NatVent - BRE Groupprojects.bre.co.uk/natvent/presentation/211_gb2.pdf · drawing air up chimney (Bernoulli effect) Solar ‘accelerator’ Damper actuator: Air flow across chimney

The Canning Crescent Centre

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PresentationPresentationof the buildingof the building

BuildingBuildingconceptconcept

MajorMajorfindingsfindings

The CanningThe CanningCrescent CentreCrescent Centre

MoreMoreinformation...information...

Back toBack to“Select a“Select abuilding”building”

MonitoringMonitoringcampaignscampaignsMonitoringMonitoring

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Building presentation (1...)

! Building information:" Architects: MacCormac Jamieson, Prichard, UK" Building Services Engineer: Atelier One, UK" Research team monitoring the building: Dr Vina Kukadia, James Pike, Martin

White, Building Research Establishment, UK

! The Canning Crescent Centre is a community day-care centre completed in1994 at a cost of £1.3 million. It is an L-shaped two-storey building with agross floor area of 1350 m2. It is located on a busy high street in WoodGreen, an urban area of London where air pollution and noise levels arehigh.

! It is a high thermal mass construction comprising a steel frame with exposedbrick walls and a concrete ground floor ceiling.

! The south west side of the building faces the busy high street where air andnoise pollution is high.

! The north east side faces a ‘clean’ enclosed garden courtyard and car park.

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Building presentation (2|)

The Canning CrescentThe Canning CrescentCentre from theCentre from thecourtyard car parkcourtyard car park

Plan view of groundPlan view of groundand first floorand first floor

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Building concept (1...)

Ventilation philosophy! Design of building and ventilation strategy is based on

" low budget so there is no mechanical ventilation" the need to protect patient confidentiality from pedestrians in the high street

overhearing conversations" the need to prevent the ingress of air pollution and noise from the high street

! Diaphragm cross walls used to provide a series of individual chimneyswhich allow air to be drawn through the building by wind and buoyancyforces.

! Fresh air for the whole building comes exclusively from the ‘clean’courtyard side.

! Window opening along the front of the building facing the high street isdiscouraged.

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Ventilation philosophy

Freshair intake

GardenCourtyard

Rooflight

High Street

ExhaustairExhaustairExhaustairExhaustairExhaustairExhaustair

Exhaustair

Series of individualSeries of individualchimneyschimneys

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! Air supply is purely byopenable windows and trickleventilators located in thewindow frames.

! Air exhaust from each roomis via a high level woodenextract grille and its ownexhaust stack.

Openable windows withOpenable windows withtrickle ventilatorstrickle ventilatorsAir extract grille atAir extract grille at

high levelhigh level

Room facing the courtyardRoom facing the courtyard


Ventilation system - room facing courtyard

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Fresh airFresh airintake onintake onexternalexternalwallwallfacingfacingcourtyardcourtyard

! Air is supplied through openings inthe external courtyard facing wall

! Air is then ducted through the footingsof the building to low level woodensupply grilles.


Ventilation system - room facing courtyard

Air supply and extract grilleAir supply and extract grillein room facing high streetin room facing high street

Low level airLow level airsupply grillesupply grille

High level airHigh level airextract grilleextract grille

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Building concept (4|)

Ventilation system - Air exhaust stackLow pressure zoneinduced below aerofoil,drawing air up chimney(Bernoulli effect)

Solar ‘accelerator’Solar ‘accelerator’

Damper actuator:Damper actuator:

Air flow across chimney

Air from internal spacesexits at high levels

! Adjustable air flowdamper in thestacks controls the air change ratein each room

! Dampers in the stack are controlledmanually and set centrally to" Fully open in the summer to aid

cooling" Almost closed in the winter to

provide reduced flow rates sufficientto maintain optimum indoor airquality and minimise energy loss

Adjustable airAdjustable airflow damperflow damper

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Building concept (5|)

Ventilation strategy! Winter ventilation strategy

" All dampers set in an almost closed position to provide background air forventilation and removal of carbon dioxide.

