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LL 13: Air Infiltration Measurement Techniques

AIVC, 2001
AIVC | LL
Bibliographic info: LL 13
Languages: English

Air Infiltration Measurement Techniques


#NO 8017 Measuring subfloor ventilation rates.

AUTHOR Hartless R, White M K

BIBINF UK, Air Infiltration and Ventilation Centre, 1994, "The Role of Ventilation", proceedings of 15th AIVC Conference, held Buxton, UK, 27-30 September 1994, Volume 2, pp687-696.

ABSTRACT This paper reports on ventilation measurements taken beneath a suspended floor of a BRE/DoE energy and environment test house. Sulphur hexafluoride was introduced into the subfloor void at a constant rate andthe resulting concentration measured. Wind speed, wind direction, and internal, external and subfloor temperatures were also recorded. A range of air brick locations were used for each run which lasted two to three days. Analysis of the data shows that subfloor ventilation rates in this test house fluctuated widely, ranging from about 3 air changes per hour (ach) to over 13 ach. Also, the subfloor ventilation rate for this house seems to be heavily influenced by the subfloor/external temperature difference rather than the wind speed, particularly when air bricks are located on sheltered subfloor walls. The main reason for this stack dependence is that there is a significant leakage path at the wall/floor junction with air moving from the subfloor void to the gap behind the plasterboard lining.

KEYWORDS (crawlspace, ventilation rate, measurement technique, floor, wall, air leakage)

#NO 8018 Standardised measurements of the cooling performance of chilled ceilings.

AUTHOR Steimle F, Mengede B, Schiefelbein K

BIBINF UK, Air Infiltration and Ventilation Centre, 1994, "The Role of Ventilation", proceedings of 15th AIVC Conference, held Buxton, UK, 27-30 September 1994, Volume 2, pp697-708.

ABSTRACT One important aim for the development of new air conditioning systems is the reduction of the total energy consumption. This can be reached by separation of cooling and ventilation in air conditioning systems, because it is more effective to transport energy by using water systems instead of air to deliver cooling energy to the consumers. This strategy was the base for the development of several chilled ceiling systems during the last years, so that at present there are many different systems on the market. One problem during the design period is to calculate the cooling performance of these systems depending on different operating conditions. So it is necessary for the companies to find characteristicdata to describe the heat transfer of these elements. But an objective comparison of different systems and an accurate planning is only possible, if these data were investigated under comparable boundary conditions.Parallel to the Germany standard organisation (DIN) the working group "Heating and cooling surfaces" of the GermanFGK e.V., in which the leading manufacturing, planning and installation companies of chilled ceiling systems are represented, had outlined a guideline to guarantee standardized measurements under clearly defined boundary conditions. It is planned to discuss the main aspects of this guideline and the conditions for measurements of the cooling performance of open convection chilled ceilingsystems.

KEYWORDS (cooling, ceiling, measurement technique, air conditioning)

#NO 8021 An experimental and theoretical investigation of airflow through large horizontal openings.

AUTHOR Kohal J S, Riffat S B, Shao L

BIBINF UK, Air Infiltration and Ventilation Centre, 1994, "The Role of Ventilation", proceedings of 15th AIVC Conference, held Buxton, UK, 27-30 September 1994, Volume 2, pp729-740.

ABSTRACT The work was concerned with measuring natural convection through a large horizontal opening of different sizes and shapes located between two rooms in a building. Airflow rates between the two rooms were measured using a tracer-gas technique. Room 1 was heated to various temperatures in the range 18C to 33C using thermostatically-controlled heaters; room 2 was unheated. A multi-point sampling unit was used to collect tracer-gas samples from each room. The concentration of SF tracer was measured using an infra-red gas analyser. The heat and mass flow rates between the two rooms were calculated from the tracer-gas concentrations and temperature differences between the two rooms. The mass flow rate was increasing the area of the opening. The mass flow of a circular opening was in most cases higher than that of a square opening. Their work also describes CFD modelling of natural convection through horizontal openings. Results were compared with values obtained from experiment.

KEYWORDS (air flow, openings, tracer gas, measurement technique, computational fluid dynamics)

#NO 8240 Estimation of design ventilation rates for buildings. 

AUTHOR Galbraith G H, McLean R C. 

BIBINF UK, Building Serv, Eng. Res. Technol; Vol 15, No 4, 1994, pp 199-203, 7 figs, 4 tabs, 10 refs. 

ABSTRACT Building fabric heat loads have decreased in recent years as standards of thermal insulation have improved. This in turn has led to an increase in the relative importance of the infiltration component of the total heat loss. The quantification of this component requires the accurate assessment of air infiltration rates under relevant environmental design conditions. Unfortunately, techniques for such assessments are much less well developed than those for calculating fabric heat loss and in many cases building services designers still rely upon the use of empirical estimates which are often unrealistic. This paper presents a case study in which a combined measurement and modelling procedure is applied to provide the designer with a more realistic estimate of air infiltration rates for an existing building. The basis of this work involves the use of the fan pressurisation measurement technique to determine actual leakage characteristics for the building envelope. This information provides real input data for a nodal airflow computer model, the results of which can then be used to estimate appropriate design ventilation rates. The case study involves application of the technique to a large secondary school undergoing refurbishment, and shows clearly that empirical estimates could have led to the installation of a severely undersized heating system. The measurements, in fact, highlighted a problem of excessive infiltration rates which required remedial action. The effectiveness of this remedial action was then confirmed by further measurements and remodelling was carried out to establish the final infiltration rates to be applied by the design engineers. 

KEYWORDS building design, ventilation rate

#NO 8521 Displacement ventilation performance - office space application 

AUTHOR Alamdari F, Bennett K M, Rose P M 

BIBINF UK, Building Services Research and Information Association. Technical Note TN 3/93, July 1993, 18 pp. 

ABSTRACT Displacement ventilation is a method that provides conditioned air to indoor environments with the view to improve air quality whilst reducing energy usage. These systems have been employed in industrial applications, notably in Scandinavia, for many years and have gained in popularity in office building spaces in recent years. Measurements of velocity and temperature fields have been performed in three modern office spaces to analyse the performance of the incorporated displacement ventilation system (1), based on thermal comfort and temperature gradient assessment (2). The measurements at one of the sites were used to verify the predicted data obtained by a microclimate computer model based on computational fluid dynamics (CFD) techniques. The model was subsequently used to study the effect of cold surfaces, infiltration, floor obstructions and supply air flow rates. Although the application of displacement ventilation is more difficult in office spaces with low ceiling heights, acceptable conditions were measured in two of the three sites considered in this study. However, both measurements and prediction indicated that secondary air flows resulting from infiltration and cold surfaces can adversely affect the ventilation performance and reduce thermal comfort. In the application of displacement ventilation care should be taken to minimise these extraneous effects. 

KEYWORDS displacement ventilation, office building, thermal comfort, numerical modelling.

#NO 8646 Development of a measurement system for multizone infiltration. 

