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About Natural Ventilation NewsThis Newsletter is produced by the

CIBSE Natural Ventilation Group Man-

agement Committee to inform mem-

bers and potential members of the

work being undertaken by the Group

to benefit the discipline of natural

ventilation within CIBSE. The manage-

ment committee wish to encourage

contact with all interested partners.

Communication can be directed to the

Group at CIBSE Headquarters or to

individual Management Committeemembers.

EditorialThis edition has been designed,

edited, and compiled by

Dr Benjamin Jones.

Tel.: 01494 897749

Email: [email protected]

The Building AdVent Project

by Professor Maria Kolokotroni

Brunel UniversityB u i l d i n g A d V e n t(www.buildingadvent.com) was a pro-gramme to identify technologies, ap-propriate to different climate zones,which can minimise ventilation energyconsumption. Its full title is Building

Advanced Ventilation Technologicalexamples to demonstrate materialised

energy savings for acceptable indoor air quality and thermal comfort in dif-ferent European climatic regions. Itwas supported by the European Com-mission under the Intelligent Energy Europe Programme and was coordi-nated by Buro Happold Engineers (UK)working in partnership with a number of European institutions.

Building AdVent had as its main objective to

support a reduction in the energy required to

deliver ventilation effectively in non-domestic

buildings by capturing good ventilation practice

and disseminating it widely. The main output isbased upon a number of case-studies of existing

buildings, incorporating a range of technolo-

gies, which have demonstrated energy savings

while ensuring a satisfactory internal environ-

ment. The buildings are spread throughout the

various climates of Europe. The project was

completed at the end of 2009 with the produc-

tion of 18 case study brochures and supporting

teaching material.

The buildings were chosen to cover the 3 cli-

matic regions, (i) Southern European climates

with a hot cooling season, (ii) North and Central

European climates with cold heating season,

and (iii) Central and maritime European cli-

mates. Most of the case studies are office build-

ings but there is also one paper storage build-

ing, one museum and some educational build-

ings. All selected buildings demonstrate meas-

ured and verified energy and environmental

performance.

Case study buildings were constructed between

2000 and 2005 and are characterised by high

architectural quality, low energy consumption,

good indoor air quality and satisfactory thermal

comfort levels. Each building presents an inter-

esting, low energy and innovative ventilation

technology with high replication potential. The

ventilation strategies include: natural ventilation

techniques, systems that control the rate of venti-

lation in response to variation of a type of activi-

this issueThe Building AdVent ProjectP.1P.1P.1P.1

Where is the Evidence?P.2P.2P.2P.2

Natural Sounds and Natural VentilationP.3P.3P.3P.3

What is the Ventilation Rate in Houses?P.4P.4P.4P.4

Thermal Comfort PredictionP.5P.5P.5P.5

Designing Intelligent SchoolsP.6P.6P.6P.6

Natural VentilationNatural VentilationNatural VentilationNatural VentilationNewsTHE NEWSLETTER

OF THE

CIBSE NATURAL

VENTILATION GROUP

D e c e m b e r2 0 1 0

I S S U E

03

The Chartered Institute of BuildingServices Engineers222 Balham High RoadLondon SW12 9BSTel.: 020 8675 5211Fax: 020 8675 5449www.cibse.org

ty and/or pollutant concentration, systems that

use heat recovery to recover the thermal energy

from exhaust air, supply of air using the buried

ducting, and radiant heating and cooling. Three

buildings from the UK were included: (a) City

Academy in Bristol, (b) The Academy of St.

Francis of Assisi in Liverpool, (c) Frederick

Lanchester Library in Coventry and (d) Red Kite

House Office Building in Wallingford.

The lecture slides produced include an introduc-

tion to energy efficient ventilation and conclude

with a discussion of the replication potential of

the various strategies. All 18 buildings are pro-

filed independently to give lecturers the freedom

to pick and choose the buildings they wish to

focus on. All slides are available in Danish,

Finnish, Greek and Portuguese versions; also

available from the website.

