collaboration.worldbank.org€¦ · web viewprepared by the world bank montreal protocol...

Maximizing Climate Mitigation Benefits through

Refrigeration and Air-conditioning Investments in

Large Buildings

Draft

Guidance Note for Task Team Leaders

Prepared by the World Bank Montreal Protocol Operations Unit

Version 1: August 2016

UNEP Ozone Secretariat Fact Sheets on HFCs and Low GWP Alternatives

October 2015

Maximizing climate mitigation benefits through refrigeration and air-conditioning Investments

Table of Contents

List of Figures and Tables....................................................................................................3

Acronyms and Abbreviations..............................................................................................4

Executive Summary............................................................................................................5

1. Introduction................................................................................................................6

Environmental impacts of refrigeration and air-conditioning........................................................6

Creating a “Win-Win-Win” environmental opportunity................................................................7

Creating a better financial return..................................................................................................7

2. Refrigeration and Air-Conditioning Use in Large Buildings...........................................8

3. Triple Win for Large Building Investment Projects.....................................................11

Win 1: Avoiding use of ODS.........................................................................................................11

Win 2: Minimising Use and Emissions of High GWP HFCs............................................................12

Win 3: Maximising Energy Efficiency...........................................................................................15

4. Check List for TTLs: Large Buildings............................................................................18

5. Bibliography and Sources of Further Information......................................................20

Appendix 1: Further Technical Information.......................................................................21

Guidance Note 6: Large Buildings 2 Version 1, May 16th 2016


List of Figures and Tables

Table 1: Emissions from refrigeration and air-conditioning systems

Table 2: Refrigeration and air-conditioning uses in large buildings

Table 3: Examples of different types of RAC equipment in large buildings

Table 4: Typical range of efficiency improvement for RAC equipment

Table 5: Procurement Guidelines – low GWP refrigerants for new RAC equipment in large buildings

Table A1: Usage and characteristics of insulation foam in large buildings

Table A2: Low GWP foam blowing agents

Figure 1: Alternative approaches to replacement of an air-conditioning chiller system

Figure 2: Categorization of refrigerants by GWP

Figure 3: Example of discounted annual costs across life cycle of RAC equipment

Figure 4: A structured approach to improving refrigeration efficiency

Figure A1: Examples of GHG Emissions from RAC equipment in large buildings

Figure A2: HCFC phase-out schedule

Figure A3: Technical maturity relationship for new low GWP alternatives

Figure A4: Ways to reduce direct GHG emissions from RAC systems



Acronyms and AbbreviationsAcronym Definition

Fluorocarbons1

CFC Chlorofluorocarbon: a family of chemicals containing chlorine, fluorine and carbon.

HCFC Hydrochlorofluorocarbon: a family of chemicals containing hydrogen, chlorine, fluorine and carbon.

HFC Hydrofluorocarbon: a family of chemicals containing hydrogen, fluorine and carbon.

HFO Hydrofluoroolefin: a family of chemicals containing hydrogen, fluorine and carbon, with a double bond in the molecule. HFOs are sometimes referred to as unsaturated HFCs (uHFCs).

Environmental impacts

GHG Greenhouse gas

GWP Global Warming Potential. The GWP compares the global warming impact of a gas to CO2 which is defined as having a GWP of 1. The GWPs of fluorocarbons are not certain and have been updated by scientists on a regular basis during the last 25 years. The Intergovernmental Panel on Climate Change (IPCC) has published a number of sets of GWPs in their Assessment Reports. The GWP values used in this Guidance Note are 100 year horizon based on the IPCC AR 4 (Assessment Report 4) values.

ODP Ozone Depletion Potential. The ODP of a chemical compound reprents a relative capacity of degradation of Stratospheric ozone compared to CFC-11 which is defined as having an ODP of 1.

ODS Ozone Depleting Substance - a gas that can cause damage to the stratospheric ozone .

Other acronyms used

ASHRAE American Society of Heating, Refrigeration and Air-conditioning Engineers

LED Light emitting diode – a new generation of high efficiency lights

PCN Project Concept Note

PU Polyurethane

RAC Refrigeration and air-conditioning

SNAP Significant New Alternatives Program: a US EPA program that lists refrigerants that can be used in specific applications

TTL Task Team Leader

VSD Variable speed drive

XPS Extruded polystyrene

1 Refrigerant naming conventions: In this Guidance Note, fluorocarbon refrigerants are referred to with the relevant family name e.g. HFC-134a or HCFC-22. Non-fluorocarbon refrigerants are referred to with an ASHRAE designated “R-number” e.g. R-717 for ammonia or R-744 for CO2.



Executive SummaryRefrigeration and Air conditioning (RAC) is increasingly used in Large Buildings in developing countries. RAC equipment are not only energy intensive but also source of either ozone depleting substances or greenhouse gasses or both. This document has been prepared to help World Bank Task Team Leaders working on projects related to large buildings consider how to maximise the environmental and financial benefits available from the optimised specification and procurement of RAC equipment.

A “triple-win” environmental opportunity has been described, combining the following features:

Win 1: Selection of a non-ozone depleting refrigerant

Win 2: Selection of a refrigerant with a low global warming impact

Win 3: Maximising the energy efficiency of the refrigeration equipment.

Win 1: Avoiding use of ozone depleting refrigerants Ozone depleting substances (ODS) are being phased out globally to protect the earth’s ozone layer. Under the Montreal Protocol the most powerful ODS (e.g. CFCs, CTC, halons, methyl bromide) are already completely phased out. The ODS with lower ozone depleting potential (mainly HCFCs) are still in the process of being phased out. In developing countries2 new refrigeration and air-conditioning equipment using HCFCs is still being sold.

Guidance is provided on how to avoid using ODS based equipment in World Bank projects.

Win 2: Using low GWP refrigerants Developed countries, as per the Montreal Protocol phase-out schedule, started first, phase-out of ODSs and used the available technically proven, non-ODS refrigerants for different applications. HFCs were proved to be the most suitable options at that time for most of the applications. The GWP of HFCs, in most of the cases, were much lower than that of ODSs they replaced. In recent years, some very low- GWP refrigerants and foam blowing agents have been developed. The developed countries are now taking a second step towards use of low GWP alternatives, driven by existing regulations in various regions. Under the Montreal Protocol there are advanced discussions for an international agreement to phase-down global production and consumption of HFCs – an agreement is expected to be reached by the end of 2016.

For developed countries the phase-own schedule of HFCs will start early and there would be significant percentage reduction of production and consumption of HFCs by 2030 in these countries. With the rapid technical development of low GWP alternatives the HFC phase-down targets being considered under the Montreal Protocol would be realistic and achievable.

The possible HFC phase-down timetable for developing countries is less clear, but it is most likely they will have a longer phase-down schedule. Developing countries can benefit from technical developments already under way. As they move away from HCFCs (ozone depleting refrigerants) they can avoid the “double step” taken in developed countries and move directly to lower GWP alternatives. Projects funded by the World Bank should be designed to encourage the early move to low GWP refrigerants in developing countries.

Guidance is provided on how to select refrigeration and air-conditioning equipment that uses refrigerants with the lowest practical and cost-effective GWP.

Win 3: Maximising energy efficiencyRAC systems in large buildings often consume significant quantities of electricity. There is a growing requirement for air-conditioned buildings in developing countries. If building development projects are funded by the World Bank it is important to maximise the energy efficiency of the new RAC systems. RAC efficiency is a complex issue and has often been not given due care may be because of 2 In developed countries HCFCs have not been used in new RAC equipment since 2005. For more

information, refer to Appendix 1.2



increased initial capital cost. . The energy saving potential is high and the financial benefits can be very significant if an energy efficiency investigation is carried out early in the project development cycle. LCCP analysis may be carried out especially for large cooling capacity of RAC installations say 100 tonne of refrigeration and above. A structured approach to such energy investigations has been described in this Guidance Note and should be adopted where possible.

