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LL 10: Carbon Dioxide Controlled Ventilation

AIVC, 2001
AIVC | LL
Bibliographic info: LL 10
Languages: English

Carbon Dioxide Controlled Ventilation


#NO 11504 Demand-Controlled Ventilation - Requirements and Control Strategies

Meier S

Sweden, Stockholm, KTH Building Services Engineering, 1998, proceedings of Roomvent 98: 6th International Conference on Air Distribution in Rooms, held June 14-17 1998 in Stockholm, Sweden, edited by Elisabeth Mundt and Tor-Goran Malmstrom, Volume 1, pp 205-212.

Most standards for air handling systems prescribe a minimum air flow rate per person per hour based on full occupancy of the ventilated space. The number of occupants may fluctuate widely, however, and demand-controlled ventilation (DCV) responds to the actual demand for air renewal. There are now sensors capable of detecting this demand, and these are a prerequisite for DCV and good air quality. Key features of DCV are the incorporation of thermal tolerance bands (heating/cooling, humidification/dehumidification), and special control strategies to reduce or even disable the air flow rate. The benefits are a reduction in running costs and automatic maintenance of indoor comfort whatever the operating conditions.

demand controlled ventilation, sensor

#NO 11533 Development of intelligent algorithms for indoor air quality control through natural ventilation strategies. 

Sutherland G, Eftaxias G, Santamouris M, Asimakopoulos D

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 10-16.

Simulations have been performed to investigate the performance of intelligent algorithms for control of indoor air quality through natural ventilation strategies whilst simultaneously meeting the requirements of thermal and visual comfort. The proposed control algorithms are founded on the knowledge base of the building physics and support the control of natural ventilation through control of the window opening, whilst simultaneously controlling the lighting, heating and cooling systems of the building. The concentration level of CO2 is taken as the indicator of indoor air quality, whilst predicted mean vote, interior illuminance levels and the daylight glare index have been adopted as the high level controlled parameters for thermal and visual comfort respectively. The impact of the controller on the overall indoor environment has been investigated.

modelling, building controls, demand controlled ventilation

#NO 11549 Controlled natural ventilation for commercial and industrial buildings. 

Knoll B, Phaff J C

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 154-167.

The Dutch organization for applied scientific research TNO in Delft developed a system of Controlled Natural Ventilation (CNV). It is produced by the Dutch ventilation firm Braked in Uden. The system controls ventilation grills and windows. Its purpose is: to compensate for fluctuating buoyancy forces (wind and temperature) so that natural ventilation flows are kept on set point value, independent of weather changes and changes in internal heat production; to optimize the air flow distribution over the building to get the highest possible ventilation efficiency; to restrict ventilation openings when draught risks occur. The CNV system is based on a computer program that simulates ventilation. A special inverse version is derived that calculates the optimal ventilation openings for a specific building on each weather condition and for each ventilation set point. The program needs input on local wind effects on the building. They are predicted with another new developed simulation tool, called the 'Cp-Generator'. This special computer program for prediction of wind pressure coefficients (Cp's) is built in as a module in the main program.

Extra features of the CNV system are: rain protection without decrease in flow rate; improved noise reduction; collaboration with mechanical ventilation; anticipation on opening doors; building leakage compensation; adjustment of both flow rate and direction to varying pollution or heat sources; smoother temperature control; special control for smoke ventilation.

building controls

#NO 11563 Building performance evaluation for indoor air quality using occupant contaminant inhalation and attribution to contaminant sources.

Takemasa Y, Moser A

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 293-304.

The emissions of building materials like volatile organic compounds and indoor airborne contaminants such as environmental tobacco smoke expose occupants to hazardous substances. Although impacts of indoor air quality problems on human health, comfort, and productivity are quite large, no adequate evaluation methodology exists to assess contaminant source control techniques and building equipment systems. Even if instant indoor concentrations of many contaminants are not always high, continuous exposures to these contaminants may cause severe problems such as manifested by the sick building syndrome.

This paper proposes a method for evaluating long-term building performance in terms of indoor air quality. The approach applies exposure assessment but focuses on building performance. It employs the concept of using the total amount of substance inhaled by persons who occupy the room. This indicator is expressed by kilograms of each contaminant inhaled by persons ever present in the building during its operational life. The values include the effects of occupant rates. Concrete procedures for deriving variations of the indicators for both gaseous and particulate contaminants are described in detail. Another concept of contribution rates of contaminant sources is introduced both for instant values and on the inhalation basis. Evaluation examples of these indicators for a simple office geometry are shown for particulate matter, carbon dioxide, and formaldehyde. The results of the case studies strongly suggest the importance of indoor material selection and ventilation strategies. The contribution rate of contaminant sources makes it easier to plan a remedy for bad indoor air quality. The applicability of these indicators and future research requirements are also discussed.

occupant reaction, building performance

#NO 11577 Heat recovery in natural ventilation design of office buildings.

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 426-437.

In the EU Joule project NatVent one of the work packages was dealing with controlled air flow inlets. During the last conference in Greece an overview was presented on availability, performances and application of controlled air flow inlets. At the presented poster an interactive IAQ computer tool was demonstrated. This tool has been improved and is now available. Some participating countries in the NatVent project have carried out special tests with the NatVent IAQ tool. The NatVent Participants were asked to design a natural ventilation system which could read the 1000 ppm CO2 requirements. The tests of the various countries will be shown. The results of this exercise are very interesting. It shows the positive effect of controlled inlets on IAQ in case of natural ventilation in offices.

natural ventilation, controlled inlets

#NO 11606 Laboratory simulation of human bioeffluents sources using carbon dioxide as a tracer gas.

Auger M R, Farant J P

Canada, Concordia University Centre for Building Studies, 1995, Indoor air quality ventilation and energy conservation in buildings. 2nd International Conference, volume 2, pp239-246, 4 figs, 1 tab, 6 refs.

An experimental setup is presented that can measure concentrations generated around a pulsating source of carbon dioxide (CO2) that simulates human respiration. The experimental setup is used to study the relationship between the ventilation efficiency and the pollutant removal efficiency of a space. These are two key parameters which describe the ability of a space in providing a comfortable and healthy environment for its occupants. Preliminary results obtained so far have focused on the conditions inside a small test chamber. Some preliminary results are presented after a discussion on current tracer gas techniques used in the field.

occupancy effects

#NO 11610 Untersuchung lueftungstechnischer Eigenschaften von Raumlueftungsgeraeten mit indikatorgasverfahren. Review of the ventilation engineering characteristics of room air ventilating equipment using the indicator gas process.