Aras Chill Dara building, Ireland

Poikkilaakso School, Finland

The Delfi Museum, Greece


2/6

by Dr. Benjamin Jones

Monodraught Ltd.

V alue for money has never been moreimportant. Those who design and man-ufacture natural ventilation productsknow that they must do exactly whatthey say on the tin, be built to last, andprovide maximum bang for buck.Manufacturers also know that theymust provide evidence for their claims.

However, it isnt difficult to knock-up a natural

ventilation device and state that it has exactly

the same build quality and performance as

those produced by established manufacturers.

But using such a system would be like buying

supermarket value brandy and being

disappointed when it doesnt taste like the Extra

Old Cognac (an average of 20 years in the

barrel) ones taste buds have adapted to. Heres

why: the difference between the two is extensive

research and professional expertise developed

over time. No two natural ventilation systems

are the same; the area and geometry of the

opening, louvres, grills, aerodynamic spoilers,

and diffuser types will all greatly affect

performance. Natural ventilation systems are,

dynamically, very complicated indeed and so an

understanding of the pressure distribution

around each opening, the flow direction and

type through each duct, and the pressure losses

through the system have to be quantified and

understood before their performance can be

determined. Preferably, this is determined using

wind tunnel analysis and quantified using CFD,

analytic models, and in-situ measurement. Only

then can this information be used to correctly

size-up natural ventilation openings for a

particular application.

However, an analysis of the fluid dynamics con-

stitutes only part of the portfolio of information

required to design and implement a successful

natural ventilation strategy. A control strategy

must also be derived to deliver enough ventila-

tion at appropriate times to ensure the thermal

comfort, health, and well-being of occupants.

The strategy can be checked using dynamic

thermal simulation software to confirm that

internal conditions are comfortable and that a

building wont overheat. However, only the

in-situ measurement of ventilation and indoor

air quality parameters over time shows how

successful a strategy is in practice. Furthermore,

in-situ intervention tests can be used to

determine the effects of particular parts of a

control strategy.

This type of research can be done in-house, but

greater kudos is gained by outsourcing it to a

University. Good scientists are always keen to

share the findings of their research in

conference proceedings and peer reviewed

journals, such as the International Journal of

Ventilation, and so those companies who are

most sure of their expertise allow this.

It could be perceived that research (especially of

post installation performance) could lead to

public relations pitfalls, but in practice it shows

that a manufacturer has acknowledged

problems and learned valuable lessons. For

example, research by Brunel University of a

WINDCATCHER natural ventilation system

shows, on balance, that it is capable of

ventilating a school classroom in accordance

with UK government requirements, but also that

a ventilation strategy can be improved by the

effective control of temperature and carbon

dioxide. These are lessons that are really worth

learning and sharing.

Consultants who specify natural ventilation

systems have to ensure that a building meets

legislative and environmental standards, such as

BREEAM requirements. As part of this client

responsibility, consultants must insist thatcontractors obtain evidence of peer reviewed

research and key design parameters from the

manufacturers of natural ventilation systems

because the responsibility for its performance

will, ultimately, lie with them.

There are no substitutes for extensive research

and professional expertise developed over time,

or for XO Cognac, and although these can cost

a little more, they are certainly value for money.

References

Jones, BM. 2010. Quantifying the

Performance of Natural Ventilation

Windcatchers . Eng.D. thesis, Brunel University.

Natural VentilationNatural VentilationNatural VentilationNatural Ventilation News

December 2010December 2010December 2010December 2010

Where is the Evidence?

The CIBSE Natural Ventilation Group

The CIBSE Natural Ventilation

Group is a large, international

group, that was founded in 1994.

The committee comprise some 40members serving a wider member-

ship of 5400.

Group Aims

The aims of the group are: to ensure natural ventilation is

properly considered at thedesign stage equally withmechanical ventilation or air conditioning;

to disseminate knowledge viaseminars and publications;

to recommend researchprojects;

to be at the forefront of knowledge about the lowenergy, environmental andeconomic performance of natural ventilation;

to work with consultants,contractors, manufacturersand researchers in pursuingthese aims.

