For main headers use Trebuchet 25pt on 28pt - Sustainability

1 For main headers use Trebuchet 25pton 28ptGPG388 Good Practice GuideCombined heat and power for buildingsSelecting, installing and operating CHP in buildings - a guide for building services engineers02 Combined heat and power for buildingsContentsOverview03 Benefits of CHP04 What is CHP?06 CHP technologies08 CHP applications14 Project appraisal18 Integrating CHP with the site26 Financing options30 Implementing & operating CHP32 What to do next33 Sources of Information34 Appendix Plant sizing and viability, a worked example 35 Glossary of terms45 This guide is supported by the Chartered Institution of Building Services Engineers (CIBSE) CHP of the Steering Committee for the CIBSE CHP Group commented on the draft guideand their contribution is gratefully acknowledged.

2 Further information on the Group is available image on the front cover is supplied courtesy of Nedalo (UK) 03 IntroductionCombined Heat and Power (CHP) is the on-sitegeneration of electricity and the utilisation ofthe heat that is a by-product of the generationprocess. For a wide range of buildings, CHP canoffer an economical method of providing heatand power which is less environmentally harmfulthan conventional methods. In these buildings,CHP is often the single biggest measure forreducing buildings-related carbon dioxide (CO2)emissions and running costs. Where applicable,building designers, specifiers and operatorsshould consider the option of CHP as analternative means of supplying energy. Where possible, buildings should be linkedtogether through heat networks to form moresignificant energy demands that benefit fromlarger CHP community heating.

3 If this is not possible, then consider supplying individualbuildings using CHP. A brief option appraisalshould always be carried out when replacingmajor plant or designing new systems to identifyif CHP might be viable. If CHP begins to look likea leading option then a full feasibility study willneed to be carried out. For detailed information,see CIBSE Applications Manual 12 (AM12).The use of CHP has proved cost-effective in avariety of buildings. CHP capacity in buildingshas doubled within the last decade and there arenow over 1,000 installations providing around400 MWe(electrical output). Due to the smallernature of the installations, only around 10% oftotal CHP capacity is in buildings and communityheating but buildings constitute around 90% ofthe total number of CHP installations, theremainder being industrial.

4 Small scale CHP isused as the prime source of heating and powerin many hospitals, hotels and leisure centres,and examples are also found in universities,residential buildings and defence CHP installations are being used withcommunity heating schemes and on some multi-building sites such as major hospitals,prisons, airports and universities. Under the Kyoto protocol, the UK government iscommitted to reducing greenhouse gas emissionsto below 1990 levels by the year 2010, andhas set a more stringent internal target to reduceCO2emissions by 20% by 2010. The governmenthas therefore set a target to encourage theinstallation of 10,000 MWeof Good Quality CHPby 2010 which could produce around 20% of theKyoto carbon savings target. The energy savingand environmental benefits of CHP are so clearand important that the government is activelyencouraging the use of this technology through a number of key incentives available to schemescertified by the CHP Quality Assuranceprogramme (CHPQA), see of this guideThis guide contains information on the design,selection, installation and operation of CHP in buildings.

5 The guide will be of interest tobuilding services engineers designing newbuildings, refurbishing/upgrading existingbuildings or in developing a site energy may also be useful to building operators andenergy managers intending to specify CHP orthose running existing guide explains what CHP is, discusses theavailable technologies and their application inbuildings. It then focuses on project appraisal as the feasibility study underpins the futureeconomics of the plant. A series of case studies isshown throughout the guide covering a range oftechnologies, applications and financing :Throughout the guide reference is made to CHP schemes and units. For the purposes of the guide, a CHP scheme mayconsist of one or more CHP units. MWemeans electrical output of the CHP in a building can: Use fuel more efficiently reduce energy costs minimise environmental emissions improve security of electricity the right application, CHP is the single biggest measure for reducing buildings related CO2emissions and running costs04 Combined heat and power for buildingsBenefits of CHPO verall energy costs can be reducedElectricity from traditional sources is a relativelyhigh cost, high emission energy due todistribution losses and the poor efficiency ofmost power stations.