AUTHOR Ohira N, Yagawa N, Gotoh N 

BIBINF USA, ASHRAE Transactions, Vol 100, Part 2, 1994, pp 692-698. 

ABSTRACT Although there has been much effort to design highly airtight structures, adequate ventilation for them has not received proper attention and an understanding of interroom ventilation is lacking. In the present work, we have developed a measurement system, using the multigas decay method, to measure multizone infiltration. The technique enables us to easily carry out on-site multizone infiltration measurements. A simple computer program to predict interroom airflow patterns has been developed, and a scale- model house was constructed to compare experimental and simulation data. They are found to be in good agreement. Ventilation measurements are made in a real residential space. The results obtained demonstrate the effectiveness of the present method 

KEYWORDS multizone, air infiltration, measurement technique

#NO 8870 A comparison of three models of air infiltration in houses against field measurement 

AUTHOR Reardon J T, Zhang J. 

BIBINF Canada, proceedings Indoor Air Quality, Ventilation and Energy Conservation in Buildings , Second International Conference, held May 9-12, 1995, Montreal, edited by Fariborz Haghighat, Volume I, pp377-384. 

ABSTRACT Three existing mathematical models of air infiltration in houses were compared with measured data to determine their relative performance with regards to accuracy and ease of use. The three models are the one developed by Sherman at the Lawrence Berkeley Laboratory, the one developed by Shaw at the National Research Council of Canada, and the Variable Flow Exponent model. Air infiltration rates in 22 Canadian houses were measured regularly over one complete heating season using the tracer gas decay technique. Weather conditions corresponding to each air infiltration measurement were obtained. The airtightness and neutral pressure levels (NPL) in each house were also measured. This measured data set provided the basis for the model comparisons. Model predictions using measured airtightness and NPL data were compared with measured air infiltration rates. All the models were found to differ from one another with statistical significance at the 95% confidence level. The Shaw model and the Sherman model offered the best prediction accuracy, both with very similar means and variances of their respective relative error values. The Variable Flow Exponent model displayed the poorest accuracy. The Shaw model has fewer input parameters, and is therefore the simplest to use. 

KEYWORDS modelling, air infiltration, mathematical modelling

#NO 9038 Implementing the results of ventilation research. Proceedings Volume 1. 

AUTHOR AIVC 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference, held Palm Springs, USA, 18 - 22 September, 1995, Proceedings, Volume 1, pp 1-294. 

ABSTRACT Proceedings of the conference, including sessions on the following subjects: energy efficient ventilation; measurement and modelling; modelling. 

KEYWORDS ventilation system, energy efficiency, measurement technique, modelling

#NO 9039 Implementing the results of ventilation research. Proceedings Volume 2. 

AUTHOR AIVC 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference, held Palm Springs, USA, 18 - 22 September, 1995, Proceedings, Volume 2, pp 295-572. 

ABSTRACT Proceedings of the conference including sessions on the following subjects: energy efficient ventilation; maintenance and long term performance; measurement. 

KEYWORDS energy efficiency, measurement technique, maintenance

#NO 9044 Short term and long term measurements of ventilation in dwellings. 

AUTHOR Blomsterberg A, Carlsson T, Kronvall J 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference Implementing the results of ventilation research , held Palm Springs, USA, 18 - 22 September, 1995, Proceedings Volume 1, pp 47-58. 

ABSTRACT A study of the reliability of systems by considering the ability of different systems to maintain a required air flow rate over time is included in a subtask of IEA Annex 27 Evaluation and Demonstration of Domestic Ventilation Systems . Measurements were performed to determine the variation in ventilation rates due to variation in climate and variation in performance of the ventilation system. The monitoring was carried out in one-family houses and apartment buildings, which are representative of the Swedish housing stock. Three different ventilation systems were examined; passive stack, mechanical exhaust and mechanical exhaust-supply. The monitoring period was started with diagnostic tests to discover if the installed ventilation system was functioning as designed and to determine certain values. The airtightness was tested. The air flows in mechanical ventilation were measured. The actual monitoring phase included measurements in dwellings of overall and local (individual rooms) ventilation rates and boundary conditions. High cost and inconvenience prevent the use of continuous monitoring of these ventilation rates. A good compromise was found to be a combination of short-term continuous and long-term averaging tracer gas measurements. The main results were: passive stack ventilation varies over time and is at times too low exhaust ventilation is reasonably constant over time if the dwelling is not leaky, but is at times too low in individual rooms balanced ventilation is almost constant over time if the dwelling is airtight. The paper presents and discusses the measurement techniques and the results from the measurements carried out during 1995. 

KEYWORDS air flow, ventilation rate, apartment building, ventilation system

#NO 9047 A low cost technique for the measurement of high ventilation rates. 

AUTHOR Alexander D K, Lannon S 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference Implementing the results of ventilation research , held Palm Springs, USA, 18 - 22 September, 1995, Proceedings Volume 1, pp 79-86. 

ABSTRACT A recent investigation into the thermal environment of tropical housing required a low cost method for the measurement of high ventilation rates. As a result a simple measurement system, using the detection of the decay of smoke density, was developed. The sensor, based on an infrared LED emitter and a silicon diode receiver, was easily portable, highly robust and could be constructed for less than 50. It was found to be suitable for the measurement of decay rates in excess of 20 air changes per hour. The visible smoke tracer required for the system was easily generated by a number of methods, including smoldering coir matting, smoke bombs and theatrical smoke generators. 

KEYWORDS ventilation rate, hot climate, humid climate

#NO 9053 Experimental validation of Ashrae SPC-129 Standard method of measuring air change effectiveness . 

AUTHOR Offermann F J III, O Flaherty M T, Waz M A, Erlin N B 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference Implementing the results of ventilation research , held Palm Springs, USA, 18 - 22 September, 1995, Proceedings Volume 1, pp 155-164. 

ABSTRACT Ashrae has developed a draft of a measurement standard, Standard 129, entitled Standard Method of Measuring Air Change Effectiveness . This standard defines a method of measurement for measuring air change effectiveness in mechanically ventilated spaces, and provides a discussion of how the values of air change effectiveness may be used to demonstrate compliance with Ashrae 62-1989. Since Standard 129 defines relatively complicated tracer gas procedures for measuring air change effectiveness, the Standard Project Committee 129P and the cognizand technical committee (TC 5.3) have recommended an experimental evaluation of the measurement procedure. The objectives of the proposed work are to obtain information on the practicality of the measurement procedures and to quantify the precision of measured values of air change effectiveness. The experimental test plan involves measuring the air change effectiveness at ten workstations in an 800 ft2 office space mock up. Tests will be repeated under fixed temperature and airflow rate conditions ten times for the step up and ten times for the step down (decay) measurement methods. Sulphur hexafluoride will be used as the tracer gas and three different sample collection techniques will be used simultaneously; line sampling, grab sampling, and integrated bag sampling. This paper presents our experimental protocol to evaluate this proposed new standard. Preliminary results will be presented at the meeting and the complete set of data will be published as an Ashrae technical paper at an upcoming Ashrae meeting. 