Links To access the Natural Ventilation

Group click on the link below or cut

and poste it into your b rowser:

http://www.cibse.org/index.cfm?go=groups.details&item=11

Committee Officers

Professor Derek ClementsProfessor Derek ClementsProfessor Derek ClementsProfessor Derek Clements----CroomeCroomeCroomeCroome

Reading University (Chairperson)

Dr. Malcolm CookDr. Malcolm CookDr. Malcolm CookDr. Malcolm Cook

Loughborough University (Secretary)

Figure 1: Computational Fluid Dynamic (CFD) software is one useful tool available to researchers of natural

ventilation systems. However, it should not be the only tool employed, but should be one of a number of research methodologies.


3/6

by Richard Cowell

Consultant to Arup

A fter decades of controlling noise frommechanical ventilation, our defensivestance against unwanted sound could

easily continue as, now, more andmore naturally ventilated buildings areplanned. The obvious attack is fromexternal noise most often road, rail,air traffic noise, or prolonged construc-tion noise. We reach for attenuated,labyrinthine air inlets, adopting unhelp-ful pressure drops, keeping out noise,trying to keep under specified noiselimits and meet poor regulation. Wehave a long history of tackling acousticissues defensively.

Without mechanical ventilation, we hear moreincoming sound and try to defend ourselves

against that. This means higher partition sound

insulation and crosstalk control. Acoustic de-

signers struggle, knocking down hurdles, help-

ing naturally ventilated solutions to fly. Creative

ideas can bring success, but, perhaps we have

a better way for building services

engineers and acousticians to ap-

proach this.

In nature, the sounds associated

with air movement are interesting.They are highly variable. They in-

form us about our surroundings;

for example, the wind in the trees,

danger from high wind speeds. At

modest and reasonably steady wind

speeds, the spectrum of sound

generated by air encountering; for

example, trees, hedges, crops and

a wide variety of other obstacles is

pleasing to most of us, see Figure

1. The spectra are similar to those

we knew from some induction units

and regenerated air noise in me-

chanical systems. Waterfalls and

distant shorelines tend to generate similarly

pleasing sound spectra. It seems that nature has

indoctrinated our taste for good ambient sound.

This Months Q&A Technology Tips

These tend to be sounds we like, rather than

sound from which we need to defend ourselves.

Indoors, we like to maintain some aural aware-

ness of what is going on outside, but will close

openings if air movement or sound levels get

too invasive. We move very quickly to defensive

behavior in our designs.

Lets challenge acoustic criteria afresh. In par-

ticular, consider:

With favorable sound spectra, there is wide

acceptance of higher background sound

levels. A well shaped NR40 is more ac-

ceptable than a poor NR35.

Building occupants tend to allow higher

sound levels when they can open windows

or, in other ways, control natural ventila-

tion. Some variation in background sound is

preferred - we may need more occupant

mobility for this.

In the future, much quieter electric/hydrogen

cars incorporate different sounds to warn of

their arrival. These and road surface noise will

tend to emphasise high frequencies (easier to

screen or attenuate). With a favorable sound

spectrum, in the future, we may be able to relax

our protective stance.Designing to hold sound pressure levels below

an NR curve is inappropriate, out-of-date, and

an obstacle to creative design of natural ventila-

tion systems. This doesnt mean that anything

goes. Good aural communication suffers with

too much background sound, even with good

spectral shape. Pleasure in natural sounding

environments diminishes if we need to hear

something specific. Sound generated by the

wind was not always helpful to the

hunter gatherer.

We should target good sound spec-

tra, let the background sound vary,

encourage mobility of building oc-

cupants, keep aural awareness of

enough external sound here is

scope for more creativity in building

design for natural ventilation, or

mixed mode systems.

Defensive acoustic design feeds on

lack of appreciation of different de-

sign disciplines. Acoustic difficulties

are feared by architects and building

services engineers. Opportunities are

spotted less often. Acousticians with

insufficient appreciation of architec-tural and services difficulties can all

too easily dig in heels to protect a workable

outcome. If we all pull back a step and re- think

some of the fundamentals, collaborating more

effectively, we have more scope to use natural

ventilation successfully.

