Environmental auditing: Estimating and reducing corporate greenhouse-gas emissions using monitoring and targeting software systems

Applied Energy 42 (1992) 269-288

Environmental Auditing: Estimating and Reducing Corporate Greenhouse-Gas Emissions using Monitoring and Targeting Software Systems P a u l K. M a r t i n , P a u l O ' C a l l a g h a n & D o u g l a s P r o b e r t Department of Applied Energy, Cranfield Institute of Technology, Bedford MK43 0AL, UK

A BS TRA C T Current concerns about global warming, the alleged increasing greenhouse effect, environmental instability and sustainable developments have prompted organisations to devise and implement environment audits. These are undertaken in order to assess the impact an organisation's activities have on the environment and should include obtaining estimates for the airborne pollution and greenhouse-gas emissions produced. Recommendations are normally made to lessen detrimental effect•s"on the environment and these aims are increasingly incorporated in organisations' environment policies• Reducing greenhouse-gas emissions and improving corporate profitability can be mutually compatible. Estimating emissions from multi-site organisations (as part of a corporate environmental audit) can be a difficult and lengthy task. The present paper describes a computer model, which has been developed to estimate corporate greenhouse-gas and airborne-pollutant emissions from readily-available fuel-invoice information and/or plant details. How monitoring and targeting techniques, developed for energy-thrift campaigns, can be used to monitor and reduce corporate greenhouse-gas emissions, with little or no capital outlay, by reducing energy waste, are also described•

NOTATION CFC CO CUSUM GHG

Chlorofluorocarbon C a r b o n monoxide Cumulative sum Greenhouse gas

269 Applied Energy 0306-2619/92/$05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain

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GWP M&T Rll R12 TEAM VOC

Paul K. Martin, Paul O'Callaghan, Douglas Probert

Global-warming potential Monitoring and Targeting Refrigerant no. 11 Refrigerant no. 12 Targeting, Energy Auditing and Monitoring (commercial computer software system) Volatile organic-compounds

Chemical symbols CH 4 Methane CO 2 Carbon dioxide NO 2 Nitrogen dioxide NO x Oxides of nitrogen N20 Nitrous oxide SO2 Sulphur dioxide

GLOSSARY

Environmental audit: in order to comply with existing legislation, a comprehensive environmental audit would (i)

assess the potentials for environmental accidents such as spillages and fire; (ii) document environmental liabilities associated with previous and existing industrial activities on the considered site; and (iii) assess the occupational health and safety hazards, including exposures of employees to poisonous materials, carcinogens, radiation, noise and vibration (see British Standard DC53255-57/91, Environmental Management Systems, November 1991). When contemplating the purchase of a site, it is wise for a comprehensive environmental audit of the site to be undertaken. The present paper is devoted to a highly specialised aspect of environmental auditing.

INTRODUCTION The UK Government is committed to reducing CO2 emissions to their AD 1990 levels by the year AD 2005.1 To achieve this target, both fuel suppliers

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and users need to make significant progress, whether it be through the installation of emission-reduction equipment at power stations or improved energy-efficiency by the end user. Although the adverse effects of an excessive 'greenhouse effect' need to be tackled on a global basis, each nation, company and indeed individual should play a part locally. For industrial and commercial organisations, emission reductions can mean less energywaste, reduced costs, and improved productivity. Fundamental to any corporate environmental policy is the need to know what detrimental or positive impacts an organisation's activities have on the environment, i.e. an environmental audit is necessary. The impacts on the environmental range from influences on the countryside to the purchasing of 'ozone-friendly' products. Such audits are undertaken either by environment consultants, management accountants or in-house staff. Invariably, the audits will cover airborne-pollutant emissions and greenhouse gases. This information will assist management in developing a corporate environmental policy to achieve a sustainable society. One problem when evaluating greenhouse-gas and airborne-pollution emissions is the lack of information, particularly concerning the types and rates of emissions. In many organisations, the largest source of greenhousegas emissions is from the combustion of fossil fuels (on site, at a power station or from a vehicle fleet). If management is able to obtain detailed information of the total greenhouse-gas or airborne-pollution emissions over all their operations, they should then be able to develop a coherent policy to achieve a reduction. This could be accomplished by: (1) (2) (3) (4)

monitoring all emissions to ascertain the quantities and sources; comparing these against those for other sites or standards; targeting reductions through individual projects; and monitoring the success of projects over time.

