Rules of Thumb - Guidelines for Assessing Building Services

Rules of Thumb (UK 3rd edition)Guidelines for assessing building services

Edited by Martin Boushear

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Rules of Thumb BSRIA 2001 3

TABLE 1: Electrical supplies and loads

TABLE 1: Capital and maintenance costs TABLE 2: Services costs as a percentage of total costs

TABLE 3: System capital and maintenance costs

TABLE 1: Floor space allowance for servicesTABLE 2: Space allowances for plant roomsTABLE 3: Miscellaneous servicesTABLE 4: Space allowances for on-floor servicesTABLE 5: Space allowances for service ducts and shaftsTABLE 6: Space allowances for catering facilitiesTABLE 7: Floor space allowance per occupantTABLE 8: Plant weight allowances

TABLE 1: Cooling loadsTABLE 2: Cooling plantTABLE 3: Solar gainsTABLE 4: Heat loads

TABLE 1: Sizing and operating characteristics of plant

TABLE 2: Water treatment

Electrical systems 26

Energy and carbon issues 24

TABLE 1: External conditionsTABLE 2: Ventilation and air conditioningTABLE 3: Information technologyTABLE 4: Room air movementTABLE 5: Noise levelsTABLE 6: Comfort data sheet

Comfort factors 16

Equipment and solar loads 14

Space and weight allowances 6

TABLE 1: Energy conversionsTABLE 2: Energy benchmarks (offices)TABLE 3: Lighting benchmarks

Contents

References 32

Cost data 27

System features 20

Rules of Thumb BSRIA 20014

The story behind the guide

All rights reserved. No part of this publication may be reproduced, stored in a retrievalsystem, or transmitted in any form or by any means electronic or mechanical includingphotocopying, recording or otherwise without prior written permission of the publisher.

Acknowledgements

BSRIA TN 15/2001 August 2001 ISBN 086022 587 9 Printed by The Chameleon Press Ltd

This publication is the third update of the Technical Note TN 17/95: Rulesof Thumb last issued in 1995. The rules have been collected from variouscontemporary sources in the building services industry and can reasonablybe held to reflect current design practices. The sources include majordesign offices, individual engineers and public domain informationpublished by BSRIA and others.

The industry review team for this project comprised: John Louis Auguste(Bovis Lend-Lease), Dennis Bastow (NHS Estates), Brian Charlesworth(Troup Bywaters & Anders), Laurie Clark (Cundall Johnston & Partners),Michelle Field (Buro Happold), Manus Freeman (SVM Partnership),Nigel Hawkes (Fulcrum Consulting), Glen Irwin (Roberts & Partners),Bob Keenan and Dr Ian Selby (Sheppard Robson, on behalf of theBritish Council for Offices), Nick Mead (ACDP), Richard Tudor (WSPGroup), and Gay Lawrence Race and John Sands (BSRIA). We wouldalso like to thank AMEC Capital Projects, BAA plc, N G Bailey, BryanFranklin, Building Design Partnership, Foggo Associates, Foremans Ltd,Hoare Lea & Partners, Max Fordham & Partners, Stanhope, and WhitbyBird & Partners for their help.

Finally, BSRIA would like to make special acknowedgement to theconsulting engineers Foremans Ltd, whose financial support has enabledBSRIA to extend the print run. BSRIA also acknowledges the editinghelp of Nigel Pavey, author of the second edition of Rules of Thumb andnow chief engineer with Foremans Ltd.

Rules of Thumb BSRIA 2001 5

What this guide will doRules of Thumb has been written to help engineers in the initial stages ofdesigning a building and its services. By gathering many of the mostcommon rules of thumb into one document, BSRIA has provided apowerful source of inital design data that every engineer should findindispensable.

Thumb rules (or heuristics as they are more properly known) areextremely useful values for use at various stages of design, such as projectinception and outline briefing, feasibility planning, the assessment ofglobal loads and space requirements. They are also useful for getting ainitial grasp of costs. Rules of thumb come in handy for carrying out"what if" calculations, and for use by senior engineers when checking thework of junior engineers.

The data have been derived from a wide variety of authoratative sources,all of which are referenced. All the figures quoted have also beenassessed for usefulness and relevance by a panel of experienced,practising services engineers.

What this guide will not doWhile every effort has been made to establish current practice, theguide's authors are keen to point out that the rules of thumb are merelyaids to the design process. They must not be used in place of detaileddesign data. The responsibility for the safe and appropriate use of thisdata therefore rests with the engineer.

Rules of Thumb has been designed to be your own personal referencedocument. Use it, add your own data to it, and guard it jealously. Andplease let us know how it works and where it can be improved.