Richard Cowell is a Consultant to Arup and a

Fellow of the Institute of Acoustics. A representa-

tive for the Institute of Acoustics (IOA) has been

kindly welcomed to attend meetings of the CIB-SE Natural Ventilation Group (for which many

thanks). We are keen to explore the mutual

learning across our disciplines, with better de-

sign in mind. The CIBSE meeting on Natural

Ventilation in the Urban Environment, at the

RIBA on December 3rd will include papers from

acousticians, and will, we hope, be attended by

a multi-disciplinary audience. We hope that

CIBSE members will also contribute to future

IOA meetings.

Natural VentilationNatural VentilationNatural VentilationNatural Ventilation News December 2010December 2010December 2010December 2010

Natural Sounds and Natural Ventilation

Figure 1: Generic preferred sound spectrum/natural sounds(such as wind, water, or a distant seashore)

Wind in Trees on Shoreline (Image courtesy of Phil Thebault at FreeDigitalPhotos.net )

Waterfall (Image courtesy of Tom Curtis atFreeDigitalPhotos.net )


4/6

by John Palmer

A Regional Director of Building

Engineering at AECOM, based in the

Birmingham office, and CIBSE Schools

Design Group Chair.

How well do we understand the venti-lation of our houses? This is an easyquestion to ask and, if you are runningcomputer models, the answer is that weunderstand it reasonably well. Theresearch effort that has gone intosuccessive revisions of Part F (inEngland and Wales) of the BuildingRegulations is significant and thefindings wide ranging. From simplesingle-zone to multi-zone ventilationand indoor air quality models,

including pollution emissions, theresults give a clear indication of whatventilation provisions we should maketo provide good indoor air quality.However, even th i s l eve l o f understanding raises a number of un-answered questions, and one of thosequestions is particularly difficult to an-swer What is the actual ventilationrate in practice?

A recent study for the Department for Commu-

nities and Local Government, established to

compare short-term monitoring methods, has

provided the opportunity to use three methods

to estimate or measure the ventilation in a re-

cent low-energy and airtight house. The design

intent was an air permeability of less than

3 m/hm: The air permeability of a building is

defined as the leakage rate at 50 Pa per square

metre of the building envelope including walls,

roofs and the total ground floor area. If one

assumes the empirical estimate of infiltration

rate being 1/20 th of the air change rate at

50 Pa this equates to an approximate infiltration

rate of 0.15 ach. (For a house, the air changerate and air permeability have similar values.)

Th

The following measurements were made over a

short period of time in the early spring of 2009:

Airtightness by fan pressurisation and de-

pressurisation;

Infiltration by carbon dioxide (CO 2) decay;

Long-term measurement using passive

perfluorocarbon tracer gas sampling (PFT).

Fan Pressurisation Permeability Tests

Fan pressurisation tests were made under a

number of ventilation conditions including thenormal occupied pattern (as lived in), the

conditions required for a Part L permeability test

(TM1 test procedure) and all trickle vents open.

Using the final permeability value, for the as

lived in condition, of 7.26 m 3/(h.m) @ 50 Pa,

the infiltration rate would be estimated at 0.36

ach when using the 1/20 th method of

estimation.

Short-Term Test Carbon Dioxide

Dosing and Decay Test

Carbon dioxide (CO 2) was used as the tracer

gas and was released in all rooms of the house

to achieve a uniform distribution of the gas in

the entire dwelling; fans were used to keep the

air well mixed during this period. Photograph a)

shows the CO 2 being released in the living

room and photograph b) shows an additional

large fan (part of the equipment required for the

blower door / air permeability test), which was

used to aid mixing. Two CO 2 analysers were

used to record the decay of the gas. Under the

test conditions, the results of the CO 2 decay test

indicated an infiltration rate of 0.34 ach.