KEYWORDS standard, air change rate, measurement technique

#NO 9054 Fan pressurization measurements by four protocols. 

AUTHOR Flanders S 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference Implementing the results of ventilation research , held Palm Springs, USA, 18 - 22 September, 1995, Proceedings Volume 1, pp 165-174. 

ABSTRACT Thirty-one independent fan pressurization measurement series were performed on seven apartments in three family housing buildings at Fort Riley, Kansas, using four protocols. The tests followed procedures in new or revised fan pressurization standards by the International Standards Organization (ISO), American Society for Testing and Materials (ASTM) and Canadian General Standards Board (CGSB). In addition, the effect of interzonal flow was considered. The three standards gave similar results. The tests during windy and calm conditions demonstrated that basic uncertainty calculations give a comparative indication of the quality of the results. The tests addressing interzonal flow did not show a strong influence on airtightness results, based on whether the adjacent units were open, closed, or pressurized at the same level. 

KEYWORDS fan pressurization, measurement technique

#NO 9055 The combined use of CFD and zonal modelling techniques to aid the prediction and measurement of ventilation effectiveness parameters. 

AUTHOR Simons M W, Waters J R, Leppard J 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference Implementing the results of ventilation research , held Palm Springs, USA, 18 - 22 September, 1995, Proceedings Volume 1, pp 175-190. 

ABSTRACT In order that sampling points may be strategically located, it is desirable to have knowledge of the spatial variation of ventilation effectiveness parameters prior to measuring them using tracer gas sampling techniques. The research described in this paper is being carried out to establish a tracer gas sampling strategy as well as to facilitate the prediction of ventilation effectiveness parameters. The procedure developed requires the division of the internal space into a large number of cells and, by the application of CFD, the mass flow rates between adjacent cells to be established. Software developed at the University to predict interzonal flows has now been interfaced with the CFD software allowing the ventilation effectiveness parameters within each cell of the CFD model to be established. Investigation of the computed values of the parameters reveals that the characteristics of many adjacent zones are almost identical. A method has been developed to combine small adjacent zones possessing similar characteristics thus allowing the model to be reduced to one of a small number of zones each possessing significantly different properties. It is demonstrated in this paper that, in the simple mechanically ventilated buildings to which the research has at present been restricted, it is possible to produce reliable contour diagrams of ventilation parameter variations from a small number of properly defined large zones. The large zones found in this way may be used both as a guide to the location of tracer gas sampling points and as the basis of a simplified model for design calculations. 

KEYWORDS computational fluid dynamics, modelling, ventilation effectiveness

#NO 9090 A report on the radon measurement in a single family house. 

AUTHOR Wang F, Ward I C 

BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference Implementing the results of ventilation research , held Palm Springs, USA, 18 - 22 September, 1995, Proceedings Volume 2, pp 561-572. 

ABSTRACT This paper presents the results of a series of measurements made in an occupied family house. Long and short-term measurements of the concentration of radon gas in the cellar and other living areas of the house were carried out. Subsequently a mechanical ventilation system was installed in the cellar and operated in both supply and extract mode with different air change rates. Further measurements of radon concentrations were carried out along with other physical parameters. The results of these tests are reported in the paper and indicate that the rate of ventilation is important in reducing the concentration of radon gas in the dwelling. 

KEYWORDS radon, measurement techniques, residential building

#NO 9238 Particulates in indoor environments: detection and control. 

AUTHOR Etkin D S 

BIBINF USA, Cutter Information Corp., 1995, 176pp. 

ABSTRACT Airborne particulates in indoor air present a health hazard to building occupants, including the potential for allergies, irritation, respiratory effects, circulatory effects, and cancer. Strategies for maintaining acceptable indoor air quality should include the removal or reduction of particulate matter of all kinds. This report discusses methods for measuring particulates and for minimising particulate levels through source control, ventilation, filtration, and other forms of air cleaning. Includes chapters on particulates in indoor environments; particulate sampling equipment and techniques; particulate source control; filtration for acceptable IAQ; filter testing and performance standards; mechanical air filters; high efficiency particulate air filters; filter maintenance; electronic air cleaners; and alternative particulate removal technology. Concludes that the science and technology of indoor particulate control begins with understanding the nature of the contaminants involved, but also involves a sophisticated understanding of particulate detection and characterisation techniques; indoor particulate source control and elimination; sound ventilation and filtration measures to reduce recirculation of particulates from indoor sources; and control of infiltration of ambient particulates through ventilation control and filtration of outdoor intake air. 

KEYWORDS particulate, indoor climate, measurement technique 

#NO 9341 Indoor-outdoor comparison on VOCs: infiltration from outdoor air. 

AUTHOR Gebefuegi I L, Calogirou A, Grassmann M, Loerinci G, Kettrup A 

BIBINF Switzerland, Indoor Air International, 1994, proceedings of Indoor Air Pollution: Innenraumschadstoffbelastung , held at the University of Ulm, Germany, 5-7 October, 1994, pp 11-18. 

ABSTRACT The indoor-outdoor comparison of volatile organic compounds was made in 52 private homes in the City of Munich, Germany. The VOC concentrations were measured by trapping with activated charcoal tubes and analyzed by capillary GC. The infiltrated NO was monitored in the indoor air. It can be concluded the benzene concentration in the indoor air is controlled by the outdoor one in approximately 30% in the investigated cases. 

KEYWORDS organic compound, outdoor air, measurement technique

#NO 9502 Instrumentation for tracer gas detection: a primer. 

AUTHOR Liddament M 

BIBINF UK, Air Infiltration Review, Vol 17, No 2, March 1996, pp 8-10. 

ABSTRACT Tracer gas concentration is measured using a gas analyser. These can be extremely complex and costly systems which add considerably to the expense of performing a tracer gas test. Various types of systems exist and it is vital that the correct detector is chosen for the gas and gas concentration used. 

KEYWORDS tracer gas, measurement technique

#NO 9832 How effective is natural ventilation? A study of local mean age of air by modelling and measurement.

Walker R R, Hayes S D, White M K

UK, Air Infiltration and Ventilation Centre (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 1, held 17-20 September 1996, Gothenburg, Sweden, pp 27-40.

A condition often assumed when designing a naturally ventilated building is where air enters at low level and leaves at high level due to the stack effect. It then follows that, at upper levels, the air may be relatively 'stale' since it has previously passed through the lower storeys. An analogous situation may arise when wind is blowing, in which the air entering through the windward face becomes stale as it passes through the building to the downwind sections. It is not well understood how ventilation may, in reality, be affected by this. To address these issues, this report describes a modelling approach using BREEZE and complimentary measurements using the Passive Tracer Gas technique to study local ventilation rates in multiroomed office buildings. Calculations show that simple ventilation flow rates, as conventionally calculated at the design stage, cannot be relied upon to indicate the true 'freshness'. Measurements show that effective ventilation can be less than current minimum occupancy requirements.

natural ventilation, ageing, stack effect, modelling, ventilation rate

#NO 9841 Experiments in natural ventilation for passive cooling.

