clean air act and chimneys

!

A guide to chimney design

and installation legislation£10

CHIMNEYDISCHARGEHEIGHTS

CHIMNEYDISCHARGEHEIGHTS

What you need to know about . . . .

T H E C L E A N A I R A C T

Clean Air Act Booklet A/W 10/1/01 3:50 pm Page 3

The Clean Air Act

Chimney Discharge Heights

Selkirk are very much aware that their chimney, flue and exhaust systems handle waste gases

and combustion products that are discharged into an already sensitive atmosphere.

Consequently, we are conscious of the need for the environment to be protected particularly

where legislation demands.

The chimney height requirement of the Clean Air Act is an area, particularly in relation to commercial

heating boilers, that is often abused, misunderstood and on many occasions blatantly ignored. As

Europe’s largest manufacturer of prefabricated residential / commercial chimney and exhaust

systems, we are often asked to advise on this subject, inquiries emanating from a broad spectrum of

the construction industry, including architects consulting engineers and heating contractors.

For global ecological reasons, air quality is now a subject being treated with high priority by many

countries. Within the UK, legislation on this subject has been with us since the 1800s. The first Clean

Air Act was enacted in 1956 and was subsequently extended and amended by the Clean Air Act

1968. Both these Acts were repealed in 1993 and consolidated into the Clean Air Act 1993. The

Environmental Protection Act 1990 regulates the emission of certain substances to air, land or water,

from various processes. The 1995 Environment [not Environmental] Act provides for the preparation

of a National Air Quality Strategy by the Secretary of State and for local authorities to review and

assess local air quality on the basis of health-based objectives for eight pollutants. The National Air

Quality Strategy was published by The Stationary Office (formely HMSO), CM3587 in March 1997;

Regulations putting the air quality objectives on a statutory basis are expected before the end of

1997. The results of local authority reviews and assessments of local air quality and the requirement

for them to take action to ensure air quality objectives are not breached may well affect the

guidelines on chimney discharge heights. Those who believe that they can circumnavigate

legislation on chimney discharge heights will find that they will contravene other environmental

legislation.

This publication has been prepared to identify the current UK Statutory Requirements for the

discharge height for chimneys serving boiler plant, diesel generators and incinerators. There are

many references within the text to the Clean Air Act, the Clean Air Act Memorandum, the

Environmental Protection Act and Technical Guidance Note (Dispersion) D1. The reader is advised

to obtain and peruse copies of these documents, and will find additional useful information on each

in the annual NSCA* Pollution Hand Book. (*National Society for Clean Air)

We have set out this booklet in a question and answer format, as it was felt this would best answer

most of the queries raised. To assist, there is an index at the back of this booklet to enable particular

subjects to be more easily found.

What you need to know!!


1

Q3 What would be defined as “very largeplant”, and who would be the approvingauthority?

A3 Within the Environmental Protection Act

there are a number of Prescribed Processes,

each of which are sub-divided into

Part A processes and Part B processes.

Part A Processes

These require an Integrated Pollution

Control (IPC) operating permit and this is

controlled by the EA (Environment Agency)

or the SEPA (Scottish Environmental

Protection Agency) as appropriate.

Processes include boilers, furnaces, gas

turbines or compression ignition engines of

a total of 50MW thermal input or greater at

one location, waste oil/recovered oil burners

of 3 MW or more, incinerators having an

aggregated works capacity of one tonne per

hour or more, and most chemical process

plants. The approving authority for chimney

discharge heights would be the EA or SEPA

as applicable.

Part B Processes

These require an Air Pollution Control (APC)

operating permit and this is controlled by the

Local Authority.

Part B. processes include boilers, furnaces,

gas turbines and compression ignition

engines having a thermal input from 20-50

MW, and waste oil /recovered oil burners

under 3 MW. The approving authority for

chimney discharge heights would be the

Local Authority in England & Wales and

SEPA in Scotland.

For a full schedule of all Part A & B processes,

see the Environmental Protection Prescribed

Processes & Substances Regulations 1991

(and subsequent amendments), or the current

National Society for Clean Air -

“Pollution Handbook”.

Q1 What legislation within the UK controlsthe emissions from commercial /industrial boiler house chimneys, dieselgenerator and incinerator exhausts etc. ?

A1 There are two main items of legislation

within the UK (excluding N. Ireland), which

control the emission of waste gases etc. into

the atmosphere . They are the Clean Air Act

1993 and the Environmental Protection Act

1990. In N. Ireland the relevant legislation is

the Clean Air (Northern Ireland) Order 1981.

An Industrial Pollution Order for N. Ireland

has been issued in draft form and is now

expected to be enacted during 1997. This

order will enforce controls in N. Ireland

similar to the Environmental Protection Act in

the rest of the UK. There is also a

requirement under the Clean Air Act to

control the emission of grit and dust from a

furnace and to avoid nuisance from odours

for example, which is covered by the

Environmental Protection Act, Part III

(Statutory nuisances and clean air), as well

as other legislation.

Q2 Do any of the Acts set a discharge heightat which waste gas emissions arepermissible ?

A2 Yes. Under sections 14-16 of the Clean Air

Act and to the requirements for BATNEEC* in

section 7(2) of the Environmental Protection

Act, the discharge height is defined as the

height, approved by the approving authority,

at which the emissions are rendered

harmless and are prevented from being a

nuisance or prejudicial to health. The

approving authority is normally, except in the

case of very large plant, the Environmental

Health Department for the Local Authority

area where the installation is located.

*(Best Available Technology Not Entailing

Excessive Cost)


2

Q4 We are primarily concerned with smallercommercial / industrial boilers,incinerators and diesel generators. Do any of the Acts set a lower limit forthe rating of equipment to be consideredunder the Act ?

A4 Yes. In the case of the Clean Air Act, which

covers England, Scotland & Wales, under

clause 14 it is an offence to operate a furnace

that burns:-

● Pulverized fuel

● Solid fuel at a rate of 45.4 kg/hr or more

● Liquid or gaseous fuel at a rate

equivalent to 366.4 kW or more

unless the height of the chimney serving

the furnace has been approved by the local

authority.

A lower limit of 150kW gross heat input is

specified in the introduction to the Clean Air

Act Memorandum, and there appears to be

no explanation as to why this variance

between the Act and the Memorandum

should exist. However, since the

Memorandum is advisory only, the figure of

366.4kW specified in the actual Clean Air Act

should be taken as the lower limit.

In the case of N. Ireland, the Clean Air Order

1981 does not set any lower limit and each

case is considered on its merits by the local

authority officer.

Q5 Why is chimney height so important andhow does it contribute to pollutioncontrol?

A5 Chimney heights offer a means of local

control of pollutants discharge into the

atmosphere from combustion plant

(including diesel generators), incineration

plant and industrial process. They are used

to control the deposition of pollutants to the

ground or their ambient concentrations over

either long or short time scales, for a variety

of purposes including health effects and

nuisance (due to odour for example). There

may also be the necessity for additional

abatement controls on the discharges from a

particular source ,e.g. the requirement of

BATNEEC* to minimize the discharge where

practically possible. However, even when

there are high levels of abatement, there is

likely to be a residual discharge that must be

effectively dispersed by means of an

adequate chimney height.

*(Best Available Technology Not Entailing

Excessive Cost)

Chimneys act as a means of control over

local pollution levels by discharging the

polluting source to a height sufficient to

ensure that the dispersion of the initial

discharge plume, where the pollutants are

most concentrated, is high above ground

level. The chimney height is arranged so that

the eventual contact of the plume with the

ground results in pollutant concentrations

Figure 1

Chimneydiscarge height

A

B

50 to 100 x discharge height

Increasing the chimney discharge height, A, makes little, if any difference to pollutantconcentration, characteristics, if B is increasedbeyond 50 to 100 x A


Memorandum take into account the type of

fuel burned, and in the case of fuels with a

sulphur content greater than 0.04%, the

geographical location, (area category) in

which the plant operates. (See clause 17 of

the Clean Air Act Memorandum and the

calculation Process on page x of this

document).

More recently there has been a need to deal

with newer types of combustion plant (e.g.

combined cycle), and with the requirements

for adequate discharge stack height for a

wide variety of smaller process plant etc. This

has been met with the Technical Guidance

Note D1.

Each of these documents is advisory rather

than mandatory so as to allow for some

variation in unusual circumstances, but a

discharge height derived from either method

would normally be considered a minimumacceptable figure. However, it should be

noted that clause 25 of the Memorandum as

well as clauses 6.2 & 6.5 of the Technical

Guidance Note D1, both set overidingminimum requirements.

There is also specific advice on minimum

chimney heights for discharge stacks in the

Process Guidance Notes issued by the DOE

Local Authority Unit dealing with the

requirements for authorization of various Part

B processes. These also contain maximum

pollutant emission limits for the process.

Q7 When calculating the chimney dischargeheight what plant rating is to be used?

A7 The maximum rated input of the plant, not

its normal operational load, is to be used when

calculating the chimney discharge height. This

applies to both the Clean Air Act Memorandum

and Technical Guidance Note D1.

In relation to Technical Guidance Note D1

reference should be made to the various

Guidance Notes issued by either the

3

being within a prescribed limit value. This

process is only effective within distances of

about 50-100 chimney heights, much

beyond which the effects of discharge height

are no longer distinguishable. The highest

pollutant concentrations usually occur within

this range. Figure 1 illustrates the point.

Q6 How then is the discharge height of achimney actually set?

A6 The calculation of effective chimney height is

a matter of great practical importance. There

are a variety of methods of doing this, either

by direct dispersion modeling or by using

one of a number of guides for this purpose.

For large plant of the type defined as Part A

Processes, (see Q3), it is common for

individual dispersion modeling studies to be

requested as part of the authorization

process. Direct dispersion modeling may

also be used for calculating chimney heights

for smaller plant where there are complex

problems due to the character of the

dispersion or the nature of the discharge.