Long-Term Infiltration Test

PTF Dosing and Sampling

A third and final test using perfluorocarbon

tracer gas sampling (PFT) was carried out by

placing gas emitters in a variety of places in the

dwelling, together with sample tubes to adsorb

the gas. The great advantage of this techniqueover any short-term test is that the building has

the time to experience a variety of weather con-

ditions through the testing period. Therefore, the

results are more likely to be representative of

the long term infiltration rates. The quantity

calculated from the measurements is the mean

age of air, whose reciprocal is the air flow rate

in air changes per hour. In this case the test

period was one week and the results of this test

gave a mean age of air of 2.46 h, which is

equivalent to an average infiltration rate of 0.41

ach.

Conclusion

It would be dangerous to draw a firm conclu-

sion from this single study, but it does show how

hard it is to be sure of the actual ventilation rate

of a dwelling. If one assumes the actual ventila-

tion rate is that recorded by the PFT method,

then this showed an infiltration rate ~20%

greater than the ventilation rate measured with

the CO 2 decay test, and ~14% greater than the

ventilation rate estimated from the blower door

test using the 1/20th

rule of thumb.

Ventilation in dwellings is a complex issue and

these discrepancies could have a real impact on

the expected indoor air quality or energy use of

houses. This is likely to be increasingly so as we

aim for zero-carbon dwellings.

Acknowledgements

Thanks are due to to Jez Wingfield of LMU, Ian

Mawditt of Building Sciences for the PTF

measurements and Willy Pane of AECOM for

the analysis.


What is the Ventilation Rate in Houses?

(a) CO 2 Dosing in the Living Room (b) Large Fan in the Lobby to Aid Mixing


5/6

by Dr. Malcolm Cook 1, Dr. TongYang 1, and Dr. Paul Cropper 2

1. Department of Civil and Building

Engineering, Loughborough University

2. Institute of Energy and Sustainable

Development, De Montfort University

Natural ventilation is now frequentlyused in modern buildings either as thesole means of ventilation or as part of a mixed-mode strategy. It not only of-fers potential energy savings but canalso lead to greater occupant satisfac-tion resulting from higher indoor air quality and increased adaptive control.Occupants in such buildings often re-mark on the airiness or freshness of their environment. But what designtools do we have at our disposal for predicting comfort parameters in suchspaces?

Computational fluid dynamics (CFD) is often

used to determine the likely performance of a

natural ventilation design and to refine im-

portant parameters such as ventilation opening

sizes and positions. In these simulations, the

detail with which occupants are represented

varies considerably, both in terms of geomet-

rical form and conditions imposed at the sur-

face of the occupant. Some cases use simple

shaped blocks of constant temperature, others

specify a constant heat flux based on an as-

sumption of the surrounding air conditions.

Some models pay little or no attention to the

radiation exchange with the environment or

make assumptions that lead to over-sizing of

heating systems or show up natural ventilation

to be far less feasible than it otherwise might be.

In some cases, CFD models are used to derive

empirically-based thermal comfort parameters

such as predicted mean vote (PMV) and predict-

ed percentage dissatisfied (PPD) of occupants.

Work currently underway by researchers at

Loughborough and De Montfort universities

uses a computational manikin of human ther-

moregulation and thermal comfort (the IESD-

Fiala model [1]) embedded within the solution

cycle of a CFD program to provide a fully cou-

pled model capable of predicting the influence

of temperature and velocity fields on human

thermal comfort and the effect of human metab-

olism and sweat excretion on the surroundings.

This provides the opportunity to model more

realistic human geometries (and the boundary

layer flows and heat transfer associated with

this) as well as the convection, radiation and

moisture transfer between the body and thesurrounding environment.

The coupled simulation system begins by setting

an initial guess for the flow field in the CFD

model. In response to this, surface temperatures

and perspiration rates are calculated for each of

59 body parts by the IESD-Fiala model and are

passed to the CFD model to be used as bound-

ary conditions. Once the CFD solution has

achieved a sufficient degree of stability, or con-

vergence, information about the local environ-

ment close to the body surface is extracted andpassed to the IESD-Fiala model, which deter-

mines the bodys response to these new condi-

tions. Updated surface temperatures and perspi-

ration rates are then returned to the CFD model

and the CFD solution process resumed. This

data exchange is repeated until the coupled

system achieves a sufficient degree of overall

convergence.

