Sunday, 12 August 2012

Energy saving in business - Cambridge City Council

In June Cambridge City Council (CCC) published their carbon management plan for 2011-2016 [1] and it is an interesting read for anyone concerned with saving money in a business environment. Granted some of the CCC services are not exactly typical - like the swimming pools - but there are others which directly relate to commercial business. They heat, cool and light their buildings, run deliveries between sites, run a concert venue (cf lecture theatre or seminar room), and a crematorium (cf incinerator) and car parks. I stated recently that the financial incentives for saving energy are fairly weak (What is the point in Carbon Accounts) mainly because fuel costs are a small fraction of most business costs and this is certainly true for CCC at the moment - fuel costs come to just 1% of their overall expenditure (£1.8 million [1] out of £183.4 million for 2010/2011 [2]). However, fuel prices are expected to rise and in any case CCC have set themselves a target to reduce their carbon emissions from energy use by 20% by 2020. According to their plan they expect to deliver this at a capital cost of only £2.3 million, with expected overall financial payback time of under 7 years. That is perhaps a bit longer than most businesses would consider reasonable, but some of the projects in the plan pay back much quicker than that. In this post I will pick out some high points from the plan - the high carbon services, the quick payback projects and those with biggest carbon savings.

By the way, the Cambridge City Council is not a unitary authority and it doesn't manage schools or transport. It does supply waste management services like street cleaning and refuse collection, public toilets, leisure services like swimming pools and the Corn Exchange concert venue (which is a grade 2 listed building), manages thousands of council houses, and also runs administrative services like planning, licensing pubs and restaurants and so on. The total spend per resident is about £1500/person/year [2] and of that fuel costs are about £15.

In order to set a baseline for their carbon reduction target, they had to get accurate figures for their energy use across a range of services. However, like most businesses they found they did not have comprehensive data even for basics like meter readings for each building - the meters would be read by utility companies and often estimated. This makes it difficult to track savings. For example if the one quarter energy use is estimated and inaccurate the correction appears in the next quarter when the meter is properly read. Then the records of energy use are wrong for both quarters and it is impossible to compare them from one year to the next or correlate energy use with the weather or seasonal activities. CCC have now installed automatic meter reading systems for electricity in almost all their buildings and they are working on the gas meters too.

Like any sensible organisation, CCC have run trials of some technologies to see how much energy they save. For example they have installed LED lighting in one of the car parks and voltage optimisation (see below) in the Guildhall. Now these can now be rolled out to other sites with confidence in the predicted costs and savings.

The big carbon sources

From the baseline, the big carbon  sources are:

Sector% of total carbon generatedExpected saving in sector How
Swimming pools23%23%Swimming pools use a lot of energy not just to keep the water in the pool circulating clean and warm but also to keep the rest of the building reasonably cool and dry. The pool room is like a massive steamy bathroom. The plan is for a whole raft of measures to improve pumping efficiency, heat retention, lighting and so on.
Car parks16%25%Savings will come from installing LED lighting and motion sensors.
Vehicles14%9%There are no easy wins in this sector. The planned savings are mainly from route optimisation on the rubbish collection service and an incentive scheme for efficient driving.
Offices13%-This will be addressed building by building. Measures planned include more efficient heating, double glazing and draught fixing, plus voltage optimisation (see below).
Crematorium5%5%Although biomass can be used as fuel it has to be dry first and it takes a lot of fuel to burn a fresh body -  200-400 kWh. CCC have achieved some savings by installing a heat recovery system but there are other options too. In Durham, a crematorium is looking to use the waste heat to generate electricity

The fast paybacks

 Payback is calculated simply as the initial cost divided by the yearly savings. Here are some of the top few:

Payback (years)Savings (tonnes CO2)Project
057Driver incentive scheme to encourage efficient driving - costs are negligible
less than 168 for officesEnergy awareness campaigns in office, community centres, the Corn Exchange and so on.  For the offices, the expected cut in emissions is 5%.
0.563Route optimisation for refuse collection - payback 0.5 years
1.12Stop/start technology for some delivery vehicles. The system automatically stops the engine when you are stuck in traffic (which happens a lot in Cambridge) but starts it quickly when the driver releases the brake. You can get it for diesel engines (review for Peugeot 208 here) or hybrids. However, the overall savings for CCC are small because it will only go into five vehicles.
1.314Optimum start controls for heating at one depot. This means adapting the heating system to the weather. When it is cold outside the heating needs time to do its work but when the mornings are a bit warmer the heating can cut in later and still hit the target temperature before the workers arrive - payback 1.3 years.