Flourentzou F, van der Maas J, Roulet C-A

UK, Air Infiltration and Ventilation Centre (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 1, held 17-20 September 1996, Gothenburg, Sweden, pp 121-134.

A naturally ventilated three level office building has been used to study basic stack ventilation configurations and the interaction between ventilation and the subsequent cooling of the building structure in summer. The research was performed in the framework of a European project on passive cooling of buildings and the objective was to validate simple ventilation algorithms and to give an experimental basis to design guidelines for night cooling techniques. The multilevel office allowed the studying of the influence of openings (size and position) on the neutral pressure level (NPL) and on airflow rates. Various cross-ventilation situations have been studied. A single flow path configuration was obtained by closing all windows and doors in the building envelope with the exception of the roof exhaust and one office window as the ventilation air inlet. Air flow patterns were traced with smoke and tracer gas. In a first set of experiments, where the only driving force is stack pressure, air velocities and the position of the NPL have been measured, and contraction and velocity coefficients as used in the Bernoulli model have been observed. In a second set of experiments, the resulting effective area of a combination of two openings in series was studied. Air flow rates derived from velocity measurements in the open doorways were found to be in agreement with the flow rates obtained with a constant injection tracer gas technique, with an uncertainty of +/-20%. Overall agreement was found between the velocity measurements and simplified models based on the Bernoulli equation. In order to cool multiple levels of a building with outside air, the position of the neutral pressure level should be controlled. The restrictions on opening size and position are discussed.

natural ventilation, passive cooling, office building, stack ventilation

#NO 9854 Maximum velocity of return flow close to the floor in a ventilated room - experimental and numerical results.

Karimpanah M T, Sandberg M

UK, Air Infiltration and Ventilation Centre (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 1, held 17-20 September 1996, Gothenburg, Sweden, pp 263-271.

The problem of sensation of draught in ventilated spaces is connected to inappropriate velocities in the occupied zone. In Scandinavia, velocities higher than 0.15 m/s are said to be an indicator of that occupants are likely to feel discomfort. Therefore knowledge of the flow field (both mean velocities and fluctuations) is necessary. Both experimental and numerical analysis of the flow field in a full scale room ventilated by a slot inlet, with two inlet Reynolds numbers 2440 and 7110, have been carried out. Results from both approaches show that the location of the maximum velocity near the floor is nearly independent of the Reynolds number. For a two-dimensional room, the maximum velocity at the floor level occurred at about 2/3 room length from the supply. The distance from the floor level is dependent on the inlet Reynolds number. The velocity profiles far away from the wall opposite to the inlet device have the same character as a wall jet profile. However, close to the corners they are transformed. The relative turbulence intensities measured in the return flow region are questionable, because of a hot wire's inability to record large fluctuations at low mean velocities. These turbulence intensities close to floor level vary from 15 to 80% and as the authors have pointed out previously hot wires do not indicate the real value of the turbulence intensities beyond 20%. Difficulties appear in numerical predictions of return flow properties. Comparison between predicted values and experimentally obtained values show a reasonable agreement. This is promising for future CFD-predictions. However, there is a need for an appropriate measurement technique that can cope with reversing flow.

air flow, draughts, human comfort, measurement technique

#NO 9856 Application of a passive tracer gas technique in naturally and mechanically ventilated school buildings.

Stymne H, Boman C-A

UK, Air Infiltration and Ventilation Centre (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 1, held 17-20 September 1996, Gothenburg, Sweden, pp 283-291.

The homogeneous emission passive tracer gas technique is described. This technique relies on an even distribution of constant tracer gas emission rate within the object to be measured, so that the emission rate per volume unit is constant. The local steady state concentration of the tracer gas is directly proportional to the mean age of air and the emission rate per volume unit. The technique was applied in 10 school buildings, of which 4 were newly constructed naturally ventilated buildings, 2 were old naturally ventilated buildings, 2 were old mechanically ventilated buildings and 2 were newly constructed supply and exhaust ventilated buildings. The result shows that the ventilation rates in naturally ventilated schools are relatively low compared to required standards. It demonstrates the importance of not only relying on the naturally induced ventilation rate, but also to use other means for improving the air quality during or between lessons, like window opening.

tracer gas technique, school, mechanical ventilation, natural ventilation, window opening

#NO 9858 Application of the tracer gas techniques for the assessment of ventilation indexes in real buildings.

Aleo F, Vitale S

UK, Air Infiltration and Ventilation Centre (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 1, held 17-20 September 1996, Gothenburg, Sweden, pp 303-310.

The work presented in this paper is aimed at the definition of tracer gas experimental procedures for measuring the air change rate, the age of air and the air change efficiency in real buildings under mechanical ventilation conditions. The measurement procedures, based on the decay method, were validated in a special experimental chamber and implemented in two rooms of a building under real operating conditions. Measurements of volumetric flow rate through the air ducts of two buildings, performed by means of the constant emission rate method, will be shown and commented. Results of some measurements obtained by tracer gas technique have been compared with values measured by using other traditional methods.

tracer gas, ventilation rate, air change rate, ageing, mechanical ventilation

#NO 9870 Multizone calculations and measurements of air flows in dwellings.

Blomsterberg A, Carlsson T, Svensson C

UK, Air Infiltration and Ventilation Centre, (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 2, held 17-20 September 1996, Gothenburg, Sweden, pp 429-443.

A study of the reliability of systems by considering the ability of different systems to maintain a required air flow rate over time is included in a subtask of IEA Annex 27 "Evaluation and Demonstration of Domestic Ventilation Systems". Measurements and calculations were performed to determine the variation in ventilation rates due to variation in climate and variation in performance of the ventilation system. Dwellings with passive stack, mechanical exhaust and mechanical exhaust-supply ventilation, representative of the Swedish housing stock, were studied. Diagnostic tests were carried out, to discover if the installed ventilation system was functioning as designed and to determine certain values eg characteristics of inlets and outlets. The airtightness was tested. The air flows in mechanical ventilation were measured. The continuous monitoring included measurements in dwellings of overall and local (individual rooms) ventilation rates, and measurements of boundary conditions, during three different monthly periods. The ventilation rates were monitored using tracer gas; passive techniques for monthly averaging and constant concentration for hourly averaging. The measured ventilation rates were simulated using COMIS, a multi-zone air flow network model. The simulated and measured average total outdoor ventilation rates agree reasonably well, while there can be disagreement for hourly rates and individual rooms. This paper presents and discusses the measurements and the calculations and compares the two.

multizone modelling, air flow, residential building

#NO 10105 Air leakage in the perspective of international standards.

Levin P A, Wilson D J, Ackerman M Y

in: Airflow performance of building envelopes, components and systems, USA, ASTM 1995, papers presented at a symposium held in Dallas, Texas, 10-11 October 1993, pp 231-247.