However, for the great majority of smaller

polluting discharges chimney heights are

determined using the published guides for

this purpose namely:-

i Third Edition of the 1956 Clean Air

Memorandum “Chimney Heights”.

Published by the Department of the

Environment.

ii Technical Guidance Note D1

(Dispersion). Published by The

Environment Agency

Both documents are available from

The Stationary Office (formerly HMSO)

The Clean Air Act Memorandum “Chimney

Heights” has been used for many years for

conventional combustion plant (mainly

heating and steam raising plant burning coal,

fuel oil or gas), and is still recommended for

this purpose. The calculations to the


A10 No. Although reference is made in the

“Scope of Memorandum”, (paragraph 3),

that it is suitable for diesel generator

exhausts, this was added some what as an

afterthought and is not strictly correct. See

paper by D J Hall, “Pollutant discharges from

stationary diesel engine exhausts”. Clean

Air; Vol. 17 No 1, 1987, pp. 9 - 20. This paper

gives a method by which the Clean Air Act

can be adapted to deal with diesel engine

exhausts, but this advice has now been

superseded by the issue of Technical

Guidance Note ‘D1’.

The discharge height for a diesel engine

exhaust should be determined using

Technical Guidance Note D1, as this method

takes account of the various pollutants

directly, and also the high discharge velocity

associated with such exhausts.

The levels of pollutants can vary significantly

from engine to engine. At present, whilst

there are no maximum limits defined in the

UK for the various pollutants, other European

Countries do impose limits, and we can

asume that some guidance will be issued by

The Environment Agency in due course. In

the meantime, for the best results, details of

the pollutant discharge in each case should

be obtained directly from the equipment

manufacturer. If this is information is not

readily available, then the break down of

pollutants given in Appendix ‘A’ of this

booklet could be used.

Q11 Does the act relate to all fuels?

A11 Yes. No fuel type is exempt. The Clean Air

Act applies to furnaces burning pulverized

fuel, solid fuel, liquid or gaseous fuel. These

are dealt with in the Clean Air Act

Memorandum under two headings namely:-

● VLS (Very low sulphur) content fuel -

defined as a fuel with less than

0.04% sulphur by mass.

Environment Agency (IPR notes) or the

Secretary of State (PG notes) which contain

guidance on emission concentration limits. A

list of these notes is given in Appendix ‘E’ of

D1. When calculating a chimney/exhaust

discharge height to D1 it can normally be

assumed that the concentrations of the

emitted pollutants are at the limit values

contained in the IPR or PG note unless the

operator has been authorized to operate

with lower limits in which case the lower

values would be used.

Q8 What if the plant operates with a highturndown ratio or a wide range ofdischarge conditions?

A8 In the case of the Memorandum this is not

considered. The chimney height is

calculated on the maximum emission and

target velocities are set at full load operation.

In the case of the Guidance Note, this is dealt

with under section 6.3 where it is

recommended that a discharge stack height

is calculated for both maximum and

minimum capacity and the highest calculated

height used.

Q9 Can the Clean Air Act Memorandum beused to determine the discharge heightfor an incinerator exhaust.?

A9 No. This is clearly stated in the introduction

to the “Scope of Memorandum” (Par. 3.).

Incinerator, as well as gas turbine exhaust

discharge heights, are best determined using

Technical Guidance Note D1. Reference

should be made to the appropriate IPR or PG

guidance note for emission concentration

limits. (see A7)

Q10 Can the Clean Air Act Memorandum beused to determine the discharge heightfor diesel generator exhausts.?

4


In normal practice this refers to Natural

Gas, LP Gas, or Premium Kerosene

(class C1 BS2869).

● Other Fuels - defined as a fuel with

greater than 0.04% sulphur by mass.

In normal practice this refers to Solid

fuel, Gas Fuel Oil, and Heavy Fuel Oil.

Q12 What fuel pollutants are considered whencalculating a chimney discharge height?

A12 In the case of boiler plant where the chimney

height is calculated via the Clean Air Act

Memorandum the major pollutants

considered are :-

● VLS fuels . . . . . . Nitric Oxide (NO)

● Other fuels . . . . Sulphur Dioxide (SO2)

When using the Technical Guidance Note D1

to calculate a chimney discharge height, all

major pollutants are taken into account.

Some typical pollutant values will be found in

tables on page 17.

Q13 Is the discharge velocity of the emissionfrom a chimney important?

A13 Yes, very important. The higher the

discharge velocity, the better the dispersion

of the pollutants. In the case of the Clean Air

Act Memorandum, the calculations assume

that an adequate exit velocity will be

achieved to prevent the plume of gas flowing

down the outside of the chimney. Target

velocities for a range of boiler ratings are

listed in the memorandum under clause 7 of

the introduction “Efflux Velocity”. All

velocities are at the equipment full load

rating. and are based on a separate

flue/chimney per boiler.

In the case of Technical Guidance Note D1,

5

the discharge velocity is part of the

calculation and will therefore have a direct

influence on the calculated discharge height.

Minimum discharge velocities are set under

clause 6.1.1 of the Guidance Note, and are

typically between 10 and 15m/s. Again, these

values are based on a separate flue/exhaust

for each discharge outlet on the equipment.

A high discharge velocity is also important

for another reason as it prevents cold air

entering the top of the chimney/exhaust,

flowing downwards and cooling the rising hot

gas and the inner surface of the chimney

wall. This can cause the formation of

condensation on the chimney wall, and in turn

lead to corrosion of the chimney construction.

In the case of high sulphur fuels, it will also

lead to the formation and emission of acid

smut from the chimney outlet.

The maintenance of an adequate discharge

velocity at all times is very difficult where

more than one item of equipment is

served by one chimney, in view of the

turndown involved.

To achieve the recommended minimum

discharge velocity, it is often necessary,

particularly with boiler plant to reduce the

internal diameter of the chimney exit by

means of a tapered cone. The correct size of

tapered cone will increase the discharge

velocity as required, but at the same time

will have, in most cases, only a limited effect

on the chimney system’s overall pressure

drop. The outlet diameter of the tapered

cone can be calculated by either of the

expressions in figure 2 opposite.

From the above, it can be seen that bothfrom an environmental as well as plantservice life viewpoint, it is highlypreferable to provide an individualexhaust/chimney from each exhaustoutlet on the equipment.


6

Q14 In some cases, particularly with naturaldraught atmospheric gas boilers, it is notpossible to achieve the recommendeddischarge velocity. What can be done inthis case?

A14 As far as boiler plant is concerned, every

effort should be made to design the

flue/chimney system so as to provide the

stated minimum exit velocity. (See Q13) This

is best achieved by providing a separate

flue and chimney system for each item of

equipment. For aesthetics, the flue pipes

could be collected in a common shroud or

cupola above roof level.

Alternatively, if a common header and

chimney system is to be provided, then the

system should be designed, incorporating

an induced draught fan if necessary, so as to

provide the required exit velocity.

By incorporating a fan, the chimney internal

diameter can be significantly reduced. The

fan motor speed can in turn be controlled by

a pressure sensing probe, so as to maintain

a constant level of draught at each boiler flue

outlet connection, irrespective of the number

of boilers operating. This will enable a high

level of boiler operating efficiency to be

achieved at all loads.

If neither of the above options are possible,

then the chimney height, C, calculated to the

Memorandum, should be further corrected

using the following expression.

H* = C + Hd where Hd = 2(W/U - 1.5)D

H* = the final corrected chimney height

in metres

C = the chimney height calculated to the

memorandum in metres

Hd = the effective reduction in stack height

due to low velocity in metres

W = the stack actual discharge velocity in m/s

U = the windspeed at the top of the stack

(normally taken as 5 m/s)

D = the stack outside diameter in metres

For discharge heights calculated to

Technical Guidance Note D1, reference

should be made to the Building Research

Establishment Report CR. 103/95 which was

prepared for the Local Authority Unit of Air

Quality Division, Department of the

Environment.

Section 4 of this report contains a

qualification to Guidance Note D1 with

reference to low efflux velocities.

4Vo

πVe

V1

V2

x 1000 = Cone outlet diameter (mm)

x D, = Cone outlet diameter (mm)

Where:- Vo = Waste gas volume @ operating temperature (m3/s)Ve = Required exit velocity (m/s)

Where:- V1 = Exit cone inlet velocity m/sV2 = Target exit velocity m/sD1 = Chimnet diameter (mm)

Note that the sides of the cone shouldtaper at an angle no greater than 30°from the vertical

30°

or

Figure 2


would be required of any other flue design.

Stack heights should continue to be calculated

by reference to the Chimney Heights

Memorandum irrespective of the details of the

flue or termination design.”

Q16 When determining a building height,from what datum is the height measured?

A16 Building height is measured to the ridge or

other highest point of a building above the

datum of general ground level as illustrated

in Figure 3. The height of a lift or tank room

etc., or any other protrusions less than 1% of

the roof area can be ignored. See also

Figures 8 & 9 related to the calculation

example on page 15.

This applies to areas around the discharge

stack where the ground slope is not greater

than 1 in 10, and the topographic effects on

dispersion are not significant. Specialist

advice may be needed in other cases where

topography is a problem.

SD

H

C

GL

SD

H

C

GL

SD

H

C

GL

SD

H

C

GL

Basementboiler Room

7

Q15 Do the special characteristics of a room-sealed balance draught flue system andterminal, enable a lower dischargeheight than the height calculated via theMemorandum to be acceptable.

A15 No. This is fully dealt with in a paper by

Dr. D J Hall in “CLEAN AIR”, Volume 17,

Number 3/4, 1987 and is obtainable either

from the National Society for Clean Air -

136 North Street - Brighton BN1 1RG.

or direct from Selkirk’s Marketing

Services Department.

The conclusions to the above paper state

the following:-

“ Whatever the benefits conferred by the

room-sealed balanced flue approach may be,

they are enjoyed only in the context of the

avoidance of fluctuating pressure differences

between combustion air inlet and flue outlet.

