compared with conventional methods of delivering heating and electricity. “It is the most appropriate technology for energy intensive 24/7 buildings like fire stations, confirms Mr. Bentley. It is an ‘easy fit’ technology, which offers the bonus of free electricity”. He added that the LFB was intent on doubling its renewable capacity with CHP as the lead technology and has an ongoing target of a 3% cut in energy use every year.

baxi2Using internal combustion engine technology, the Dachs mini-CHP generates electricity while it is running and produces heat as a by-product, which is captured and used for water and space heating. At times of peak demand, for example in winter when additional heat may be required to maintain indoor temperatures, the BMS will automatically switch the CHP from supplying domestic hot water and divert it to supplement the heating circuit, with standby gas-fired water heating boosting hot water volumes.

Made to Measure
Heat meters were installed with every Dachs mini-CHP to measure output and Automatic Meter Reading (AMR) helps establish a detailed picture of energy patterns via the gas and electricity metering. Digital panels showing the energy produced and carbon saved in ‘real time’ are prominently displayed in all reception areas.

In just four months, LFB’s station at Battersea received 4,100 kWh of electricity from the Dachs mini-CHP and 1,730kWh from PV. The combined systems were calculated to reduce the site’s carbon footprint by 13 tonnes a year. Battersea has reported a £2,500 annual saving on fuel costs. This means that the payback on the purchase cost of the CHP system could be less than six years.

As any CHP unit that is not running, for any reason, can have a serious impact on overall carbon savings, all Dachs mini-CHP engines have built-in modems. These can be interrogated remotely over a standard internet connection, allowing performance to be tracked and provision made for the delivery of any necessary maintenance parts during planned service visits.

The Long Running Solution
“Fire stations are ideal for mini-CHP,” said David Shaw, LZC National Sales Manager for Baxi Commercial. “Any building with a significant heat load will get the most out of their mini-CHP system as it will be running almost continuously generating low cost, low carbon electricity and generous amounts of ‘free’ heat. This makes mini-CHP very financially attractive; particularly as energy costs continue to rise.”

The Carbon Trust carried out extensive field trials in the UK and concluded that “a mini-CHP unit can provide savings of between 15 and 20% when it is applied as the lead boiler”. It works best in applications with high and continuous heating loads like hospitals, leisure centres, sheltered accommodation, fire stations, homes with swimming pools etc. because the longer it is running to meet heating demand the more efficient it is.