There exist a number of national standards and a draft international standard for the fan pressurization method for measuring air leakage. Although the standardized methods in principle are the same, the way of interpreting and presenting the results is different. In previous studies, houses that have a relatively large leakage area at a low pressure difference (4 to 10 Pa) can still seem comparatively airtight at a high pressure difference (50 Pa). This face is a consequence of differences in the flow exponent in the power-law equation, which is the normal equation used to fit to the data points, and can be a source of error when trying to compare the relative airtightness of houses. Extrapolating results from high pressure differences to low pressures, which are out of the measured range, can thus result in substantial errors. Air leakage testing of windows normally starts at 50 Pa which should be accounted for when trying to use these results as inputs in network air infiltration models. Measurement results on low pressure air leakage are discussed in the paper and compared with high pressure air leakage. Pressurization test date from 105 tests in one house at the Alberta Home Heating Research Facility are used for the study. The tests were made automatically over a seven-month period in low wind conditions. A wide range of pressure differences were tested and the results cover the test specifications for most standards. In addition to comparing standards, these tests were used to measure seasonal effects on air leakage in a wood-frame house with a plastic film air/vapor barrier. The results show some significant differences between the standards, and also a variation with month of test, indicating a seasonal variation in air leakage.

air leakage, measurement technique, fan, pressurisation, standard, wood frame, pressure difference


#NO 10108 Measured airflows in a multifamily building.

Palmiter L, Heller J, Sherman M

in: Airflow performance of building envelopes, components and systems, USA, ASTM 1995, papers presented at a symposium held in Dallas, Texas, 10-11 October 1993, pp 7-22.

A method has been developed to measure real-time airflow in multifamily buildings. This method uses a multi-tracer measurement system (MTMS) and simultaneous measurements of pressure, temperature, and environmental conditions. These measurements are evaluated along with the results of blower door and flowhood fan tests to develop a complete picture of the airflow patterns in multifamily buildings due to temperature differences, wind, and mechanical ventilation. Six units in an unoccupied three-story multifamily building in Portland, Oregon were tested for a period of eight days during February and March 1992 using this method. The apartments were equipped with timer-controlled ventilation fans that were set to come on at regular two-hour intervals throughout the test period, enabling a thorough evaluation of the effect of various fan conditions on the flow of air from the outside as well as between units. The average ventilation rate from natural driving forces alone (wind and stack effects) was about 40 m3/h per unit, or 0.22 air changes per hour (ACH). The average ventilation rate during the periods with all ventilation fans running was 75 m3/h (0.41 ACH). There was also a significant amount of inter-apartment airflow, which was dominated by flow from lower units to the unit directly above from temperature-driven stack effects. Operating all exhaust fans together had little effect on the interzone flows; however, operation of a single exhaust fan significantly increased the interzone flow to that apartment from all adjacent units. The percentage of total airflow that was outdoor air was found to be lower for higher units than for lower units.

infiltration, tracer gas techniques, indoor air quality, multizone air flow


#NO 10255 Ventilation measurements in a cinema.

Jin Y, Sorensen B R, Sveen S E

UK, Air Infiltration and Ventilation Centre, 1996, supplementary paper presented at "Optimum Ventilation and Air Flow Control in Buildings", 17th AIVC Annual Conference, Gothenburg, Sweden, 17-20 September 1996, 11 pp, 9 figs, 9 refs.

The paper reports on the ventilation measurements in a cinema using the tracer-gas technique. Both the local and room air exchange efficiencies were measured. The two tracer-gas methods, "step-up" and "step-down (decay)", were used alternately when the cinema was in use to enable a continuous measurement of air-exchange efficiencies under various occupancies. The air exchange efficiencies were found to be very close to that for a perfect mixing, with little influence from the occupants. This might be due to that the cinema had a downward mixing ventilation with a larger air change rate. The air exchange efficiencies were found to be lower with the decay method than with the step-up method. The results also show that the decay method was more stable than the step-up method for evaluating the local air exchange efficiencies. However, both are stable for evaluating room air exchange efficiencies.Other parameters such as the CO2 concentrations and temperatures were also measured. Due to good mixing in the cinema, the thermal stratification was found to be small. However, the difference between the CO2 concentrations in the occupied zone was found larger with higher occupancy. The CO2 concentrations were found to be higher in the occupied zone than the room-average ones.

cinema, measurement technique, tracer gas


#NO 10266 Infiltration and ventilation in Russian multi-family buildings. 

Armstrong P, Dirks J, Klevgard L, et al 

USA, Washington DC, American Council for an Energy Efficient Economy (ACEEE), Proceedings of the 1996 Summer Study on Energy Efficiency in Buildings, "Profiting from Energy Efficiency" 

Equivalent leakage areas (ELAs) of 50 Russian apartments were measured under three conditions: 1) as found, 2) exhaust vents sealed, and 3) vents, electric boxes and windows sealed, in 12 buildings of similar construction. Distributions of ELA per unit of apartment volume are presented for the three conditions. Apartment ELAs were found to vary slightly with floor, indicating that the level of occupant-applied weatherstripping is a function of occupants' perception of infiltration rates and that lower floor occupants perceive larger infiltration rates than upper floor occupants. This is consistent with the infiltration simulation results. Simplified models for overall infiltration as a function of indoor-outdoor temperature difference, wind speed and forced ventilation rate are developed. The FEDS discrete retrofit optimization program is described and preliminary results of its application to Russian multi-family buildings are presented. 

air leakage, measurement technique, apartment building


#NO 10586 Air distribution in an office building as measured with a passive tracer gas technique.

Stymne H, Boman C A

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation and Cooling", 18th Annual Conference, held Athens, Greece, 23-26 September 1997, Volume 1, pp 379-388.

A passive tracer gas technique, the homogenous emission technique was utilised for measuring the air distribution in a part of an office building with displacement ventilation. Measurements were made during one winter period and one summer period. During the winter period the ventilation was run continuously, while on/off regulation was used during the summer period. The result from the winter measurement shows that the displacement effect was satisfactory but less pronounced close to the window-side of the office. The paper discusses the effect of on/off ventilation strategy on the requirement of the measurement technique and the implications of such strategy on air quality. It is shown that the homogeneous emission tracer gas technique yields the true average mean age of air, also during transient conditions, but that special precautions must be taken when using intermittent sampling of the air.

air distribution, tracer gas

#NO 10591 Measurements and control of air motions within a building.

Blomqvist C, Sandberg M

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation and Cooling", 18th Annual Conference, held Athens, Greece, 23-26 September 1997, Volume 1, pp 427-436.

There are a number of methods available concerning with distribution of air in buildings. Within control research, one can find new control algorithms which have not yet been used in practice. These new algorithms open the possibility of developing and implementing of new demand controlled ventilation systems. In a building the internal air motions are due both differences in temperature and pressure differences caused by the ventilation system. Therefore, one fundamental question is to what extent is it possible to control the air motions within a building using fan powered ventilation in combination with temperature control. The aims of this paper is to report on measurements done to examine the influence of temperature differences between rooms on the air exchange through open doors in a building and to explore the use of modern control technique to minimise the temperature difference. The result of the measurements shows that even very small (0.1-0.2 C) temperature differences between rooms cause bi-directional air flows in the doorways of a magnitude that exceed the flow rates caused by the mechanical ventilation system. Therefore it is necessary to control the temperatures in the rooms to make it possible for the ventilation system to distribute the air to those parts of the building where it is needed.

air flow, measurement technique

#NO 11457 Energy efficient ventilation of large enclosures. Technical Synthesis Report. IEA ECBCS Annex 26.

