The PROBE building

1. The PROBE building The PROBE- Building Architect of renovation: Y. Wauthy Building physics consultant: BBRI (55 occupants ) Building presentation Design issue Building concept Low heating consumption Summer comfort Indoor Air Quality Monitoring results Major findings More information... Back to “Select a building” NatVent

2. Building presentation (1...) • The PROBE building was built in 1975. It is a 2 storey building, situated on the test site of the BBRI in a very quiet environment. The exterior walls are non insulated cavity walls and the building has a flat roof. • PROBE stands for Pragmatic Renovation of Office Buildings for a Better Environment. The renovation works started in 1994 and were finished in 1998. The renovation project included: • New fuel boiler, thermostatic valves and improvement regulation system • Addition of thermal insulation to flat roof • Installation of mechanical ventilation with IR presence detection • Replacement of single glazing by low-e gas filled double glazing • External solar shading with automatic control • Large louvres for night ventilation • Artificial lighting with luminance control and electronic ballast • The renovation project is a demonstration project. All renovation works are relatively small-scale retrofitting. Hence this renovation strategy is applicable for a lot of present-day office buildings

3. 14 m 40 m N Building presentation (2|) • About 30% of the façade surface is glazed. • The building is subdivided into cellular offices at the east and west side of a central corridor. The offices have exposed plastered ceilings and the offices are separated by brickwork walls. Internal View (after renovation) Plan view (first floor)

4. Design issue • Before the renovation, there were two problems with the internal environment of the PROBE-building: • relatively bad indoor air quality in winter time. The reason being the comparatively airtight building shell had no provision for ventilation • serious overheating problems in summer time • Besides comfort consideration also environmental concerns played a role in the renovation strategy. In this demonstration project, special attention was paid to the energy consumption of the building: • reduction of energy use for heating (fuel) • reduction of lighting energy consumption (electricity)

5. Building concept (1…) • The renovation had three aims: • 1. lower energy use in winter time • 2. better thermal comfort in summer time • 3. better indoor air quality (in winter time) • The strategies followed to meet these objectives are explained in the following slides. VENTILATION plays an important role in these strategies. There is however a very important difference between two types of ventilation: • Large ventilation flows • At night: no noise exigencies Thermal summer comfort Intensive Night Ventilation (& Thermal Mass) • Small ventilation flows • During office hours Indoor Air Quality Demand controlled mechanical ventilation

6. Building concept (2…)Energy use in winter time • Energy use in winter time was reduced through several measures • improving the heating installation: • new fuel boiler • thermostatic radiator valves and • a better regulation system • The single glazing was replaced by low-e argon filled double glazing. This means a reduction of the U-value from 5,8 W/m2K to 1,1 W/m2K • 7,5 cm extra glass wool insulation was placed on the roof. Hence the U-value of the roof decreased from 0,91 W/m2K to 0,34 W/m2K . Moreover this measures has also a positive contribution to the thermal summer comfort as the indirect solar gains are reduced(see chapter ‘Summer comfort’).

7. Building concept (3…)Thermal summer comfort • The strategy followed to achieve lower internal temperatures consist of a package of passive measures. • Scheme of the strategy: • Important remark: one can only expect an acceptable indoor summer comfort by the total effect of all measures GLOBAL STRATEGY for thermal comfort under summer conditions REDUCTION of GAINS: indirect solar gains direct solar gains internal gains FREE-COOLING & STORAGE: night ventilation & thermal mass

8. g-value=X/Y Y X Building concept (4…)Thermal summer comfortHeat gains - indirect solar gains • During warm summer days the radiation of the sun can be up to 1.000 W/m2. If this heat flux strikes an opaque surface, a part of the heat is transmitted by conduction, convection and radiation to the indoor. These heat gains are called ‘indirect solar gains’. • The indirect solar gains through the roof of the buildings are reduced from 4,0% to 1,5% of the inclining solar radiation by a supplementary insulation layer of 7,5 cm glass wool.