As far as the control of pollution is concerned,

the room-sealed flue does NOT enable lower

stack heights or less constrained location than

Figure 3

H = building height

C = chimney discharge height

GL = ground level

SD = separation distance


ridge of the building roof is outsidedistance 5 U, how is the building heightto be determined?

A18 This is best illustrated in Figure 4. If the ridge

of the roof is beyond the distance 5 U, (Fig 4

a) the building height is taken as the height

of the eaves. If the ridge is within the

distance 5 U , (Fig. 4b), then the building

height is taken to the ridge.

Q19 Some buildings are rather complex inshape and can have various sections ofdiffering heights and widths. How is thisdealt with?

A19 Large buildings of this type are broken up

into two or more parts, and each part treated

as a separate building. (See also Fig. 3 on

page 9 of the Memorandum, and Fig. 5 on

page 35 of Technical Guidance Note D1). In

addition, on page 16 of Technical Guidance

Note D1, clause 5.4.3 provides information

on the effective height and width of trees,

lattice towers and other porous structures,

which can influence chimney height. This

data can be equally applied to calculations

according to the Memorandum.

8

Q17 When considering the correction ofchimney height relevant to buildings,how is the distance 5 U and the buildingwidth and height measured

A17 The distance 5 U is really a radial dimension

with the chimney at the centre. All buildings

falling within this radius are to be considered

when correcting the chimney height for

building effect. In practice, it will be relatively

easy to discount a number of smaller

buildings within this radius, and commonly

one building will be obvious as the single

dominant structure.

The building width “B”, is measured at right

angles to a line connecting the centre of the

chimney to the nearest point of the building.

This can be seen more clearly in the

illustrations used in the Calculation Processes

described on page 15. (Defined also in

Figure 2 on page 8 of the Memorandum, and

Figure 8 on page 36 of Technical Guidance

Note D1).

Q18 In cases where a chimney serving a small gas fired boiler is locatedclose to or on the outside wall of thebuilding, where the highest point or the

Figure 4

(a) (b)

5U

HC

5U

HC


9

Q20 In some instances, a chimneytermination can be located close to atank / plant-room, the height of whichhas not been included in the calculationsbecause the area is less than 1% of theroof area. The termination could then bean undesirable lower height than the tank/ plant-room. Within what separationdistance should the chimney terminationbe raised above the tank / plant-roomroof, and by how much?

A20 This situation is covered in section 25.c of

the Memorandum which states that a

“chimney should never be less than the

height of any part of an attached building

with a distance 5 U. In the circumstances

described in the question therefore, if the

chimney is within a distance of 5 U from a

tank/plant-room, then it should extend to a

height of 0.6 U above the tank/plant-room

roof. (See “common case” in clause 23 of the

Memorandum). However, if the plant-room

has ventilation air inlet louvres, the chimney

should extend to a height of 3m above the top

of the louvres in accordance with section 25.a.

Q21 1n a boiler room containg more than one boiler, how is the chimney height determined?

A21 The Clean Air Act Memorandum did not

envisage multiple discharges in close

proximity being treated separately. In terms

of building down-wash effects, it is the

NB : 5U is calculated on the combineddischarge of ALL chimneys

5U

cumulative discharge that is important. As a

general rule, if the discharges are contained

within a distance 5 U, based on the

combined discharge, they should be treated

collectively, see Figure 5. Outside this

distance, they can be treated individually.

Q22 In some cases, dependent on the building design and application, andparticularly with small boiler plant, itmay be more practical to provideindividual vertical chimney for eachappliance, rather than to provide acommon chimney or cluster. Within whatseparation distance between chimneyscan each boiler chimney discharge beconsidered separately?

A22 If practical, the flues from all boilers should

be collected together in a common multi-

flued chimney system/s, the discharge

height being calculated on the combined

emission of all boilers. If this is not practical,

and a separate chimney system is to be

provided for each boiler, then the 5 U rule as

described previously in A21 would apply.

However, if one of the discharges is

significantly smaller than the others, and is

separated by less than 5 U, it may

considered separately, subject to Local

Authority approval.

Q23 What if there are boilers at more than onelocation on the same site?

A23 If possible, the flues from all boilers should

be collected together in a common multi-

flued chimney system, the discharge height

being calculated on the combined emission

of all boilers. (See A21). However, if this is

not practical a chimney system, multi-flued if

necessary, should be provided at each

location. When calculating the discharge

height for each location, the 5 U rule

previously described in A21 will apply.

See Figure 6 overleaf.

Figure 5


'x'

1 2 3 4 5

10

Q24 What if an Incinerator and/or Generatorexhaust/s is to be included with boilerflues in a multi-flued chimney system?

A24 In this case the chimney height would be

calculated using Technical Guidance Note

D1, because the introduction of the

incinerator/ generator exhaust takes it

outside the scope of the Memorandum. Again

the total combined emission is important but

this is treated differently depending on the

spacing of the individual flues. (See section

6.4 of Guidance Note D1).

Q25 How should Stand-by plant beconsidered?

A25 Stand-by plant should be included in the

chimney discharge height calculation, if its

inclusion would significantly increase the

rate of emission or significantly change the

type/level of the various pollutants. In cases

where multiple boiler plant is used, one of

which is a stand-by in case of failure of one

of the others, its capacity may be omitted

from the chimney height calculations. Where

there is a standby fuel, (for example, gas-oil

in case of interrupted gas supply), the

chimney stack height should be based on

that for the most polluting fuel.

Q26 When considering the height of thevarious buildings, if a building has noopenable windows can it be ignored, orits height effectively reduced?

A26 Most definitely not. The object of the

exercise is to place the chimney discharge

at a height were the discharge plume can be

dissipated safely over a large area as

described earlier in A5. If the discharge

plume strikes a building shortly after leaving

the chimney exit then the pollutants will be

brought to ground level in a greater

concentration than is desirable.

Q27 Is it permissible under anycircumstances to discharge flue gas at alow level from commercial boiler plant?

A27 Yes. Under clause 26 of the Clean Air Act

Memorandum provision is made, subject to

certain conditions, for certain fan diluted

emissions to be installed to discharge at a

height above ground that is below the roof

level of the building. Note, however, that

there remains a minimum height of 3m, (2m

if input is less than 1MW), above the ground,

elevated walkways, openable windows or

ventilation air intake grills in such

installations. (See sections 27 & 28 of the

If ‘x’ is less than 5U, based on the combined emission of stacks 1 to 5, then the dischargeheight for all 5 is based on the combined emission of stacks 1 to 5.

If ‘x’ is greater than 5U, based on the combined emission of stacks 1 to 5, then two individualsystems would apply, one based on the combined emission of stacks 1 to 3, and the other onthe combined emission of stacks 4 and 5.

Figure 6


11

Chimney Heights Memorandum). This

arrangement applies principally to gas fired

equipment and is restricted to relatively low

ratings because as the input rating increases

the size of intake and exhaust louvre can

become very large and impractical.

A common fault with such systems is

that the exhaust louvre is NOT set to

discharge at an angle of about 30° above the

horizontal as recommended in clause 27.f. of

the Memorandum. Failure to meet this

requirement means that the flue gas can be

entrained down the wall surface thus

preventing the dispersal of the pollutants and

increasing their concentration in the local

area, which defeats the intention of the

relaxation. See Figure 7.

Fan diluted flue systems should never be

permitted to discharge into an enclosed, or

almost enclosed, ‘well’ or courtyard.

Q28 Finally, are the calculations to determinea chimney discharge height difficult?

A28 Whilst the text so far may not give such an

impression, the calculations required for the

Clean Air Act Memorandum are actually

quite simple and straightforward. In addition

most of the results can be found by using the

alignment charts at the end of the

Memorandum, and we have included our

own simple tables at the end of this booklet,

which enable the chimney height to be

determined for 95% of Clean Air Act

Memorandum applications, i.e., where only

one building is to be considered.

The calculations required for the

Technical Guidance Note are more

complicated mathematically, but the results

can again be simply obtained from a set of

charts at the end of that booklet.

The final calculated discharge height should

be rounded to the nearest metre, always

rounded up in the case of D1.

At the end of each of the guides,

worked examples are given which are

also very helpful in determining the

calculation procedure.

In each case, the discharge heights

calculated using either of the above

methods, should be regarded as a guide,

rather than a mathematically precise

definition of the discharge stack height. The

conclusion may need to be modified in the

light of particular local circumstances or of

practical experience. (See clauses 29 & 30

of the Clean Air Act Memorandum).

Figure 7Louvre orientation on fan dilution systems

Diluted combustiongases

Drainage

Louvres should slope upwards atan angle of not less than 30° fromthe horizontal

Unobstructeddischargee.g. clear ofoverhang

Figure 7


The final chimney discharge height MUST always be approved by the approving authoritywhich in most cases is the local Environmental Health Department.

When carrying out calculations to either the Clean Air Act Memorandum or GuidanceNote D1, the various separation distances and building measurements should not betaken as exact or precise dimensions, but rather as a guide in each case.

It should always be borne in mind that the object of the exercise is to obtain an effectiveand safe chimney discharge height, rather than a minimum discharge height.

!

12

COMPUTER DISK

To accompany this booklet, Selkirk have a computer

disk which contains simple to use programs for all of

the calculations required in determining the

discharge height of a chimney.

Copies of the disk are available to consulting design

engineers free of charge direct from Selkirk’s

Marketing Services Department at Barnstaple.

Telephone 01271 334332.

Acknowledgments

Thanks are due to Dr. David Hall of the Building

Research Establishment for discussions on the

content of this document, and for his comments on

the draft.

Dr. Hall was involved with the Third Edition of the

Memorandum on Chimney Heights, was

responsible for the New Guidance Note D1 and

acts in an advisory capacity to both Environmental

Health Officers on behalf of the Air Quality Division,

DETR (Department of the Environment, Transport &

the Regions), and to the Environment Agency.