Check List for TTLs: Large Buildings

Step Activity Specific actions

Con

cept

sta

ge

Identify the need for RAC equipment in the project

Review the design of the project and ensure that climate benefits of using climate friendly cooling equipment is reflected in the PCNCalculate climate benefits of using a low GWP refrigerant and improved efficiency

App

rais

al

stag

e

Identify refrigeration, air-conditioning and foam insulation requirements

Review investment plan and identify all cooling equipment that will need to be purchasedCategorise systems by size (kW cooling), temperature level and application (see Tables 2 and 3)Refine the calculation of climate benefits

Impl

emen

tatio

n/ P

rocu

rem

ent

Win 1 opportunities Avoid all ODS

Check whether any ODS are specified – only HCFCs are likely as all other ODS already bannedFor large equipment ensure HCFCs are not usedFor small equipment only use HCFCs if other options have been ruled out

Win 2 opportunities Avoid high GWP HFCs

Check which refrigerants and foam blowing agents have been specifiedIdentify GWP of any HFCs specified Consider whether lower GWP HFCs are available for the application (see Table 5 and Appendix 1, Table A3)Check availability of relevant lower GWP alternatives in the geographic region concernedNever use refrigerants with a very high GWP (>2,500 e.g. HFC-404A, HFC-507A)If cost-effective, use a refrigerant with an ultra-low GWP (<10, e.g.HFO-1234ze)Consider moderate GWP refrigerants (GWP 150 to 1500) if required.



1. IntroductionThis Guidance Note has been prepared to help Task Team Leaders (TTLs) involved with investments in large buildings. It describes the financial and environmental benefits that can be achieved through optimised investments in refrigeration and air-conditioning (RAC) equipment.

Environmental impacts of refrigeration and air-conditioning Large buildings can make significant use of RAC, as described in Section 2 of this Guidance Note. RAC systems have the potential to create 3 different environmental impacts as shown in Table 1.

Table 1: Emissions from refrigeration and air-conditioning systems

Type of emission Emission Source Environmental

Impact

Direct emission

Leakage of a refrigerant that is an ozone depleting substance (ODS) Ozone damage

Leakage of a refrigerant with high global warming potential (GWP)

Global warmingIndirect emission

CO2 emitted from power station supplying electricity to operate RAC equipment

Some RAC systems use ozone depleting substances (ODS) as refrigerants. The production and consumption of most powerful ODS, such as CFCs, CTC, halons, methyl bromide, etc., have already been phased out globally under the Montreal Protocol. Other ODS, such as HCFCs, are still used in developing countries. HCFCs cause stratospheric ozone depletion and are in the process of being phased out over the next decade and are often being replaced by HFCs.

HFCs do not damage the ozone layer, but contribute significantly to global warming. The global warming potential (GWP) of HFCs can be several thousand times higher than CO2. The international community is negotiating a global phase-down of the production and consumption of HFCs; it is hoped that an agreement will be concluded during 2016.

All RAC systems use a significant amount of electricity, which gives rise to CO 2 emissions if the power station supplying electricity burns fossil fuels. The use of electricity is the dominant source of greenhouse gas (GHG) emissions from most RAC equipment. See Appendix 1.1 for further details. There is excellent potential to improve RAC system efficiency, which has the potential to create financial savings as well as reductions in GHG emissions.

Developed countries started using HFC refrigerants in the 1990s to meet their Montreal Protocol commitments to phase out use of HCFCs. Developing countries have only just started to phase out production and consumption of HCFCs – a process that will not be completed until 2030. In many circumstances, RAC users in developing countries can avoid the use high GWP HFCs and can immediately switch to lower GWP alternatives. Developing countries can benefit from the recent technical innovations resulting in development of ultralow and low GWP refrigerants. Appendix 1.2 provides further information about the phase down schedule for HCFCs in developing countries and the rapid development of new low GWP refrigerants.

Creating a “Win-Win-Win” environmental opportunity To maximise the climate benefits of World Bank investments, it is important to consider the three environmental impacts shown in Table 1 for any large building RAC project. Some projects might only consider these issues in isolation. Consider the two examples illustrated in Figure 1:

Example A: a project involving installation of RAC equipment, but no attention given to climate change or ODS issues. By using an ODS and by ignoring energy efficiency, an opportunity to reduce environmental impact has been lost. This is a “Lose-Lose-Lose” project



Example B: the investment plan screens all the environmental opportunities and includes the avoidance of ODS, avoidance of a high GWP HFC and significant improvements to energy efficiency. This is a “Win-Win-Win” project and has clear environmental advantages. In most cases it will also have better financial return.

Figure 1: Alternative approaches to replacement of an air-conditioning chiller system

Other combinations are possible e.g. a project that avoids ODS but ignores the other 2 opportunities would be “Win-Lose-Lose”. It is clearly of advantage to take steps during an investment appraisal to ensure all World Bank projects are Win-Win-Win”

Creating a better financial return Financial benefits can be achieved by maximising the synergies that connect these three environmental opportunities. These benefits are highly project-dependent and might occur at 3 different levels:

a) At the beneficiary-level, for the RAC system purchaser. Improved energy efficiency can provide highly cost-effective electricity cost savings during the life of the RAC plant. Good refrigerant management (e.g. design for low leakage) will reduce maintenance costs.

b) At a macro-level, for a large development project. Improved refrigeration system energy efficiency should lead to a lower peak electricity demand and reduced infrastructure costs related to the supply of electricity.

c) At a national level a switch from HCFCs to low GWP refrigerants will avoid the “double-step” investment costs that occurred in developed countries. This could considerably reduce the overall costs of achieving the global phase down of HFC consumption that is expected to be introduced under the Montreal Protocol.

2. Refrigeration and Air-Conditioning Use in Large Buildings

The main uses of RAC in large buildings are for:

a) air-conditioning of individual rooms or whole buildings


Win 1: ODS emissions: zero

Win 2: Direct GHG emissions: zero

Win 3: Indirect GHG emissions – 30% reduction through improved efficiency

Example B: Win-Win-Win

Refrigerant: R-717

High efficiency

Leakage levels low

Win 1: ODS emissions

Win 2: Direct GHG emissions

Win 3: Indirect GHG emissions – no change in efficiency

Example A: Lose-Lose-Lose

Refrigerant: HCFC-22

Poor efficiency

Leakage levels highOld system being

replaced:

Refrigerant: HCFC-22

Poor efficiency

Leakage levels high

Indirect GHG

emissionDirect GHG

emissionODS

emission


b) specialised air-conditioning related to computer facilities

c) refrigeration of food and drink products for catering requirements for building occupants or visitors

d) specialised applications in specific building types e.g. refrigeration for ice rinks in leisure facilities.

The use of ODS and HFCs in large building RAC is summarised in the Tables below:

Table 2 provides examples of the most common requirements for cooling equipment in large buildings. It is important to recognise that the requirements for RAC vary significantly across the different sub-sectors.

Table 3 provides examples of the various different refrigeration and air-conditioning technologies that are used and includes details of the most commonly used refrigerants, with an emphasis on the use in developing countries. Because there are such widely differing requirements for RAC, there are also a very wide range of different technologies available. The examples in Table 3 are just to illustrate the wide range of equipment that might be encountered.

Some of the systems are relatively small e.g. a refrigerated food storage. These small systems are similar in size to domestic refrigerators and only contain a few hundred grams of refrigerant. However, some large building RAC systems are very large, containing more than 500 kg of refrigerant and delivering over 1 MW of cooling (e.g. an air-conditioning system for a large office building).