Moser A, et al

UK, Air Infiltration and Ventilation Centre, 1998, 35pp.

Large enclosures have become a major feature of modern building design. Spaces such as atria and covered areas are used in all varieties of buildings including office complexes, shopping malls, airports and public buildings. Essentially they create an environment protected from the outdoor climate in which a wide range of activities is possible. However such spaces demand very careful design to ensure good indoor air quality and thermal comfort and to protect occupants from the risk of fire and smoke spread. Describes the Annex 26 project and summarises information about proven technology for the design of ventilation in such spaces. The report covers analysis and prediction techniques; measurement techniques; case studies; and lessons learned.

large building, energy efficiency, atrium

#NO 11541 Airtightness Measurements in three dwellings in Rome. 

Fasano G, Giogiantoni G, Guili G

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 85-92.

Airtightness measurements are not yet common in the Italian dwelling stock. In the framework of the MICA-ENEA contract, three dwellings were chosen to study the energy performance on the influence of natural agents. The majority of the dwellings in Italy still nowadays rely on natural ventilation and records of the fluid dynamic and energy performance are not contractual documents among the parties involved. Since building airtightness is an important parameter to be investigated in case of natural ventilation, this study takes into consideration three typical examples of the Italian dwelling stock located in three different districts of the urban area and cover the range of constructions starting from the beginning of the century up to eighties before the actual heavy decrement of the new constructions.

The three dwellings are located in Rome and they have the following characteristics:

1. dwelling located downtown in a 1915 building (Dw-1),

2. dwelling located in the south-east region of the city, in the residential areas built in the 70's (Dw-2),

3. dwelling located in the north region of the city, in the residential areas built in the 80's (Dw-3),

The instrumentation to be used included a blower door, data logger and computer with the dedicated software to perform depressurization tests up to 50 Pa, to obtain ACH and ELA and in general all the parameters which might be of interest to foresee the behaviour of the dwellings during natural ventilation under the influence of the urban environmental conditions.

measurement technique, airtightness, modelling

#NO 11565 Measurement of heat and mass transfer through typical staircases.

Peppes A A, Santamouris M, Asimakopoulos D N

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 314-322.

This paper is concerned with heat and mass transfer through two typical staircases. The first staircase connects the two individual floors of a two-storey building, and the other connects the three individual floors of a three-storey building. A series of experiments have been performed in order to study the buoyancy driven flow between the floors. A single tracer gas decay technique was adopted. Temperatures at various points on each floor were constantly monitored and air velocity measurements were also provided at some specific locations. The heat and mass flow rates between the two floors, through the first staircase, were calculated from the tracer gas concentrations. The analysis of experimental data gives relations for the mass and heat flow rate as a function of temperature difference between the floors, and of the geometry of the particular staircase. Simulations of the same configurations have been carried out, using validated CFD algorithms. Airflow rates estimated by these simulations showed very good agreement with experimental values. The mass flow rates through the second staircase are estimated using the CFD method. In addition, the paper discusses the airflow patterns in the staircases.

stairwell

#NO 11930 The principles of a homogeneous tracer pulse technique for measurement of ventilation and air distribution in buildings.

Stymne H, Boman C A

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

The principles of a new tracer gas technique is described in the paper. The new technique involves pulse injection of tracer gas and has the same advantages as the previously known homogeneous emission technique. It can for example advantageously be used in large buildings and buildings with many rooms and yields information on the distribution of ventilation air within the building. However, contrary to the homogeneous emission technique, yielding the average ventilation performance during an extended time, the new technique allows measurement during short term periods. The new technique is based on homogeneous pulse injection, which means that pulses of tracer gas are injected in each zone in a zone-divided building, with amounds which are proportional to the zone volumes and integrating sampling of tracer gas concentration. Theoretical and practical aspects of the technique are described.

tracer gas, air distribution

#NO 12072 Airflow patterns in Schonbrunn Palace.

Holmberg J G, Kippes W

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 189-196, figs, refs.

The purpose of this study is to find more information of the complicated air flow pattern in the Sch÷nbrunn Palace. The aim is to improve the control of the air infiltration. We have used a passive tracer gas technique, a special case of the constant injection technique, called the homogeneous emission technique. The results give Air Change Rates (ACH) of 0,7 to 1,7 in different rooms and parts of the palace. Wind driven ventilation dominates stack driven ventilation. We found a considerable air flow between floors. Simple one zone calculations of air leakage over windows partly confirms the ACH measured. The palace management will use the results of the investigation in the ongoing planning process to improve the indoor climate and abating the indoor deterioration.

air flow patterns, air exchange efficiency, air tightness, tracer gas, large building

#NO 12214 Comparison of modelled and measured tracer gas concentrations in a multizone building.

Sextro R G, Daisey J M, Feustel H E, Dickerhoff D J, Jump C

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 696-701.

Few detailed comparisons of modelled and measured pollutant concentrations in multizone buildings have been published. The COMIS air flow and contaminant transport model permits simulation of the effects of building and HVAC operation, as well as the influence of the local meteorology, on air flows within the building. We have recently used this model to simulate the release of a gas-phase tracer in a three-story, multi-room building located at Dugway Proving Ground, Utah, USA. Following detailed leakage and flow-path characterisation measurements of the building, experiments were conducted in which tracer gas concentrations were measured as a function of time in each room of the building. Comparison of the simulations with these detailed measurements showed reasonable-and in some cases, quite good - agreement. The paper describes some details of the experiments and modelling and discusses the differences between the observed and the predicted concentrations.

tracer gas, modelling, measurement technique, multizone building

#NO 12216 Prediction of the indoor air quality trend in a dwelling in the Mediterranean climate.

Giorgiantoni G, Giuli 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 708-713.

The purpose of this study was to evaluate the indoor air quality parameters in a residential dwelling using information from the field. The subject was a typical example of the modern Italian dwelling stock, built in the 1980s in a residential area in the northern part of Rome. The dwelling was constructed from pre-cast panels using industrial building techniques. The windows were steel-framed and painted. Airtightness was measured to obtain the ACH (air changes per hour) at 50 Pa pressure difference, and ELA (equivalent leakage area). Other parameters which were also measured to predict the behaviour of the dwelling during natural ventilation the influence of the urban environmental conditions. The data were used as input to simulations using the NIST multizone model CONTAM96 to predict the contaminant distribution within the dwelling during normal activities such as cooking, smoking etc. The combined use of field measurements and computer simulation produces a better evaluation of the pollutant trends than previously available, since quantities such as airtightness of windows and frames previously had to be estimated from background literature, based mainly on factory test, which ignore quality of workmanship during construction.

residential building, air tightness, natural ventilation

#NO 12228 Computational analysis of indoor air and temperature distribution in an office space.