Thanks are also due to Barrie Meridew and Ken

Jess of Selkirk Ltd for the formulation and technical

supervision of this booklet.


1213

CALCULATION PROCESS(Clean Air Act Memorandum only)

For the majority of cases, (95%), where one

building is to be considered which is wider than

it is high, the tables on pages 18 to 25 can be

used to calculate the final chimney height.

1 Determine the uncorrected chimney height,

“U” from the appropriate fuel table,

bearing in mind that the appropriate area

category, (geographical location), should

be used where applicable. (See also A6 as

well as the area category list opposite).

2 If the uncorrected height, “U”, is less than

2.5 times the height of the building to which

it is attached or any other building within

5 U of the chimney, then the chimney

height should be increased as follows.

Otherwise the final chimney height remains

as “U”, and as is acceptable.

3 Consider all buildings within a radius 5 U

from the chimney position. If there is only

one obvious building to be considered as

described above, then the corrected

height, “C”, can be obtained from the

appropriate “corrected height” column in

the appropriate table. If there is more than

one building, then refer to the calculation

procedure in the Memorandum. If in any

doubt as to whether more than one

building should be considered, it is

preferable to complete the calculation for

more than one building as per the

Memorandum, as this may result in a lesser

chimney height than if only one building is

considered.

4 Consider the following overriding minimum

requirements and increase the chimney

height if appropriate.

● A chimney should terminate at least 3m

above the level of any adjacent area to

which there is general access, i.e.,

ground level, roof area, openable

window or ventilation intake grill.

(See also A20).

● A chimney should never be less than the

calculated uncorrected chimney height.

● A chimney should never be less than the

height of any part of an attached building

within a distance of 5 U. (See also A20).

The tables on page x are Selkirk copyrightand have been prepared using the followingdata:-

■ All Output ratings are 85% of input rating

■ Fuel Specification

35sec Oil - Cv (gross) = 45.6Mj/kg

Sulphur % = 0.3*

Heavy Oil- Cv (gross) = 42.9Mj/kg

Sulphur % = 3.5*

*maximum allowable by BS 2869

Area Categories (geographical location) as taken from Clause 17 of the Memorandum.

A an undeveloped area where development is

unlikely;

B a partially developed area with scattered

houses;

C a built-up residential area;

D an urban area of mixed industrial and

residential development;

E a large city or an urban area, of mixed

heavy industrial and dense residential

development;


14

Calculation examples

Example 1

55m

90º

18m

10mhigh

Figure 8

Chimney system comprisingthree individual chimneys ona triangular support mast, (or it could be one commonchimney serving all boilerplant).

Roof tank room 3m x 3mby 2,5m high.

Roof area is 1020m2

Illustration is not to scale.

Building height is always the highest point of the buildingmeasured from a datum of the ground level (see Q & A16).In this example the building height is 25m.

Building width is always thewidest face of the building at rightangles to the separation distance.In this example, the buildingwidth is 55m.

Chimneydischargeheightmeasured fromdatum of thegeneral groundlevel.See also theillustration for Q & A16.

Building separation distance is always a horizontal lineconnecting the closest point of the building to the centre ofthe chimney position. See also the illustration for Q & A16.In this example, the building separation distance is 18m.


15

1a Fuel - Natural Gas

Total output of three boilers = 5000kW

Efficiency ≅ 85%

∴ Total input = 5882kW

From Table A, the uncorrected height U = 3.9m

∴ 5 x U = 19.7m

The uncorrected height is less than 2.5 times the

building to which it is attached, (in this case the

boiler house), and any other building within 5 x U.

The chimney height will therefore require to be

corrected for building effect.

The separation distance from the centre of the

chimney to the closest point of the office block

= 18m.

As this separation distance is less than 5 x U and

the office block is the tallest building within a radius

of 5 x U from the chimney centre, the chimney

height will need to be corrected to take into

account the height of the office block.

The office block height is 25m. The additional

height of the of the roof tank room can be ignored,

as its area, (9m2), is less than 1% of the total office

block roof area, (1020 m2).

The office block width is measured along a line

which extends to capture the widest frontage facing

the chimney, (55m in this case), and which is

determined at right angles to another line drawn

from the centre of the chimney to the closest point

of the building. This other line denotes the

separation distance, which in this case is 18m.

As there is only one building to be considered; the

office block, and it is wider than it is high, then the

corrected height can be interpolated from Table D

as 27m.

Check that the overriding requirements of note 4

above, (Clause 25 of the Memorandum), are

satisfied. If no further adjustment is required, then

the Corrected Discharge Height = 27m above

ground level.

1b Fuel - 35sec. Oil

Total input as previous calculation = 5882kW.

From the Area Categories on page 13, select an

area type that best describes the location where

the boiler plant will be installed. For this example,

the Area Category is “D”.

From Table B, and Category “D”,

the uncorrected height U = 11.4m.

∴ 5 x U = 57.1m.

The uncorrected height is less than 2.5 times the

height of the building to which it is attached and

any other building within 5U. The chimney height

will therefore need “correction” for building effect.

The office block is still the tallest and most obvious

building within a radius of 5U from the centre of the

chimney.

The office block height, (25m), and width, (55m),

remain as previous, and the corrected height can

be interpolated from Table D as 32m.

Check overriding minimum requirements as

previous, and if further adjustment is not required,

the Corrected Discharge Height

= 32m above ground level.

The shaded sections in the tables on pages 18, 20

and 23, represent the data extracted for the above

sample calculations.


16

H20m

90º SDii

SDi

BuildingNo. 2

BuildingNo. 1

H15m

BW

CH

Example 2

This calculation is an example in which two

buildings are considered where two boilers are

served by individual chimneys on a common mast.

The example is best read step by step in

conjunction with the procedure set out in within the

Memorandum, as this will explain some of the

variable inputs used in the calculation, e.g. “D” ,

which is just one of the Area Categories.

Data

Total output = 20,466kW

Efficiency = 80%

Total input = 25,582kW

Fuel = 42.9Mj/kg

Sulphur content = 3.5%

Fuel usage - W = 25582 x 3600 = 2,146kg/hr

42.9 x 1000

SO2 Emission - R = 0.02 x 2146 x 3.5 = 150kg/hr

Figure 9

See Figures 3, 4 and 8 formore explanation of heightsand separating distances.

CH = Chimney Discharge Height.

BW = Building width of 58m.

SD i = Separating distance to Building No.1 of 45m.

SD ii = Separating distance to Building No.2 of 32m.

Illustration is not to scale.


17

1st Example

Area Category = “D” (Mixed industrial /residential)

Adjusted SO2 emission- Ra = 150 x 1.3 = 195 kg/hr

Uncorrected height = U x 1950.5 - 0.9 x 1950.67 = 39m

Two buildings within a radius of 5U to be

considered.

Building No. H W K T

1 20 6 6 29

2 15 58 15 37.5

Tm = 37.5

Hm = 20

U > Tm ∴ C = U

Chimney discharge height = 39m

Fuel Oil (0.3 and 3.5% Sulphur)

Pollutant Discharge rate (g/kg of fuel burned)

Generator Boiler

3.5% 0.3% 3.5% 0.3%

Sulphur Sulphur Sulphur Sulphur

Sulphur Dioxide (S02) 70 6 70 6

Nitric Oxide (NO) 22 3.2

Nitrogen Dioxide (NO2) 3 0.23

2nd Example

Area Category = “C” (Residential area)

Adjusted SO2 emission - Ra = 150 x 1 = 150 kg/hr

U = 5 x 1500.5 - 0.9 x 1500.67 = 35.4m

Building No. H W K T

1 20 6 6 29

2 15 58 15 37.5

Tm = 37.5

Hm = 20

C = Hm + U 1 -

C = 20 + 35.4 1 - = 36.5m

Chimney discharge height = 37m

Typical Pollutant Values for generators and boilers.

Gas

Pollutant Discharge rate (g/m3 of fuel burned)

Generator Boiler

Sulphur Dioxide (S02) N/A N/A

Nitric Oxide (NO) 9 3

Nitrogen Dioxide (NO2) 1 0.02

Hm

Tm( )20

37.5( )


18

Table D Uncorrected Chimney Height (U) for a range of Input/Output ratingsTable

Natural Gas

A

Shaded area relates to input for sample calculation 1a

Output Kw Input Kw U 5 x U Output Kw Input Kw U 5 x U

125 147 0.4 2.2 4,800 5,647 3.8 19.2150 176 0.5 2.4 4.900 5,765 3.9 19.5200 235 0.6 2.9 5,000 5,882 3.9 19.7250 294 0.7 3.3 5,100 6,000 4.0 19.9300 353 0.7 3.6 5,200 6,118 4.0 20.2350 412 0.8 4.0 5,300 6,235 4.1 20.4400 471 0.9 4.3 5,400 6,353 4.1 20.6450 529 0.9 4.6 5,500 6,471 4.2 20.8500 588 1.0 4.9 5,600 6,588 4.2 21.1600 706 1.1 5.5 5,700 6,706 4.3 21.3700 824 1.2 6.1 5,800 6,824 4.3 21.5800 941 1.3 6.6 5,900 6,941 4.3 21.7900 1,059 1.4 7.0 6,000 7,059 4.4 22.0