Roderic BunnPublisher

How to use this guide

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TABLE 1: Floor space allowance for services (as a percentage of floor area)

Design area Application Other information Rule of thumb Ref Your notes and comments

All services Simple factory 4% 26Offices and commercial 6 10% 26Hi-tech building 15 30% 26

Air conditioning (excluding Fan coil system 15 25% 26boilers & refrigeration) VAV system 3 45% 26

Cooling towers and air-cooledcondensers 03 15% 26

Electrical services (excluding 05 15% 26sub-stations and standbygeneration sets)

Lift motor rooms 02 05% 26

Refrigeration (excludingcooling towers) Central plant 1 2% 26

Ventilation Toilet extract 03 1% 26Supply and extract system 3 5% 26All air low velocity system 4 6% 26

Space and weight allowancesWhen to use: During the early stages of design prior to plant selection or system analysisWhere to use: Plant room sizes, riser cupboard locations and plant capacitiesWatch out for: Poor information that fails to allow for installation, commissioning or maintenance

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TABLE 2: Space allowances for plant rooms (floor area)

Table 2 continued


Air cooled condenser and space forcontrols installation and

maintenance 25 + kW/200 m2 29

Air handling units With extract/recirculation 8 m2 per m3/s 29

Without extract/recirculation 5 m2 per m3/s 29

Boilers Boiler plant 08 18% 26(percentage floor area) & calorifiers Oil tank room 1 2% 26

Boilers Boilers, pumps, Output: 100 kW 15 m2 x 3 m 29(floor area and height) piping and space for Output: 200 kW 25 m2 x 3 m 29

installation and Output: 1000 kW 80 m2 x 4 m 29maintenance Output: 4000 kW 140 m2 x 5 m 29

Calorifiers Calorifiers, pumps, Vertical (1 m3) 10 m2 x 3 m 29(floor area and height) pipework, controls Vertical (5 m3) 20 m2 x 4 m 29

and space for Vertical (10 m3) 25 m2 x 5 m 29installation and Vertical (15 m3) 60 m2 x 3 m 29maintenance

Horizontal (1 m3) 25 m2 x 3 m 29Horizontal (5 m3) 30 m2 x 3 m 29Horizontal (10 m3) 45 m2 x 3 m 29Horizontal (15 m3) 60 m2 x 3 m 29

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Chillers (water cooled) With pumps, Output: 1000 kW 50 m2 x 3 m 29Floor area times height pressurisation, Output: 2000 kW 63 m2 x 3 m 29

pipework and Output: 3000 kW 83 m2 x 35 m 29control panels Output: 4000 kW 108 m2 x 4 m 29

Chillers (air cooled) Located outside. Output: 200 kW 39 m2 29Includes space for Output: 400 kW 53 m2 29installation and Output: 600 kW 75 m2 29maintenance Output: 800 kW 84 m2 29

Output: 1000 kW 98 m2 29Output: 1200 kW 116 m2 29

Cold water storage Single cold water tank FA: Floor areaIncludes space for V: gross storage m3

installation and 1 m high FA: 10 + V/075 m2 29maintenance but add 2 m high FA: 10 + V/16 m2 29space for 3 m high FA: 10 + V/24 m2 29pressurisation plantor circulation pumps

Cold water storage Minimum for Offices 10-20 litres/person 4hot and coldoutlets Hotels, childrens home,

residential nursery,convalescent home 135 litres/bed space 4

Table 2 continued

TABLE 2: Space allowances for plant rooms (floor area)

Space and weight allowances

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Cold water storage Minimum for Restaurant 7 litres/meal 20(domestic) continued hot and cold Day school 15-20 litres/pupil 20

outlets Hostel 90 litres/bed space 20

Cooling towers FA: Floor area(kW: heat rejection) FA: 50 + kW/66 m2 29

Sub-station 2000 kVAtransformers 47 m2 29Switchgear HV switchgear 14 m2 29

HV + LV switchgear 27 m2 29

Standby generation Standby sets andaccessories FA: Floor area FA:15 + kVA/30 m2 29

Uninterruptible power supply Single module system(add space forbatteries) FA: Floor area FA: (2 + kW/200) x 2 m2 29


Control panels & distribution Front panel controls, Fixing height range 1200 1800 mm 18boards wall-mounted or floor (above finished floor

standing or operating platformlevel)

LTHW boiler plant Oil storage tanks, If tank fails, walls andcomponent criteria for distillate & residual doors treated toleakage containment fuel oils contain spillage Tank contents + 10% 19

TABLE 3: Miscellaneous services

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TABLE 4: Space allowances for services (depth of clear space in ceiling/floor void)


Air conditioning VAV 350 750 mm 16VRV 450 mm 16Recessed chilled beams 350 450 mm 16Surface chilled beams 250 mm 16Chilled ceilings 250 mm 16Fan coils 450 mm 27Ducted air system 450 mm 27