Heidt F D, Fischer T

Germany, HLH, Vol 49, No 10, 1998, pp 74-77, 2 figs, 1 tab, 10 refs, in German

During the refurbishment of older buildings, the installation of central ventilation and exhaust air systems is very complex, since these require ventilation ducts. Even so, where controlled ventilation is a requirement as well as heat recovery from the outlet air, it is possible to use room air ventilating equipment.

tracer gas, refurbishment

#NO 11652 Detailed monitoring of the Canning Crescent Centre, London.

Kukadia V, Pike J, White M

UK, Building Research Establishment Ltd (BRE), CR 272/98, 20 pp.

The objective of this study was to determine the performance of the ventilation strategy in providing adequate indoor air quality for metabolism (removal of carbon dioxide) and thermal comfort all year round. Minimisation of the ingress of external pollution (in particular from vehicular traffic) into the internal environment was also an important consideration. The monitoring protocol developed by the NatVent Consortium was used as a basis for the measurements. This report gives details of the measurements carried out together with results, conclusions and any recommendations for improvement of the ventilation strategy and its operation.

ventilation strategy, thermal comfort

#NO 11674 Improvement of indoor air quality in four problem homes.

Shaw C Y, Salares V, Magee R J, Kanabus-Kaminska M

UK, Building and Environment, No 34, 1999, pp 57-69, 3 figs, 4 tabs, 5 refs.

The occupants of six houses suffered from symptoms which improved upon leaving their houses. In a previous study, tests were conducted in these six houses to measure various physical parameters related to their indoor environments. Four of these houses were subsequently renovated to improve indoor air quality. Tests were repeated on the four houses to assess the effectiveness of the applied remedial measures. The post-renovation tests which were identical to the pre-renovation tests, included measurements of air temperature, relative humidity, ventilation rates, air distribution patterns, levels of carbon dioxide, concentrations of formaldehyde, and concentrations of volatile organic compounds.

This paper describes the remedial measures applied to these houses. Also presented is a comparison of the ventilation conditions and concentrations of chemical contaminants in the houses before and after the renovation. 

residential building, sick building syndrome

#NO 11677 Sensor-based demand-controlled ventilation: a review.

Fisk W J, de Almeida A T

UK, Energy and Buildings, No 29, 1998, pp 35-45, 5 figs, 1 tab, 43 refs.

With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation is modulated over time based on the signals from indoor air pollutant or occupancy sensors. SBDCV offers two potential advantages: better control of indoor pollutant concentrations, and lower energy use and peak energy demand. Based on theoretical considerations and on a review of literature, SBDCV has the highest potential to be cost-effective in applications with the following characteristics: (a) a single or small number of pollutants dominate so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy. At present, most SBDCV systems are based on monitoring and control of carbon dioxide (CO2) concentrations. There is a limited number of well-documented case studies that quantify the energy savings and the cost-effectiveness of SBDCV. The case studies reviewed suggest that in appropriate applications, SBDCV produces significant energy savings with a payback period typically of a few years.

sensor, demand controlled ventilation

#NO 11678 A study of a control strategy utilizing outdoor air to reduce the wintertime carbon dioxide levels in a typical Taiwanese bedroom.

Chao N T, Wang W A, Chiang C M

UK, Energy and Buildings, No 29, 1998, pp 93-105, 13 figs, 8 tabs, 18 refs.

A CO2 concentration of more than 1000 ppm has been monitored in Taiwanese bedrooms during sleeping hours in the wintertime. The high indoor CO2 levels were caused by poor ventilation due to insufficient ventilation rates. This study sought to reduce the wintertime CO2 concentration level in a typical Taiwanese bedroom with less outdoor air to maintain thermal comfort. CO2 was used as an indicator to assess whether an adequate ventilation rate has been obtained to dilute or remove harmful pollutants. With the help of the thermal buoyancy effect, the CO2 generated in the bedroom was effectively removed by means of less outdoor air. Through computational fluid dynamics simulations, the appropriate window and transom locations with the corresponding outdoor air supply volume, as well as the lowest possible outdoor air temperature were identified.

outdoor air, bedroom

#NO 11679 Wohnen mit Bedarfslueftung. Erfolgskontrolle Wohnsiedlung "Hausaecker" Winterthur. Dwellings with demand controlled ventilation. Feedback on the Winterthur project.

Hartmann P

Switzerland, EMPA, January 1998, 12 pp, in German.

Summary report of a case study which considered systems with mechanical ventilation and heat recovery in new houses in Switzerland.

demand controlled ventilation, heat recovery

#NO 11685 Natural ventilation and automation with manual overriding are health solution.

van Paassen A H C, Lute P J

TVVL-REHVA Symposium: Healthy Buildings in Relation to Building Services, 17-21 February 1992, Utrecht, The Netherlands, pp 79-92, 8 figs, 1 tab, refs.

The need for individual control with manual overriding combined with controlled natural ventilation is discussed. It is made plausible that with these two facilities problems related with the Sick Building Syndrome can be avoided.

This principle is applied in a so-called passive climate system. A system is devised setting the level of heating and ventilation by controlling motors fitted to radiators, ventilation openings in window, Venetian blinds and outside shading. Moreover, it will switch on the lighting when natural lighting is inadequate. The system comprises a weather station on the roof, a network of sensors and controllers in each room hooked up to a control computer. The room controllers can be overridden manually by the occupants.

With computer simulations it has been demonstrated that through nocturnal air cooling with opened windows and predictive control a comfortable indoor climate can be realised year round, provided that the internal load lies between 15 and 20 W/m2. Higher loads require additional mechanical cooling. Moreover, it is shown that a proper combination of controlled natural ventilation and mechanical cooling leads to an enormous reduction in energy consumption. It can be reduced to 20% of the amount that is normally required in buildings with closed facades. Moreover, the capacity of the cooling room unit can be reduced with 50%. The ability to remove internal heat and the costs of the passive climate system is compared with that of more conventional systems. It has been shown that the passive system is very promising and that the option with the additional cooling unit is superior to all the other systems.

occupant control

#NO 11729 Control of passive solar system.

van Paassen A H C

in: 2nd European Conference on Architecture, 4-8 December 1989, Paris France, 376-379, 3 figs, 1 tab, 7 refs.