These are the basic management actions that are fundamental to energy monitoring and targeting: they are now commonly employed to improve fuel efficiency and effectiveness. For large boiler plants, gas-sampling equipment is often used to monitor the emissions accurately and continuously: the data are Usually stored and analysed by computer. In multi-site organisations, such as local authorities, health boards, and the retail and banking sectors, the installation of continuous monitoring equipment on all sites to determine the corporate impact is at present prohibitively expensive (though undoubtedly will occur increasingly in the future). Nonetheless, estimates can profitably be made now using readily-available fuel-invoice information taken from meter readings.

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By monitoring the energy consumption for a site, estimates can be made of the greenhouse-gas emissions using conversion factors, or input/output models in the case of CFCs. This method o f estimating gas emissions, although not as accurate, is considerably cheaper than installing flue,gas analysis equipment. Analogous methods are also being used by the Department of the Environment to produce the annual Digest of Environmental Protection and Water Statistics.

OVERVIEW: G R E E N H O U S E GASES A N D AIRBORNE POLLUTANTS The main m a n - m a d e contributors to the so-called greenhouse effect are listed in Table 1. The relative contributions of the gases in the atmosphere, to the greenhouse effect, are shown in Fig. 1. 2 Although carbon dioxide, the major offender, is released into the atmosphere naturally when living matter breathes, dies and decays, 'man-made' emissions a r e a considerable additional source. These occur mainly from the combustion of fossil fuels and account for 75% of the total carbon-dioxide releases, a Methane is the second most influential gas, although CFCs and the emissions of N O Xare likely to be the most significant contributors in m a n y organisations.

CFCs (11.5%)

co2 (61~) cM

4

(is~)

Fig. 1. Contributions to the greenhouse effectin AD 1990 integrated over a 100-yeartime horizon shown as a proportion of the total. 2

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TABLE !

Sources of Greenhouse Gases Carbon dioxide, CO 2 Methane, CH4 Oxides of nitrogen, NOx Tropospheric ozone, 0 3

Chlorofluorocarbons, CFCs

--Power stations, general combustion of fossil fuels, vehicle emissions and deforestation --Coal mines, ruminating cattle, wet-land agriculture. landfills, commercial gas and oil fields --Fertilizers and the burning of fossil fuels --Complex series of chemical reactions involving sunlight, oxygen, oxides of nitrogen and VOCs produced from vehicle emissions --Air-conditioning equipment, aerosols, foamed plastics, refrigerators and solvents TABLE 2

Sources of some Airborne Pollutants Sulphur dioxide Carbon monoxide Volatile organic-compounds

--Power stations; as well as the combustion of sulphurcontaining fuels - - R o a d transport; incomplete combustion of fossil fuels --Industrial processes, e.g. requiring the use of solvents: and motor vehicles

When fossil fuels are burnt, pollutant gases, i.e. notably SO 2 and NO x, are given off. Airborne pollutants (see Table 2) can have detrimental effects on the environment and so should be included in each environmental audit. In the atmosphere, SO 2 combines with rainwater to form dilute sulphuric acid: this 'acid rain' causes damage to plant-life and stone-built constructions. Carbon monoxide is a toxic gas that can cause ill-effects to the human respiratory, central nervous and cardiovascular systems together with impaired physical co-ordination, vision and judgement. VOCs, in addition to combining to produce the secondary greenhouse-gas ozone, are considered as air pollutants because some hydrocarbons can cause drowsiness, eye irritation and coughing or may be carcinogenic even at low concentrations. ESTIMATING AND REDUCING CORPORATE GREENHOUSEG A S EMISSIONS Motivating factors The motivation for a company to reduce harmful emissions is likely to be into one or more of the following: (1) increasingly severe pertinent legislation (2) carbon taxation, so inhibiting fossil fuel combustion (3) to gain a competitive edge

