the velux building - bre groupprojects.bre.co.uk › natvent › presentation › 204_ch1.pdf ·...

The The Velux Velux BuildingBuilding

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PresentationPresentationof the buildingof the building

The designThe designissueissue

The buildingThe buildingconceptconcept

The winterThe wintermonitoringmonitoring

The summerThe summermonitoringmonitoring

MajorMajorfindingsfindings

The VELUXThe VELUXbuildingbuilding

MoreMoreinformation...information...

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

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Project presentation Project presentation (1...)(1...)

! The Velux building is situated in central Switzerland in the tableland.

! This area is characterised by a moderate and sometimes windy climate.

! The building was renovated in 1992: the former flat roof was topped by twoadditional floors with tilted outside walls resulting in the new roof.

! The building is used as an administration building of a factory for windowfittings.

! The building has many cellular offices, an open plan office and a bigshow room. The rooms have a lot of internal mass: exposed ceilings andtiled floors (the internal walls and external walls are light-weightconstructions).

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! A production facilities forwindows fittings is attachedto the back of the building.

! The building is located in aquiet industrial zone nextto a low frequented road atthe edge of a river. Noiseand pollution are not aproblem.

Part under investigation

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Part under investigationFactory

CellularCellularofficesoffices

Open planOpen planofficeoffice

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1st floor

The basement and theThe basement and thetwo lower floors consist oftwo lower floors consist of

cellular officescellular offices..

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Project presentation Project presentation (5|)(5|)

3rd floor

The two top floors areThe two top floors aredesigned as an designed as an openopenplan officeplan office (2 (2dndn floor) floor)and a and a show roomshow room (3 (3rdrd

floor).floor).

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The design issue The design issue (1...)(1...)

Windows furnishedwith electronic actuators

! As the building is used forthe administration of awindow fitting factory,window fixtures and fittingsare seen as very importantfeatures by the occupants.

! Windows furnished withelectronic actuatorsrepresent one of the newproducts of the company.

! The windows areautomatically controlled witha manual override . Thisimproves the user-acceptance.

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The design issue The design issue (2|)(2|)

! To achieve the goals three control strategies were used:" Automatically timer controlled system (e.g. for night ventilation and

cross ventilation during the work breaks)," Automatically opened windows depending on weather conditions

(e.g. wind velocity, rain)." Manual operated system (The windows can also be manually

controlled during working hours),

! The aim is for the occupants to get naturalventilation via the windows with electronicactuators.

! Thanks to the open architecture of the staircaseof the building the stack effect is consideredto provide a sufficiently strong force forventilation.

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The building concept The building concept (1...)(1...)

Indoor Air Quality during office hoursIndoor Air Quality during office hoursStrategy for IAQ:

! During breaks (early in themorning and at noon) thewindows are automatically(time controller) opened for 5minutes to ventilate thebuilding.

! During the heating season, thebuilding is only ventilatedduring some periods to avoidtoo high ventilation losses

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global strategy for summer comfortglobal strategy for summer comfortThe risk of overheating is reduced by:

! Shading devices: external screens are installed on the all façades. Thescreens are controlled manually.

! The building and the thermal mass (exposed ceilings) of the building iscooled down by intensive ventilation based on the stack effect. Thewindows are automatically opened:" during working hours in the afternoon if the outside temperature is

higher than the inside temperature

" at night (time control)

" Moreover, the automatic control of the windows take weatherconditions into account (see next slide... → ).

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automatic control & outside conditionsautomatic control & outside conditions

Ventilation control is afunction of externalconditions (seeschematic).

The outside conditionsare measured by rainand wind sensors.

nice weather nice weather and wind

rain rain and wind

south-west south-east north-east south-west south-east north-east

3rd floor

2nd floor

1st floor

Ground floor

Basement

3rd floor

2nd floor

1st floor

Ground floor

Basement

closedalways closed (security)open

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overviewoverview

SummertimeSummertime WintertimeWintertime

during officeduring officehourshours

outsideoutsideoffice hoursoffice hours

→ time-controlled shorttime ventilationduring breaks -to improve IAQ→ if Text< Tint:intensiveventilation(weathercontrolled) - toimprove summercomfort

intensiveventilation(weathercontrolled) - toimprove summercomfort

during officeduring officehourshours

outsideoutsideoffice hoursoffice hours

→ time-controlled shorttime ventilationduring breaks -to improve IAQ

no ventilation

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The building concept The building concept (5|)(5|)

user acceptance through independenceuser acceptance through independenceduring working hoursduring working hours

All the automatically controlledwindows can also becontrolled manually (seecontrol device). This permitsthe building users to operatethe desired windows duringthe working hours inaccordance with their requiredcomfort.