Drainage 100 mm dia. 10 25 mm per m run 27Soil and waste 150 mm dia. 7 16 mm per m run 27

Lighting Fluorescent 100 150 mm (access) 16Downlighter 150 300 mm 16

Power and communications Multi-core cables andlighting cables 100 200 mm 16

Power and data(heavy line) 200 250 mm 16

Computer rooms 300 mm 16


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TABLE 5: Space allowances for service ducts and shafts


Air ducting Typical ducting size 02 m2/m3/s 30

Lift shafts Between 4 18 floors Internal shaft areain office-type buildings A: floor area/

storey (250 m2 min),N: Floors 3+A(N-4)/250 m2 30

Mechanical service Simple pipework Depth needed to openriser riser access door/pane when

width of door varieswith size/type of pipeor depth of service/duct 690 mm 17

Pipework Pipe: 20 mm dia. 100 mm x 100 mm 30Pipe: 25 mm dia. 120 mm x 120 mm 30Pipe: 32 mm dia. 130 mm x 130 mm 30

Three-sided riser Minimum depthfrom services to (open)access door/panel 690 mm 17

Service ducts Vertical service duct Floor space served byvertical service (radius) 15 23 m 30

Aspect ratio of verticalservice duct 2:1 4:1 30

Total duct area as %of gross floor area 2% 30

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Kitchen and dining facilities Kitchens including Min. requirements:preparation and Up to 100 meals 04 m2/meal 31storage Up to 500 meals 025 m2/meal 31

For single sittings Ratio of kitchenspace to dining space 033:1 to 05:1 31

For multiple sittings Ratio of kitchen spaceto dining space 1:1 31


TABLE 6: Space allowances for catering facilities


General offices 12 17 m2/person 4

Trading desks, callcentre, work stations 4 6 m2/person 4

Enclosed offices 15 m2 (or more)per person 4

TABLE 7: Floor space allowance per occupant (net internal area)

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TABLE 8: Plant weight allowances


Single boiler 500 kW 1500 kg 391500 kW 4250 kg 392500 kW 6500 kg 39

Single storage steel calorifier 4 m3 1250 kg 39 8 m3 2500 kg 39 12 m3 3300 kg 39

Single non-storage mild-steel 500 kW 150 kg 39heating calorifier 1000 kW 225 kg 39

1500 kW 275 kg 392000 kW 325 kg 39

Single water-cooledliquid chiller 1500 kW 10 000 kg 39

3000 kW 20 000 kg 394500 kW 30 000 kg 39

Single air-cooled liquid chiller 500 kW 6 000 kg 391000 kW 11 000 kg 391500 kW 14 000 kg 39

Single generator 500 kVa 5000 kg 391000 kVa 8000 kg 391500 kVa 11 000 kg 39

Single UPS system 100 kVa 1250 kg 39 300 kVa 2750 kg 39 500 kVa 4250 kg 39


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Equipment and solar loads

TABLE 1: Cooling loads


Banks 160 W/m2 34

Computer suites 400 W/m2 approx 34

Hotels 150 300 W/m2 34

Offices (general) 125 W/m2 34Interior zones morethan 7 m from windows 75 W/m2 34

Perimeter zones 60% glazing 120 W/m2 34up to 6 m 65% glazing 180 W/m2 34

Restaurants 220 W/m2 34

Retail buildings 140 W/m2 34

TABLE 2: Cooling plant


Central cooling plant Load/m2 of floor area 125 W/m2 36Load/m3 of floor vol. 40 W/m3 36

Distributed cooling plant Load/m2 of floor area 140 W/m2 36Load/m3 of floor vol. 45 W/m3 36

Electrical power for kW/kW cooling Central plant 05 kW/kW 36refrigeration plant capacity Distributed plant 078 kW/kW 36

When to use: For estimates of thermal loads used to assess plant and terminal equipment sizesHow to use: To determine total solar and internal gains, multiply the loads by total floor areaWatch out for: Solar gains depend on glazing and shading, and contribution of thermal mass


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General buildings Floor area 90 W/m2 (30 W/m3) 34

Educational buildings 100 W/m2 34

Industrial buildings 80 W/m2 34

Offices 70 W/m2 34

Residential buildings 60 W/m2 34

Infiltration: air heating load 75 W/m3 34

Retail buildings 110 W/m2 34

Other heat gains Offices Metabolic 10 W/m2 16Lighting 12 W/m2 16

General offices Office equipment 15 25 W/m2 16

TABLE 4: Heat loads

TABLE 3: Solar gains (over floor area)


Windows with (June-Sept) South facing 250 W/m2 of glass 34internal blinds (June-Sept) East-West facing 150 W/m2 of glass 34

Clear double-glazed withinternal blinds Out-of-town building All data for 6 m deep, 2650 W instant 39

1500 mm wide module. 2490 W lag (mass) 39U-value 33 W/m2K.