Most RAC applications large buildings operate at one of three temperature levels i.e.: air-conditioning to keep an occupied space at around 20oC, storage of chilled of food products at temperatures in the 3oC to 5oC range and storage of frozen food products in the -20oC to -25oC range. However, some building types include unusual requirements for specialised equipment such as those found in leisure facilities or research laboratories.

This Guidance Note deals with RAC systems. It is useful to note that there is often an associated use of insulating foam e.g. for the insulation of building fabric and insulation of pipes and vessels used in RAC systems. Foam insulation was historically manufactured using ODS blowing agents – this is still common in developing countries mainly by small and medium scales. Some of the alternatives now used in developed countries are high GWP HFCs. Table A1 in Appendix 1.3 gives some details about the use of insulating foam.



Table 2: Refrigeration and air-conditioning uses in large buildings

Sector Main Sub-sectors Examples of Cooling Requirements

Offices

Single occupancy

Multiple occupancy

High rise

Low rise

Air-conditioning

Canteen facilities

Computer room cooling

Shopping Centres

Department stores

Food stores

Food service

Small shops

Air-conditioning Food retail display and storage

Restaurant refrigeration

Sports and Leisure

Ice rinks

Indoor ski slopes

Swimming pools

Sports Halls

Air-conditioning

Heat pumps (e.g. swimming pools)

Ice rink cooling

Artificial snow

Arts and EntertainmentTheatresCinemasConcert HallsMuseums and Art GalleriesLibraries

Air-conditioning

Restaurant refrigeration

Other large buildingsData centres Exhibition CentresResearch laboratories

Air-conditioning

Specialist computer cooling

Specialist research cooling



Table 3: Examples of different types of RAC equipment in large buildings

Equipment Type Equipment Characteristics

Small room air-conditioning Used for: room air-conditioning. Single or multi-split configurations

Refrigerant charge (kg):1 to 10

Cooling capacity (kW): 2 to 40

Common ODS refrigerants: HCFC-22

Common HFC refrigerants: HFC-410A HFC-407C

Example low GWP alternatives: HFC-32 blends of HFCs/ HFO (e.g., HFC-446A, HFC-447A, HFC-452B

Multi-room VRF air-conditioning Systems connecting multiple indoor units to an outdoor condensing unit.


Cooling capacity (kW): 40 to 150


Common HFC refrigerants: HFC-410A

Example low GWP alternatives: HFC-32, HFC-446A HFC-447A, HFC-452B

Water chillers for central air-conditioning

Used for: large air-conditioning systems e.g. in university buildingsIntegrated unit for chilling of water in shell and tube heat exchanger and water cooled condenser


Cooling capacity (kW): 200 to 2,000

Common ODS refrigerants: HCFC-22 HCFC-123

Common HFC refrigerants: HFC-134a HFC-410A

Example low GWP alternatives: HFO-1234ze, HFO-1234yf, HFO-1233zd R-717 (ammonia)

District cooling Large chilled water systems serving several buildings

Refrigerant charge (kg):1,000 to 10,000

Cooling capacity (kW): 2,000 to 20,000

Common ODS refrigerants: HCFC-22 HCFC-123

Common HFC refrigerants: HFC-134a

Example low GWP alternatives: HFO-1234ze HFO-1233zd, HFO-1234yf, R-717 (ammonia)

Specialist refrigeration Used for various applications such as ice rinks and ski centres


Cooling capacity (kW): 100 to 1,000


Common HFC refrigerants: HFC-134a HFC-404A

Example low GWP alternatives: HFC-513 A, HFO-1234ze, HFO-1234yf, R-717 (ammonia R-744 (CO2)



3. Triple Win for Large Building Investment ProjectsTo maximise the synergies between environmental issues and other investment priorities it is important to screen any RAC equipment in projects at both the concept and appraisal stages. This will ensure that implementation takes into consideration these aspects through appropriate RAC procurement and ultimately create a Win-Win-Win project, ensuring that:

Win 1: There is no use of ODS in any new equipment

Win 2: Direct GHG emissions (related to refrigerant leakage) are minimised. This is achieved by using low GWP refrigerants and by designing plants to achieve low levels of leakage.

Win 3: Indirect GHG emissions (related to energy consumption) are minimised. This is achieved by improving energy efficiency.

In the following three sections further details are provided for each of these important opportunities.

Win 1: Avoiding use of ODSThe phase-out of the high- ODP ODS, such as CFCs, CTC, halons, methyl bromide, was completed in developing countries by 2010. There are no new installations of RAC with CFCs, however, there may be several installations still working with CFCs. Due care is to be taken to avoid emissions of CFCs during maintenance of these equipment.

The phase out of HCFCs, which are ODS, has begun in developing countries. All countries now have an HCFC phase-out management plan (HPMP) approved by the Multilateral Fund (MLF) for the implementation of the Montreal Protocol and developing countries are eligible to receive funding to meet the Montreal Protocol compliance obligations of phase-out of HCFCs.

The phase-out of HCFCs in developing countries is based on the control of consumption of HCFCs on the schedule that illustrated in Appendix 1.2, Figure A2. In particular:

During the period 2015 to 2020 there is a 10% cut in the availability of HCFCs

This is followed by a 35% cut in 2020 and a 67.5% cut in 2025.

HCFC phase-out will be completed by 2030 with a service tail of 2.5% between 2030 and 2040.

However, there are no bans under the Montreal Protocol on specific applications of HCFCs, such as the manufacture of RAC equipment. This means that new equipment using HCFCs is still being sold in some developing countries. For small equipment, such as room air-conditioning systems, HCFC based equipment may be the cheapest available. However, large equipment such as air-conditioning water chillers that should run for 20 to 30 years, it is a risky strategy to purchase new equipment with HCFCs as the phase-out of HCFCs will create severe shortage of HCFCs during the working life of the equipment. This could make it impossible to maintain the equipment in proper working order.


Win 1: Implications for World Bank InvestmentsTTLs should use the following guidelines:

Never use any of the ODS that have already been phased out (e.g. CFCs) Never use HCFCs on new large RAC equipment Avoid using HCFCs on new small equipment such as room air-conditioning Include an estimate of the climate benefits of avoiding the use of ODS in your PCN.

As a good practice, the TTL should investigate alternatives that are not ODS. These are discussed in the next section.


Win 2: Minimising Use and Emissions of High GWP HFCsWin 1 (avoiding the use of HCFCs) is often achieved by using HFCs, refrigerants that do not damage to the ozone layer but with high GWPs. World Bank investments can create quantifiable climate co-benefits if new RAC systems are procured without using high GWP HFCs. During 2016, global controls on production and consumption of HFCs will probably be introduced under the Montreal Protocol. Reduced HFC usage will also count towards national climate targets set via INDCs3 and can support World Bank climate targets. Using refrigerants with the lowest practical GWP will have environmental benefits and in the longer term will have financial benefits, as the high GWP HFCs will become very expensive.

Ways to reduce direct GHG emissions in RAC equipment For existing plants, it is possible to reduce the direct emissions by reducing leakage rates through improved maintenance. It is also possible to retrofit some existing RAC systems that use very high GWP refrigerants with a lower GWP alternative. See Appendix 1.4 for further details.

For new plants, it is important to procure equipment that:

a) uses a refrigerant with the lowest GWP that is considered practical and cost-effective

b) is designed to have low levels of leakage emissions.

Refrigerants can be categorised by “GWP-level” as shown in Figure 2. The levels chosen are somewhat arbitrary, but they create a useful framework for a World Bank procurement screening process.