1,000 1,176 1.5 7.5 6,100 7,176 4.4 22.21,100 1,294 1.6 7.9 6,200 7,294 4.5 22.41,200 1,412 1.7 8.4 6,300 7,412 4.5 22.61,300 1,529 1.8 8.8 6,400 7,529 4.6 22.81,400 1,647 1.8 9.2 6,500 7,647 4.6 23.01,500 1,765 1.9 9.6 6,600 7,765 4.7 23.31,600 1,882 2.0 9.9 6,700 7,882 4.7 23.51,700 2,000 2.1 10.3 6,800 8,000 4.7 23.71,800 2,118 2.1 10.7 6,900 8,118 4.8 23.91,900 2,235 2.2 11.0 7,000 8,235 4.8 24.12,000 2,353 2.3 11.4 7,100 8,353 4.9 24.32,100 2,471 2.3 11.7 7,200 8,471 4.9 24.52,200 2,588 2.4 12.0 7,300 8,588 4.9 24.72,300 2,706 2.5 12.4 7,400 8,706 5.0 24.92,400 2,824 2.5 12.7 7,500 8,824 5.0 25.12,500 2,941 2.6 13.0 7,600 8,941 5.1 25.32,600 3,059 2.7 13.3 7,700 9,059 5.1 25.52,700 3,176 2.7 13.6 7,800 9,176 5.1 25.72,800 3,294 2.8 13.9 7,900 9,294 5.2 25.92,900 3,412 2.8 14.2 8,000 9,412 5.2 26.13,000 3,529 2.9 14.5 8,100 9,529 5.3 26.33,100 3,647 3.0 14.8 8,200 9,647 5.3 26.53,200 3,765 3.0 15.1 8,300 9,765 5.3 26.73,300 3,882 3.1 15.3 8,400 9,882 5.4 26.93,400 4,000 3.1 15.6 8,500 10,000 5.4 27.13,500 4,118 3.2 15.9 8,600 10,118 5.5 27.33,600 4,235 3.2 16.2 8,700 10,235 5.5 27.53,700 4,353 3.3 16.4 8,900 10,353 5.5 27.63,800 4,471 3.3 16.7 9,000 10,588 5.6 28.03,900 4,588 3.4 17.0 9,100 10,706 5.6 28.24,000 4,706 3.4 17.2 9,200 10,824 5.7 28.44,100 4,824 3.5 17.5 9,300 10,941 5.7 28.64,200 4,941 3.5 17.7 9,400 11,059 5.8 28.84,300 5,059 3.6 18.0 9,500 11,176 5.8 28.94,400 5,176 3.6 18.2 9,600 11,294 5.8 29.14,500 5,294 3.7 18.5 9,700 11,412 5.9 29.34,600 5,412 3.7 18.7 9,800 11,529 5.9 29.54,700 5,529 3.8 19.0 10,000 11,765 6.0 29.8


Area Category A B C D E

Output InputkW kW U 5 x U U 5 x U U 5 x U U 5 x U U 5 x U

125 147 1.2 5.9 1.4 7.0 1.6 7.9 1.8 9.0 2.0 10.0150 176 1.3 6.4 1.5 7.7 1.7 8.7 2.0 9.9 2.2 11.0200 235 1.5 7.4 1.8 8.8 2.0 10.0 2.3 11.4 2.5 12.7250 294 1.7 8.3 2.0 9.9 2.2 11.2 2.6 12.8 2.8 14.2300 353 1.8 9.1 2.2 10.8 2.5 12.3 2.8 14.0 3.1 15.5350 412 2.0 9.8 2.3 11.7 2.6 13.2 3.0 15.1 3.4 16.8400 471 2.1 10.5 2.5 12.5 2.8 14.2 3.2 16.1 3.6 17.9450 529 2.2 11.1 2.7 13.3 3.0 15.0 3.4 17.1 3.8 19.0500 588 2.3 11.7 2.8 14.0 3.2 15.8 3.6 18.1 4.0 20.0600 706 2.6 12.9 3.1 15.3 3.5 17.3 4.0 19.8 4.4 21.9700 824 2.8 13.9 3.3 16.5 3.7 18.7 4.3 21.4 4.7 23.7800 941 3.0 14.9 3.5 17.7 4.0 20.0 4.6 22.8 5.1 25.3900 1,059 3.2 15.8 3.8 18.8 4.2 21.2 4.8 24.2 5.4 26.9

1,000 1,176 3.3 16.6 4.0 19.8 4.5 22.4 5.1 25.5 5.7 28.31,100 1,294 3.5 17.4 4.1 20.7 4.7 23.5 5.4 26.8 5.9 29.71,200 1,412 3.6 18.2 4.3 21.7 4.9 24.5 5.6 28.0 6.2 31.01,300 1,529 3.8 18.9 4.5 22.6 5.1 25.5 5.8 29.1 6.5 32.31,400 1,647 3.9 19.7 4.7 23.4 5.3 26.5 6.0 30.2 6.7 33.51,500 1,765 4.1 20.3 4.8 24.2 5.5 27.4 6.3 31.3 6.9 34.71,600 1,882 4.2 21.0 5.0 25.0 5.7 28.3 6.5 32.3 7.2 35.81,700 2,000 4.3 21.7 5.2 25.8 5.8 29.2 6.7 33.3 7.4 36.91,800 2,118 4.5 22.3 5.3 26.5 6.0 30.0 6.9 34.3 7.6 38.01,900 2,235 4.6 22.9 5.5 27.3 6.2 30.9 7.0 35.2 7.8 39.02,000 2,353 4.7 23.5 5.6 28.0 6.3 31.7 7.2 36.1 8.0 40.12,100 2,471 4.8 24.1 5.7 28.7 6.5 32.5 7.4 37.0 8.2 41.12,200 2,588 4.9 24.6 5.9 29.3 6.6 33.2 7.6 37.9 8.4 42.02,300 2,706 5.0 25.2 6.0 30.0 6.8 34.0 7.7 38.7 8.6 43.02,400 2,824 5.1 25.7 6.1 30.6 6.9 34.7 7.9 39.6 8.8 43.92,500 2,941 5.3 26.3 6.3 31.3 7.1 35.4 8.1 40.4 9.0 44.82,600 3,059 5.4 26.8 6.4 31.9 7.2 36.1 8.2 41.2 9.1 45.72,700 3,176 5.5 27.3 6.5 32.5 7.4 36.8 8.4 42.0 9.3 46.52,800 3,294 5.6 27.8 6.6 33.1 7.5 37.5 8.5 42.7 9.5 47.42,900 3,412 5.7 28.3 6.7 33.7 7.6 38.1 8.7 43.5 9.6 48.23,000 3,529 5.8 28.8 6.9 34.3 7.8 38.8 8.8 44.2 9.8 49.13,100 3,647 5.8 29.2 7.0 34.8 7.9 39.4 9.0 45.0 10.0 49.93,200 3,765 5.9 29.7 7.1 35.4 8.0 40.1 9.1 45.7 10.1 50.73,300 3,882 6.0 30.2 7.2 35.9 8.1 40.7 9.3 46.4 10.3 51.53,400 4,000 6.1 30.6 7.3 36.5 8.3 41.3 9.4 47.1 10.4 52.23,500 4,118 6.2 31.1 7.4 37.0 8.4 41.9 9.6 47.8 10.6 53.03,600 4,235 6.3 31.5 7.5 37.5 8.5 42.5 9.7 48.4 10.7 53.73,700 4,353 6.4 31.9 7.6 38.0 8.6 43.1 9.8 49.1 10.9 54.53,800 4,471 6.5 32.4 7.7 38.6 8.7 43.7 10.0 49.8 11.0 55.23,900 4,588 6.6 32.8 7.8 39.1 8.8 44.2 10.1 50.4 11.2 55.94,000 4,706 6.6 33.2 7.9 39.6 9.0 44.8 10.2 51.1 11.3 56.74,100 4,824 6.7 33.6 8.0 40.0 9.1 45.3 10.3 51.7 11.5 57.44,200 4,941 6.8 34.0 8.1 40.5 9.2 45.9 10.5 52.3 11.6 58.14,300 5,059 6.9 34.4 8.2 41.0 9.3 46.4 10.6 52.9 11.7 58.74,400 5,176 7.0 34.8 8.3 41.5 9.4 47.0 10.7 53.6 11.9 59.44,500 5,294 7.0 35.2 8.4 42.0 9.5 47.5 10.8 54.2 12.0 60.14,600 5,412 7.1 35.6 8.5 42.4 9.6 48.0 11.0 54.8 12.2 60.84,700 5,529 7.2 36.0 8.6 42.9 9.7 48.6 11.1 55.4 12.3 61.4