As above with flat slab Plus brise soleil 1860 W instant 391710 W lag (mass) 39

As above with coffered slab Plus brise soleil 1860 W instant 391680 W lag (mass) 39


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TABLE 1: External conditionsDesign area Application Other information Rule of thumb Ref Your notes and comments

Winter design temperatures Without surplus -4C 37for heating boiler capacity

With 20% surplus Single-storey building -3C 37boiler capacity Other buildings -1C 37

Rate of loweringoutdoor design temp.with altitude abovesea level -06C/100 m 37

Summer design temperature Dry bulb temp. 28C 37

for air conditioning Wet bulb temp. 19C 37

Comfort factors

TABLE 2: Ventilation and air conditioningDesign area Application Other information Rule of thumb Ref Your notes and comments

Ventilation: recommendedmaximum temperature Offices 95% operation/year 25C 4

Air conditioning: recommendedmaximum temperature Offices 95% operation/year 24C (or lower) 4

IT rooms by classification Type A IT rooms Specifically designedand built for IT equipment(ideally, isolated fromoffice areas) Dedicated IT room

required 38

When to use: During the early stages of designWhere to use: When setting inernal environmental conditons based on known or assumed loadsWatch out for: Specific client requirements, and contexts that allow greater latitude in design settings


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TABLE 3: Information technologyDesign area Application Other information Rule of thumb Ref Your notes and comments

IT rooms by classification Type B IT rooms Designed for intensive(continued) use of IT equipment at

workstations (whereair-conditioning mustbe used) Air-conditioned office,

room or workspace 38

Type C IT rooms Room where ITequipment is used atworkstations (may usenatural or mechanical

ventilation) Non air-conditionedoffice, room orworkspace 38

TABLE 4: Room air movement


Maximum recommended In Winter 015 m/s 37mean air velocities In Summer 025 m/s 37

At 21C 015 m/s 37At 22C 02 m/s 37At 23C 025 m/s 37At 24C 03 m/s 37On back of neck 02 m/s 37

Papers will lift atvelocities in excess of 08 m/s 37

Television and 02 03 m/s 2broadcasting studios


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TABLE 5: Noise levelsDesign area Application Other information Rule of thumb Ref Your notes and comments

Recommended maximum Very quiet rooms Concert halls, soundbackground noise levels studios NR 20 37

Quiet rooms Bedrooms, theatres,churches NR 25 37

Private rooms Small offices, libraries,living rooms NR 30 37

Public rooms General offices,classrooms, small shops NR 35 37

General areas Reception areas,restaurants NR 40 37

Work areas Kitchens, computerrooms, large shops NR 45 37

Industrial areas Factories NR 50 or above 37

Intelligibility of telephone Satisfactory Up to NR 50 37conversation at background Slightly difficult Up to NR 60 37noise levels Difficult Up to NR 75 37

Unsatisfactory Over NR 75 37

External noise level criteria for If more than 10 dBA Complaints expected 37new noise (above background noise) If less than 5 dBA Marginal 37

Limiting distances for speech Up to NR 40 7 m 37intelligibility (background noise Up to NR 45 4 m 37level) Up to NR 50 22 m 37

Up to NR 55 12 m 37Over NR 70 Too noisy 37

Comfort factors


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TABLE 6: Comfort data sheet

Your notes and comments

Building Type Internal design temperature Humidity Infiltration Ventilation Ventilation Lighting level Noise levelSummer Winter (% RH) (ac/h) fresh air air change (Lux) (NR)

Cinemas (sedentary role) 21-23C 19-21C 5010% RH 05 ac/h 8 l/s/person 6-10 ac/h 300 lux NR25-NR30

Computer rooms (general) 21-23C 19-21C 505% RH 1 ac/h 8 l/s/person 4-15 ac/h 300 lux NR35-NR45

Education (teaching spaces) 21-23C 19-21C 505% RH 2 ac/h 8 l/s/person 6-10 ac/h 300 lux NR25-NR35

Exhibition hall/conference facilities 21-23C 19-21C 50-55% RH 025-05 ac/h 8 l/s/person 1 ac/h 300 lux NR40

Factory/warehouse 21-23C 11-21C 5010% RH 025-25 ac/h 8 l/s/person 6 ac/h 750-1000 lux NR45-NR65

Fitness/health clubs (equipment rooms) >18C 12-18C 40-70% RH 075 ac/h 8 l/s/person 4 ac/h 300 lux NR30-NR40

Hospitals (ward and patient areas) 23-25C 22-24C 50-60% RH 2 ac/h 8 l/s/person 3 ac/h 50-100 lux NR30-NR35

Hotels (bedrooms) 21-23C 19-21C 5010% RH 1 ac/h 8 l/s/person 6-10 ac/h 50-100 lux NR20-NR30