" Local control of dampers allows increased rates of air flow in individual officeswhen required.

! Summer ventilation strategy" Dampers in the stacks are set in the fully open position to maximise air flow

rates to cool the thermal mass of the building." Automatic roof lights open up to purge the heat from the building during the

night time." Solar heated double glazed panels at the top are intended to provide increased

buoyancy and hence extract flow rate.

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Monitoring campaign (1...)

! Aims of monitoring campaign:" To determine the performance of the ventilation strategy all year round in

terms of– Thermal comfort– Removal of carbon dioxide– Minimising ingress of external pollution into the building

" To provide recommendations for improvement of ventilation system ifnecessary

! Monitoring was carried out in" four offices

– Two facing the high street, ground and first floor.– Two facing the courtyard, ground and first floor.

" corridor" high street" seminar room

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Monitoring campaign (2...)

Location of measurementsTemperature sensor

Hot-wire anemometer

T

T

A

Noise meter

Sample tube

External sample point

3

4

Dosing tube

Busy High Street

Courtyard

N

Seminar room

Location of measurementsLocation of measurements

Plan viewPlan view

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Monitoring campaign (3|)

different campaigns! Winter monitoring

" Monitoring carried out over 1week in March 1997

– Air change rates– Local air velocity– Temperature

# Internal mean radiant# External air

– Humidity– Carbon dioxide

! Summer monitoring" Monitoring carried out over 1

week in July1997– Air change rates– Temperature

# Internal mean radiant# External air

– Humidity– Carbon dioxide

! Indoor Air Quality and othermeasurements" Monitoring carried out over 1

week in March 1997– Carbon monoxide– Nitrogen oxides– Sulphur dioxide– Noise

" Air flow rate through inlet grille" Occupant questionnaire and

interviews

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Monitoring results (1…) - winter

! Results for office 3 - good representation of all monitoredoffices

" Ventilation rates of 1 to 2 air changes per hour (ach) wereobtained. Mean internal daily temperatures varied between 17-25°C. This is slightly higher than a design temperature of 18°C.

" Relative humidity levels varied between 40 to 60%.

" Carbon dioxide levels increased in the presence of occupantsbut reduced rapidly to background levels of 400 ppm in theirabsence. This also occurred in summer.

" Local air velocities averaged at 0.1 ms-1 (not shown)

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Monitoring results (2...) - winter

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14/03 12:00 15/03 12:00 16/03 12:00 17/03 12:00 18/03 12:00 19/03 12:00 20/03 12:00 21/03 12:00

Week between Fri 14 March 1997 and Fri 21 March 1997

Int.

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Air ChangeRate

The fresh air supply is sufficient → The IAQ is acceptable: the CO2-concentrations are below the limit of 1200 ppm.

The air change rate is sometimes relatively high, when the office is notoccupied. This leads to unnecessary energy losses. This problem occursbecause the settings of the flow dampers are not clear to the occupants.

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Monitoring results (3...) - summer

Results for office 3 - good representation of all monitored offices

! Ventilation rates of about 2-3 ach were generally obtained; andabout 17 ach when the dampers in the stack were manuallyopened for periods of one hour.However the night ventilation strategy was not implemented. Thisis mainly due to the fact that the settings of the flow dampers arenot clear to the occupants.

! Mean internal daily temperatures varied between 17 to 27.5°C.

! The IAQ is acceptable: the CO2 -concentrations are below the limitof 1200 ppm.

Monitoring results: see next slide… →

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Monitoring results (4...) - summer

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01/07 00:00 02/07 00:00 03/07 00:00 04/07 00:00 05/07 00:00 06/07 00:00 07/07 00:00 08/07 00:00

Week between Tues 1 July 1997 and Mon 7 July 1997

Int.T

emp

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Ext.