19

Table D Uncorrected Chimney Height (U) for a range of Input/Output ratings

35sec. Oil CV (gross) 45.6Mj/kg Sulphur % = 0.31st of 2 pages

U and 5 U by Area Category

Table B




4,800 5,647 7.3 36.4 8.7 43.3 9.8 49.1 11.2 55.9 12.4 62.14,900 5,765 7.4 36.8 8.8 43.8 9.9 49.6 11.3 56.5 12.5 62.75,000 5,882 7.4 37.1 8.8 44.2 10.0 50.1 11.4 57.1 12.7 63.35,100 6,000 7.5 37.5 8.9 44.7 10.1 50.6 11.5 57.7 12.8 64.05,200 6,118 7.6 37.9 9.0 45.1 10.2 51.1 11.6 58.2 12.9 64.65,300 6,235 7.6 38.2 9.1 45.5 10.3 51.6 11.8 58.8 13.0 65.25,400 6,353 7.7 38.6 9.2 46.0 10.4 52.0 11.9 59.3 13.2 65.85,500 6,471 7.8 39.0 9.3 46.4 10.5 52.5 12.0 59.9 13.3 66.45,600 6,588 7.9 39.3 9.4 46.8 10.6 53.0 12.1 60.4 13.4 67.05,700 6,706 7.9 39.7 9.4 47.2 10.7 53.5 12.2 61.0 13.5 67.65,800 6,824 8.0 40.0 9.5 47.6 10.8 53.9 12.3 61.5 13.6 68.25,900 6,941 8.1 40.3 9.6 48.0 10.9 54.4 12.4 62.0 13.8 68.86,000 7,059 8.1 40.7 9.7 48.4 11.0 54.9 12.5 62.5 13.9 69.46,100 7,176 8.2 41.0 9.8 48.9 11.1 55.3 12.6 63.1 14.0 70.06,200 7,294 8.3 41.4 9.8 49.2 11.2 55.8 12.7 63.6 14.1 70.56,300 7,412 8.3 41.7 9.9 49.6 11.2 56.2 12.8 64.1 14.2 71.16,400 7,529 8.4 42.0 10.0 50.0 11.3 56.7 12.9 64.6 14.3 71.76,500 7,647 8.5 42.3 10.1 50.4 11.4 57.1 13.0 65.1 14.4 72.26,600 7,765 8.5 42.7 10.2 50.8 11.5 57.5 13.1 65.6 14.6 72.86,700 7,882 8.6 43.0 10.2 51.2 11.6 58.0 13.2 66.1 14.7 73.36,800 8,000 8.7 43.3 10.3 51.6 11.7 58.4 13.3 66.6 14.8 73.96,900 8,118 8.7 43.6 10.4 52.0 11.8 58.8 13.4 67.1 14.9 74.47,000 8,235 8.8 43.9 10.5 52.3 11.9 59.3 13.5 67.6 15.0 74.97,100 8,353 8.9 44.3 10.5 52.7 11.9 59.7 13.6 68.0 15.1 75.57,200 8,471 8.9 44.6 10.6 53.1 12.0 60.1 13.7 68.5 15.2 76.07,300 8,588 9.0 44.9 10.7 53.4 12.1 60.5 13.8 69.0 15.3 76.57,400 8,706 9.0 45.2 10.8 53.8 12.2 60.9 13.9 69.5 15.4 77.17,500 8,824 9.1 45.5 10.8 54.2 12.3 61.3 14.0 69.9 15.5 77.67,600 8,941 9.2 45.8 10.9 54.5 12.3 61.7 14.1 70.4 15.6 78.17,700 9,059 9.2 46.1 11.0 54.9 12.4 62.1 14.2 70.9 15.7 78.67,800 9,176 9.3 46.4 11.0 55.2 12.5 62.5 14.3 71.3 15.8 79.17,900 9,294 9.3 46.7 11.1 55.6 12.6 62.9 14.4 71.8 15.9 79.68,000 9,412 9.4 47.0 11.2 55.9 12.7 63.3 14.4 72.2 16.0 80.18,100 9,529 9.5 47.3 11.3 56.3 12.7 63.7 14.5 72.7 16.1 80.68,200 9,647 9.5 47.6 11.3 56.6 12.8 64.1 14.6 73.1 16.2 81.18,300 9,765 9.6 47.8 11.4 57.0 12.9 64.5 14.7 73.6 16.3 81.68,400 9,882 9.6 48.1 11.5 57.3 13.0 64.9 14.8 74.0 16.4 82.18,500 10,000 9.7 48.4 11.5 57.7 13.1 65.3 14.9 74.4 16.5 82.68,600 10,118 9.7 48.7 11.6 58.0 13.1 65.7 15.0 74.9 16.6 83.18,700 10,235 9.8 49.0 11.7 58.3 13.2 66.1 15.1 75.3 16.7 83.68,800 10,353 9.9 49.3 11.7 58.7 13.3 66.4 15.1 75.7 16.8 84.09,000 10,588 10.0 49.8 11.9 59.3 13.4 67.2 15.3 76.6 17.0 85.09,100 10,706 10.0 50.1 11.9 59.7 13.5 67.6 15.4 77.0 17.1 85.59,200 10,824 10.1 50.4 12.0 60.0 13.6 67.9 15.5 77.5 17.2 85.99,300 10,941 10.1 50.6 12.1 60.3 13.7 68.3 15.6 77.9 17.3 86.49,400 11,059 10.2 50.9 12.1 60.6 13.7 68.7 15.7 78.3 17.4 86.99,500 11,176 10.2 51.2 12.2 61.0 13.8 69.0 15.7 78.7 17.5 87.39,600 11,294 10.3 51.5 12.3 61.3 13.9 69.4 15.8 79.1 17.6 87.89,700 11,412 10.3 51.7 12.3 61.6 13.9 69.7 15.9 79.5 17.6 88.29,800 11,529 10.4 52.0 12.4 61.9 14.0 70.1 16.0 79.9 17.7 88.7