Without control high solar fractions are difficult to obtain from Trombe walls, direct solar gains, and rock bins. Integration of all these techniques by control is absolutely necessary. A short review is given of the available sensors, actuators, and control systems. The control of individual solar techniques as well as several combinations are discussed; for instance, the control strategy for the combination of direct solar gains and Trombe Wall. Based on literature general conclusions are given about the energy efficiency of these systems in relation with the control strategy. A more detailed analysis is made of a cost effective simple passive solar system with adjustable window devices such as insulating rolling shutters, shading devices and vent windows. The benefits of modern control such as predictive control are compared with respect to simple and straightforward control strategies. Emphasis is put on the application of controlled ventilation for the maintenance of comfort in summer. Natural ventilation is strongly recommended here because of its passive character. In this paper special attention is given to the various digital control systems designed in a concerted action of the project PASTOR of the commission of the European Communities.

passive solar building, building controls

#NO 11737 Kontrollierte Lueftung im Niedrigenergiehaus. Controlled ventilation in a low energy house.

Luedemann B, Schmitz G

Germany, HLH, Vol 49, No 8, 1998, pp 21-26, 5 figs, 1 tab, 13 refs, in German.

The article demonstrates the learning ability of users to favour purely mechanical ventilation of their apartment by doing without window ventilation. This technology is decisive for achieving a saving in primary energy.

low energy house, controlled ventilation

#NO 11749 Dwelling houses operative energetical claims minimalization by using controlled ventilation systems.

Kalas J, Vranayova Z

Slovenia, Maribor, University of Maribor, 1998, proceedings of Third SITHOK-3 International Congress, May 9-11, 1998, Maribor, Slovenia, pp 205-209, 4 tabs, 4 refs.

The renovation of the dwelling stock in the Slovak Republic's primary mission is to achieve an increase in dwelling environment quality and to reduce the energy consumption. To achieve such a reduction, we must consider the air tightness to be of prime concern, although bearing in mind that an infiltration air change may alter indoor air quality leading to health concerns. This can be achieved through a controlled ventilation systems application.

residential building, controlled ventilation

#NO 11807 Filterung und Feuchtemessung in der Abluft von innenliegenden Baedern und Toiletten. Filtration and humidity in the exhaust air of bathrooms.

Trogisch A, Franzke U

Germany, Ki Luft- und Kaeltetechnik, No 12, 1998, pp 578-581, 8 figs, 2 tabs, 7 refs, in German.

The inadequate dissipation of humidity from living spaces and enclosed bathrooms has become a significant problem area in recent years. This can be attributed both to the replacement of old, poorly sealed windows by new windows with better seals, and to the increasing use of tiles and other building materials which hinder an adequate absorption of water vapour.

The residents tend to reject repeated opening of windows for ventilation purposes on grounds of ensuing energy costs. The result is the formation of mould both in the living rooms and in the bathrooms.

The installation of humidity controlled ventilation in bathrooms without windows involves the danger, that a drop below the dew point at the humidity sensor may lead to unwanted continuous operation. This, in turn, will result in a very short service life for the filters and excessive energy consumption.

Possible solutions are to be sought both in the construction of the building and in a controlled process of ventilation.

humidity, filtration, bathroom, window, humidity controlled ventilation

#NO 11886 Application of CO2-based demand-controlled ventilation using ASHRAE standard 62: optimising energy use and ventilation. 

Schell M B, Turner S C, Shim R O

USA, ASHRAE, 1998, in: the ASHRAE Transactions CD, proceedings of the 1998 ASHRAE Annual Meeting, held Toronto, Canada, June 1998, 8 pp, 10 figs, 1 tab, refs.

CO2-based demand-controlled ventilation (DCV), when properly applied in spaces where occupancies vary below design occupancy, can reduce unnecessary overventilation while implementing target per-person ventilation rates. A recent interpretation of ANSI/ASHRAE Standard 62-1989, Interpretation IC 62-1989-27, has affirmed that carbon dioxide (CO2)-based demand-controlled ventilation (DCV) systems can use CO2 as an occupancy indicator to modulate ventilation below the maximum total outdoor air intake rate while still maintaining the required ventilation rate per person, provided that certain conditions are met.

This paper, co-written by the author of the interpretation, provides guidelines on the application of CO2-based DCV. In addition, a method is presented that allows reasonable estimates of the actual ventilation rate per person being effectively delivered to the space, based on comparing predicted CO2 ventilation levels with CO2 levels logged in an occupied space. Finally, a model is presented to evaluate various CO2-based DCV strategies to predict their delivery of target per-person ventilation rates within the lag times required by the standard.

carbon dioxide, standard

#NO 11927 The use of multipoint monitoring as a tool for commissioning buildings for IAQ.

Bearg D W

USA, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc (ASHRAE), 1999, in: the ASHRAE Transactions CD, proceedings of the 1999 ASHRAE Winter Meeting, held Chicago, USA, January 1999, 8 pp, 9 figs, refs.

One basic goal of the commissioning process is to make sure that the HVAC system is functioning as intended. In particular, it is intended that the HVAC system not only provide adequate ventilation for the building occupants but also achieve adequate pressurization of the occupied spaces to prevent the infiltration of unconditioned air. One technique for evaluating the performance of the HVAC system in these areas is to use continual, multipoint monitoring of carbon dioxide, carbon monoxide, and dew point at selected locations in the building and the HVAC system.

Specific performance evaluations provided by multipoint continual monitoring of these parameters include a determination of the amount of outdoor air delivered to the occupants for ventilation, an evaluation of the uniformity of the amount of ventilation provided to the different locations served by a given air-handling unit (AHU), an evaluation of the adequacy of the system operation in completely purging the building overnight of air contaminants from the previous day's occupancy, the identification of the infiltration of unconditioned air into occupied spaces, the identification of the magnitude and frequency of reentrainment of building exhaust, and the identification of the magnitude and frequency of the introduction of vehicle exhaust from nearby traffic.

Specific examples of all of these performance evaluations are presented and discussed in this paper. In addition, these ongoing evaluations of system performance can not only identify the presence of problems but can also evaluate the effectiveness of mitigation efforts to correct and eliminate these problems. The use of continual, multipoint monitoring of these parameters, therefore, can yield improved indoor air quality (IAQ) in buildings from initial occupancy throughout their useful life.

indoor air quality, commissioning, monitoring, air conditioning

#NO 12028 Modern ventilation technology for Ancient Wonder.

Anon

UK, Building Services & Environmental Engineer, March 1999, p 7.

Describes efforts to improve the ventilation in the King's Chamber in the Great Pyramid at Giza, where the present system was proving inadequate to clear the humidity and carbon dioxide generated by the large number of daily tourists. The technical proposal accepted was for a mechanical ventilation system. The fans were specially balanced to avoid vibrations on the pyramid.

museum, ventilation system, antiquities

#NO 12123 Numerical simulation of natural ventilation of a bedroom in a warm climate.