Figure 2: Categorisation of refrigerants by GWP

Notes to Figure 2:

GWP categories: these are based on the various GWP thresholds used in the European Fluorinated Gases Regulation (EU 517/2014)

HFO: hydro-fluoro-olefin. HFOs are recently introduced refrigerants with ultra-low GWP (in the range 1 to 10). There are several different HFO molecules, such as HFO-1234ze, HFO-1234yf, HFO-1233zd and HFO-1336mzz. They are also referred to as “unsaturated HFCs”. HFOs are sometimes used as a component in refrigerant blends that also contain HFCs, such as HFC-448A and HFC-454A

Ideally the alternatives to HFCs should be in the Ultra-Low GWP category. Unfortunately, many of the Ultra-Low GWP alternatives have properties that limit their application. For example: ammonia is

3 INDCs: Intended Nationally Determined Contributions – the climate change targets set by individual countries


High pressure

Ammonia (0); CO2 (1); Propane (3); Various HFOs

Currently none available, but some under development

HFC-32 (675); HFC-513A (631); HFC-450A (601); HFC-454A (239)

HFC-448A (1387); HFC-449A (1397); HFC-134a (1430)

HFC-410A (2088); HCFC-22 (1810); HFC-407C (1774)

HFC-404A (3922); HFC-507A (3985)

Toxic

Higher flammability Lower flammability Non-flammable

Examples and PropertiesGWP

Ultra low <10

Very low 10 - 150

Low 150 - 750

Moderate 750 - 1500

High 1500 - 2500

Very high >2500


toxic and slightly flammable; CO2 operates at a much higher pressure than most other refrigerants; propane is highly flammable. Whilst these difficulties can be overcome through innovative designs, they may have an impact on capital cost or on plant performance. The most cost-effective alternative to a high GWP refrigerant might be one with a Low or Moderate GWP (in the range of 150 and 1400).

For large buildings it is often possible to cost effectively and efficiently use a refrigerant with an Ultra-Low GWP. This may not be possible in all situations due to non-availability of ultralow GWP refrigerant based RAC equipment for all applications, but it is always possible to avoid refrigerants in the Very High GWP Category (such as HFC-404A) and refrigerants in the High category can be avoided in most situations.

There is rapid technical development of low GWP alternatives. Numerous options available in 2016 were not available just 2 or 3 years ago. The rapid technical development is being driven by existing controls on HFC use in developed countries. Due to these controls it can be expected there will be continued development of low GWP alternatives and increasing experience of using them.

Selecting a Low GWP Refrigerant The selection process requires good expertise in refrigeration engineering, so must be undertaken with care by a suitable expert. Details of various available low GWP refrigerants are given as “procurement guidelines” in Section 4 of this Guidance Note, Table 5. Low GWP blowing agents for insulation foam are listed in Appendix 1.4, Tables A2. The boxes below provide some example information.

Some general guidelines are as follows:

Due to the rapid rate of technical development, the comments above and information in Table 5 will be out of date quickly! Up to date information of the latest refrigerants should always be used.

The commercial availability of low GWP alternatives is likely to vary across different regions of the world. The alternatives listed in Table 5 are already widely available in many developed countries. Currently they are less available in developing countries. This is expected to change quickly over the next few years, with commercial availability becoming much more widespread than at present. World Bank financed projects that use low GWP technologies will help encourage the market development of these products in developing countries.

Many of the low GWP alternatives have some degree of flammability. Some are categorised as “lower flammability” e.g. ammonia, HFC-32, HFO-1234ze. Others are categorised as “higher flammability” e.g. propane. See Appendix 1.4 for further details about flammability.


Water chillers

There are several ultra-low GWP options that can be selected in commercially available chillers. Chillers can be located in restricted access areas (e.g. a special machinery room or a roof-top) which makes it easier to address any safety issues (e.g. flammability). New HFOs including HFO-1234ze and HFO-1233zd will be widely used for chillers.

Split air-conditioning

Some buildings make significant use of small split air-conditioning systems. It is difficult to use an ultra-low GWP refrigerant for this application. There has been rapid development of HFC-32 (GWP 675) as a replacement to R-410A (GWP 2088). Less refrigerant is required when HFC-32 is used, so the direct global warming impact is reduced by around 75%. HFC-32 has lower flammability – it can be safely used in small split systems. Blends of HFCs/HFO can also be used.

District cooling

District cooling systems are very large installations that will operate for in excess of 30 years. They are usually based on very large water chillers located in a dedicated building. Any of the safety issues (e.g. toxicity or flammability) can be dealt with in the design of the plant room. The chillers for district cooling should always use an ultra-low GWP refrigerant


Estimating the climate co-benefits of using low GWP refrigerants The climate benefits of using low GWP refrigerants can be expressed in terms of “tonnes CO 2

equivalent” and added to other climate benefits related to energy efficiency measures. To estimate the benefits, it is necessary to consider the difference in GWP between a business-as-usual high GWP refrigerant and a lower GWP selection. It is also necessary to make an estimate of the likely leakage rate during operation, maintenance and at end-of-life. The World Bank Montreal Protocol Team have created a simple spreadsheet tool to help TTLs estimate these climate co-benefits. This tool can be downloaded from www.xxx.yyy

Cost impact of using a low GWP refrigerant The cost impact of using low GWP refrigerants needs to be considered on a case-by-case basis during the project concept and appraisal stages. It is difficult to give definitive information about costs because:

a) there are widely ranging RAC applications in large buildings, e.g. in terms of size and temperature level

b) low GWP technology is maturing very quickly, hence price impacts of some of the newest refrigerants are falling quite rapidly

c) the price impact in Country A may be different to Country B because of current commercial availability of low GWP options in different geographic locations.

Refrigerants only represent a small proportion of the cost of a RAC installation – typically being less than 1% of the total cost. Hence, the cost of the refrigerant is not necessarily the crucial factor.

The common fluorocarbon refrigerants (e.g. HCFC-22, HFC-134a, HFC-404A, and HFC-410A) cost around $5 to $10 per kg. Ammonia and CO2 (both are ultra-low GWP) are cheaper than this – typically only $2 to $4 per kg. The new HFO refrigerants (and new blends that contain HFOs) are currently much more expensive than the common fluorocarbons – typically in the range of $15 to $100 per kg. However, the refrigerant price itself is only part of the story – the type of refrigerant selected can have a significant impact on the cost of the major components in a system such as compressors and heat exchangers. A small ammonia system is likely to be more expensive than a small HFO system, despite the fact that the refrigerant itself is much cheaper. System size can also have a significant influence – a large ammonia system is likely to be cheaper than a large HFO system.



During the project concept and appraisal phase, consider what refrigerants are appropriate

Never use refrigerants with a very high GWP (>2,500 e.g. HFC-404A, HFC-507A) Where possible, consider use of a refrigerant with an ultra-low GWP (e.g. ammonia,

HFO-1234ze, HFO-1234yf, blends of HFCs/HFOs) If an ultra-low GWP refrigerant is not appropriate, use a low or moderate GWP

refrigerant (GWP 150 to 1,500) if possible. Include an estimate of the climate benefits of using low GWP refrigerants in your

PCN.

http://www.xxx.yyy/


Win 3: Maximising Energy EfficiencyThe energy related CO2 emissions dominate the total GHG emissions from RAC systems used in large buildings. Maximising energy efficiency is an essential part of any investment in the buildings sector that involves RAC equipment. Win 3 is often the biggest prize, especially in terms of improved financial investment returns.

There are excellent opportunities to improve energy efficiency of existing RAC systems and, in particular, of new equipment. Unfortunately, energy efficiency is often neglected in RAC projects, usually because the investor is unaware of the opportunities that are available and because of an unbalanced focus on low capital cost. In this section of the Guidance Note we will describe a structured approach to improving efficiency and illustrate this with a number of Case Studies that show the excellent financial returns that can be achieved.

Energy efficiency improvements have the dual benefits of excellent financial returns and reduced GHG emissions. The cost of energy always dominates the lifecycle cost of a refrigeration or air-conditioning system. This is illustrated in Figure 3.