Tinker J A, Al-Garny A M

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 774-779.

There is a growing demand for buildings to have a high indoor air quality environment. Two of the main elements that contribute to this quality are temperature and air distribution within the occupied space. In modern office buildings particularly in hot climates, care must be taken to design the most economical air distribution system that provides comfort for the occupants. There are many techniques available to predict the air distribution patterns in the space at design stage, but these are often not very accurate. In one of the techniques, scaled models are used to collect data on air distribution patterns but this is expensive, time consuming and it is not possible to include all the room parameters. There are also problems associated with scaling. Recent innovations in air modelling are more wide-ranging in their analysis and are also more cost effective. These include computer simulation modelling in two or three dimensional form so that spatial factors such as air temperature, velocity and pollutant concentration distribution can be predicted with a reasonable degree of accuracy. In this paper a Computational Fluid Dynamics (CFD) model was used to predict air velocities, temperatures and air distribution patterns in an office building in a hot climate. Experimental data was collected in an office space in Dhahran, Saudi Arabia and the space was then modelled in a CFD code. Measured data was compared with that predicted by the software to gain confidence in the technique. Once confidence had been gained, the office air supply and extract system were re-designed to improve the quality of the indoor air in the space. The paper reports on the technique and shows how computer modelling can be used successfully at design stage to predict and consequently improve the final air quality parameters in an occupied space.

temperature distribution, hot climate

#NO 12264 A method for measuring air cleaner effectiveness.

Bohanon H R, Nelson P R, Wilson R 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 679-684.

Air cleaners are unitary devices that contain filtration media and fans. They are marketed for cleaning air in rooms. There is no current method for measuring the effectiveness of these devices in rooms of the size where they are typically installed. The proposed method provides engineers and manufacturers with a tool for evaluating and predicting applied air cleaner performance. Test results provide the effective ventilation rate of the device. This rate can be stated in terms of the whole room average, or for specific regions of concern, such as work areas, within the room. This method provides information about mixing or removal effectiveness, location optimisation, and system performance efficiency.

air cleaning, measurement technique

#NO 12298 Measurement of ventilation, air distribution and inter-zonal air flows in a 4-storey historic building using a passive tracer gas technique.

Holmberg J G, Stymne H, Boman C A, Astrom 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 815-820.

Air temperature, air humidity and ventilation has been measured in a Swedish baroque castle. Results are presented for a measurement campaign comprising four periods under varying climatic conditions. A passive tracer gas method, known as the homogeneous emission technique has been used to measure the ventilation rates and air distribution in the building. As the palace is essentially unheated, wind pressure is the main driving force for ventilation. The air change rate is highly varying and differs considerably in different parts of the building (0.5-1.5 ACH). The result of window renovation in certain rooms indicates that adding inner windows seems to be a possible means to reduce infiltration rate and stabilise the indoor climate. Other means of retrofitting are also discussed.

measurement technique, air flow

#NO 12300 Error estimation of blower door measurements by computer simulation.

Geissler A

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 827-832.

Computer simulation of building airtightness measurements shows the effect of changes in pressure distribution across the building envelope due to wind force and temperature difference on measurement accuracy. The wide range of leakage distributions, wind directions and velocities considered give information on the boundaries of these uncertainties. For wind velocities on site of ( site(3m/s, the additional uncertainty in the flow rate at 50Pa (Q50) found is comparable to the uncertainty due to standard pressure gauges or operator (about 3%). The additional uncertainty for on site wind velocities of no more that ( site(4,7 m/s is in the range of 7%. This is comparable to overall uncertainty in calm conditions. Unfavourable building location, leakage distribution and unlucky choice of external pressure taps can lead to significantly larger uncertainties in the measured flow rates of 10% for on site wind velocities of 3 m/s up to 40% for on site wind velocities of approx. 4.7 m/s, though.

computer simulation, measurement technique

#NO 12309 Measurement of air flow rates and ventilation efficiency in air handling units.

Roulet C-A, Foradini F, Deschamps L

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 5, pp 1-6.

Air handling units do not always function as planned: airflow rates are often larger than required, the recirculation rate is not at its set-point value and parasitic shortcuts sometimes decrease dramatically the ventilation efficiency. A dedicated diagnosis, based on the tracer gas dilution technique can easily detect such dysfunction, and help to cure the defects. Within the framework of the Joule-Thermie AIRLESS project, a measurement protocol, which includes the planning of measurement and the interpretation algorithms, was developed on the basis of years of practice in such measurements and implements and implemented in a user-friendly computer programme. The protocol was applied to several air handling units in various buildings. This contribution presents the method applied, the principles used in the test protocol, and some measurement results. 

air flow rate, ventilation efficiency

#NO 12312 Storage and processing oil contamination on new HVAC components: development of measuring methods.

Pasanen A V, Liesivuori 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 5, pp 19-24.

The HVAC components are usually made of galvanised sheet metal which is covered by a corrosion protection and also lubricant oils are used in machine tools in manufacturing of the components or ducts. The aim of this study was to test and develop a consistent method to determine oil concentrations on component surfaces. Two swiping methods and a filter contact method were tested. In al of them the analysis based on IR-spectrometry. The results show that oil concentration is quite high and unequally distributed on the surface of the sheet metal containing corrosion protection oil. The concentrations were low on the sheets treated with chromium acid. The filter contact method showed the best recovery 91% (2% while the recoveries were 55-65% with the swiping methods. the detection limit for the filter contact method was 4mg/m2 and 1mg/m2 for the others. 

air conditioning, measurement technique

#NO 13066 Airflow through louvers: an experimental and CFD study.

Sharples S, Maghrabi A

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 16.

There has been a growing interest in the use of natural ventilation in buildings to supplement or replace mechanical air supply systems. However, for buildings in busy urban areas the potential to use natural ventilation can be limited by excessive noise entering through natural ventilation openings such as windows and trickle ventilators. Such openings tend to have large open areas to enhance air flow while offering a very low resistance to the transmission of external urban noise. Traditional treatments for controlling the ingress of noise through an opening tend to increase significantly the air flow resistance of the opening, thereby making natural ventilation non-viable. This paper describes some experimental studies of alternative forms of noise control that do not create an increased resistance to air flow. The first alternative was a passive system consisting of a panel containing sound absorbent material fixed in front of a ventilation opening. The second alternative investigated was an active noise control system which attempted to sample the urban noise spectra close to the inlet opening and neutralise the noise by injecting the inverse spectra ('anti-noise') in to the air supply. Finally, a hybrid system incorporating both the passive and active techniques was tested. Initial results suggest that this hybrid approach may yield a design strategy that allows urban buildings to benefit from natural ventilation whilst maintaining an acceptable internal acoustic environment. 

air flow, measurement techniques

#NO 13075 The discharge coefficient - experimental measurement of a dependence on density contrast.

Hunt G R, Holford J M

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 26.

At sufficiently high Reynolds numbers, the discharge coefficient Cd associated with a sharply contracting flow through a square-edged opening is, in general, taken to be constant. The effect of buoyancy forces, due, for example, to temperature differences between the air on either side of the opening, is ignored.