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Air ChangeRate

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Monitoring results (5...)

Indoor air quality! Carbon monoxide (CO), nitrogen oxide (NO), nitrogen dioxide (NO2) and

sulphur dioxide (SO2 ) levels were well within recommended air qualityguidelines

Measuredgas

Measuredmean

concentrations

Recommended air quality guidelines

ExpertPanel on Air

QualityStandards

WorldHealth

Organisation

EuropeanCommunity

CO (ppm) 0.31 101 101 -

CO2 (ppm) 400 - - -

NO (ppb) 222 - - -

NO2 (ppb) 432 1502 801 1051

SO2 (ppb) 22 1003 1222 942

1 8-hour mean2 1-hour mean3 15-min mean

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! Occupants reactions were as follows:" Cold down draughts from the high level extract grilles were felt during the

winter; as a result the grilles were sealed with plastic film and cardboard." Electrical fan heaters were used as auxiliary heat sources in the winter." During the summer there was considerable overheating in the offices facing

the courtyard.

Monitoring results (6|)

Occupant questionnaires

Extract grille covered with cardExtract grille covered with card

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Findings & Improvements (1...)

!! Issues and lessons learnt:Issues and lessons learnt:" Summer-time comfort could be improved by a more effective

intensive night ventilation, which would cool down the thermal mass.The ventilation system functions were ineffective due to severalreasons:

– Master stack damper control labelling was unclear and resulted in thewrong setting being applied during the summer period.

– Inadequate maintenance of dampers resulted in the dampers being ‘stuck’in the closed position even in the summer.

– Dampers being leaky or ‘stuck’ in the open position resulted in cold downdraughts during the winter.

– High pressure losses in the stack may have contributed to reduced airchange rates.

" Summer-time comfort could also be improved by installing externalshading devices to reduce the solar gains through the windows.

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Conclusions (2...)

!! Suggested improvements:Suggested improvements:" Removal of air flow dampers in each exhaust stack." Replacement of inlet and outlet openings with conventional slide

control grilles." Central damper settings should be clearly marked ‘open’ for the

summer and ‘closed’ for the winter." To prevent cold down draughts, a small low-energy priming fan is

recommended." In the design calculations all pressure drops need to be accounted

for.

!! Conclusion:Conclusion:" Air intakes from the ‘clean’ garden courtyard side ensured that the

ingress of external pollution and noise was minimised." ….

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Conclusions (3|)

!! Suggested improvements:Suggested improvements:" ..." Regular maintenance of the ventilation system and correct labelling of

the dampers are required to ensure correct operation." All controls should be readily understood and be easy to operate by

maintenance staff, facilities managers and office staff." The operation of the building can be substantially improved by

introducing the modifications suggested.

The BRE research team would like to express their thanks to! N Morris, M Osbourne and M Strachan from the Canning Crescent

Centre, UK! I Logan from MacCormac, Jamieson, Prichard! J Grace from Atelier One, UK! Martin Liddament from the Air Infiltration and Ventilation Centre, UK

More information...

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Find more information on the PROBE building in the following documents:

\Reports \Monitoring Reports \Summary Reports\gb2summ.pdf" global presentation of the buildings (±4p./building)" contents: building description - ventilation strategy and technology -

winter and summer monitoring results - conclusions

\Reports \Monitoring Reports \Detailed Reports\gb2det.pdf" detailed reports of all 19 monitoring campaigns (±20p./campaign)" contents: monitoring set up - analysis of results - conclusions

You can read and print pdf-files with the Acrobat® Reader®3.0. Program. This program is free.Download it from the Acrobat web site: www.adobe.com ORrun the installation file ar32e301(1).exe in the directory\Installation

NatVent - BRE Groupprojects.bre.co.uk/natvent/presentation/211_gb2.pdf · drawing air up chimney (Bernoulli effect) Solar ‘accelerator’ Damper actuator: Air flow across chimney

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