Figure 3: Example of discounted annual costs across life cycle of RAC equipment

The end user is likely to accrue significant financial benefits if energy efficiency is properly addressed. In developing countries there may be further benefits if there is often a shortage of electricity supply. Improving the efficiency leads to a lower peak electricity demand and reduced infrastructure costs related to the supply of electricity.

When a new RAC plant is required or an old plant is being replaced there is an excellent opportunity to use a design concept that improves efficiency significantly. An efficient plant does not necessarily cost more than an inefficient one!

Case Study 1 illustrates a large air-conditioning system that benefitted from a proper appraisal of the variations in cooling requirements encountered through the annual operating cycle.

Potential for efficiency improvementThe potential for energy saving is highly application specific. In most cases the potential to improve RAC efficiency is much higher than for other energy using systems such as boilers. Table 4 illustrates the potential for refrigeration efficiency improvement.

Table 4: Typical range of efficiency improvement for RAC equipment

Energy saving Payback period

New plant 25% to 50% 0 to 3 years

Existing plant 15% to 25% 1 to 2 years


Case Study 1: Chiller for large office building

A large water chilling system is planned for a new office building. The lowest cost option (in terms of capital cost) was a single large chiller with a cooling capacity of 1,000 kW. However, an energy review showed that the building only required such a high amount of cooling when operating in the hottest weather conditions. Most of the year the load was considerably lower. A single large chiller operating at part load can be very inefficient. By carefully selecting a number of smaller chillers it was possible to increase the overall operating efficiency by over 25% - the extra investment paid back in less than 2 years.


The importance of “Temperature Lift” A refrigeration system “collects” unwanted heat at a low temperature and transfers that heat into the ambient surroundings at a higher temperature. A useful analogy is to compare a refrigeration plant to a pulley system that lifts a weight. In a “heat pulley”, the weight is a quantity of heat that is raised up through a “temperature lift” – the temperature lift is equivalent to the physical height difference in a mechanical pulley system. Two efficiency factors are illustrated by the heat pulley analogy:

a) Energy consumption depends on “the size of the weight” – the bigger the heat load, the more energy that must be used.

b) Energy consumption depends on “temperature lift” between the product being cooled and the ambient – the bigger the temperature lift, the more energy that must be used. This is illustrated in the adjacent diagram – it takes more energy to provide refrigerated cooling on a hot day than on a cooler one.

What many refrigeration plant designer and system operator do not realise that the impact of temperature lift is quite dramatic, in terms of energy efficiency. A simple rule of thumb is that just 1 degree C extra temperature lift will add between 2% and 4% to the energy used by a plant. Through bad design or bad plant operation it is easy to “accidentally” add an extra 10 or 15 degrees C to the temperature lift – that could add 20% to 40% to the total energy consumption.

The important “heat pulley rules” that follow from this are:

The “cold end” of a refrigeration plant (the evaporating temperature) should be as high as possible

The “hot end” (the condensing temperature) should be as low as possible

There are many ways in which these rules are broken, as illustrated in Case Studies 2 and 3.


Case Study 2: Minimising the heat load

One of the heat pulley rules is to minimise the size of the heat load on a RAC system. The heat load of a building such as an office is made up of the heat gains through the fabric of the building, the heat gains through fresh air ventilation and the various internal heat gains from electrical equipment such as lighting, computers, etc. If care is taken at the design stage it is possible to reduce some of these heat loads. For example: external shading of the windows can reduce the solar gain; use of LED lighting will reduce the lighting heat load; use of variable speed ventilation fans will reduce extra heat input. In many situations the total heat load can be reduced by over 20%.

Case Study 3: Raising the chilled water temperature

Large buildings are often air-conditioned using a chilled water system. The choice of the chilled water temperature has an influence on the energy efficiency. The second heat pulley rule is to minimise the temperature lift. By raising the chilled water temperature from 6oC to 9oC the chiller will provide cooling with a 10% to 15% efficiency improvement. Larger air cooling heat exchangers will be required, but the extra investment can pay back in under two years. Also, it may be possible to use the control system to raise the chilled water temperature at times of low heat load (in cool weather), providing savings at no extra cost.


A structured approach to identify efficiency opportunities There is no lack of good refrigeration efficiency opportunities – the problem is that they are not always easily identified. Using a structured approach helps ensure the best opportunities are spotted. The key steps are summarised in Figure 4. Details about the 4 key stages are given in Appendix 1.5.

Figure 4: A structured approach to improving refrigeration efficiency

Impact of refrigerant selection on energy efficiencyThe choice of the most appropriate refrigerant can have an important impact on energy efficiency. Whilst a refrigerant with the lowest practical GWP should be selected, this must be done in conjunction with energy efficiency considerations. A bad low GWP refrigerant selection could result in increased energy use and total GHG emissions would rise. Some important considerations include:

Refrigerant with good efficiency at relevant operating conditions. The most efficient refrigerant will depend on operating temperatures. The best refrigerant for a chilling plant might not also be the best refrigerant for a freezing plant.

Size of system. Large plants can often use ammonia – the cost of dealing with safety issues (toxicity and lower flammability) is offset by financial benefits, e.g. in relation to reduced energy costs. On small equipment ammonia may not be the most cost-effective option. In case of small cooling capacity equipment currently either HCFCs or HFCs are being used. Several ultralow-GWP alternatives have been developed and commercialized. Efforts should be made to avoid the use of high-GWP refrigerants and foam blowing agents while replacing HCFC based equipment and new RAC installations.

Use of a secondary refrigerant. Many large plants use a “secondary refrigerant”. The primary refrigerant is used in a chiller that cools a secondary refrigerant, usually water. The secondary refrigerant is pumped to serve the cooling loads. This can be convenient and from a safety as well as reduced charge perspective it helps because the primary refrigerant can be kept within a restricted access machinery room which results in reduction of direct emissions. However, use of a secondary refrigerant can significantly reduce the energy efficiency. This option needs careful evaluation to ensure optimum energy efficiency and minimum refrigerant emissions. There could be a trade-off between energy efficiency and the quantity of charge of the plant (emissions of refrigerant)



Ensure that energy efficiency is considered before an investment decision is made Be aware of the excellent energy efficiency opportunities that may be available for

refrigeration systems used in large buildings For large equipment always carry out an energy efficiency assessment using the structured

approach described in this Guidance Note Include an estimate of the climate benefits of improved efficiency in your PCN.


4. Check List for TTLs: Large Buildings

Step Activity Specific actions

Conc

ept s

tage

Identify the need for RAC equipment in the project

Review the design of the project and ensure that climate benefits of using climate friendly cooling equipment is reflected in the PCN

Calculate climate benefits of using a low GWP refrigerant and improved efficiency

Appr

aisa

l sta

ge Identify refrigeration, air-conditioning and foam insulation requirements

Review investment plan and identify all cooling equipment that will need to be purchased

Categorise systems by size (kW cooling), temperature level and application (see Tables 2 and 3)

Refine calculation of climate benefits

Impl

emen

tatio

n/ P

rocu

rem

ent

Win 1 opportunities

Avoid all ODS

Check whether any ODS are specified – only HCFCs are likely as all other ODS already banned

For large equipment ensure HCFCs are not used

For small equipment only use HCFCs if other options have been ruled out

Win 2 opportunities

Avoid high GWP HFCs

Check which refrigerants and foam blowing agents have been specified

Identify GWP of any HFCs specified

Consider whether lower GWP HFCs are available for the application (see Table 5 and Appendix 1, Table A3)

Check availability of relevant lower GWP alternatives in the geographic region concerned

Never use refrigerants with a very high GWP (>2,500 e.g. HFC-404A, HFC-507A)

If cost-effective, use a refrigerant with an ultra-low GWP (<10, e.g.HFO-1234ze)

Consider moderate GWP refrigerants (GWP 150 to 1500) if required.