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(4) employee pressure (5) customer pressure (6) improvement of public relations. The greatest motivator is legislation, or its threat: thereby companies are required by law to remain below certain limits or otherwise incur a cost penalty. In the UK, such legislation is mainly focused on airborne pollutants and not the greenhouse gases. However, targets have been set, e.g. for CFCs, the government is committed to phasing out their production and consumption by AD 2000 in line with the agreement arrived at during the 2nd London Conference in 1990 with respect to the revised Montreal Protocol. As the White Paper 'This C o m m o n Inheritance--Britain's Environmental Strategy '1 states, 'it will clearly be necessary to take further measures over aperiod o f years to stabilize CO 2 emissions at 1990 levels by AD 2005'. In the long term, these will inevitably have to include increases in the relative (unit) prices of different forms of fossil fuels and other energy resources: these could be achieved by taxation. However, it would appear that, in the short term, direct fuel taxation may not be used, although there may be a willingness to see unit-fuel prices raised. In the long term, the pricing mechanism is likely to be utilised in an attempt to reduce emissions. This would influence the local profitability and competitiveness of companies if the energy supplied from fuels having a high carbon-content cost significantly more than those having a low carbon content. Nevertheless such measures could lead to fuel switching and promote the achievement of greater energy efficiency. Some companies see the conversion to the environmentally-sustainable use of ambient energy and the generation of environmentally-friendly products as positive marketing ploys to entice consumers to buy such products or increase market share. These products may be more expensive (than the customer's previous choice) to produce yet there is a growing consumer demand. This has occurred owing to the public's rising concern regarding degradation of the local environment by pollution and the effects of longerterm adverse trends. Further motivating factors ensued in response to customer or consumer demand. For instance, a local authority may insist that any new cookers purchased for their schools must be designed and constructed so as to be of a high level of energy effectiveness. In a survey, commissioned by the Department of the Environment 1989, 3 on public attitudes to environmental problems, it was found that 72% of people were either worried or very worried by the alleged warming of the atmosphere by the excess greenhouse effect. These concerns are being passed on to product suppliers through consumer pressure-groups.

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The Environment Council, a charitable organisation to promote environmental care and awareness and which is sponsored by over 500 commercial and industrial organisations, has found that interviewees for professional vacancies are increasingly asking companies about their environmental policies when assessing whether or not they wish to work for that company. However, the deciding factor that makes an organisation respond positively to reducing greenhouse-gas and pollution emissions could be one of many reasons but financial considerations are usually uppermost.

Corporate emissions One of the main areas of ignorance concerning corporate greenhouse-gas emissions is in identifying what emissions occur, as well as the rates and the sources. It is only when this information is collected that directors can devise and implement a coherent policy to achieve reductions. Most greenhouse-gas emissions are likely to arise from the combustion of fossil fuels, either within the organisation or at the power station. In addition, the use of CFCs in air-conditioning plants, refrigerators and as aerosol propellants will also contribute. A reasonably-accurate way of estimating the fossil-fuel derived emissions produced by an organisation, is by continuously monitoring air samples in the flues of each boiler and vehicle. However, in most cases and particularly with multi-site organisations, this would be both impractical and costly. An alternative way is to monitor the gas, electricity, oil, coal and propane supplied to the organisation and apply a conversion-factor (i.e., amount of pollutant emitted per GJ of energy expended) to reflect the emissions from particular combustion equipment. To obtain a good first approximation, a standard conversion-factor could be used for conventional burners, whereas special combustion equipment, such as low-NO x burners, would have different conversion factors. In the case of a local authority, the electricity, gas and oil usages at all schools, sheltered housing, libraries, recreational and office buildings would need to be monitored in order to predict the total emissions emanating from buildings. For the vehicle fleet~ the quantities of diesel fuel, petrol and propane employed would also need to be monitored. The fuel-use information is usually readily available via fuel invoices. In the case of electricity and gas, these are normally issued monthly or quarterly, whereas, coal and oil use is invoiced after delivery which may be several times per month in winter whereas no deliveries occur in summer. With coal and oil use, it is wise to back-up the invoice information with monthly stock-level checks.