10,000 11,765 10.5 52.5 12.5 62.5 14.2 70.8 16.1 80.7 17.9 89.6

Shaded area relates to input for sample calculation 1b

35sec. Oil CV (gross) 45.6Mj/kg Sulphur % = 0.3

20


2nd of 2 pages

Table B





5,000 5,882 21.6 108.1 23.2 115.9 24.4 121.9 25.7 128.4 26.8 133.9

5,200 6,118 21.8 109.0 23.4 116.9 24.6 122.8 25.9 129.4 27.0 134.9

5,400 6,353 22.0 109.8 23.5 117.7 24.7 123.7 26.1 130.4 27.2 135.9

5,600 6,588 22.1 110.6 23.7 118.6 24.9 124.7 26.3 131.4 27.4 136.9

5,800 6,824 22.3 111.4 23.9 119.4 25.1 125.5 26.5 132.3 27.6 137.9

6,000 7,059 22.4 112.1 24.1 120.3 25.3 126.4 26.6 133.2 27.8 138.8

6,200 7,294 22.6 112.9 24.2 121.0 25.4 127.2 26.8 134.1 28.0 139.8

6,400 7,529 22.7 113.6 24.4 121.8 25.6 128.0 27.0 134.9 28.1 140.6

6,600 7,765 22.9 114.3 24.5 122.6 25.8 128.8 27.2 135.8 28.3 141.5

6,800 8,000 23.0 115.0 24.7 123.3 25.9 129.6 27.3 136.6 28.5 142.4

7,000 8,235 23.1 115.7 24.8 124.0 26.1 130.3 27.5 137.4 28.6 143.2

7,200 8,471 23.3 116.3 24.9 124.7 26.2 131.1 27.6 138.1 28.8 144.0

7,400 8,706 23.4 116.9 25.1 125.4 26.4 131.8 27.8 138.9 29.0 144.8

7,600 8,941 23.5 117.6 25.2 126.1 26.5 132.5 27.9 139.6 29.1 145.6

7,800 9,176 23.6 118.2 25.3 126.7 26.6 133.2 28.1 140.4 29.3 146.3

8,000 9,412 23.8 118.8 25.5 127.4 26.8 133.9 28.2 141.1 29.4 147.1

8,200 9,647 23.9 119.4 25.6 128.0 26.9 134.5 28.4 141.8 29.6 147.8

8,400 9,882 24.0 119.9 25.7 128.6 27.0 135.2 28.5 142.5 29.7 148.5

8,600 10,118 24.1 120.5 25.8 129.2 27.2 135.8 28.6 143.1 29.8 149.2

8,800 10,353 24.2 121.1 26.0 129.8 27.3 136.4 28.8 143.8 30.0 149.9

9,000 10,588 24.3 121.6 26.1 130.4 27.4 137.1 28.9 144.4 30.1 150.6

9,200 10,824 24.4 122.1 26.2 131.0 27.5 137.7 29.0 145.1 30.5 152.6

9,400 11,059 24.5 122.7 26.3 131.6 27.7 138.3 29.1 145.7 30.8 153.8

9,600 11,294 24.6 123.2 26.4 132.1 27.8 138.8 29.3 146.3 31.0 155.1

9,800 11,529 24.7 123.7 26.5 132.7 27.9 139.4 29.4 146.9 31.3 156.4

10,000 11,765 24.8 124.2 26.6 133.2 28.0 140.0 29.5 147.5 31.5 157.6

10,200 12,000 24.9 124.7 26.7 133.7 28.1 140.5 29.6 148.1 31.8 158.8

10,400 12,235 25.0 125.2 26.8 134.2 28.2 141.1 29.7 148.7 32.0 160.0

10,600 12,471 25.1 125.7 27.0 134.8 28.3 141.6 29.8 149.2 32.2 161.2

10,800 12,706 25.2 126.1 27.1 135.3 28.4 142.1 30.0 149.8 32.5 162.3

11,000 12,941 25.3 126.6 27.2 135.8 28.5 142.7 30.1 150.4 32.7 163.5

11,200 13,176 25.4 127.0 27.2 136.2 28.6 143.2 30.4 151.9 32.9 164.6

11,400 13,412 25.5 127.5 27.3 136.7 28.7 143.7 30.6 153.0 33.1 165.7

11,600 13,647 25.6 127.9 27.4 137.2 28.8 144.2 30.8 154.0 33.4 166.8

11,800 13,882 25.7 128.4 27.5 137.7 28.9 144.7 31.0 155.0 33.6 167.9

12,000 14,118 25.8 128.8 27.6 138.1 29.0 145.2 31.2 156.0 33.8 169.0

12,200 14,353 25.8 129.2 27.7 138.6 29.1 145.7 31.4 157.0 34.0 170.0

12,400 14,588 25.9 129.7 27.8 139.0 29.2 146.1 31.6 158.0 34.2 171.1

12,600 14,824 26.0 130.1 27.9 139.5 29.3 146.6 31.8 159.0 34.4 172.1

12,800 15,059 26.1 130.5 28.0 139.9 29.4 147.1 32.0 160.0 34.6 173.2

13,000 15,294 26.2 130.9 28.1 140.4 29.5 147.5 32.2 160.9 34.8 174.2

13,200 15,529 26.3 131.3 28.2 140.8 29.6 148.0 32.4 161.9 35.0 175.2

13,400 15,765 26.3 131.7 28.2 141.2 29.7 148.4 32.6 162.8 35.2 176.2

13,600 16,000 26.4 132.1 28.3 141.6 29.8 148.9 32.7 163.7 35.4 177.2

13,800 16,235 26.5 132.5 28.4 142.1 29.9 149.3 32.9 164.7 35.6 178.1

14,000 16,471 26.6 132.8 28.5 142.5 29.9 149.7 33.1 165.6 35.8 179.1

14,200 16,706 26.6 133.2 28.6 142.9 30.0 150.1 33.3 166.5 36.0 180.1

14,400 16,941 26.7 133.6 28.7 143.3 30.1 150.6 33.5 167.4 36.2 181.0

14,600 17,176 26.8 134.0 28.7 143.7 30.4 152.1 33.6 168.2 36.4 181.9

14,800 17,412 26.9 134.3 28.8 144.1 30.6 152.9 33.8 169.1 36.6 182.9

15,000 17,647 26.9 134.7 28.9 144.4 30.7 153.7 34.0 170.0 36.8 183.8

21


1st of 2 pages Heavy Oil CV (gross) 42.9Mj/kg Sulphur % = 3.5


Table C




15,200 17882 27.0 135.1 29.0 144.8 30.9 154.5 34.2 170.8 36.9 184.715,400 18118 27.1 135.4 29.0 145.2 31.1 155.3 34.3 171.7 37.1 185.615,600 18353 27.2 135.8 29.1 145.6 31.2 156.0 34.5 172.5 37.3 186.515,800 18588 27.2 136.1 29.2 146.0 31.4 156.8 34.7 173.4 37.5 187.416,000 18824 27.3 136.4 29.3 146.3 31.5 157.6 34.8 174.2 37.6 188.216,200 19059 27.4 136.8 29.3 146.7 31.7 158.3 35.0 175.0 37.8 189.116,400 19294 27.4 137.1 29.4 147.0 31.8 159.1 35.2 175.8 38.0 190.016,600 19529 27.5 137.5 29.5 147.4 32.0 159.8 35.3 176.6 38.2 190.816,800 19765 27.6 137.8 29.6 147.8 32.1 160.6 35.5 177.4 38.3 191.717,000 20000 27.6 138.1 29.6 148.1 32.3 161.3 35.6 178.2 38.5 192.517,200 20235 27.7 138.4 29.7 148.5 32.4 162.0 35.8 179.0 38.7 193.317,400 20471 27.8 138.8 29.8 148.8 32.5 162.7 36.0 179.8 38.8 194.117,600 20706 27.8 139.1 29.8 149.1 32.7 163.5 36.1 180.5 39.0 195.017,800 20941 27.9 139.4 29.9 149.5 32.8 164.2 36.3 181.3 39.2 195.818,000 21176 27.9 139.7 30.0 149.8 33.0 164.9 36.4 182.1 39.3 196.618,200 21412 28.0 140.0 30.0 150.1 33.1 165.6 36.6 182.8 39.5 197.418,400 21647 28.1 140.3 30.1 150.5 33.3 166.3 36.7 183.6 39.6 198.118,600 21882 28.1 140.6 30.3 151.7 33.4 167.0 36.9 184.3 39.8 198.919,000 22353 28.2 141.2 30.6 153.0 33.7 168.3 37.2 185.8 40.1 200.519,200 22588 28.3 141.5 30.7 153.6 33.8 169.0 37.3 186.5 40.2 201.219,400 22824 28.4 141.8 30.8 154.2 33.9 169.7 37.4 187.2 40.4 202.019,600 23059 28.4 142.1 31.0 154.8 34.1 170.3 37.6 187.9 40.5 202.719,800 23294 28.5 142.4 31.1 155.4 34.2 171.0 37.7 188.6 40.7 203.520,000 23529 28.5 142.7 31.2 156.0 34.3 171.6 37.9 189.3 40.8 204.220,200 23765 28.6 143.0 31.3 156.6 34.5 172.3 38.0 190.0 41.0 205.020,400 24000 28.6 143.2 31.4 157.2 34.6 172.9 38.1 190.7 41.1 205.720,600 24235 28.7 143.5 31.6 157.8 34.7 173.6 38.3 191.4 41.3 206.420,800 24471 28.8 143.8 31.7 158.4 34.8 174.2 38.4 192.1 41.4 207.121,000 24706 28.8 144.1 31.8 159.0 35.0 174.8 38.6 192.8 41.6 207.821,200 24941 28.9 144.3 31.9 159.6 35.1 175.4 38.7 193.4 41.7 208.521,400 25176 28.9 144.6 32.0 160.2 35.2 176.1 38.8 194.1 41.8 209.221,600 25412 29.0 144.9 32.1 160.7 35.3 176.7 39.0 194.8 42.0 209.921,800 25647 29.0 145.2 32.3 161.3 35.5 177.3 39.1 195.4 42.1 210.622,000 25882 29.1 145.4 32.4 161.9 35.6 177.9 39.2 196.1 42.3 211.322,200 26118 29.1 145.7 32.5 162.4 35.7 178.5 39.3 196.7 42.4 212.022,400 26353 29.2 145.9 32.6 163.0 35.8 179.1 39.5 197.4 42.5 212.722,600 26588 29.2 146.2 32.7 163.6 35.9 179.7 39.6 198.0 42.7 213.423,000 27059 29.3 146.7 32.9 164.7 36.2 180.9 39.9 199.3 42.9 214.723,200 27294 29.4 147.0 33.0 165.2 36.3 181.5 40.0 199.9 43.1 215.323,400 27529 29.4 147.2 33.2 165.8 36.4 182.1 40.1 200.5 43.2 216.023,600 27765 29.5 147.5 33.3 166.3 36.5 182.6 40.2 201.1 43.3 216.623,800 28000 29.5 147.7 33.4 166.8 36.6 183.2 40.4 201.8 43.5 217.324,000 28235 29.6 148.0 33.5 167.4 36.8 183.8 40.5 202.4 43.6 217.924,200 28471 29.6 148.2 33.6 167.9 36.9 184.4 40.6 203.0 43.7 218.624,400 28706 29.7 148.5 33.7 168.4 37.0 184.9 40.7 203.6 43.8 219.224,600 28941 29.7 148.7 33.8 168.9 37.1 185.5 40.8 204.2 44.0 219.824,800 29176 29.8 148.9 33.9 169.5 37.2 186.0 41.0 204.8 44.1 220.525,000 29412 29.8 149.2 34.0 170.0 37.3 186.6 41.1 205.4 44.2 221.126,200 30824 30.1 150.6 34.6 173.0 38.0 189.9 41.8 208.9 44.9 224.725,400 29882 29.9 149.7 34.2 171.0 37.5 187.7 41.3 206.5 44.5 222.325,600 30118 30.0 149.9 34.3 171.5 37.6 188.2 41.4 207.1 44.6 222.925,800 30353 30.0 150.1 34.4 172.0 37.8 188.8 41.5 207.7 44.7 223.526,000 30588 30.1 150.4 34.5 172.5 37.9 189.3 41.7 208.3 44.8 224.1

22

2nd of 2 pages


Heavy Oil CV (gross) 42.9Mj/kg Sulphur % = 3.5


Table C


0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 14 14.5 15

H

6 7 7 7 8 8 8 8 9 9 9 10 10 10 11 11 11 11 12

8 9 9 9 10 10 10 10 11 11 11 12 12 12 13 13 13 13 14

10 11 11 11 12 12 12 12 13 13 13 14 14 14 15 15 15 15 16

12 13 13 13 14 14 14 14 15 15 15 16 16 16 17 17 17 17 18

14 15 15 15 16 16 16 16 17 17 17 18 18 18 19 19 19 19 20

16 17 17 17 18 18 18 18 19 19 19 20 20 20 21 21 21 21 22

18 19 19 19 20 20 20 20 21 21 21 22 22 22 23 23 23 23 24

20 21 21 21 22 22 22 22 23 23 23 24 24 24 25 25 25 25 26

22 23 23 23 24 24 24 24 25 25 25 26 26 26 27 27 27 27 28

24 25 25 25 26 26 26 26 27 27 27 28 28 28 29 29 29 29 30

26 27 27 27 28 28 28 28 29 29 29 30 30 30 31 31 31 31 32

28 29 29 29 30 30 30 30 31 31 31 32 32 32 33 33 33 33 34

30 31 31 31 32 32 32 32 33 33 33 34 34 34 35 35 35 35 36

32 33 33 33 34 34 34 34 35 35 35 36 36 36 37 37 37 37 38

34 35 35 35 36 36 36 36 37 37 37 38 38 38 39 39 39 39 40

36 37 37 37 38 38 38 38 39 39 39 40 40 40 41 41 41 41 42

38 39 39 39 40 40 40 40 41 41 41 42 42 42 43 43 43 43 44

40 41 41 41 42 42 42 42 43 43 43 44 44 44 45 45 45 45 46

42 43 43 43 44 44 44 44 45 45 45 46 46 46 47 47 47 47 48

44 45 45 45 46 46 46 46 47 47 47 48 48 48 49 49 49 49 50

46 47 47 47 48 48 48 48 49 49 49 50 50 50 51 51 51 51 52

48 49 49 49 50 50 50 50 51 51 51 52 52 52 53 53 53 53 54

50 51 51 51 52 52 52 52 53 53 53 54 54 54 55 55 55 55 56

12 12 13 13 13 14 14 14 14 15 15

14 14 15 15 15 16 16 16 16 17 17

16 16 17 17 17 18 18 18 18 19 19

18 18 19 19 19 20 20 20 20 21 21

20 20 21 21 21 22 22 22 22 23 23

22 22 23 23 23 24 24 24 24 25 25

24 24 25 25 25 26 26 26 26 27 27

26 26 27 27 27 28 28 28 28 29 29

28 28 29 29 29 30 30 30 30 31 31

30 30 31 31 31 32 32 32 32 33 33

32 32 33 33 33 34 34 34 34 35 35

34 34 35 35 35 36 36 36 36 37 37

36 36 37 37 37 38 38 38 38 39 39

38 38 39 39 39 40 40 40 40 41 41

40 40 41 41 41 42 42 42 42 43 43

42 42 43 43 43 44 44 44 44 45 45

44 44 45 45 45 46 46 46 46 47 47

46 46 47 47 47 48 48 48 48 49 49

48 48 49 49 49 50 50 50 50 51 51

50 50 51 51 51 52 52 52 52 53 53

52 52 53 53 53 54 54 54 54 55 55

54 54 55 55 55 56 56 56 56 57 57

56 56 57 57 57 58 58 58 58 59 59

23

Uncorrected height ‘U’