Win 3 opportunities

Maximise energy efficiency

Ensure energy efficiency aspects are carefully considered

For large systems carry out full energy efficiency review, using structured approach described in Guidance Note

Consider financial benefits related to the refrigeration plant itself and also the wider benefits such as reduced electrical



generating requirements



Table 5: Procurement Guidelines – low GWP refrigerants for new equipment in large buildings

Type of equipment

High GWP HFC to be avoided (GWP)

Lower GWP alternatives (GWP)

Flammability Category4 Comments

Small split air-conditioning

HFC-410A (2,088)

HFC-407C (1,774)

HFC-32 (675)

HFC-447A (582)

HFC-452B (461)

2L

2L

2L

Various lower flammability refrigerants are being introduced for small room air-conditioning systems. These have a much lower GWP than HFC-410A which is the most commonly used HFC. Currently there are no ultra-low GWP options for split air-conditioning systems. Propane is being considered for very small split systems but flammability is a constraint.

VRF or ducted air-conditioning for multi-room applications

HFC-410A (2,088)

HFC-407C (1,774)

HFC-32 (675)

HFC-447A (582)

HFC-452B (461)

HFC-513A (631)

2L

2L

2L

1

VRF systems can provide a very efficient air-conditioning system and can also provide heating to parts of a building if required. However, with larger refrigerant charge it is more difficult to use lower flammability (2L) refrigerants in VRF units than in smaller split systems. They can be used in some applications with appropriate safety precautions e.g. leak detectors and automatic ventilation. If a non-flammable refrigerant is required it is possible to use ducted systems and a refrigerant such as HFC-513A

Water chillers

HFC-410A (2,088)

HFC-407C (1,774)

HFC-134a (1,430)

HFO-1234ze (7)

HFO-1233zd (5)

R-717 ammonia (0)

R-290 propane (3)

2L

1

2L

3

Ultra-low GWP alternatives already available. Newly commercialised HFO-1234ze quickly becoming available as a replacement for HFC-134a in medium pressure chillers. HFO-1233zd recently commercialised and becoming available as a replacement for HCFC-123 in low pressure chillers. Ammonia a possibility but high toxicity may limit applicability and increase cost. Propane a possibility but high flammability may limit applicability and increase cost.

Ice rinks HFC-404A (3,922)

HFC-134a (1,430)

R-717 ammonia (0)

R-744 CO2 (1)

2L

1Ammonia is widely used for ice rinks. CO2 has been introduced more recently.

Data centresHFC-410A (2,088)

HFC-134a (1,430)

HFO-1234ze (7)

R-717 ammonia (0)

R-744 CO2 (1)

2L

2L

1

Historically data centres made significant use of refrigeration to remove heat from computer systems. In recent years it has been recognised that in cool climates refrigeration can be completely or partially eliminated. Where refrigeration is still required (e.g. in hot ambient conditions, there are various ultra-low GWP options available.

4 Flammability categories based on ISO 817 and ISO 5149 3 = higher flammability; 2 = flammable; 2L = lower flammability; 1 = no flame propagation



5. Bibliography and Sources of Further InformationLinks to other documents:

In this series of Guidance Notes Other WB documents of relevance.



Appendix 1: Further Technical InformationThis section provides further technical details related to some of the issues discussed in the main Guidance Note. The following topics are dealt with in this Appendix:

1. Split of greenhouse gas emissions from RAC systems: this shows examples of the split of GHG emissions between direct (refrigerant leakage) and indirect (energy related).

2. Avoiding high GWP refrigerants during HCFC phase-out: this describes the HCFC phase out schedules for developing countries and explains the possibility to “leap-frog” high GWP HFC technologies.

3. Insulation foam: this describes the use of insulating foam and gives details of ODS, HFC and low GWP blowing agents.

4. Technical details about Win 2 – minimising use and emissions of high GWP HFCs: this gives details about ways of avoiding the use of high GWP HFC refrigerants, including a list of low GWP alternatives and a discussion about flammability.

5. Technical details about Win 3 – maximising energy efficiency: this provides a description of how to carry out a structured energy efficiency evaluation, illustrated with some case studies.

Appendix 1.1: Split of greenhouse gas emissions from RAC systems There are two distinct sources of GHG emissions from RAC systems:

Direct GHG emissions are created by refrigerant leakage from RAC equipment. Direct emissions are measured in tonnes CO2 equivalent, which is calculated by multiplying the tonnes of refrigerant emitted by the refrigerant GWP

Indirect GHG emissions are from the electricity required to operate the equipment

The balance between these two sources depends on the refrigerant used, the rate of refrigerant leakage and the type and efficiency of electric power generation. For RAC systems used in large buildings, the total GHG emissions are dominated by indirect emissions from electricity use as shown in Figure A1. These pie charts emphasise the importance of maximising energy efficiency.

Figure A1: Examples of GHG Emissions from RAC equipment in large buildings


Direct GHG Emissions: refrigerant leakage

Indirect GHG Emissions: CO2 from energy use


Appendix 1.2: Avoiding high GWP refrigerants during HCFC phase-outThe schedules for the phase-out of HCFC consumption under the Montreal Protocol are summarised in Figure A2. Developed countries (non-A55) started phasing out HCFCs with a consumption freeze in 1996. As shown in the blue line in Figure A2, by 2015 there was a 90% cut in consumption, with complete phase-out due in 20206.

Figure A2: HCFC phase-out schedule

Developing countries (A5) are still using significant quantities of HCFCs. As shown in the red line in Figure A2, the first cut of 10% was in 2015. This will be followed by a 35% cut in 2020, 67.5% cut in 2025 with complete phase-out due in 20307.

When developed countries starting using HCFC alternatives in the 1990s there were relatively few low GWP alternatives available. Some of the most cost effective alternatives at that time were high GWP HFCs. With the benefits of hindsight, it should be recognised that developed countries made a mistake to move from ODS to high GWP alternatives. Developed countries are now needing to take a second investment step, to replace high GWP HFC technologies with low GWP alternatives.

Developing countries have only recently started to phase out their use of HCFCs. There is a risk that developing countries will also use high GWP alternatives when phasing out HCFCs and repeat the error made by developed countries. This is undesirable from an environmental perspective and it could add considerably to overall the financial burden of the Montreal Protocol. World Bank projects using funds from the Multilateral Fund (MLF) for the implementation of the Montreal Protocol Multilateral Fund would need to phase-out the production and consumption of HCFCs, but currently they might ignore the climate impacts. Projects funded from other sources could conceivably still be using HCFCs in new equipment, although this is unwise.

5 In the Montreal Protocol, developing countries are referred to as Article 5 (A5) countries. Developed countries are non-A5.

6 A residual quantity of 0.5% is allowed in non-A5 countries from 2020 to 2030 for maintenance of RAC systems

7 A residual quantity of 2.5% is allowed in A5 countries from 2030 to 2040 for maintenance of RAC systems



It is important to recognise that there has been rapid development of low GWP alternatives, driven by strong policy measures in various regions including the EU, Japan and the USA. Developing countries can benefit from these developments and “leapfrog” the high GWP step by moving directly from HCFCs to low GWP alternatives. It is important that this possibility is investigated prior to a World Bank investment being made. World Bank investments in developing countries can benefit from the technology improvements already being made in various developed countries. There are strong regulatory drivers that are creating a rapid rate of change in relation to new low GWP alternatives to HFCs e.g.

in Europe via HFC phase-down in the 2014 EU F-Gas Regulation

in the USA via the 2015 “delisting” of certain high GWP refrigerants under the US EPA SNAP

in Japan via the 2013 Act on Rational Use and Proper Management of Fluorocarbons.