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Usually fuel invoice information will be stored and logged by the accounts department, which pays the bills. However, it is normal that only financial information is stored and not the relevant quantities of fuels and electricity used or delivered. Nevertheless, the energy manager may have that information available from an energy-monitoring and targeting system where costs and consumption are stored. These monitoring and targeting systems may be developed 'in-house' or supplied by a specialist software house and almost invariably are computer based. They often have the capacity to monitor the diesel fuel and petrol used in a vehicle fleet, although it is normal for the transport (rather than the energy) manager to have ultimate responsibility for the use of these fuels. The emissions derived from the generation of the electricity used and the CFC losses are more difficult to estimate. When electricity is used within an organisation, there is usually no associated direct emission of greenhouse gases within that organisation. However generating electricity using fossil fuels as the primary feedstock, will have resulted in polluting emissions. In the UK, a national grid-structure exists and power is generated from fossilfuel, nuclear and hydroelectric power-stations. Therefore an estimate of emissions can be based on the government's statistical figures for the previous year. As the proportion of electricity generated from the various sources and also the combination of fossil fuels used per year will change, the conversion factor alters each year. The release of chlorofluorocarbons occurs predominantly as a result of leaks from refrigerators, aerosol propellants and erasing fluids. The main releases within buildings are through the weeping or catastrophic losses of refrigerants from air-conditioning plants. 4 If CFC-emitting plants or items can be identified and their behaviours monitored, an estimate of the associated emissions can be made.

Estimating emissions To determine an organisation's greenhouse-gas contribution resulting from the use of fossil fuels, conversion factors are required to determine the emissions consequent upon the energy expenditure. These factors can be confusing and are dependent upon whether the calculations are based on primary or delivered energy use, gross or net calorific values, the time base over which the emissions are estimated and whether or not the emissions are presented in terms of carbon output. Emission factors, based solely upon combustion calculations for a site, reveal the actual amount of associated emissions from that site (see Fig. 2). However, this method does not provide a true indication of the total emissions caused by the use of a given quantity of energy on that site.

277

Encironmental auditing

~JO| "--~ ~

~

omlalolonal

Fig. 2. Delivered-energy-useemissions. For instance, in the case of electricity use, it is likely that no emissions will be made 'on-site' and, given the above scenario, the emissions from the use of 1 kWh of electricity would be zero. However, the fossil fuels are combusted at the power station in order to produce the electricity for the consumer. Also there will be energy expended in getting the primary feedstock to the power station, as well as distribution losses in the electricity transmission lines. In the case of fuel oil, energy will have been expended in order to extract the crude oil and deliver it to the refinery and then convert it to fuel oil. With coal, energy will have been used to extract the coal from the ground and transport it from the mine to the power station: in addition, the emissions of methane that occur from collieries must also be considered. Emission factors should therefore account for these 'up-stream' emissions (e.g. see Fig. 3). Values for these conversion factors can be derived using a combination of annually-published government statistical information. The Digest of Environmental and Water Statistics 3 uses airborne-pollution emission estimates, as calculated by the Warren Spring Laboratory, in their U K Emissions of Air-Pollutants. 5'6 Table 3 shows emission factors derived from these data. To determine primary energy use based emissions we must include fuel used by each industry for extracting, converting, distributing and transmitting the various fuels to the end user. 7 Deriving conversion factors for electricity use is more complicated. In the UK, the primary fuel source for generating electricity in 1989 was coal

1

1

Im

l

I--'1 uo.

mira

l

1

1

emlulono

emlulono

emissions

Fig. 3. Emissions associated with the use of energy.

Paul K. Martin, Paul O'Callaghan, Douglas Probert

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TABLE 3 The Average Amounts in kg of Pollutants Emitted per Unit of Energy Delivered Based on UK Average Figures 5

Fuel

Coal Fuel oil Gas oil LPG Natural gas

Emission CO 2 (kg/GJ)

CH4 (10 - 3g/Gi)

SO 2 (kg/GJ)

NO~ (kg/Gd)

VOC (g/GJ)

CO (g/GJ)

94.6 72-7 69-1 65.1 53.4

34-2 17.5 19.2 18.1 18.1

1.04 0.91 0.11 ---

0.188 0.172 ~0.1 ~0.1 ~0.1

~2.7 1.38 1.52 1.43 1.43

160 11.7 5.3 2.4 2.4

(66%), followed by nuclear fission (21%), oil (8%) and imported electricity from France (4-2%), the remainder being hydro power. To determine a primary conversion factor for electricity, we must obtain the total emissions derived from the use of each fuel and divide by the total available electricity after distribution losses. Primary and delivered emission factors have been calculated previously for CO28 although this investigation did not extend to other emissions. A summary of primary-energy use, based emission factors, is given in Table 4. The emission values are only approximations; the factors varying each year. This will be because of improved techniques in deriving UK pollution TABLE 4 Summary of Average Emissions Based Upon per Unit of Primary Energy Delivered