Chiang C M, Chou P C, Lai C M, Wang W A, Chao N T

Sweden, Stockholm, KTH Building Services Engineering, 1998, proceedings of Roomvent 98: 6th International Conference on Air Distribution in Rooms, held June 14-17 1998 in Stockholm, Sweden, edited by Elisabeth Mundt and Tor-Goran Malmstrom, Volume 2, pp 563-567, 3 figs, 1 tab, 14 refs.

This study utilizes the two-chamber model to simulate naturally ventilated airflow through a window opening in a common-type bedroom in Taiwan. Standard k-epsilon turbulence model is implemented to account for such a natural convection flow pattern. The driving force in this space is mainly the heat flux generated by occupant's skin. The result shows that under normal operation indoor, carbon dioxide (indoor air contaminant for IAQ) is less than 1000 ppm. ASHRAE Standard recommended.

computational fluid dynamics, natural ventilation, multizone modelling

#NO 12161 Experimental investigation of natural ventilation in an office building.

Jurenka M, Voit P

EPIC '98, Volume 2, pp 612-617, 3 figs, 1 tab.

The work presented in this paper was done in 1997 as a final thesis in mechanical engineering, supervised by TRANSSOLAR Energietechnik GmbH in cooperation with the Institute for Thermodynamics and Heat Technology (ITW), University of Stuttgart. The contents of the work is the investigation of natural ventilation through window openings (single sided and cross ventilation) in an existing office space. Both measurements and computer simulation have been conducted.

As a result of the work the original ventilation system was modified by assembling high-level opening lights that are automatically controlled and driven by electric motors. Depending on indoor temperature, outdoor temperature, carbon dioxide concentration and wind speed the control system adjusts the required opening area. In addition the control system provides a timer to ventilate the office space during night time to cool down the thermal mass of the building.

natural ventilation, office building, building controls, modelling

#NO 12166 Natural controlled ventilation: performances and standards.

Canziani A, Cavanna G, Daniotti B, Fantucci A, et al

EPIC '98, Volume 3, pp 712-717.

As everybody knows, today the air quality of an indoor environment may have several effects on our health; the beginning of serious breathing pathologies and of some forms of cancer, are with no doubt due to the presence of polluting and extremely noxious agents in the places we most frequently use.

That's the reason why it is very important that indoor rooms are correctly aired also in our homes where, due to several incidental factors, the healthiness of the environment is still guaranteed by the mere and discretionary operation of users of opening the windows.

In considering the growing attention drawn to these problems and in agreement with the provisions of the 3rd essential requirement laid down in Common Directive 89/106, 'Hygiene, Health and the Environment', ICITE has undertaken to develop a research and experimentation study aimed at establishing a device for the controlled natural ventilation of residential environments.

The main objectives have focused on the technical and performance-oriented characteristics of the devices that are already available on the Community markets and on the regulative aspects for what concerns air healthiness in domestic environments, while the final phase of the work, still in progress, will give new developing guidelines, both in regulative and productive terms. Surveys carried out on existing buildings pointed out a preference for one particular device, supplied with a self-adjusting ventilator which works according to the changing weather conditions, but able to control a certain kind of natural ventilation even with strong external winds and rain. Such a device was chosen mainly because of the declared peculiarity of mechanical factory control in any situation, since the greatest part of the market supply is oriented towards closing devices beyond fixed levels of internal pressure, thus restoring the tightness conditions of the environment.

controlled ventilation, ventilation performance, standard

#NO 12190 Experimental studies of the air quality evaluation.

Barbat M, Richalet V, Guarracino G

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 1, pp 30-35.

Three buildings are investigated to study the indoor air quality and the impact of the outdoor air pollution. These buildings, a swimming pool, a school and a nursery are located in an urban area. So, during experimental studies, typical outdoor and indoor pollutants such as carbon monoxide, nitrogen dioxide, carbon dioxide, and total volatile organic compounds are monitored. Also, the relative humidity and the temperature are carried out. The analysis allows us to reveal several points. Except for C02 and punctually TVOC, the recorded indoor pollutant concentrations are very low in comparison with standard values, despite the symptoms and discomfort perceived by occupants. Moreover, thanks to the attenuation phenomenon, outdoor pollution has an insignificant impact on the indoor air pollution. For these buildings, it seems that C02 or TVOC could be the best parameters to use for demand control ventilation system.

outdoor air, sports building, school, kindergarten, carbon monoxide, nitrogen dioxide, carbon dioxide, TVOC, humidity

#NO 12193 Development of a demand control strategy in buildings using radon and carbon dioxide levels.

Chan G Y, Chao C Y, Lee D C, Chan S W, Lau H

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 1, pp 48-53.

Air change rates, indoor radon and carbon dioxide levels were monitored in a lecture theatre in the Hong Kong University of Science and Technology. Two preliminary measurements (Cases 1 and 2) and one series of demand control ventilation simulation (Case 3) were made to investigate the indoor air quality of the lecture theatre. Radon and carbon dioxide levels were found to be relatively high in Case 1 and later improved at the expense of operating the system catering for maximum occupancy in Case 2. In Case 3, the average radon and C02 levels inside the lecture theatre were kept under 200 Bq/m3 and 1000 ppm during lecture hours, respectively. These results led to the possibility of developing a demand control strategy (Case 4) using radon and carbon dioxide levels as control parameters for fresh air intake. This new demand control ventilation has an estimated energy saving potential of 440A.

demand controlled ventilation, radon, carbon dioxide, tracer gas

#NO 12197 Good indoor climate and air quality in energy efficient houses.

Saari M, Laine J

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 1, pp 70-75.

Two energy-efficient single-family houses (known as ESPI houses) with competitive overall costs were set up during the study in Finland. The consumption of energy for room heating in ESPI houses was reduced to a half at the construction stage, by employing simple solutions which can be used by every builder. The level of thermal insulation of the houses was improved remarkably. The houses were equipped with a controlled ventilation system and an efficient exhaust air heat recovery unit. One of the houses was oil heated and the other was electrically heated. In ESPI houses the indoor air quality and thermal climate were good. Against common opinion there was no conflict between low energy consumption and good indoor air quality. Most important thing was adequate and energy-efficient ventilation. The consumption of energy for room heating in ESPI houses was 60 kWh/m2 per year. The total -heating bill of the ESPI houses was only EUR 27-38 per month. Due to the reduced heating demand the heating system can be simplified, and as a result the building costs do not increase significantly.

residential building, single family house, thermal insulation, heat recovery, controlled ventilation

#NO 12211 School ventilation - gymnasiums in primary schools.