6 Only around 40% of theenergy used in electricity generation is deliveredas electricity. Local CHP will generally achievesavings on electricity costs (including any salesto third parties) that should more than offset theincrease in fossil fuel (usually gas) requirementsand maintenance costs. In certain cases furthersavings from reduced maximum demand chargescan also be improvementsEach kWh of electricity supplied from theaverage fossil fuel power station results in the emission of over half a kg of CO2into theatmosphere. Typically, gas-fired boilers emit around one quarter of a kg of CO2per unit of heat generated. CHP has a lower carbonintensity of heat and power production thanthese separate sources and this can result inmore than a 30% reduction in emissions of CO2, thus helping to reduce the risk of globalwarming.

7 It will also reduce the emission of SO2,the major contributor to acid rain, and help toconserve the world's finite energy resources. The primary energy benifits can be clearly seenin the figure below. Increased security of power supplyThe CHP plant can be configured to continue tosupply power should the grid fail. Conversely,the local electricity network can provide powerwhen the CHP plant is out of flow diagram - CHP vs. conventionalBenefits of CHP 05 Benefits available to Good Quality CHPThe CHP Quality Assurance (CHPQA) programme specifies the threshold criteria for Good Quality schemes that are certified under the programme qualify for a range of benefits:Climate Change Levy exemption the CCL, introduced in 2001, levies an additional cost on top ofprevious energy prices and affects almost all non domestic buildings.

8 The CCL can often amount toaround 10-15% of typical running costs. Fuel input to Good Quality CHP qualifies for exemption fromCCL, which can often reduce payback periods by 1-2 years. Additionally, there is no levy on heatoutput and power output from GQCHP also qualifies for exemption from Capital Allowances (ECAs)- provide a tax incentive to encourage the purchase of energyefficient technologies as defined on the energy efficiency technology list ( ). Thiscovers a wide range of technologies including Good Quality CHP. The ECA permits businesses to offset100% of the capital cost of these technologies against tax in the first year, instead of having tospread the tax write-off over, say, 10 years. This can save around 7-8% of the capital cost over theplant life from Business Rating where business rates apply, Good Quality CHP can bring reductionsin the amount certification can also be used as a way of demonstrating regulatory compliance:The Building Regulations- Part L (2002) in England and Wales now sets minimum efficiencies (basedon maximum carbon intensities) for heating systems at full load and 30% load, based on the overalloutput of the system.

9 Where CHP is included, then special adjustments can be made to take intoaccount the benefit of the on-site electricity generation in reducing emissions from power through CHPQA is a way of demonstrating that the heat and power efficiencies of theCHP have been estimated in a satisfactory way for the purposes of Combined heat and power for buildingsWhat is CHP?Combined heat and power is the generation ofthermal and electrical energy in a single this way, optimum use can be made of theenergy available from the fuel. CHP installationscan convert up to 90% of the energy in the fuelinto electrical power and useful heat. Thiscompares very favourably with conventionalpower generation which has a delivered energyefficiency of around 30-45%.

10 CHP installations can run on natural gas, bio-gasor diesel (gas oil). Reliability of CHP is generallygood with availability factors of over 90% beingcommon. The energy balance of a typical CHPplant is shown range of CHP available for buildings is: Micro CHP (up to 5 kWe) Small scale (below 2 MWe)- Spark Ignition engines - Micro-turbines (30-100 kWe)- Small scale gas turbines (typically 500kWe) Large scale (above 2 MWe)- Large reciprocating engines- Large gas Turbines The high efficiencies achieved are much greaterthan conventional power stations, reducing theamount of primary energy required to satisfy agiven heat and electrical load. Site energy costcan be reduced significantly using CHP. Thedelivered energy consumed on a site willincrease due to CHP but overall primary energyconsumption and CO2emissions will decrease.