Energy .[brm

Emission C02 a (kg/GJ)

Coal Fuel oil Gas oil LPG Natural gas

CH 4 (10- 3 kg/GJ)

SO 2 (kg/GJ)

NO x (kg/GJ)

VOC (g/GJ)

CO (g/GJ)

98.5 82.4 78-8 74.8 56.4

35.4 20.2 21.9 20.8 19.1

1-06 0-99 0.19 0.08 ~ 0.005

0-191 0.193 0-121 0-121 0-111

2.74 1.59 !.65 1.65 1.51

162.7 14.7 5.4 5.4 3.1

232"6

73.0

2.57

0.47

6.3

346.7

Electricity (1989 average)

Note: Losses in electricity generation, mining, fuel production, refining, distribution and transmission have been included. Emission factors are based on estimates of UK emissions 5 and energy u s e 7 and may vary from year to year as the type of fuel used to generate electricity changes and fuel production and conversion techniques improve. a CO2 is expressed as carbon.

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emission statistics and changes in the methods of power generation. The proportions of electricity generated from coal, gas, oil, hydro-electric and nuclear power stations will vary as functions of unit fuel costs, which will affect the emissions generated. Power stations may also become more efficient, flue desulphurisation may be practised or low-NO x burners may be added. The emission factors in Table 4 can be used to estimate monthly or annual emissions from a site by multiplying the energy use by the emission factor for that particular fuel. If more accurate data are known for a specific site through the use of flue-gas monitoring equipment, this information should be used in preference to the estimated figures and adjusted to incorporate extraction, conversion and distribution losses. Also, if emission-reduction equipment, such as low-NO x producing burners for a boiler, is installed at a site, appropriately amended figures should be used. Some emission factors for vehicles are given in the 'UK Emissions of AirPollutant' report. 5 These are limited however because the emissions are related to the performance of the vehicle. To determine emissions from a vehicle fleet, it is necessary to know how much fuel each vehicle or type of vehicle uses. This information may be known by the transport manager. A mathematical model can be created with which to estimate corporate greenhouse-gas and airborne-pollution emissions from the direct or indirect combustion of fossil fuels within buildings or plants from what is normally readily-available data (see Fig. 4). Monthly fuel invoices or, if available, meter or sub-meter readings are used as inputs into the model. These delivered energy units are converted to c o m m o n energy-units using the gross calorific value of each fuel and then multiplied by the appropriate emission factor to determine the emissions of each year. Site emissions are estimated by simply summing the emissions of each particular gas as a result of the various fuel types used.

Chlorofluorocarbons Estimating an organisation's impact on the environment as a result of the use of CFCs is more difficult and has to be handled in a different way to the combustion of fossil fuels. The processes of CFC release can be modelled simply through an input-output model, as shown in Fig. 5. Three categories of release have been identified, namely: (i) consumables such as aerosols, sprays, paints and polishes; (ii) fixed or semi-fixed plant such as airconditioning or refrigeration plant; and (iii) out-building fabrics. These categories are dependent on how the releases are made. In all cases, these can usually be estimated, and with air-conditioning plant, loss assessments could be undertaken by a maintenance engineer. If these can be achieved within an

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Patti K. Martin, Patti O'Callaghan, Douglas Probert

BweS/PL~rr FUEL INVOICES/

PURCHASES

METER READINGS

PLANT SURVEY MAINTENANCESHEETS Rll R12 eto

RECOVERY/

d

] emlxlon factors I c~

l

RE-CYCLE

T I re'm~,f~or, I

co= NO x

VOC

OH4

[IS

Ozone

G.W.P. I FACTOR

I G.W.P.

FACTORJ

I

1

CORPORATE AIRBORNEPOLLUTION EMISSIONS

I CORPORATE GLOBALWARMING POTENTIAL

Fig. 4. Procedure for estimating corporate greenhouse and airborne-pollution emissions within buildings.

organisation, the figures should be used in the model in preference to estimates.

Consumables The CFC releases from aerosols and paints, m a y be relatively low, and are likely to be reduced further as CFCs are banned in order to conform to the Montreal Protocol. If the CFC consumable items within an organisation can be identified through an audit, they can be monitored at purchase. There can therefore be a debit a t purchase or this could be averaged out over the lifetime of the product. In the case of an aerosol, this may be released from a store a m o n t h after purchase and be gradually used over a period of a month.