Libraries (reading rooms) 24-25C 22-23C 505% RH 025-075 ac/h 8 l/s/person 3-4 ac/h 300 lux NR30-NR35

Museums and galleries (display, storage) 21-23C 19-21C 50-55% RH 1 ac/h 8 l/s/person 3-4 ac/h 200 lux NR30-NR35

Offices (general, BCO data) 24C 22C 35-40% RH 025-05 ac/h 8-12 l/s/person 4-6 ac/h 300-500 lux NR25-NR40

Retail (shops/stores) 21-23C 19-21C 455% RH 05-1 ac/h 8 l/s/person 3-8 ac/h 500-750 lux NR35-NR45

Swimming pools (pool halls) 23-26C 23-26C 40-70% RH 05 ac/h 0-15 l/s/m2 (of wetted area) 300 lux NR 40-NR50


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Table 1 continued

TABLE 1: Sizing and operating characteristics of plantDesign area Application Other information Rule of thumb Ref Your notes and comments

Air handling unitsAir face velocity Heating coil 25 4 m/s 36

Cooling coil 10 25 m/s 16

Air supply Heating mode 30C (max) 16temperatures Cooling mode 13C (min) 16

Coil water velocity Air discharge 06 2 m/s 36

Water pressure drop 10 40 kPa 16Steam pressure drop 033 172 bar 36

Air distributionFrom source Ceiling diffusers Limit of throw 8 m 36

Surface projections Not to exceed50 mm within 1mof diffuser outlet 36

Non-zoning partitions Maximum height 66% of ceiling height 36

Sill diffusers Allowance for grille Allow 03 mwidth 36

Boiler plant capacity Power per unit area 120 W/m2 floor area 3640 W/m3 volume 36

When to use: During outline design before the architect has finalised space planningWhere to use: For determining the spatial and operational characteristics of main plantWatch out for: The rules for boiler and cooling plant are based on unit floor area or unit volume


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Table 1 continued


Boiler plant efficiency Boiler efficiency Typical efficiency 75% 36Efficiency losses Blowdown (steam) 2% 36

Casing 3% 36Flue 15 20 % 36

Boiler plantTypical seasonal Condensing boilers Underfloor or warmefficiencies water system 90% 22

Standard size radiators,variable temp circuit(weathercompensation) 87% 22

Standard fixed-temperature emitters(83/72C flow/return) 85% 22

Non-condensing Modern high efficiencyboilers boilers 80 82% 22

Good modern boilerdesign closely matchedto demand 75% 22

Typical good boiler 70% 22

Chiller plant capacity 1 kW/person 36

Fuel storage Class D oil Volume per kW 40 litres/kW 36

DuctworkTypical duct velocities Low velocity systems 3 5 m/s 36

High velocity systems 75 15 m/s 36


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Ductwork Inlet louvres (through free area) 25 m/s 36

Maximum pressure drop Low velocity systems 1 Pa/m 36rates (per m run) High velocity systems 8 Pa/m 36

Typical system resistances Low velocity supply 900 Pa 36(including air handling plant) Low velocity extract 400 Pa 36

High velocity supply 15 2 kPa 36

Air leakage system loss (%) Low pressure systems Class A 6% 15Med. pressure systems Class B 3% 15High pressure systems Class C 2% 15

Fans Electrical input (kW) 16 x total fan pressure(kPa) x volume flowrate (m3/s) 36

Temperature rise of air Total fan pressure 1C per kPa 36

Fan capacity of ventilated space Offices 14 litres/s per m3 23Restaurants 35 litres/s per m3 23Retail stores, halls, theatres 21 litres/s per m3 23

Heating systems

Total system volume Domestic systems Approx. value 6 x boiler size (kW)+10% 3(system size, in litres) Commercial systems Approx. value 10 x boiler size (kW)+10% 3

Capacity per unit area ofradiator surface Conventional system 1 litre/m2 36

Capacity per unit of power Boilers 15 litres/kW 36produced (boilers, radiators) Aluminium, cast radiator 3 litres/kW 36

Table 1 continued

System features


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E xtruded aluminium 12 litres/kW 36Steel panel radiators 5 litres/kW 36

PipeworkCapacity per unit length of 15 mm diameter pipe 025 litres/m 36of steel pipe 20 mm diameter pipe 04 litres/m 36

25 mm diameter pipe 06 litres/m 3632 mm diameter pipe 12 litres/m 3640 mm diameter pipe 15 litres/m 36

Water velocity 15 50 mm pipe dia. 075 15 m/s 36Conventional systems Over 50 mm pipe dia. 125 3 m/s 36