The technical developments are taking place in the following steps:

a) Low GWP fluids are commercialised and recommended for specific applications.

b) Products and equipment using the low GWP fluids are developed and used by “early adopters”.

c) Growing demand in regulated developed countries enables the new products to be optimised and improved, resulting in lower investment costs and improved energy efficiency.

d) Well proven products become available in other geographic regions.

This product development cycle is illustrated in Figure A3. Early adopters have faced extra costs for related to the development and use of new products using low GWP alternatives. Due to existing regulatory controls in certain developed countries these first costs have already been fully amortised for some products, with the latest models being cost competitive with older high GWP designs. For some products the development cycle is still at an early stage, but within the next 3 to 5 years many low GWP products will have reached a mature state of development. World Bank projects can support technology transfer of mature technologies (low cost and high efficiency) into developing countries.

Figure A3: Technical maturity relationship for new low GWP alternatives


Design improved: better performance

Sales volume increased lower costs

Costs high for early adopters

Time since new product introduced

Improving performance and reducing cost


Appendix 1.3: Insulation foamLarge buildings make use of polyurethane (PU) or extruded polystyrene (XPS) insulating foams. In developing countries, these foam products might still be manufactured using ODS blowing agents. In all developed countries there has been a switch away from ODS – sometimes to high GWP HFCs. Table A1 illustrates the use of foam and describes the types of blowing agents that might be used during manufacture.

Table A1: Usage and characteristics of insulation foam in large buildings

Sector Main Sub-sectors Examples of Foam Types

Building fabric insulationWall insulation

Floor insulation

Roof insulation

PU laminated boards

PU metal faced panels

PU spray foam

Extruded polystyrene boards (XPS)

Refrigeration plant insulationRefrigerant pipework

Evaporators

Large vessels

PU pipe section

PU block foam

Foam Type Blowing agents

Polyurethane

panels, board, block and spray foam

Commonly used ODS blowing agents: HCFC-141b

Commonly used HFC blowing agents: HFC-245fa HFC-365mfc

Low GWP alternatives: hydrocarbons (pentane) HFO-1336mzz HFO-1233-zd

Extruded polystyrene

BoardsCommonly used ODS blowing agents: HCFC-142b HCFC-22

Commonly used HFC blowing agents: HFC-134a HFC-152a

Low GWP alternatives: CO2 hydrocarbons HFO-1233zd



Appendix 1.4: Technical details about Win 2 – minimising use and emissions of high GWP HFCs

There are five distinct opportunities to reduce the direct GHG emissions from RAC systems as illustrated in Figure A4.

Figure A4: Ways to reduce direct GHG emissions from RAC systems

Existing RAC Systems

For existing plants, it is possible to reduce the direct emissions by reducing leakage rates. This can be done by investing in better maintenance practices and by the replacement of components that are shown to give rise to significant levels of leakage. For large RAC equipment used buildings (e.g. air-conditioning chillers) it is often possible to reduce refrigerant leakage from existing equipment by over 25%. This reduces direct GHG emissions and saves money for replacing leaked refrigerant. In many cases, reduced leakage also leads to improved cooling performance and better energy efficiency.

New RAC Systems

For new plants, the key opportunity is to use a refrigerant with a low GWP. There is also a good opportunity to specify a “low-leakage” design.

Table 5 lists a number of low GWP alternatives that can be considered for different RAC applications. For large systems and chiller systems an ultra-low GWP alternative is likely to be cost effective. For small and medium sized systems, it may be necessary to use a refrigerant with a low or moderate GWP.

Table A2 provides information about low GWP foam blowing agents.



Table A2: Low GWP foam blowing agents

Type of foam High GWP HFC to be avoided (GWP)

Lower GWP alternatives

(GWP)

Flammability Category8 Comments

Polyurethane

Panels, board, appliances, block

HFC-245fa (1,030)

HFC-365mfc / HFC-227ea blends (960 to 1,100)

Pentane (5)

Methyl formate (<25)

Methylal (<25)

HFO-1233zd (5)

HFO-1336mzz (9)

HFO-1234ze (7)

Flammable

Flammable

Flammable

Non-flammable

Non-flammable

Non-flammable9

Flammable blowing agents, especially cyclo-pentane and iso-pentane are already widely used for appliances (e.g. domestic refrigerators) and in factories manufacturing large volumes of steel faced panels (e.g. for cold store insulation) or boards (e.g. for building wall insulation). There are high initial investment costs to safely use a hydrocarbon blowing agent, but these are amortised against a low cost blowing agent.

In factories producing smaller volumes (e.g. block foam) investments in safety measures are often too high – HFCs such as HFC-245fa have proven more cost effective.

HFOs have recently been introduced and have very good insulation properties – these low GWP alternatives may become a popular option.

Polyurethane

Spray foam

HFC-245fa (1,030)

HFC-134a / HFC-245fa blends (1,100 to 1,300)

HFO-1233zd (5)

HFO-1336mzz (9)

Supercritical CO2 (1)

Non-flammable

Non-flammable

Non-flammable

For spray foam applications a hydrocarbon blowing agent cannot be used safely. Various non-flammable options have recently become available.

Extruded polystyrene HFC-134a (1,430)

HFO-1234ze (7)

CO2 (1)

Dimethyl ether (1)

Non-flammable

Non-flammable

Flammable

CO2 has been used for some years. HFO-1234ze has recently been introduced and may become a very good low GWP option.

8 The flammability categories used in Table 5 only apply to refrigerants. The foam blowing agents in Table A2 are either flammable or non-flammable 9 HFO-1234ze is designated as non-flammable for foam applications in most regions. It is designated as lower flammability for foam applications in Japan and in

all regions for refrigeration and air-conditioning applications.



Safeguarding Issues

Most HCFC and HFC refrigerants are non-flammable and this is a characteristic that made them a popular choice for many end user applications. The non-flammable property of most HFCs simplifies the manufacture, installation and maintenance of refrigeration equipment. If a non-flammable refrigerant leaks there will be no risk of fire.

One of the reasons that most HFCs are non-flammable is that their molecular structure is very stable. Unfortunately, this property also gives HFCs a relatively long atmospheric life and a high GWP. Low GWP alternatives usually have less stable molecules – this is good from a GWP perspective, but it results in many alternatives being flammable.

Historically there were plenty of non-flammable refrigerant options available. This made it is easy to apply a simplistic and conservative approach to flammability: if a flammable fluid is considered undesirable then select a non-flammable refrigerant instead.

This simplistic approach is not ideal when there are fewer non-flammable fluids to choose from. To make more widespread use of low GWP alternatives, it is important to recognise that there are widely varying “levels of flammability”. There is a continuous spectrum of flammability which includes:

Higher flammability fluids (flammability category 310) – these are very easy to ignite and can burn with explosive impacts. The most common examples are hydrocarbons (HCs) such as propane and butane. These have very useful properties for use as refrigerants and foam blowing agents but appropriate safety precautions must be taken as they exhibit both a high likelihood of ignition and a high severity of consequences following ignition

Flammable fluids (category 2) – they are more difficult to ignite, but once ignited will continue to burn and could create a significant hazard.

Lower flammability fluids (category 2L) – these are very difficult to ignite, once ignited they burn “gently” and might be extinguished when the source of ignition is removed. Lower flammability fluids create a smaller fire risk than an equivalent amount of a more flammable fluid. Compared to higher flammability refrigerants, category 2L refrigerants such as HFO-1234yf or HFC-32 have a very low likelihood of ignition (a high energy ignition source and a high gas concentration are both required) and the consequences of ignition much less severe (because of a very low burning velocity).

Non-flammable fluids (category 1) – these cannot be ignited.