Eian P K, Borresen B A, Oie L, Sorensen B R

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 1, pp 385-389.

The main objective of this study was to determine the ventilation demand for a gymnasium in the primary school based on verified metabolic rate. Norwegian guidelines recommend 6.0 met as the activity level to be used when calculating the outdoor air flow rate in a gymnasium. Younger pupils have a lower body mass and metabolic capacity than adults, and their demand for ventilation is therefore lower. The metabolic rate has been assessed by measuring the pupils emission of the dominating bioeffluent CO2, during intensive gymnastic activity. The emission of CO2 was found to be 41 l/s per pupil which corresponds to an equivalent metabolic rate of 2.5. When allowing a maximum Predicted Percentage Dissatisfied (PPD) of 30% this gives an outdoor air flow of 17 l/s per pupil as a set point value, which is less than half of the 44 l/s per pupil based on design recommendations for the Norwegian guidelines.

school, gymnasium, ventilation system, carbon dioxide

#NO 12233 Evaluation of domestic ventilation system performance by COMIS model for Japanese conditions.

Yoshino H, Liu J, Horiuchi M, Sawachi T

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 2, pp 36-41.

The purpose of this paper is to evaluate the performance of four kinds of ventilation systems from the point of view of air exchange, indoor air pollution, and space heating load under Japanese conditions by numerical simulation. TVOC and CO2 are selected to characterise the indoor air quality impact to residents. The results show that the equivalent leakage area has great influence on air movement. In addition, compared with other kinds of ventilation systems, mechanical central supply and exhaust ventilation system shows its advantages for minimising energy consumption and maintaining an acceptable indoor air quality.

numerical simulation, carbon dioxide

#NO 12245 Thermal and ventilation characteristics in a room with underfloor air-conditioning system.

Han H, Chung K S, Jang K J

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 2, pp 344-349.

It is the object of the present paper to investigate indoor environmental characteristics of an office building with an underfloor air conditioning system. Thermal conditions in the room were monitored including horizontal and vertical temperature distributions, supply and exhaust air temperatures and globe temperature. Indoor air quality was investigated by measuring carbon monoxide, carbon dioxide and airborne particulates. Velocity distributions around a floor air terminal and thermal comfort around a supply air terminal were also investigated. Room ventilation characteristics were obtained by a pulsed tracer gas technique. It shows that the underfloor air conditioning system provides good ventilation characteristics in cooling modes, while airborne particulate levels are comparable with those found in conventional ceiling supply systems. The detailed temperature and velocity information can be used to design the floor layout to improve the performance of the UFAC systems.

air conditioning, floor

#NO 12246 Ventilation, energy and IAQ impacts of mechanical ventilation in a US dwelling.

Persily A K

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 2, pp 350-355.

Based on concerns about indoor air quality and trends towards tighter envelope construction, there has been increasing interest in mechanical ventilation of residential buildings in the United States. This paper reports on a simulation study of indoor air quality, ventilation and energy impacts of several mechanical ventilation approaches in a single-family residential building. The study focuses on a two-story house in the northwestern United States and employs the multizone airflow and contaminant dispersal model CONTAM96. The contaminants studied include carbon monoxide, carbon dioxide, nitrogen dioxide, water vapour, fine particles and a generic volatile organic compound. One-year simulations were performed for a base case of envelope infiltration, passive inlet vents with intermittent mechanical exhaust, outdoor intake to the forced-air system return balanced by mechanical exhaust, and continuous exhaust. Results discussed include whole building air change rates, energy consumption and contaminant.

indoor air quality, residential building

#NO 12263 Destruction of VOC using photocatalyst under UC light irradiation - the influence of UV wavelength on mineralisation.

Sakamoto K, Fukumuro T, Ishitani O, Kohno H

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 2, pp 673-678.

A variety of gaseous pollutants in indoor air now are becoming an object to control. Thus, we studied a removal technique using TiO2 photocatalyst under 365 nm or 254 nm UV-light irradiation for toluene, benzene, formaldehyde and acetaldehyde as examples of hazardous volatile organic compounds (VOCs)s, in order to get detailed analytical data for products derived from these contaminants. Although these compounds were effectively destructed not only C)2, but also high concentration of toxic compounds, such as aldehydes were formed in the case of under 365 nm UV-light irradiation. However, TiO2, photocatalysis under 254 nm UV-light irradiation made possible to achieve high removal ratio of VOCs. In addition, a high conversion ratio to CO2, was obtained. The purification technique using TiO2 photocatalyst under 254 nm UV-light irradiation is more effective than that under 365 nm UV-light irradiation.

health, carbon dioxide

#NO 12284 Indicators of natural ventilation effectiveness in twelve New Zealand schools.

Bassett M R, Gibson P

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 4, pp 298-303.

Classrooms in New Zealand schools are mostly low rise buildings with natural ventilation designs, sized for summer cooling. This study has investigated winter ventilation performance in twenty four classrooms in twelve primary schools in the Wellington region. Its purpose has been to provide baseline data on the effectiveness of existing natural ventilation, along with approximate pollutant profiles on which to base new mixed mode ventilation designs. Detailed measurements of indicator airborne micro-organisms, total volatile organic compounds, respirable particulates, and formaldehyde were completed in twelve classrooms, along with longer term logging of carbon dioxide concentrations and physical conditions. Records of metabolic carbon dioxide were used to estimate ventilation rates, which were later compared with mean infiltration rates determined from airtightness measurements. Airtightness data for the twenty-four classrooms followed the same trend seen in residential buildings, which is for modern construction to be much more airtight than older buildings. In contrast to residential buildings the indicated ventilation rates were much higher than background infiltration rates.

natural ventilation, school

#NO 12295 Experimental development of a natural controlled ventilation device.

Cavanna G, Daniotti B, Oliveri E, Varone G

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 4, pp 364-369.

The Building Components Technology Department of ICITE, the Central Institute for Industrialisation and Technology in Building of the Italian National Research Council has started am experimental research on natural controlled ventilation devices. Today the air quality of an indoor environment may have several effects on our health, due to the presence of polluting and extremely noxious agents in the places we most frequently use. That is the reason why ICITE has undertaken to develop a research and an experimentation study aimed at establishing a device for the controlled natural ventilation of domestic environments. In the report we will present the first experimental results about setting a calibrated opening to guarantee the needed air flow rate, independently of the pressure difference between indoor and outdoor environment. These results will be used as design characteristics to define the final solution for the prototype device. Another objective has focused on the technical and performance-oriented characteristics of the devices that are already available on the Community market and on the regulative aspects for what concerns air healthiness in domestic environments.

health, controlled ventilation

#NO 12340 Energy impact of ventilation: estimates for the service and residential sectors. 