Big savings

LED lighting is already saving 145.4 tonnes CO2 per year at one multi storey car park. That means a cut of around 250 MWh/year of electricity or 670 kWh/day - more than 2 months worth of your average house. This is a 75% reduction in the lighting energy used at that site [3]. The payback time was 5.6 years for the first project which is much longer than I would expect for a straight lamp for lamp swap (see Should I buy LED bulbs). However in this case the lighting layout was completely redesigned to improve security by minimising shadows which meant new cabling too. CCC will be installing LEDs in three more car parks and trying out motion sensors for further savings. They are also planning LEDs for house lighting at the Corn Exchange.

Variable Speed Drives will be installed at the two largest swimming pools to improve the efficiency of pumps and fans in the water circulation and air conditioning systems. VSDs can be used in anything with a motor which needs to run at less than maximum speed most of the time. The energy savings can be very high because a VSD running at half speed uses much less than half the energy. Together with a Building Energy Management System these drives are expected to save 274 tonnes CO2/year and pay for themselves financially in less than 2 years.

Voltage optimisation installed in the Guildhall has saved 20 tonnes/year with a payback time of less than 5 years and the plan is for this technology to be rolled out to up to 10 more sites. Voltage optimisers fit between the grid power supply and the building ring mains and they reduce the supply voltage to 220V. 220 V is the traditional standard for electricity in mainland Europe and most equipment we use can tolerate a range from 215 V to 250 V with no problem. For equipment such as computers with switch mode power supplies the devices will simply take a higher current to compensate for the lower voltage and the power consumption is the same. Heating loads will run slower so kettles will take longer to boil but, again,  the overall energy use is the same. For incandescent or fluorescent lighting there will be energy savings of around 20% but the lamps will produce less light. LED lighting is like the switch mode power supplies and there will be no difference in power. There are significant savings for conventional motors, though not with variable speed drives. A study for Ofgem of voltage optimisation in a domestic setting found typical energy savings around 5% [4].



There are some very fast payback projects but they are not usually high in savings; the large savings are expected from technology changes rather than behaviour changes.  This may be simply because it is hard to predict how much staff can save easily, for example by remembering to turn off lights when not needed,  and especially how well they will keep this up in the longer term. Raising awareness in the staff is not enough - they need to be motivated to change their habits and set a new norm which is maintained unconsciously and adopted by new staff too. Ultimately, you want your staff to be concentrating on their jobs rather than saving energy.

One tactic not mentioned in the plan is simply setting a policy of choosing energy efficient products when replacing or buying new equipment. This principle applies to everything from hand dryers and coffee makers to computers and printers. It isn't in the plan because it doesn't need special funding.  In fact it doesn't cost very much, if anything, it only needs management to keep an eye on it.

The biggest savings are from the swimming pools which are the biggest carbon sources to start with. It would be a lot harder to achieve the 20% overall cut by 2020 without some easy wins there.

The savings CCC are planning are not revolutionary, just evolving greater efficiency in the provision of existing services. The new rubbish collection routes still visit every house once a week. The new car park lighting is better than before but for less electricity. It hasn't been too hard to find enough savings to meet the 20% target - but what about the next 20%? No doubt technology will continue to improve especially as energy prices continue to rise. However, there could be much larger savings from adapting services. For example, if we are happy to wear a jumper at home, what about in the office? Could we run the swimming pools a little cooler (which would please the more serious athletes no end)? Could we take our rubbish bins to the end of the street to be collected, rather than just the pavement outside? We can also choose less energy intensive ways to dispose of our bodies. It's our council and if we want more savings we can ask for them.

The tactics the CCC is using so far - staff energy awareness campaigns, LED lighting, variable speed drives, better heating systems - can all be adopted by commercial businesses and save money too. In a rational world financial pressure should be enough to drive similar projects in most organisations; in practice, maybe a word in the ear of your facilities manager would not go amiss.

[1] Cambridge City Council Carbon Management Plan 2011-2016
[2] Cambridge City Council Annual Report and Statement of Accounts 2010/2011
[3] Cambridge City Council saves energy and reduces carbon emissions with award winning car park lighting (MHA lighting)
[4]  Energy Saving Trial Report for the VPhase VX1 Domestic Voltage Optimisation Device (Ofgem, 2011)


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