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CONSUMABLI~ - ~ l s - spruys

•p-

ram

. i ~ l n ~,

FIXED M,ANT - ~--coaditionlag

. rdriV~flon [ ~

RECOVERY OR TRANSFER

BUILDING FABRIC - the.real f~mlatioa

Fig. 5. Simpleinput-output model showingCFC releases in buildings. If CFC-containing products are purchased regularly and frequently, a debit allocated to the month of purchase could be used. Fixed plan t The main releases of CFCs within buildings occur through commercial refrigeration and' air-conditioning plants. The refrigerants used in these plants are usually R11 and R12. Ifa refrigerator is hermetically sealed for its total life-time, it is possible that no emissions will occur at all on site, yet if unfortunately the plant is disposed of, say, on a refuse tip, a 'debit' must be made to the company immediately it is disposed of. If, however, the refrigerant is disposed of in an environmentally-sensitive way, whereby the refrigerant is recovered or recycled, no 'debit' need be made to the company at all. In most cases, however, two types of leakage ensue from air conditioning plants: (i) operational losses and (ii) catastrophic losses. An operational loss is the weeping of refrigerant through glands and seals and can be detected during regular maintenance by the amount of refrigerant required to top up the system. The maintenance engineer may undertake this task as a matter of course and would not, necessarily, take down details of the amount of fluid used for this 'top-up'. If the building operator insisted on receiving this

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Paul K. Martin, Paul O'Callaghan, Douglas Probert

information, it could be used in a computer model of CFC releases. Catastrophic losses could be logged in a similar way. A catastrophic loss is when a leak occurs and all the refrigerant is lost due to a fault in the system, i.e. a relatively large amount of the CFC is released into the atmosphere. Calculating emissions from refrigeration and air-conditioning plants means that a maintenance engineer must keep proper records which are given to the environment/energy manager to input into the model. A catastrophic loss may occur once every 5 to 10 years, whereas operational leakages occur at a rate of up to 13% per year of the total refrigerant content maintained in the system.4 A figure could be estimated for the catastrophic loss on a monthly basis. If accurate records are not kept of when major losses occur, a monthly debit can be given. Although a major loss would be instantaneous and debited to one month it would not be known when exactly that occurred. Therefore it would be reasonable to average this out over the duration between catastrophic losses.

mX

Monthly Operational Loss = 12~-~

(1)

where X is the annual operational loss expressed as a percentage of m the total mass of refrigerant in the system expressed in kg. m

Monthly Catastrophic Loss-- 12--Y

(2)

where Y is the number of years between catastrophic losses.

Building fabrics The third type of CFC release by an organisation would be from its building fabric. These releases would ensue over a period of time and be dependent upon the materials employed. 9 These provide only a small contribution to greenhouse-gas emissions when compared with the previously mentioned ones. Releases from the slow emissions out of in-place thermal insulants are acknowledged as a source of CFC releases.

Global warming potential The GWPs of the different greenhouse gases vary. Once emissions can be determined they can be multiplied by a GWP factor, which is normally expressed in terms of CO2 equivalent. The variance in published values for GWPs for the various greenhouse gases are considerable, l° The Intergovernmental Panel on Climate Change findings are now considered to provide a consensus of opinion and GWPs from Working G r o u p 1 are given

283

Environmental auditing TABLE 5

Global Warming Potentials 2 Gas

Estimated LiJ'etime

Global warming potential over indicated period from the present

()'ears)

20 ),ears

100 years

500 ),ears

Carbon dioxide Methane Nitrous oxide CFC-I 1 CFC-12

~ 10 150 60 130

1 63 270 4 500 7 100

1 21 290 3 500 7300

1 9 190 1 500 4500

HCFC-22 CFC-113 CFC- 114 CFC- 115 HCFC- 123

15 90 200 400 1'6

4 100 4 500 6 000 5 500 310

1 500 4200 6 900 6 900 85

510 2 100 5 500 7 400 29

HCFC-124 HFC-125 HFC-134a HCFC-141b HCFC-142b HCF- 143a HFC-152a CC14 CH3CC13 CF3Br

66 28 16 8 19 4I 1.7 50 6 110

1 500 4 700 3 200 1 500 3 700 4 500 510 1 900 350 5 800

430 2 500 1 200 440 1 600 2 900 140 ! 300 100 5 800

150 860 420 150 540 1 000 47 460 34 3 200

in T a b l e 5. N e v e r t h e l e s s these values are subject to uncertainties, as are all G W P factors. T h e ' p o t e n c y ' o f e a c h gas varies w i t h time. S o m e gases c a n r e m a i n in the a t m o s p h e r e for h u n d r e d s o f y e a r s w h e r e a s others, s u c h as m e t h a n e , h a v e relatively s h o r t lives.