Orme M

UK, Air Infiltration and Ventilation Centre (AIVC), 1998, Technical Note 49, 43 pp, 15 figs, 5 tabs, refs.

Considers air change energy use in thirteen major industrialised countries, and the effect that air change energy use has on carbon dioxide emissions due to the use of fossil fuels, both directly in combustion appliances, and indirectly as electricity. In order to quantify the energy impact of air change on total energy use, the AIVC has been undertaking a study of current estimates for non-industrial buildings. The potential for reduced energy use by improved ventilation control is also briefly reviewed. It is found that air infiltration and ventilation together account for a significant proportion of energy sue in buildings. This report outlines the findings from a study into estimating the full impact of air change on building energy use. Considering the non-industrial building stock of the 13 countries collectively, the total annual loss of heating energy due to air change is estimated to amount to 48% of delivered space conditioning energy (including heating equipment losses). Stated in terms of delivered space heating energy alone (i.e., excluding space cooling), this rises to 53%. If the outdoor air supply rate per occupant were to be universally reduced to a minimum level, taking into account metabolic needs and pollutant loads, then it is conceivable that the heating air change energy loss could be reduced to approximately a third of the current level. The consequent reduction in the total carbon dioxide emissions from the service and residential sectors (for all end uses) would be in the region of 20% per year. The results emphasise that air change related energy losses are as important as conduction and equipment losses (including "flue" losses) in dissipating delivered space conditioning energy from buildings. In fact, as national standards, regulations or codes of practice improve the thermal integrity of building and increase equipment efficiency, it is expected that ventilation and air movement will become the dominant loss mechanism.

energy use, air change rate, calculation techniques

#NO 12352 Air quality and ventilation rates in school classrooms I: air quality monitoring.

Lugg A B, Batty W J

UK, Building Serv Eng Res Technol, Vol 20, No 1, 1999, pp 13-21, 13 figs, 6 tabs, 11 refs.

Indoor air quality was monitored at two schools in Essex, UK (located on the same site) during the week 3 - 7 November 1997. The objective was to determine whether the ventilation rates within the building were adequate to provide acceptable air quality to the occupants. Airborne carbon dioxide concentration was determined using continuous infrared detectors. A class base in each school was monitored for a two-day period. Occupancy patterns and window/door opening were observed during the first day of each period. Air temperature was also recorded. Indoor carbon dioxide levels exceeded those recommended for acceptable indoor air quality for a large proportion of the occupied period. Fresh air ventilation rates were below recommended guidelines.

carbon dioxide concentration, air change rate, window opening behaviour

#NO 12369 Indoor air quality investigations at five classrooms.

Lee S C, Chang M

Denmark, Indoor Air, No 9, 1999, pp 134-138, 3 figs, 2 tabs, refs.

Five classrooms, air-conditioned or naturally ventilated, at five different schools were chosen for comparison of indoor and outdoor air quality. Temperature, relative humidity (RH), carbon dioxide (CO2), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter with diameter less than 10(m (PM10), formaldehyde (HCHO), and a total bacteria counts were monitored at indoor and outdoor locations simultaneously. Respirable particulate matter was found to be the worst among parameters measured in this study. The indoor and outdoor average PM10 concentrations exceeded the Hong Kong standards, and the maximum indoor PM10 level was even at 472 (g/m3. Air cleaners could be used in classrooms to reduce the high PM10 concentration. Indoor CO2 concentrations often exceeded 1,000(l/l indicating inadequate ventilation Lowering the occupancy and increasing breaks between classes could alleviate the high CO2 concentrations. Though the maximum indoor CO2 level reached 5,9000(l/l during class at one of the sites, CO2 concentrations were still at levels that pose no health threats.

particulates, carbon dioxide, school, pm10

#NO 12457 Advanced ventilation design for commercial, industrial and institutional facilities: Displacement and demand-controlled ventilation can be applied in combination with enthalpy recovery.

Turner W A

USA, Heating, Piping and Air Conditioning, October 1999, pp 61-66, 6 figs.

Describes how displacement and demand-controlled ventilation can be applied in combination with enthalpy recovery. Focuses on the indoor air quality components of IEQ, and also touches on IEQ and "sustainability" concerns along the way. Brief case studies from office, educational, and industrial buildings are presented to support the design concept discussions.

heat recovery, ventilation design

#NO 12458 Ventilation responds to the carbon-dioxide challenge.

Andrews I

UK, Building Services and Environmental Engineer, October 1999, pp 22-23.

Describes the UK government's recent drive to review the Building Regulations Document L "Conservation of fuel and power", revealed in a recent round of consultative workshops. By assessing the practical scope for energy savings achievable through revisions to the Building Regulations, the workshops were a significant first phase of the review, where FETA representation and the work of the FETA Document L steering committee has ensured that the industry's views have been clearly presented and absorbed. The most significant development so far as domestic ventilation is concerned is that the energy performance of the existing building stock is now under the spotlight - not just new buildings as at present. The indications are that regular in-service testing and rating of existing buildings might be expected. This could involve pressurisation tests for airtightness, thermographic assessment of insulation performance and tougher planning controls being applied when buildings are extended or adapted to new uses - thereby generally upgrading the UK building stock. 

age of building stock, home energy rating programme

#NO 12521 A study of the operation of a novel naturally ventilated building using computational fluid dynamics.

Miles S

UK, London, Chartered Institution of Building Services Engineers (CIBSE), 1999, Proceedings of "Engineering in the 21st century - the changing world", CIBSE National Conference '99, held 4-5 October 1999, Harrogate International Centre, pp 338-345, 4 figs, 5 refs.

In response to an increased awareness of the impact of building related energy consumption on emissions of carbon dioxide, attention has turned to the task of making buildings more energy efficient. Although this is a key element in the design of a new building, it is important also that the occupants' expectations of a comfortable and healthy environment are met. Computer simulations of the airflow and thermal environment within a naturally ventilated building have been made using a finite-volume CFD model. Indoor climatic conditions and the effectiveness of cross-ventilation channels and solar-assisted ventilation shafts on a warm summer day, with a light breeze, have been examined. This case study facilitates a better understanding of some of the complex interrelated issues associated with natural ventilation.

case study

#NO 12530 The use of a mixed gas sensor in the study of indoor air quality and its application to demand based ventilation.