This increases the useracceptance of the system.

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Slide with monitoring set-upSlide with monitoring set-up! Continuous measurements of

" Carbon Dioxide (CO2 )," Ventilation Rate," Temperature" Humidity," Indoor air velocity

were made over one week periods during" February 1997," August 1997,

in" the meeting room in the basement" one cellular office on the ground floor" two cellular offices on the first floor (south-west and north-east façade)" one open plan on the second floor" the show room on the third floor

The cellular office on the first floor on the south-west building side was selected as beingrepresentative. The monitoring results of this office is shown in the following chart.

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Indoor Temperature [°C] Air Change [1/h] Outside Temperature [°C]

Winter monitoring Winter monitoring (1...)(1...)

typical winter day - monitoring resultstypical winter day - monitoring results

Indoor temperature sometimes toohigh due to problem with control ofheating system

Occupants open the windows because oftoo high temperatures →→→→ relatively highventilation losses

No ventilation at night = No ventilation losses

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Winter monitoring Winter monitoring (2...)(2...)


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12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00

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Indoor Temperature [°C] Air Change [1/h] Outside Temperature [°C] Carbon Dioxide [ppm]

CO2 rises during the office hours neverabove 1200 ppm (max. conc. :guideline)

Good Indoor Air Quality

Windows are during some minutes autom. opened in the morning

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Winter monitoring Winter monitoring (3|)(3|)


! Due to a problem with the control of the heating system, indoortemperatures were too high. For this reason windows were manuallyopened to cool the building. This leads to high ventilation losses. It is clearthat a better heating control will result in a considerable reduction of theheating consumption in wintertime.

! At night all windows are well closed to avoid ventilation losses.

! The IAQ in the offices is always acceptable (<1200ppm).

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Summer monitoring Summer monitoring (1...)(1...)

typical summer day - monitoring resultstypical summer day - monitoring results

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IndoorTemperature [°C] Air Change [1/h] Outside temperature [°C]

Very warm day (34°C)

Acceptable peak indoor temperature (28°C)

Intensivenightventilation( >10 ACH )

Indoortemperaturedrops due tonight ventilation

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12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 0025-27.08.1997

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IndoorTemperature [°C] Air Change [1/h] Outside temperature [°C]

= Windows are automatically opened at 8,13 and 18hto improve the IAQ. The other ventilation peaks are dueto manually opened windows.

The influence on the IAQ is given on next slide...

Summer monitoring Summer monitoring (2...)(2...)


Intensivenightventilation(>10 ACH)

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Summer monitoring Summer monitoring (3|)(3|)


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IndoorTemperature [°C] Air Change [1/h]

Outside temperature [°C] Carbon dioxide [ppm]

There is a clear relation between IAQ during the officehours and the air change rate: High ventilation rate →→→→low CO2 concentration

The IAQ is always below the limit of 1200 ppm

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Major findings Major findings (1...)(1...)

summer comfortsummer comfort! Summer comfort:

" Thanks to the night ventilation and the shading devices, big overheatingproblems were avoided.

! Shading devices:" The efficacy of the external screens could be increased by an automatic

control instead of manual control.! Night Cooling:

" For security reasons, windows on the ground floor are not opened atnight → no night cooling. Therefore the offices on the ground floor havean appreciable overheating problem in summer.

" User behaviour: Closed doors during the night obstruct often the nightcooling in summertime. Clear user instructions could help.

" A comparison of inside and outside temperature suggest that the nightcooling effect could be used even more intensively by opening thewindows at least 3 hours earlier.

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Major findings Major findings (2...)(2...)

summer comfortsummer comfort! Night Cooling (optimisation of ventilation & stack effect):

" The openable area on each floor produced an unequal air change ratewhich resulted in a reduced night cooling effect and an increased riskon overheating for the upper floors.

" A better analysis of the relation between the opening surfaces andtheir height above the ground (analysis of the neutral level pressure)can increase the night cooling efficiency.

Pressure diff. linePressure diff. line

BETTER...

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! In Winter:" Due to problems with the controls for the heating system

indoor temperatures were too high. Windows are opened to coolthe building. This lead to unnecessary ventilation losses. In orderto avoid ventilation due to overheating in winter, the heatingsupplied to the offices on the south-west building side should bereduced significantly especially in the sunny winter afternoons.

" The IAQ is acceptable

! In Summer:" The IAQ is acceptable

Major findings Major findings (3|)(3|)

indoor air qualityindoor air quality

More information...More information...

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

\Reports \Monitoring Reports \Summary Reports\ch1summ.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\ch1det.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

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