Steam pressure drop Initial pressureper 100 m pipe run 6% 36

Water pressure Conventional systems Over 50 mm pipe dia. 100 300 Pa/m 16

Water velocity (system) Small bore 1 m/s 36Microbore 12 m/s 36

Corrosive water 2 m/s max 36

Steam velocity Superheated steam 40 60 m/s 36Saturated steam 30 40 m/s 36Exhaust 20 30 m/s 36

Capacity per unit of finned area Finned tube coils 49 litres/m2 36

PumpsHead pressure (pump head) Pressure (in kPa),

length (m) 036 x circuit length 36Water treatmentAdditives required Copper pipework With steel pipework Add 10% to water 36

Frost protection Glycol concentration 30% of system vol. 16


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TABLE 1: Energy conversions

Energy and carbon issues


Carbon dioxide emission(Kg CO2/kWh delivery) by fuel Natural Gas 019 kg CO2/kWh 1

Oil 025 kg CO2/kWh 1Electricity Average 046 kg CO2/kWh 1Coal 030 kg CO2/kWh 1

CO2 to Carbon Divide by 367 1

TABLE 2: Energy benchmarks (offices)


Naturally ventilated (cellular) Energy costs over Good practice 3.50 m2 tfa 1Type 1, simple relatively treated floor area (tfa) Typical 6.00 m2 tfa 1small building, sometimesconverted residential, Gas or oil Good practice 79 kWh/m2 1100 3000 m2 (delivered) Typical 151 kWh/m2 1

Electricity Good practice 33 kWh/m2 1(delivered) Typical 54 kWh/m2 1

Naturally ventilated (open plan) Energy costs over Good practice 4.50 m2 tfa 1Type 2, purpose-built, sometimes treated floor area Typical 7.00 m2 tfa 1converted industrial space, 500 m2

4000 m2 Gas or oil Good practice 79 kWh/m2 1(delivered) Typical 151 kWh/m2 1


Table 2 continued

When to use: When determining total building energy consumptionWhere to use: From briefing onwards through to design and operation (See also CIBSE TM22)Watch out for: Change to the carbon conversion ratios which are continually being updated


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Air conditioned (standard) Energy costs Good practice 8.00 m2 tfa 1Type 3, purpose-built, speculative Typical 14.00 m2 tfa 1often intensively used,2000 8000 m2 Gas or oil Good practice 97 kWh/m2 1

(delivered) Typical 178 kWh/m2 1


Air conditioned (prestige) Energy costs Good practice 13.00 m2 tfa 1Type 4, national or regional Typical 20.00 m2 tfa 1head office, purpose-built to highstandards, intensively used and Gas or oil Good practice 114 kWh/m2 1extensive storage, parking and (delivered) Typical 210 kWh/m2 1leisure facilities, 4000 20 000 m2


TABLE 2: Lighting systems


Lighting benchmarks Type 1 Good practice 12 W/m2 1Typical 15 W/m2 1

Type 2 Good practice 12 W/m2 1Typical 18 W/m2 1




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TABLE 1: Electrical supplies and loadsDesign area Application Other information Rule of thumb Ref Your notes and comments

Electrical supply Electrical motors Above 3 kW rating 3-phase supply 16Electrical motors Up to and including

3 kW rating Direct on-linestarting 16

Electrical motors Above 4 kW rating Assisted start 16

Electrical services load(per m2 of building floor area) Lighting 10 12 W/m2 16

Small power 15 45 W/m2 16

Air conditioning 60 W/m2 35

Passenger lifts 10 W/m2 35

Small computer room Net area 200 400 W/m2 16

Bespoke call centre Net area 500 1000 W/m2 16

Total load (kVA) Total building load Total kW/08 35Design allowance for futureexpansion (%) % increase in load Add 25% to

existing capacity 35

When to use: To determine electrical supply requirements in buildingsWhere to use: When assessing the connected capacity in terms of unit floor areaWatch out for: Allowances for expansion, particularly for on-floor communications rooms


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TABLE 1: Capital and maintenance costs in /m2

Cost of m&e services by building typeCost data

Table 1 continued


Factories Owner occupied 64 161 25For letting 1995 figure + 10% 34 78 32

(2001 adjustment)

Hospitals District general 393 556 25Private 415 654 25

Offices For letting Non air-conditioned 170 190 25(Category A standard) Fully air-conditioned 280 410 25

Offices Owner occupied) Non air-conditioned 210 280 25Fully air-conditioned 310 500 25

Civic Fully air-conditioned 350 500 25

Residential housing Local authority Two-storey houses 71 97 25Medium rise flats 96 126 25

Schools Secondary/middle schools 163 241 25

Universities Arts buildings 212 268 25Science buildings 213 395 25

Shopping centre Department store 1995 figure + 10% 223 347 322001 adjustment)

Warehouses High bay 86 171 25

When to use: As a general guide to the outline services costs of specific building typesWhere to use: At the briefing stage onwards and during assessment of m&e tendersWatch out for: Additions or amendments to the generic building type which might alter costs