Lower flammability refrigerants such as HFOs (e.g. HFO-1234yf), blends of HFOs with HFCs (e.g. HFC-452A) and certain moderate GWP HFCs (e.g. HFC-32) are likely to become a commonly used option for building RAC systems. . Ammonia is a lower flammability (category 2L) refrigerant, it is not widely acceptable for large RAC installations.

Other safeguarding issues to be considered include:

a) Toxicity: ammonia is an excellent low GWP alternative for large refrigeration equipment. It is toxic and requires appropriate safety measures to be included in the design.

Pressure: CO2 operates at a much higher pressure than all other refrigerants. Most RAC systems have a peak pressure below 25 bar whereas CO2 systems have a peak pressure above 125 bar. The plant design must take this into account

Note: Make sure safety standards, such as IEC 60335-2-40, ISO 5149 and ISO 817 are followed while using flammable or toxic or high pressure refrigerants.

Appendix 1.5: Technical details about Win 3 – maximising energy efficiency

10 Flammability categories based on ISO 817 and ISO 5149



Figure 3 of the main Guidance Note shows a structured approach the identification of cost-effective energy saving opportunities in both new and existing refrigeration systems. Further details of each of the 4 steps in the structured approach are provided below.

Understanding the cooling load One of the most common mistakes in RAC plant design is to make an over-simplistic assessment of the cooling load.

Many plants are designed by only considering the “design point” – i.e. the peak cooling load under the warmest ambient conditions. This is wrong as most plants only operate near the design point for a few days per year. It is important to optimise the efficiency of the plant under a wide range of relevant part load conditions:

the plant must of course be sized to meet the design point peak load condition

but, the design should take into account the far more common operating conditions of reduced cooling load and lower ambient temperature

this can only be done if you properly assess the cooling load profile through the daily and seasonal variations in operation and ambient temperature

Case Study 1 (in main Guidance Note) is an example of a significant efficiency improvement being made with a better understanding of the cooling load – by recognising that the plant would be significantly over-sized if it was selected for the design point load.

Another important opportunity is “free cooling”. Mechanical refrigeration should only be used when other more efficient and lower cost forms of cooling are not available. Air-conditioning systems can incorporate free cooling in periods of cool weather, as illustrated in Case Study 4.

Design and selection of main components Once the cooling load has been properly understood the plant design can be based on:

a) The minimum practical peak cooling requirement, allowing for incorporation of heat load reduction measures such as free cooling (see for example Case Study 4)

b) A good understanding of how the load varies on daily, weekly and seasonal timescales.

The plant design needs to take place in two distinct steps:

1) The overall system design needs to be selected to maximise efficiency

2) The individual main components need to be selected to maximise efficiency

System Design


Case Study 4: Free cooling of buildings

An air-conditioned building is typically held at a temperature around 20oC. In summer the ambient temperature is above 20oC and a refrigerated air-conditioning system is required. However, in many climates the ambient temperature is below 20oC for a significant part of the year (taking seasonal effects and day/night temperature differences into account. Buildings may still require cooling because of internal heat gains created by equipment, lights and people. At times of low ambient temperature it is possible to provide “free cooling” using ambient air, either via a fresh air ventilation system or through the use of cooling towers. The savings depend on the way that the ambient temperature varies and on the amount of internal heat gain. This opportunity is worth investigating on large building developments.


Choice of the best overall system design can be a complex issue and might be subject to conflicting priorities e.g. energy efficiency and safety. It is beyond the scope of this Guidance Note to provide much detail on system design, but it is important to be aware that various design decisions can have a big impact on efficiency. Some of the most important considerations include:

Selection of the appropriate temperature level for cooling. Refrigeration is more efficient when carried out at the highest possible temperature. The “energy penalty” for cooling below the optimum level is severe – typically a loss of 2% to 4% efficiency per oC.

Choice of cycle e.g. single stage versus two stage. Large systems for loads below -15 oC usually justify the extra cost and complexity of two stage compression.

Selection of compressors of appropriate size. Compressors are inefficient when operating at low load. Select compressors that will usually operate at high load. For example, if the peak load is 1000 kW but the plant often runs at under 200 kW a good selection could be 2 compressors rated at 300 kW and 2 rated at 200 kW.

Is heat recovery worth considering? Refrigeration systems reject waste heat to the atmosphere. In some situations, it may be possible to cost effectively include a heat recovery system e.g. to heat process water or water used for cleaning.

Component Design

When the system design has been specified and the refrigerant has been selected it is then important to select key components with maximum efficiency. In particular:

Compressors. These are the main electricity using component of a refrigeration system but many are purchased without selecting for best efficiency. Refrigeration compressors can vary in efficiency between <50% and >80% depending on design and operating conditions. The compressors should have peak efficiency at the most common operating conditions – that is usually not the “design point” conditions.

Evaporators. The type and size of the evaporators needs careful optimisation. The smallest practical temperature difference between the product being cooled and the refrigerant evaporating temperature will maximise efficiency.

Condensers. The type and size of the condensers needs careful optimisation. For large systems evaporative condensers can give the best efficiency (e.g. compared to air cooled).

Auxiliaries. Ensure auxiliaries (pumps, fans, lights etc.) are also selected for maximum efficiency and for controllability.

Optimised plant control Some of the most cost effective opportunities for improving efficiency relate to improved control. Many refrigeration systems have very poor controls, with fixed set points that do not respond to the regular variations in cooling load and in ambient weather conditions. Controls for new plants should be specified to ensure that energy efficiency is maximised under all operating conditions. The large cooling capacity RAC systems should use Building Management Systems (BMS) for energy conservation. On existing plants controls can be adjusted or modified to achieve the same objective. Key aspects of control are:

a) Ensure cooling load is “controlled” e.g. do not over-cool

b) Respond to variations in ambient temperature and cooling demand

c) Avoid high condensing temperatures

d) Avoid low evaporating temperatures

e) Avoid part load operation of compressors

f) Minimise auxiliary power (and related heat input)

These control opportunities are illustrated in the Case Studies below.



Monitoring and maintenanceMost large RAC systems lack the monitoring equipment that would allow the plant to be regularly checked to ensure good efficiency. In a recent survey of 130 large RAC systems in the UK, each site was asked whether they had any electricity sub-meters on their RAC plant. The average RAC electricity cost for these installations was estimated at over $0.5 million per year, but, as illustrated in the pie chart, nearly 75% had no electricity sub-metering. The situation in developing countries is likely to be even worse. Good metering is essential – and is very low cost if installed at the same time as a new refrigeration system.

Three types of data are required to diagnose energy wasting faults on refrigeration plant:

a) Electricity sub-meters on each compressor and on large pumps and fans

b) Pressure and temperature gauges on various parts of the refrigeration circuit (e.g. evaporating and condenser pressure)

c) Data on “influencing variables” e.g. production level and weather

With data as described above it is possible to check plant performance on a regular basis (e.g. weekly) and spot maintenance related problems or incorrect control settings. Energy savings in excess of 20% are often achieved with a good monitoring and maintenance regime.


Case Study 5: Avoid Head Pressure Control

Many plants are fitted with a head pressure control (HPC) system that keeps the condensing temperature high in cool weather conditions. HPC is very wasteful – to maximise efficiency a plant should have “floating head pressure” that allows the condensing temperature to fall to the lowest practical level. Annual savings can be >25%. In some cases these savings can be achieved with no capital investment, by simply adjusting HPC settings. To maximise the benefits, investments such as a better expansion valve may be required.

Case Study 6: Use Variable Speed Fans

Evaporator fans in cold storage rooms and ventilation fans in air-conditioning systems are often run at full load 24 hours per day. The heat load created by the fans can be substantial, especially when the overall heat load in the building is low. Fitting a variable speed drive (VSD) to fans can make significant savings. If the fan speed is reduced to 80%, the flow falls to 80% but the power drops much more to 50%. For much of the time a fan can be controlled well below 100% speed with significant annual savings.

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