Moore A, Murray M J

UK, London, Chartered Institution of Building Services Engineers (CIBSE), 1999, Proceedings of "Engineering in the 21st century - the changing world", CIBSE National Conference '99, held 4-5 October 1999, Harrogate International Centre, pp 568-575, 5 figs, 1 tab, 5 refs.

Demand Based Ventilation systems are potentially valuable in terms of energy saving in building with fluctuating occupation patterns. Most demand based ventilation systems are controlled by CO2 measurement. However this approach cannot take account of other polluting elements found in indoor air.

This paper will describe the results of a study of the indoor air quality in a recently built university library with continuous ventilation. The literature relating to typical levels of naturally occurring gases, volatile organic compounds and microbes, in indoor air is considered. The range of pollutants in indoor air is discussed and various methods of measuring them are tested and compared.

In particular a mixed gas air quality sensor is used to monitor air quality in an attempt to measure the efficacy of the instrument as controller for a demand based ventilation system.

A questionnaire based on the BRE Office Environment Survey is used to establish the building users perception of indoor air quality.

The questionnaire analysis and the performance of the mixed gas sensor are compared to assess the suitability of the sensor as a controller for a ventilation system.

Results indicate that mixed gas sensor control for demand based ventilation systems may well be the way forward for better air quality and optimum energy conservation.

demand controlled ventilation

#NO 12618 The impact of demand-controlled and economizer ventilation strategies on energy use in buildings.

Brandemuehl M J, Braun J E

USA, ASHRAE Transactions, Annual Meeting 1999, Seattle, 11 pp, 12 figs, 8 tabs, refs.

The overall objective of this work was to evaluate typical energy requirements associated with alternative ventilation control strategies for constant air volume (CAV) systems in commercial buildings. The strategies included different combinations of economizer and demand controlled ventilation, and energy analyses were performed for four typical building types, eight alternative ventilation systems, and twenty U.S. climates. Only single zone buildings were considered so that simultaneous heating and cooling did not exist. The energy savings associated with economizer and demand controlled ventilation strategies were found to be very significant for both heating and cooling. In general, the greatest savings in electrical usage for cooling with the addition of demand controlled ventilation occur in situations where the opportunities for economizer cooling are less. This is true for warm and humid climates and for buildings that have relatively low internal gains (i.e., low occupant densities). As much as 20% savings in electrical energy for cooling were possible with demand controlled ventilation. The savings in heating energy associated with demand controlled ventilation were generally much larger but were strongly dependent upon the building type and occupancy schedule. Significantly greater savings were found for buildings with highly variable occupancy schedules and large internal gains (i.e., restaurants) as compared with office buildings. In some cases, the primary heating energy was virtually eliminated by demand controlled ventilation as compared with fixed ventilation rates. For both heating and cooling, the savings associated with demand controlled ventilation are dependent on the fixed minimum ventilation rate of the base case at design conditions. 

carbon dioxide controlled ventilation, cooling, energy saving

#NO 12619 Why CO2?

Liddament M W

UK, Air Infiltration Review, Vol 18, No 1, December 1996, pp 1-4, 2 figs, 1 tab, refs.

Describes how carbon dioxide is metabolically produced and can therefore be associated with the presence of occupants. Also it is relatively easy and inexpensive to measure, and it is fairly stable. In principle CO2 can be used to evaluate the ventilation rate, determine the proportion of outdoor air that is blended with recirculated air and provide an indication of perceived indoor air quality. Goes on to discuss CO2 and toxicity, outdoor or background CO2 concentration, indoor concentration, steady state concentration, transient concentration, "perceived" indoor air quality, and measurement methods.

carbon dioxide

#NO 12620 Association of ventilation rates and CO2 concentrations with health and other responses in commercial and institutional buildings.

Seppanen O A, Fisk W I, Mendell M J

Indoor Air, No 9, 1999, pp 226-252, 7 tabs, refs.

This paper reviews current literature on the associations of ventilation rates and carbon dioxide concentrations in non residential and non industrial buildings (primarily offices) with health and other human outcomes. Twenty studies, with close to 30,000 subjects, investigated the association of ventilation rates with human responses, and 21 studies, with over 30,000 subjects, investigated the association of carbon dioxide concentration with these responses. Almost all studies found that ventilation rates below 10 Ls-1 per person in all building types were associated with statistically significant worsening in one or more health or perceived air quality outcomes. Some studies determined that in creases in ventilation rates above 10 Ls-1 per person, up to approximately 20 Ls-1 per person, were associated with further significant decreases in the prevalence of sick building syndrome (SBS) symptoms or with further significant improvements in perceived air quality. The carbon dioxide studies support these findings. About half of the carbon dioxide studies suggest that the risk of sick building syndrome symptoms continued to decrease significantly with decreasing carbon dioxide concentrations below 800 ppm. The ventilation studies reported relative risks of 1.5-2 for respiratory illnesses and 1.1-6 for sick building syndrome symptoms for low compared to high low ventilation rates.

carbon dioxide, sick building syndrome, commercial building

#NO 12692 Monitoring for ventilation and airtightness.

Bearg D W

USA, ASHRAE Transactions, Winter Meeting 2000, Dallas, 9 pp, 10 figs, refs.

The object of this paper is to show how the monitoring of key IAQ parameters can provide feedback on building performance in the areas of ventilation and airtightness. The availability of this information can then lead to the more effective operation of the building and its HVAC system because the operators will have better information on system operation. The monitoring of carbon dioxide (CO 2 ) concentrations, for instance, provides feedback on many aspects of HVAC performance, especially ventilation. Feedback on ventilation performance includes information on the adequacy of ventilation, the uniformity of ventilation, and the effectiveness of the overnight purge. Coupled with the monitoring of humidity, feedback on airtightness and energy efficiency also becomes available. The monitoring of multiple parameters of the indoor environment at strategically selected multiple locations in buildings, therefore, can provide important information on HVAC performance. As such, it can improve the management of buildings by reducing the amount of uncertainty in this performance. The better the operators know what the HVAC system is doing, the better they can optimize its performance for both ventilation adequacy and minimum energy use. 

indoor air quality, building monitoring

#NO 12813 Technical synthesis report: a summary of IEA ECBCS Annex 18 - Demand controlled ventilating systems.

Mansson L-G, Svennberg S A, Liddament M W

UK, Coventry, ESSU, 1997, Technical Synthesis Report (TSR) 02, 42 pp.