This two-way data transfer is thought to be par-

ticularly important when modelling naturally

ventilated spaces where air velocities are low,

because the effect that a human body has on

the local environment is potentially more signifi-

cant than in other environments where velocitiesare often higher.

Figures 1 and 2 show the coupled system in use

to simulate natural ventilation in a school class-

room. The model comprises open windows with

cross ventilation to a stack driven purely by

buoyancy forces generated by the room occu-

pants. The detailed image is taken from a simu-

lation which was used to investigate the differ-

ences exhibited by the new coupled system

alongside a more traditional, simplified shape

model of a human with a constant heat flux.

Although still in progress, the work demon-

strates how a coupled model approach can

lead to a more accurate prediction of the con-

vective-radiative split at the human body surface

to generate a more buoyant plume and ulti-

mately a greater ventilation rate in buoyancy-

driven natural ventilation. The coupled system

also predicts dynamic thermal sensation using

one of the worlds most respected and widely

validated cybernetic models of human heat

transfer and thermoregulation.

The full article can be found in the September

2010 edition of the CIBSE Journal. Further de-

tails about the coupling procedure can be

found in the Journal of Building Performance

Simulation, pp. 233-243, Volume 3, Number

3, 2010.

References

[1] Fiala D. Dynamic Simulation of Human

Heat Transfer and Thermal Comfort. PhD

Thesis, De Montfort University, 1998.


Thermal Comfort Prediction Using Coupled Modelling

Figure 1: Air temperature predictions in a naturally ventilated classroom with ambient temperature of 21C. In this case, the predicted dynamic thermal sensation for the manikin was 0.73 (slightly cool)

with a natural ventilation flow rate of 14 litres/sec/person.

Figure 2: Temperature distributions around the IESD-Fiala model compares with simplified shapes for occu-pants showing the differences in surface temperature and buoyant plume structures.


6/6

by Prof. D Clements-Croome,

Dr. D Mumovic, Dr. S MacMillian,

and Dr. Z Samad

Buildings can enhance teaching andlearning by high quality design and

management. The physical environ-ment affects the not only the body butthe mind in terms of concentration.Unfortunately the environment in manyschools is tiring for pupils and teachers.This article summarises the findings of research into the design and manage-ment processes and proposes a seriesof actions which can increase the likeli-hood of attaining school architecturewhich is fresh and pleasant for pupilsand teachers.

Barriers exist between consultants and

contractors. The traditional janitor caretaker is

now the site manager but has this ensured that

the facilities management really takes place in

practice? There is a demand to lower energy

consumption but this cannot be done at the

expense of quality environments for the learning

process to take place in. Evidence based

research and practice is used here to give

recommendations for designing and managing

intelligent schools which are responsive to user

needs.

Two recent research studies show that the

guidelines provided in Building Bulletin (BB) 98

(Briefing Framework for Secondary School

Projects) are regularly seen to constitute the

minimum accepted standards for a school facili-

ty that, in their opinion, were often used as

criteria for assessing costs. In contrast, there are

contractors and consultants who, rather

pragmatically, believe in the importance of

prioritising the aspects that are most important

to the individual school. However, their priorities

regarding contextual fit and their views on thepotential impact of the school on the individual

and the wider community differ from those of

architects. They also considered the money

allocated to building a school facility is not

enough.

Numerous attributes of design quality are

considered to be quite subjective and are given

varying importance by different stakeholders.

This is particularly apparent for attributes such

as aesthetically pleasing and contextual fit.

Different views and expectations concerning theschool environment clearly exist. Omnipresent

was the expressed need to view the design

quality of a school as incorporating more than

just the building. But so too was the difficulty of

giving sufficient allowance to the commercial

context in any judgement of quality of the

design. Thus, it is not surprising that practition-

ers frequently emphasise the challenges they

face in attempting to operationalise notions of

design quality. Whilst there is common

acceptance of the complexity of designing a

school, agreement regarding the importance of

Th

the different components of the school system

and how to prioritise between them is still to be

achieved. The multiple purposes of educational

facilities and the conflicting views of design

quality combine to make finding a balance

between fitness for purpose, cost

effectiveness and buildability of the facility a

very difficult task indeed. Ultimately, the now

scrapped Building Schools for the Future (BSF)

programme presented an unprecedented

opportunity for institutional change.