9. Building concept (5…)Thermal summer comfortHeat gains - direct solar gains • Direct gains are the solar gains through transparent surfaces (windows). They can lead to the well known ‘GREENHOUSE effect’. An acceptable indoor summer comfort is impossible, without a reduction of the solar gains to an acceptable level. • External shading is the most effective way to reduce the direct solar gains. • As the PROBE-project is a demonstration project, different solutions were applied to reduce the direct solar gains: • on the south façade (cafeteria): internal blinds • on the east façade: inclined extern. solar protection • on the west façade: vertical external screens (pictures of solutions - see next slide...) SOUTH FAÇADE new glazing with internal blinds

10. Building concept (6…)Thermal summer comfortHeat gains - direct solar gains - shading devices CONTROL The external shading devices are automatically controlled by a weather sensor on each façade. However this control can be manually overruled for each office. WEST FAÇADE vertical external screens new framework with large grilles for intensive night ventilation EAST FAÇADE inclined external screens existing framework with removable large grill for night ventilation

11. Building concept (7…)Thermal summer comfortNight Ventilation • The objective of night ventilation is to cool down the thermal mass of the building with large air flows of external cold air at night. • Two elements are essential in this strategy: • large air flows • thermal mass • The PROBE-building is a very massive building. Moreover the thermal mass is very accessible: the plastered concrete ceilings are exposed and the internal walls are heavy brickwork walls (see picture). Internal View (after renovation)

12. Building concept (8…)Thermal summer comfortNight Ventilation • The intensive night ventilation is based on a concept of CROSS VENTILATION: during warm periods at night the large grills and the internal doors are open to allow a cross flow EAST FAÇADE existing framework with removable large grill for night ventilation WEST FAÇADE new framework with large grilles for intensive night ventilation

13. Exhaust Exhaust TOILETS Supply controlled by infrared sensors CORRIDOR Supply controlled by infrared sensors OFFICES Building concept (9…)Indoor air Quality • A mechanical demand controlled ventilation system supplies fresh air in the offices during the office hours. • The air extraction is located in the toilets. • The supply device of each office is controlled by an IR presence detector. Hence offices which are not occupied are not ventilated. Knowing that the average occupancy in the PROBE-building is around 50% during office hours, the occupancy sensors produce saving of 30% to 40% of the ventilation losses. Air supply device with IR-presence detector

14. Ventilation of the PROBE-building SUMMER WINTER Day-time: infrared controlled mechanical ventilation Night-time: intensive natural ventilation Day-time: infrared controlled mechanical ventilation Night-time: no ventilation Building concept (10|)The ventilation strategy - overview The ventilation system of the PROBE building consists of two part Mechanical ventilation system for IAQ • works only during office hours • relatively small flows Night ventilation for thermal comfort • works only at night during warm summer periods • large air flows

15. 9 10 11 12 13 14 15 16 17 8 7 6 5 4 3 2 1 N = office with night ventilation = doser = sampler Monitoring results (1…) • The building was monitored during the summer of 1997. The monitoring was focused on the offices at the east side of the building on the first floor (see plan view). • Parameters such as temperatures, air flows and heat fluxes were measured • During the monitoring campaign of ‘97 the renovation works was incomplete: • No solar protection on west side of the building • Only offices 3 & 6 had ventilation grilles and were ventilated intensively at night Set-up of the tracer gas measurements

16. Monitoring results (2…) Summer of 1997 - renovation not yet completed: Temperatures in Office 3 and 4: Clear effect of the night ventilation of Office 3  lower temperatures

17. Monitoring results (3|) Summer of 1998 - renovation completed: Temperatures in offices on the west side of the building during extremely warm week The internal temperatures (max.27°C) are considerably lower then the exterior temperatures (max.31°C).

18. Major findings • The monitoring results prove that acceptable summer comfort levels can be achieved by a global strategy of: • reducing the heat gains: solar gains and internal gains • applying natural ventilation in combination with thermal mass • Only the global effect of all measures gives an acceptable comfort • The renovation concept of the PROBE building is a very practical concept of small-scale improvements. This renovation concept is applicable for a lot of existing offices. Acknowledgement: The renovation of the PROBE-building was funded by the Walloon Region and several industrial partners:

19. 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 OR run the installation file ar32e301(1).exe in the directory \Installation More information... The PROBE- Building Find more information on the PROBE building in the following documents: \Reports \Monitoring Reports \Summary Reports\be1summ.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\be1det.pdf • detailed reports of all 19 monitoring campaigns (20p./campaign) • contents: monitoring set up - analysis of results - conclusions Building presentation Design issue Building concept Low heating consumption Summer comfort Indoor Air Quality Monitoring results Major findings More information... Back to “Select a building” NatVent