USE OF ENERGY MONITORING-AND-TARGETING SOFTWARE SYSTEMS T h e p u r p o s e s o f e n e r g y m o n i t o r i n g - a n d - t a r g e t i n g s y s t e m s are p r i n c i p a l l y to: (1) (2)

d e t e r m i n e where, h o w m u c h a n d w h e n e n e r g y is used; highlight inefficiencies a n d w a s t a g e s t h r o u g h c o m p a r i s o n s identification o f trends;

and

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Paul K. Martin, Paul O'Callaghan, Douglas Probert

(3) implement reductions and set targets; and (4) monitor the success of each energy-saving measure. Monitoring and targeting is now the generic term for the technique which started to gain wide acceptance in the UK in the early 1980s. Studies 11 have shown that energy-cost savings of between 4% and 18% can be achieved through the use of these techniques. A requirement of a M & T system is to collect and store fuel-use figures and costs, analyse these and determine performance behaviour, which can be displayed at meetings in graphical and tabular formats. This enables management to make informed judgements in order to reduce energy consumptions. There are three main types of M & T system which are determined by the way that information is collected, stored and analysed:

(i)

manual, (ii) DIY spreadsheet, and (iii) commercial software. The way in which data are collected, converted, analysed and displayed in the T E A M M & T software system is shown in Fig. 6, i.e. how fuel-invoice or meter-reading information can be used and converted using conversionfactors. The software will default to the standard conversion factor unless more accurate information is available. Figure 7 shows the increase in CO 2 emissions resulting from an undetected fault in the heating-control system. The fault resulted in boilers heating a school continuously 24h per day and was not detected for 13 months so resulting in a large energy wastage. Comparing year-on-year emissions can reveal unfavourable trends. Prompt corrective action should be taken to ensure the problem is not sustained for a prolonged period of time. The ability to group data from different sites together for analysis is an important feature. The emissions can then be compared with those from other similar sites to determine whether the contributions are relatively high, low or typical. Although simple comparisons will still hide inefficiencies, this is a useful start. In the case of, say, schools, it could be questioned why the emission per unit floor area of one school is twice that of another. Investigation may reveal inefficiencies, differences in primary fuel or CFCreleasing items used. Importantly it provides the ability to question why. Table 6 shows a comparison across various sites. The M & T system can be used to monitor not only the estimated emissions and compare the performances at different sites but also to monitor the success of projects over time. The cumulative sum (CUSUM)

Environmental auditing fuel Invoices

meter readings

weather

oo=

~

285 productpurchases CFCt

DATABASE conversionto common energy

units

1

emlsslon/re-c~cling factors

global warming potentta]

ANALYSIS complutsons weather corrections leaguetables ratios trends CUSUM

REPORTING • graphical and tabular reports - grouping - weekly, monthly,quarterly, annual - summaryreports

Fig. 6.

Monitoring and targeting software operation. G r a n g e - P a r k School B u s h e y

CO 2

(kg)

zm~

0

Fig. 7.

MAMJJASONDJFMAMJJASONDJFMAMJ

Monthly CO 2 emissions before and after a heating-control fault occurred.

Paul K. Martin, Paul O'Callaghan, Douglas Probert

286

TABLE 6 Example of Computer Print-Out Comparing per Unit-Floor-Area Data for Various Schools for the Period of One Year from March 1989 to February 1990 Inclusive

School

Grange-Park Bushey Westfield Hitchin Sele Francis Bacon Fearnhill Margaret Dane Newhaven Nobel Jane Campbell Total (Average)

Total emitted C02 (kg)

Floor a r e a (m 2)

646 850 460 762 434 473 344 724 266 372 284 670 223 270 207 931 226 490 164 154

6058 5 600 6 982 7 114 5 700 6 790 5 496 5 602 6 389 5 401

106.77 82.28 62'23 48.46 46.73 41.92 40.62 37.12 35.45 30-39

3 259 631

61 132

(53.32)