However a research study by University College

London shows that many new BSF schools are

failing to achieve the expected targets related to

both energy consumption and indoor air

quality.

This evidence was supported by a BSRIA

commentary in May 2009 concerning Energy

Performance Certificates in which it was stated

that, by the end of 2008, only 43 out of 92

schools had performed in asset rating efficiency

bands A-C ( www.bsria.co.uk/news/epc-schools ).

a. post-occupancy performance of five low

energy schools in the UK shows that four of

the schools evaluated had higher carbon

emissions than the median UK school

building. It was found that the increase in

the use of IT, as well as more stringent

internal air quality standards, is r esponsible

for the high energy consumption. The less

obvious reasons include inadequate

training to operate building management

systems and failure to understand the effect

of occupant behaviour on energy use in

schools. Note that all five school buildings

were completed in the period from 2001 to

2005, and were characterised by

comparable gross floor areas and similar design criteria. This study advocates the

continuing use of post occupancy

evaluation to ensure that a rapid feedback

loops enable designers to understand

better the real design requirements for

school buildings.

b. a number of newly built BSF schools with

different ventilation strategies has been

monitored thoroughly across a range of

environmental conditions and this has

revealed a number of conclusionsregarding school design and build quality.

The studies showed that complex

interaction between thermal comfort,

ventilation and acoustics when providing

good classroom design presents

considerable problems for designers.

Overall, it would seem that the basic

requirement of 1500 ppm of carbon

dioxide is achieved as a consequence of

the window areas being just sufficient to

provide the required level of fresh air with

low and intermittent occupancies. To meet

the higher supply rate of 8 l/s per person

the window installations frequently provide

inadequate openable area. Furthermore, it

has been concluded that the ventilation

provision may be inadequate to remove

excess heat without causing discomfort

from draughts. Note that all studied

schools were built between 2004 and

2006 and were in compliance with the

Building Bulletin 93 (Acoustic Design of

Schools) that significantly revised the stand-

ard for acoustic performance.

It seems that multiple purposes of educational

facilities and the conflicting views of design

quality combine to make finding a balance

between fitness for purpose, cost

effectiveness and buildability of the facility a

very difficult task indeed.

Other studies by the University of Reading show

that CO 2 affects pupils concentration levels

and the need for fresh air is just as important as

temperature requirements.

The BSF programme had a Minimum Design

Standard. The procurement period was 75

weeks. CABE assessors made a review of initial

design bids in weeks 2330 and further

reviews until the end of the procurement period.

This gave time for the design to evolve and

hopefully ensures enough thinking time.

The review was based on 10 quality criteria. The

assessors could include designer architects and

engineers; local authority professionals;

members of partnership for schools; and educa-

tionalists. It is not clear that this solved the prob-

lems which can occur at the later stages of con-

struction, commissioning and facilities manage-

ment. We have to ensure that all the team of clients, consultants, contractors and others all

have the same mission and values if we want to

attain the aspirations described here.

Acknowledgements

Part of this work was financed by EPSRC.

Paulina Cardellino, Roine Leiringer and others

have also researched the Reading University

findings presented in this article.

About the Authors

Emeritus Professor Derek Clements-Croome isDirectory of the Intelligent Buildings Research

Group at the University of Reading and Chair of

the CIBSE Natural Ventilation Group.

Dr Dejan Mumovic is a Lecturer in Environmental

Design and Engineering at the Bartlett School of

Graduate Studies, University of London, and is the

Secretary of the CIBSE Schools Design Group.

Dr Sebastian MacMillan is an affiliated Lecturer of

the Department of Architecture, University of Cam-

bridge.

Dr Zulkiflee Bin Abdul Samad is a Senior Lecturer

in the Faculty of the Built Environment at the Uni-

versity of Malaya, Malaysia.


Designing Intelligent Schools

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