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TABLE 2: Services costs per square metre as a percentage of total cost

Cost data


Arenas (indoor) Mechanical 1999 data, gross 9% 7Electrical internal floor area 12% 7Total m&e 21% 7Lift installations 1% 7Other 78% 7Total cost 100% 7

Call centres Mechanical 1999 data (gifa) 10% 8Electrical 17% 8Total m&e 27% 8Lift installations 1% 8Other 72% 8Total cost 100% 8

Cinemas: multiplex Mechanical 2000 data (gifa) 1% 13(shell construction) Electrical 8% 13

Lift installations 6% 13Total m&e 9% 13Other 85% 13Total cost 100% 13

Cinemas: multiplex Mechanical 2000 data (gifa) 19% 13(cinema fit-out) Electrical 13% 13

Total m&e 32% 13Lift installations 0% 13Other 68% 13Total cost 100% 13

Table 2 continued


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Conference centres Mechanical 2000 data (m2 gifa) 8% 5Electrical 11% 5Lift installations 3% 5Other 78% 5Total m&e 19% 5Total cost 100% 5

Data/computer centres Mechanical 2001 data (per m2) 30% 14Electrical 61% 14Lift installations Not included 14Other 9% 14Total m&e 91% 14Total cost 100% 14

Health & fitness centres Mechanical 1998 data (m2 gifa) 13% 9Electrical 11% 9Lift installations 1% 9Other 75% 9Total m&e 24% 9Total cost

100% 9

Offices: city Mechanical 2000 data 46% 6(shell & core only) Electrical (m2 gifa) 37% 6

Total m&e 83% 6Lift installations Not included 6Other 17% 6Total cost 100% 6

Offices: urban commercial Mechanical and 1999 data(category A standard fit-out) public health (per m2 nia) 66% 12

Electrical 34% 12Total cost 100% 12

Table 2 continued


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Offices: out-of-town Mechanical 1999 data 57% 11commercial (shell & core) Electrical (per m2 gifa) 30% 11

Total m&e 87% 11Other 13% 11

Offices: out-of-town Mechanical & 1999 data 78% 11commercial (category A public health (per m2 nia)standard fit-out) Electrical 22% 11

Offices: urban commercial Mechanical 1999 data 47% 12(shell & core) Electrical (per m2 gifa) 32% 12


Supermarkets Mechanical 2000 data 15% 10(services fit-out) Electrical (per m2 gifa) 31% 10


Ventilation Low velocity 1995 figure + 10% 67 113 33(capital costs) High velocity (2001 adjustment) 71 119 33

then 25%

Cost data


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Air conditioning Unit air conditioners 1995 figure + 10% 67 113 33(capital costs) All-air systems (2001 adjustment) 82 136 33

Air/water system then 25% 109 181 3391 151 33

Air conditioning Unit air conditioners 1995 figure + 10% 14 22 33(maintenance costs) All-air systems (2001 adjustment) 14 22 33

Air/water system then 25% 14 22 33

Air conditioning 1995 figure + 10%(average capital costs) (2001 adjustment)

then 25% 148 248 33

TABLE 3: System capital and maintenance costs (/m2)

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Ref Title Publication Year Publisher ISBN

1 Energy use in offices Energy Consumption Guide 19 2000 BRECSU

2 Television studios, Section B2, page B2-14 CIBSE Guide B 1986 CIBSE

3 Fry Technology (Fernox Manufacturers) Fry Technology UK Ltd 2000 Fry Technology

4 Best Practice in the specification for offices BCO Guide 2000 2000 British Council of Offices 0-9524131-2-4

5 Cost model: Conference Centres Building 3 November 2000 2000 The Builder Group 0007-3318

6 Cost model: City Offices Building 24th March 2000 2000 The Builder Group 0007-3318

7 Cost model: Indoor arenas Building 10th September 1999 1999 The Builder Group ISSN 1365-5671

8 Cost model: Call Centres Building 16th July 1999 1999 The Builder Group ISSN 1365-5671

9 Cost model: Health & fitness centres Building 11th September 1998 1998 The Builder Group ISSN 1365-5671

10 Cost model: Supermarkets Building Services Journal April 2000 2000 The Builder Group ISSN 1365-5671

11 Cost model: Out-of-town commercial offices Building Services Journal April 1999 1999 The Builder Group ISSN 1365-5671

12 Cost model: Urban commercial offices Building Services Journal February 1999 1999 The Builder Group ISSN 1365-5671

13 Cost data: Multiplex Cinemas Davis Langdon & Everest 2000 Davis Langdon & Everest Website

14 Cost model: Data/computer centres Building Services Journal January 2001 2001 The Builder Group ISSN 1365-5671

15 DW/144 Specification for sheet metal ductwork. Part 8, Appendix A:

Air leakage from ductwork, system leakage loss Heating and Ventilating Contractors Association 1998 HVCA 0-903783-27-4