CO 2

emission (kg/m 2)

difference technique is used extensively in energy monitoring. 12 The technique can also be used to monitor emission reductions. The example in Fig. 8 shows the success of three energy-saving measures implemented over a period. The vertical line coincides with the introduction of the first energysaving measure. A movement towards the top right quarter shows a cumulative increase in CO 2 emissions whereas a movement towards the bottom right shows a cumulative decrease. The horizontal line shows a 'business-as-usual' scenario. The first energy-saving measure resulted in an increase as the measure proved unsuccessful. The second measure (4 months later) turned the line to approach the cumulative decrease quarter. Two months later a third energy-saving measure was implemented, which further changed the angle of the line so that the rate of savings increased slightly. The total emission reductions to date can therefore be shown together with the cost savings. Once information has been collected and analysed in an M & T system, there is a need to disseminate the results to management. This can be in the form of high-quality computer-generated reports, preferably graphical or tabular outputs. To avoid 'information pollution', it is important that only relevant information is feported and the frequency of reports generated is considered carefully. An example of the reporting frequency within an organisation would be where quarterly summary reports are provided, for the board of directors, to indicate the success of an environmental campaign. Detailed monthly or weekly reports could also be provided to the area/site supervisors to provide quick feedback and detailed performance reports.

Environmental auditing

287

Town Hall 2 3 !r T

Cumuldve Increase

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Fig. 8. CUSUM plot showing cumulative CO2 increase, decrease and cost savings resulting from three energy saving measures (1, 2 and 3). Fuel: gas; range: March 1988 ~ February 1990.

CONCLUSIONS A significant proportion of an organisation's greenhouse-gas and airbornepollution emissions from buildings occurs through the direct or indirect combustion of fossil fuels. In multi-site organisations such as health and local authorities, banks and retail organisations, estimates of emission can be made using computer models utilising readily-available information (e.g. purchasing bills). These data can be used when undertaking corporate environmental audits and provide the management with information useful for the formation of a corporate environmental policy. Energy-monitoring and targeting software for energy mangement, now widely used, can be extended to estimate and monitor greenhouse-gas emissions from buildings or CFC use. Various analysis and presentation techniques can be utilised to monitor the success of an emission-reduction campaign. These systems can provide companies with a practical and inexpensive integrated energy-and-environment management information system.

288

Paul K. Martin, Paul O'Callaghan, Douglas Probert REFERENCES

I. Department of the Environment, This Common Inheritance. White Paper on the Environment, Department of the Environment, HMSO, London, September 1989. 2. Intergovernmental Panel on Climate Change: the Scientific Assessment. Working Group l, University Press, Cambridge, UK, 1990. 3. Department of the Environment, Digest of Environmental Protection and Water Statistics. Department of the Environment, UK, HMSO, London, 1990. 4. Butlers D. J. G. & John, R. W., Implications of the use of CFC alternatives on the building industry. C.I.B.S.E. Conference, Canterbury, UK, April 1991. 5. Munday, P. K., UK emissions of air pollutants, 1970-1988. Warren Spring Laboratory, Stevenage, UK, Report L.R. 764 (AP)M, March 1990. 6. Eggleston, H. S. & Mclnnes, G., Methods of the compilation of UK pollutantemission inventories. Warren Spring Laboratory, Stevenage, UK, Report L.R. 634 (AP)M, December 1987. 7. Department of Energy, Digest of United Kingdom Energy Statistics, 1990. Department of Energy, HMSO, London, 1990. 8. Shorrock, L. D. & Henderson, G., Energy use in buildings, and carbon dioxide emissions. Building Research Establishment Report, Garston, UK, 1990. 9. Baldwin, R., The Environmental Assessment Method (BREEAM): The current state of play. Buildings and their Environmental Impact Conference, Building Research Establishment Report, Garston, UK, October 1990. 10. Badr, O., Probert, S. D. & O'Callaghan, P., Chlorofluorocarbons and the environment: scientific, economic, social and political issues. Applied Energy (in press). 11. Anon., The Application of Monitoring and Targeting to Energy Management. Energy Efficiency Series No. 8, Energy Efficiency Office, HMSO, London, 1988. 12. Harris, P., Energy Monitoring and Target Setting using CUSUM. Cheriton Technology Publications, Cambridge, UK, 1989.