We hypothesise that the buoyancy force may result in a significant reduction in the discharge coefficient associated with the flow through a square-edged opening in a horizontal surface. We test this hypothesis by deducing Cd from laboratory measurement of the two-layer stratification produced by a localised buoyancy source in an enclosure which ventilates passively in a displacement mode. Experiments were performed at small scale in a water tank using saline solutions to generate buoyancy forces.

In the absence of a buoyancy contrast, the discharging flow contracts due to inertial effects giving Cd ( 0.6. In the presence of a buoyancy contrast, our results show that the discharge through a horizontal vent takes the form of a rising plume-like flow, which may contract further giving a smaller value of Cd. The plume-like discharge is characterised by conditions at the discharge opening, which we represent by a single dimensionless parameter ?d - the discharge parameter. Our results demonstrate that once a critical value of ?d is exceeded, Cd exhibits a strong dependence on the density contrast and rapidly decreases with increasing ?d. The implications of a dependence of Cd on density contrast are for potentially serious errors in the prediction of airflow rates if a constant value of Cd is assumed.

measurement techniques, air flow, buoyancy

#NO 13079 Experimental testing of a homogeneous tracer pulse technique for measurement of ventilation and air distribution in buildings.

Stymne H, Hansson P, Boman C A

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 30.

A number of single tracer gas techniques (decay, step-up, homogeneous constant emission, inlet pulse and homogeneous pulse) suitable for measuring the local mean ages of air in multi-zone buildings exist, each having their advantages and drawbacks. The characteristics of the different available techniques are compared from theoretical and practical points of view. The homogeneous pulse technique has not been experimentally validated before. This technique relies on pulses of tracer gas being injected into the different zones in amounts, which are proportional to the zone volumes. Some advantages with the "homogeneous pulse" technique, compared with the "inlet pulse" technique, are that the pulses can be injected at any time path, that they must not necessarily be short and that the evaluation of local mean ages of air involves a simple total time integration of concentration, making it possible to utilise integrating air samplers (e. g. adsorption tubes).

The homogeneous pulse technique is tested against the decay technique in a five-room indoor test house, using both automatic and manual injection of tracer gas. It is shown that this technique yields results as accurate as the decay technique. Using manual injection (with syringe), however, requires special caution in order to achieve a uniform distribution of the injection in a room and to avoid redistribution while walking between rooms.

tracer gas techniques, measurement techniques, multizone building

#NO 13095 Quantifying ventilation needs in Local Authority housing - a case study.

Richardson G, Eick S A, Harwood D 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 46.

A Tool Kit was developed to assess indoor air quality. The Tool Kit was designed to be robust, reliable, universal and to provide data that could be linked with other studies assessing health, social factors and building conditions for any given locality. A case study using the Tool Kit to assess 116 Local Authority houses is described.

rental housing, indoor air quality, ventilation needs, measurement techniques

#NO 13096 Airflow rate performance of various ventilation systems. Results of measurement

in a typical Belgian dwelling.

Loncour X, Wouters P

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 47.

This paper presents the results of ventilation measurements taken in a non-occupied one-storey dwelling situated in the countryside. The measurements of the ventilation rates in the different rooms have been obtained by the use of tracer gases with the constant concentration technique. Four configurations of ventilation systems have been tested successively. The ventilation systems tested consist of natural air supply and mechanical exhaust. Both 'normal' air supply grilles and self-regulating grilles have been tested. The exhaust system installed is a mechanical system without regulation.

The results show the importance of the ventilation in dwellings, the selection and dimensioning of effective ventilation devices as well as the correct use of the equipment installed.

air flow, ventilation system, residential building

#NO 13099 Ventilation performances in French dwellings: results from field observations and measurements.

Guillot K, Litvak A, Kilberger M, Boze D

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 50.

This paper presents a recent field measurement study undertaken in 1999 on 73 recently built French dwellings. The study presented the opportunity to assess the conformity and the performances of the dwelling ventilation systems and to assess the impact of infiltration on airchange rates. The following aspects were analyzed: (1) the type of ventilation facilities in the dwellings ; (2) the defaults in the installed systems and in their operation ; and (3) the measured air flow rates, as compared to the French standard required levels. For each dwelling, we investigated the infiltration air exchange contribution as compared to the total air change rate. For this, on site depressurization tests were performed on each dwelling with the ® blower door ¯ technique. With a first measurement, we assessed the sole air leakage rate, while with a second test, we measured the total air change rate (including air flow through ventilation air inlets). Comparison of results led us to assess the infiltration air contribution into the total air exchange rates. The results of the study show a significant proportion of defaults in ventilation systems, in terms of conformity as well as in terms of global performance.In addition, airflow rate assessments reveal a significant contribution of air infiltration when compared to the total airchange rates. 

field measurements, infiltration, ventilation, residential building

#NO 13109 Airtightness of French dwellings: results from field measurement studies.

Litvak A, Guillot K, Kilberger M, Boze D

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 60.

A field measurement study of the airtightness of 73 - less than 5 year old - French dwellings was led between 1999 and 2000. Buildings have been selected and classified according to the construction structure, the thermal insulation and the occupancy mode. Using a fan-depressurization technique, we assessed the air leakage rate of each dwelling with two depressurization tests. Meanwhile quantifying air leakage rates, we observed qualitatively the most frequent locations of air leakage paths using a smoke detection method and infrared thermography. We assessed the ratio of the air leakage rate weighted by intrinsic dimensions of each construction, namely : the unheated surfaces and the heated volume. From our results, we compare the performances of the different types of dwellings and we assess the impact of the envelope airtightness on the building ventilation efficiency. We show that thermal performances of buildings can be dramatically affected according to the dwelling construction characteristics. Finally, we discuss the potentials for reducing indoor air infiltration with a view to improve the indoor air quality and the energy efficiency of buildings.

air tightness, residential building, field measurements, air infiltration, building envelope

#NO 13372 Field measurement results of the airtightness of 64 French dwellings.

Litvak A, Kilberger M, Guillot K

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 2, pp 1093-1098, 6 figs, 1 tab, refs.

This work presents a field measurement study, investigating the airtightness of 64 French dwellings less than ten years old. Buildings have been classified according to the type of construction (masonry or timber frame) and of occupancy mode (multi- or single-family). Using a fan-depressurisation technique, we assessed the air leakage rate of each dwelling, based on a theoretical flow model that relates the infiltration airflow rate to the differential pressure. Meanwhile quantifying air leakage rates, we also observed the locations of air leakage paths using a smoke detection method and infrared thermography. In order to compare the results obtained among the sample of dwellings, we assessed the ratio of the air leakage rates divided by intrinsic characteristics of each construction, namely the unheated surfaces and the heated volume. We compared the performance of the French dwellings measured in this study, as a function of the different building types. The results of this work show that construction characteristics can play a significant role on buildings' airtightness, as well as on the interpretation itself of the performance.

Airtightness, field measurements, dwellings, infiltration, ventilation, buildings, air leakages


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