Summarises the work of IEA ECBCS Annex 18 on demand controlled ventilation. The objective of Annex 18 was to develop actions, methods and strategies for demand controlled ventilation and to help with the introduction of such systems. The knowledge amassed from the working groups of the participating countries was summarised in a Source Book which was designed to form the basis of manuals adapted to suit individual countries. This summary covers principles of demand controlled systems; "dominant" or "control" pollutants; selecting a sensor; other issues; applications and case studies - dwelling and work premises; savings; conclusions. Appendices list Annex 18 and other DCV related publications.

demand controlled ventilation, pollutant, sensor, case study

#NO 12814 Experimental validation of CO2 based occupancy detection for demand-controlled ventilation.

Wang S, Burnett J, Chong H

Indoor and Built Environment, No 8, 1999, pp 377-391, 20 figs, 11 refs.

On-line ventilation control based on carbon dioxide (CO2) measurement and the dynamic CO2 balance in indoor spaces has been validated using a dynamic algorithm for two existing buildings. Occupancy profiles estimated using the dynamic algorithm were compared with the true occupancy profiles and the occupancy profiles estimated using a steady-state algorithm based on the steady-state Co2 balance. The dynamic algorithm estimates the changes of occupancy without significant delay. The steady-state algorithm is comparable only at a high air change rate and shows a considerable delay when the number of air changes per hour in a space is small. This phenomenon was investigated using computer simulation.

carbon dioxide, occupancy effects, demand controlled ventilation

#NO 13056 Demand controlled ventilation in schools - energetic and hygienic aspects

Weinlader H, Beck A, Fricke J

UK, Air Infiltration and Ventilation Centre, proceedings of "Innovations in Ventilation Technology", 21st AIVC Annual Conference, held The Hague, Netherlands, 26-29 September 2000, paper 6

In this study, we investigated the indoor air quality (IAQ) in classrooms with exhaust ventilation systems and in naturally ventilated classrooms. In the latter, we found peak CO2-concentrations of more than 4000 ppm. 1500 ppm was exceeded during 40 to 86% of teaching time, dependent on class size. The windows were opened rarely in winter which led to low mean air exchange rates of 0.20 - 0.23 h-1. The operation of mechanical ventilation systems improved IAQ considerably. Peak CO2-concentrations decreased to less than 2500 ppm. 1500 ppm was exceeded for only 7 to 57% of teaching time. Mean air exchange rates of 0.36 - 0.41 h-1 were determined. The higher air exchange rates caused no measurable increase in heating demand. With respect to mould problems, no significant amount of viable airborne fungi was found. This didn't change if children were present. The viable airborne bacteria concentration increased during the lessons. No difference in viable airborne bacteria concentration was found in mechanically and naturally ventilated classrooms as long as the windows were closed. Results indicate, that wide opened windows in naturally ventilated classrooms may increase viable airborne bacteria concentration due to air turbulence, but this is to be investigated further. The acceptance of the mechanical ventilation systems by the teachers was very good. No problems with draught or noise were reported.

demand controlled ventilation, school, hygiene, mould, carbon dioxide

#NO 13057 Performance of demand controlled ventilation: case study, energy savings and 

practical rules.

Bernard A-M, Blazy M, Lemaire M-C

UK, Air Infiltration and Ventilation Centre, proceedings of "Innovations in Ventilation Technology", 21st AIVC Annual Conference, held The Hague, Netherlands, 26-29 September 2000, paper 7

In order to assess the real performances of different demand controlled ventilation (DCV) systems, two of the systems were installed in meeting rooms of an office building.

The first system is controlled by movement detection on terminal units and has been installed in a small meeting room which is regularly used.

The second system is controlled by CO2 detection and frequency variation on fan. It has been installed in a large meeting room (30 people seated, up to 50 people standing).

The systems have proved to be energy saving with the correct CO2 levels. Meeting rooms have low occupation rate because there are generally less people in meetings than the maximum allowed. Simulations have also taken place on full office buildings to estimate the variation of savings for different occupation rates and the influence of DCV in meeting room and offices on the total building ventilation losses. Practical rules for owners on how to identify the correct DCV systems were drawn up in order to produce a guide.

demand controlled ventilation, energy conservation, ventilation rate, air change rate

#NO 13058 On ventilation needs - towards demand controlled ventilation in dwellings.

Bergsoe N C

UK, Air Infiltration and Ventilation Centre, proceedings of "Innovations in Ventilation Technology", 21st AIVC Annual Conference, held The Hague, Netherlands, 26-29 September 2000, paper 8

Ventilation needs in dwellings must be determined on the basis of both requirements to the indoor air quality and necessary control of moisture conditions. As a first step towards development of energy efficient ventilation strategies for demand controlled ventilation in future dwellings, theoretical analyses comprising a literature study and mathematical simulations have been carried out. In view of the provisions in the current Danish Building Regulations, and based on existing knowledge on contaminants and contaminant sources in the indoor climate, the humidity conditions are regarded as the determining factor for the ventilation requirements in future dwellings. The mathematical simulations indicate that the basic ventilation in a typical apartment under normal use can be reduced by 20-30 percent, compared with provisions in current building regulations, without compromising the indoor climate. Thus, through suitable control of the ventilation, on average, energy savings can be achieved on the energy consumption for ventilation in multi-storey buildings.

demand controlled ventilation, residential building, ventilation needs, moisture, humidity

#NO 13184 Optimised indoor air quality and energy saving strategies for quality buildings in Mediterranean climates: compatible objectives with comfort and environment issues?

Malheiro da Silva I

UK, Oxford, Elsevier, 2000, proceedings of Roomvent 2000, "Air Distribution in Rooms: Ventilation for Health and Sustainable Environment", held 9-12 July 2000, Reading, UK, Volume 1, pp 13-22, 9 figs, 5 tabs, refs.

The sick building syndrome is a growing concern in terms of health and is an important factor in occupancy behaviour. The building sector takes up more than 35 % of the global primary energy use in developed countries. Those two main concerns in building services design are closely related, demanding an accurate balance between strategies focused on energy consumption reduction and indoor air quality improvement, whereas controlled natural ventilation potential must be considered as an important contribution. Designers must be aware of these facts and integrate, in the final solution for buildings, the global environment concerns and comfort standards leading all together to the quality (Q) building label. The aim of this paper is to establish, in a consistent way, that those main aspects are compatible between them and can play an important role in comfort and environment issues. This approach has been used in the design of several buildings in EXPO'98 and, from one of them, field measurements are reported, confirming design estimations.

indoor air quality, energy saving, natural ventilation, air conditioning, thermal comfort


 


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