Table D Corrected height (c) for a range of U and building height (H)

Based on C = H + 0.6 x U (See clause 23 of Memorandum)

Shaded area relates to inputfor sample calculation 1a

Shaded area relatesto input for samplecalculation 1b

H = the building height in metres measured to its ridge or highest point, ignoring lift or tank rooms, or any other projection having an area of less than 1% of the roof area

Table D

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48

50


25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30

25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30

25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30

27 27 28 28 28 29 29 29 29 30 30

29 29 30 30 30 31 31 31 31 32 32

31 31 32 32 32 33 33 33 33 34 34

33 33 34 34 34 35 35 35 35 36 36

35 35 36 36 36 37 37 37 37 38 38

37 37 38 38 38 39 39 39 39 40 40

39 39 40 40 40 41 41 41 41 42 42

41 41 42 42 42 43 43 43 43 44 44

43 43 44 44 44 45 45 45 45 46 46

45 45 46 46 46 47 47 47 47 48 48

47 47 48 48 48 49 49 49 49 50 50

49 49 50 50 50 51 51 51 51 52 52

51 51 52 52 52 53 53 53 53 54 54

53 53 54 54 54 55 55 55 55 56 56

55 55 56 56 56 57 57 57 57 58 58

57 57 58 58 58 59 59 59 59 60 60

59 59 60 60 60 61 61 61 61 62 62

61 61 62 62 62 63 63 63 63 64 64

63 63 64 64 64 65 65 65 65 66 66

65 65 66 66 66 67 67 67 67 68 68

H

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48

50

24

15.5 16 16.5 17 17.5 18 18.5 19 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5

17 18 18 18 19 19 19 19 20 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5

19 20 20 20 21 21 21 21 22 22 22 23 23 23 24 24 24 24 25

21 22 22 22 23 23 23 23 24 24 24 25 25 25 26 26 26 26 27

23 24 24 24 25 25 25 25 26 26 26 27 27 27 28 28 28 28 29

25 26 26 26 27 27 27 27 28 28 28 29 29 29 30 30 30 30 31

27 28 28 28 29 29 29 29 30 30 30 31 31 31 32 32 32 32 33

29 30 30 30 31 31 31 31 32 32 32 33 33 33 34 34 34 34 35

31 32 32 32 33 33 33 33 34 34 34 35 35 35 36 36 36 36 37

33 34 34 34 35 35 35 35 36 36 36 37 37 37 38 38 38 38 39

35 36 36 36 37 37 37 37 38 38 38 39 39 39 40 40 40 40 41

37 38 38 38 39 39 39 39 40 40 40 41 41 41 42 42 42 42 43

39 40 40 40 41 41 41 41 42 42 42 43 43 43 44 44 44 44 45

41 42 42 42 43 43 43 43 44 44 44 45 45 45 46 46 46 46 47

43 44 44 44 45 45 45 45 46 46 46 47 47 47 48 48 48 48 49

45 46 46 46 47 47 47 47 48 48 48 49 49 49 50 50 50 50 51

47 48 48 48 49 49 49 49 50 50 50 51 51 51 52 52 52 52 53

49 50 50 50 51 51 51 51 52 52 52 53 53 53 54 54 54 54 55

51 52 52 52 53 53 53 53 54 54 54 55 55 55 56 56 56 56 57

53 54 54 54 55 55 55 55 56 56 56 57 57 57 58 58 58 58 59

55 56 56 56 57 57 57 57 58 58 58 59 59 59 60 60 60 60 61

57 58 58 58 59 59 59 59 60 60 60 61 61 61 62 62 62 62 63

59 60 60 60 61 61 61 61 62 62 62 63 63 63 64 64 64 64 65

15.5 16 16.5 17 17.5 18 18.5 19 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5 25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30

In the shaded area, C = U because U>2.5 x H(See clause 21 and 25b of the Memorandum)




Table E



30.5 31 31.5 32 32.5 33 33.5 34 34.5 35 35.5 36 36.5 37 37.5 38 38.5 39 39.5 40

25

In the shaded area, C = U because U>2.5 x H(See clause 21 and 25b of the Memorandum)


30.5 31 31.5 32 32.5 33 33.5 34 34.5 35 35.5 36 36.5 37 37.5 38 38.5 39 39.5 40

30.5 31 31.5 32 32.5 33 33.5 34 34.5 35 35.5 36 36.5 37 37.5 38 38.5 39 39.5 40

30.5 31 31.5 32 32.5 33 33.5 34 34.5 35 35.5 36 36.5 37 37.5 38 38.5 39 39.5 40

30.5 31 31.5 32 32.5 33 33.5 34 34.5 35 35.5 36 36.5 37 37.5 38 38.5 39 39.5 40

32 33 33 33 34 34 34 34 35 35 35.5 36 36.5 37 37.5 38 38.5 39 39.5 40

34 35 35 35 36 36 36 36 37 37 37 38 38 38 39 39 39 39 40 40

36 37 37 37 38 38 38 38 39 39 39 40 40 40 41 41 41 41 42 42

38 39 39 39 40 40 40 40 41 41 41 42 42 42 43 43 43 43 44 44

40 41 41 41 42 42 42 42 43 43 43 44 44 44 45 45 45 45 46 46

42 43 43 43 44 44 44 44 45 45 45 46 46 46 47 47 47 47 48 48

44 45 45 45 46 46 46 46 47 47 47 48 48 48 49 49 49 49 50 50

46 47 47 47 48 48 48 48 49 49 49 50 50 50 51 51 51 51 52 52

48 49 49 49 50 50 50 50 51 51 51 52 52 52 53 53 53 53 54 54

50 51 51 51 52 52 52 52 53 53 53 54 54 54 55 55 55 55 56 56

52 53 53 53 54 54 54 54 55 55 55 56 56 56 57 57 57 57 58 58

54 55 55 55 56 56 56 56 57 57 57 58 58 58 59 59 59 59 60 60

56 57 57 57 58 58 58 58 59 59 59 60 60 60 61 61 61 61 62 62

58 59 59 59 60 60 60 60 61 61 61 62 62 62 63 63 63 63 64 64

60 61 61 61 62 62 62 62 63 63 63 64 64 64 65 65 65 65 66 66

62 63 63 63 64 64 64 64 65 65 65 66 66 66 67 67 67 67 68 68

64 65 65 65 66 66 66 66 67 67 67 68 68 68 69 69 69 69 70 70

66 67 67 67 68 68 68 68 69 69 69 70 70 70 71 71 71 71 72 72

68 69 69 69 70 70 70 70 71 71 71 72 72 72 73 73 73 73 74 74


H

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

46

48

50



Table F


A

additional chimney height In calculation process on page 13

approval 2, 3, 4

area category 6 and in calculation process on page 13

B

balanced flue 15

building height 16, 17, 18, 19,

building width 17, 19,

C

calculations 28 and page 13

chemical process plants 3

chimney height 5, 6, 21, 23, 16

clean air act memorandum 1, 2, 4, 5, 6, 7, 9, 10, 11, 12, 13, 21, 27, 28

combined cycle 6

combined emission 21, 22

common flue 21, 22

common header 14, 21

complex building 19

cone 13 and Figure 2

corrected height In sample calculation on page 13

D

diesel generator exhausts 4, 10, 24

discharge height 2, 3, 6

discharge plume 26

discharge velocity 13

dispersion 6

dispersion modeling 6

dust 1

E

effective chimney height 6

engines 3

equipment rating 4, 7, 13

exhaust louvre 27

exhausts 1

exit cone 13

exit velocity (efflux velocity) 13, 14

F

fan (induced draught) 14

fan dilution 27

final discharge height 14

fuels 11

full load 8

G

gas turbine exhaust 3, 9

gas-oil 25

gaseous fuel 4

generator exhaust 4, 10, 24

geographical location 6 and in calculation process on page 13

grit 1

ground level 16

guidance note 8

guides (published) 6

I

incinerator 1, 3, 9, 24

individual chimney 22

induced draught fan 14

initial discharge plume 5

L

large plant 6, 3

lattice tower 19

legislation 1

lift room 16,20

lift room area 16, and in sample calculation on page 13

liquid fuel 4

26

IndexSubject Location

(No’s. = Q & A paragraphs)Subject Location

(No’s. = Q & A paragraphs)

local authority 4

location 3, 6, 15, 21, 23

louvres 20, 27

low discharge velocity 14

low level discharge 27

lower limit 4

M

maximum emission 8

minimum chimney height 6

multi-flued chimney 23, 24

N

nitric oxide 12

normal operating load 7

Northern Ireland 1, 4

nuisance 2

O

odours 1

P

plant location 3, 6, 15, 21, 23

plant room 18, 20

plume 5, 13, 26

pollutant concentration 5

pollutants 3, 5, 12, 25 Also tables on page 17

pollution 1, 5, 6, 15

porous structure 19

prescribed processes 3

process guidance notes 6

pulverized fuel 4

R

rated input 7

rating 13

reduced load 7, 8

roof 20

roof area In sample calculation on page 13

roof buildings 16,20

roof level 27

room-sealed balanced

flue system 15

S

solid fuel 4

stand-by plant 25

sulphur 11

sulphur dioxide 12

T

tank room 16, 20

tank room area 16, and in sample calculation on page 13

tapered cone 13

target velocities 8

technical guidance note D1 6, 13, 18, 24

trees 19

turndown ratio 8

U

“U” 17, 18, 19 and in sample

calculation on page 13

uncorrected height In sample calculation on page 13

V

velocities 8, 13

ventilation air intake 27

very large plant 3

VLS 11

VLS fuels 12

W

waste oil 3

windows 26


27

Notes

The information, tables and sample calculations in this document are intended to

provide guidance on the correct application of chimney system discharge dictated by

the Clean Air Act Legislation. Whilst we consider the information contained to be

accurate, users are advised where necessary to check any calculations and clear all

applications with an appropriate authority


clean air act and chimneys

Documents