16 Industry Review - Rules of Thumb publication, May 2001 Rules of Thumb Industry Review Committee 2001 BSRIA Not published

17 Space requirements for plant access, operation and maintenance:

Defence Works Functional Standard, Design and Maintenance Guide 08 Defence Estate Organisation (Works), Mo D 1996 HMSO 0-11-772785-7

- Section 4, Figure D4 Mechanical surface risers


Defence Works Functional Standard, Design and Maintenance Guide 08 Defence Estate Organisation (Works), Mo D 1996 HMSO 0-11-772785-7

- Section 4, Figure D10 Control Panels and Distribution Boards


Defence Works Functional Standard, Design and Maintenance Guide 08 Defence Estate Organisation (Works), MoD 1996 HMSO 0-11-772785-7

- Section 5, Section 5.1 Central station plant, 5.1.1 LTHW boilers

20 Public health engineering, extract from Table 2.3 CIBSE Guide G 1999 CIBSE 0-900953-87-X

Recommended minimum storage of cold water for domestic purposes

for hot and cold outlets CIBSE Guide G 1999 CIBSE 0-900953-87-X

21 Public health engineering, Extract from Table 2.11 Measured daily hot

water consumption in various types of commercial buildings CIBSE Guide G 1999 CIBSE 0-900953-87-X

22 Energy efficiency in buildings, Table 9.1 Seasonal (boiler) efficiencies CIBSE Guide F 1998 CIBSE 0-900953-861

References

33R

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humb B

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IA 2001

Ref Title Publication Year Publisher ISBN

23 Energy efficiency in buildings, Table 6.2 Basic fan capacity benchmarks CIBSE Guide F 1998 CIBSE 0-900953-861

24 Energy efficiency in buildings, Table 7.1 Chiller plant capacity CIBSE Guide F 1998 CIBSE 0-900953-861

25 Spons Mechanical and Electrical Services Price Book 2001 2001 Spon Press 0-415-24280-0

26 Space allocation for services, Table 2: floor space Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

27 Space allocation for services, Table 3: depth of ceiling space Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

28 Space allocation for services, Table 4: depth of floor space Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

29 Space allocation for plant rooms, Table 6: floor area Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

30 Space allocation for service ducts and shafts, Table 7 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

31 Space allocation for catering facilities, Table 9 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

32 Cost of M&E services by type of building and service, Table 10 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

33 System capital and maintenance costs, Table 11 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

34 Thermal Loads, Table 12 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

35 Electrical loads by type of load, Table 14 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

36 Sizing and operating characteristics of air system plant,Table 16 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

37 Design requirements or rules of thumb for air systems, Table 17 Rules of Thumb, 2nd Edition 1995 BSRIA 0-86022-4198

38 Guide to the accommodation and operating

environment for Information technology (IT) equipment BS 7083, 1996 1996 BSI 0-580-26705-9

39 Facade Engineering: Fun with Facades Building Services Journal, August 1997 1997 The Builder Group ISSN 1365-5671

The Knowledge Experts

Air Tightness, which undertakes the testing of buildings and other enclosures

CORE, the Centre for Operations Research, providing consultancy, researchand training in business, technology and construction management

Energy and Environment services including boiler and combustioninvestigations, troubleshooting, water and environmental consultancy

FM Engineering Centre specialising in electrical services, controls, naturalventilation, building energy performance, condition monitoring and allmaintenance issues

Information services including regular publications, help desk, library and on-line database

Instrument Solutions, offering hire, calibration and retail sales

MicroClimate Centre providing computer and physical modelling and siteinvestigations of comfort

Process and Productivity, improving design and installation processes and sitepractices and providing design guidance

Testing and Certification of building services products in an independent andaccredited test facility

Worldwide Market Intelligence offering consultancy and multi-client studiesacross the global building services industry

Find out more about BSRIA by visiting our web site at:www.bsria.co.uk

Old Bracknell Lane West, Bracknell, Berkshire RG12 7AH UKT: +44 (0)1344 426511 F: +44 (0)1344 487575

E: [email protected] W: www.bsria.co.uk

For independent andauthoritative research, producttesting, consultancy andmarket intelligence, look nofurther than BSRIA.

Our 120-strong team of buildingservices experts can provide the bestsolutions to the most searchingquestions. And you can be assured ofcomplete confidentiality andindividual service at all times.

The sheer range of our expertise,gained from nearly 50 years ofexperience, means we are able tomeet the technical and informationneeds of everyone involved inbuilding services, from consultingengineers, contractors andmanufacturers to building operators,government bodies and utilities.

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Rules of Thumb - Guidelines for Assessing Building Services

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