AIVC, Air Infiltration Review, Volume 17, No 1, December 1995

Complementing the Results of Ventilation

16th AIVC Conference Report

19th-22nd September 1995, Hyatt Grand Champions Resort, Palm Springs, California, USA
Malcolm Orme, AIVC

The 16th Annual AIVC Conference, held at the Hyatt Grand Champions Hotel in Palm Springs, California, attracted 53 presentations and participants from all AIVC participating countries. Topics covered included:

Richard Karney, Director of the Building Systems and Materials Division at the US Department of Energy , delivered the Welcome Address and introduced the Keynote Speaker, Commissioner Jannane Sharpless from the California Energy Commission , who spoke about the need for long-term public investment to complement the research and development projects funded by private industry.

Energy Impact

Several presentations focused on energy consumption. The first by Don Colliver (University of Kentucky , USA) outlined the results of a study to determine the energy necessary to condition a fixed flow rate of outside air to various heating and cooling set points. Later on, Jürgen Röben, of the Universität Essen in Germany, discussed the benefit of low energy dehumidification, achieved with an open cycle liquid desiccant system, whilst Professor Fritz Steimle, also from Essen, described how the separation of sensible cooling from latent heat removal can allow a more energy efficient system.

Standards

A workshop on standardisation encouraged various speakers to give an informal presentation on the current situations in their respective countries. Codes and Standards were also the subject of several papers delivered throughout the conference and included a presentation by Gene Tucker (EPA , USA) about the current revisions to ASHRAE Standard 62-1989 "Ventilation for Acceptable Indoor Air Quality". Also from the USA, Bud Offermann (Indoor Environmental Engineering) demonstrated the procedure for an experimental evaluation of ASHRAE Standard 129 "Standard Method of Measuring Air Change Effectiveness".

Offices and Large Enclosures

Measurements to determine ventilation effectiveness in four mechanically ventilated New Zealand office buildings highlighted the importance of planning the ventilation system around the floor layout. Continuing with offices, Peter Wouters (BBRI, Belgium) described the installation and operation of an infra-red (IR) detector controlled ventilation system. It was shown that, provided attention was paid to duct airtightness, then the IR detection facility can provide significant energy savings. Elia Sterling (T.D.Sterling & Assocs, Canada) summarised the planning and design of some prototype energy efficient offices, and Earle Perera (BRE , UK) illustrated how trickle ventilators are able to supply adequate background ventilation for occupied offices. Alois Schälin (Federal Institute of Technology , Switzerland) reported on both the method of predicting air flows through open aircraft hanger doors using transient thermal models and computational fluid dynamics (CFD) and the possibility of using huge air curtains to reduce heat loss in such structures . From Sweden, Sture Holmberg (National Institute of Occupational Health ) showed encouraging results from field measurements, carried out in the plastics industry, of the principles of practical displacement ventilation. Two strategies for cooling (without dehumidification) in non-residential buildings were explained by Andrew Martin (BSRIA, UK) and Willigert Raatschen (Dornier GmbH, Germany). The UK strategy concerned the use of automatic controls for natural ventilation and passive cooling, whereas the German author presented the testing of a thermosyphoning facade system.

Ventilation in the Home

Lars-Göran Månsson (LGM Consult AB, Sweden) discussed the various criteria influencing domestic ventilation system performance . As part of the same study , Johnny Kronvall (J & W Consulting Engineers AB, Sweden) described the simulation of passive stack ventilation (PSV) in a single family house and suggested possible improvements. From the Swedish National Testing & Research Institute, Thomas Carlsson outlined the results of calculations for mechanical exhaust and balanced mechanical systems, concluding that outdoor air should be supplied only via the bedrooms for both these systems. Also, Åke Blomsterberg, from the same organisation, contrasted the outcome of long-term monitoring of a representative sample of dwellings in Sweden for different ventilation systems and also showed the results of an occupant survey of indoor climate and user interaction in post-1988 single family Swedish dwellings. Findings reported by Duncan Hill (CMHC ) of an occupant survey in Canada concluded that increased consumer education and refinement of controls and maintenance strategies would be needed to ensure more success with mechanical ventilation with heat recovery (MVHR).

Ulf Krüger (Chalmers University , Sweden) proposed that slot inlet devices are very difficult to position without causing thermal discomfort. He justified this with studies of temperature and air velocity distributions around these devices in relation to occupation zones in residential buildings. Still in Scandinavia, Jørn Brunsell (Norwegian Building Research Institute) reported field tests of dynamic insulation in four houses. These revealed that it is essential for the air flow to remain constant, irrespective of climate, occupants, or infiltration.

Retrofit

Retrofit activities are very important, because the existing building stock is substantially larger in size than the new building stock. The number of buildings in need of renovation is therefore significant. Peter Op 't Veld (NOVEM bv, The Netherlands) described the E'novation programme of renovation of dwellings, in which buildings with high energy use, poor indoor air quality (IAQ) and often moisture and mould growth, were made more energy efficient (by an average of 39%) with, in addition, improved IAQ. An overview of a French guide to assist in the choice and sizing of PSV systems for apartment retrofits for ventilation and gas exhaust flues was given by Jean-Georges Villenave of CSTB . From VTT Building Technology in Finland, Jorma Sateri argued that the installation of heat recovery in existing Finnish multi-family buildings would be economically feasible if their airtightness was 2 to 3 air changes per hour at 50 Pa, or better.

Mites, Mould and Moisture

Jan Nielsen (Danish Building Research Institute, Denmark) measured humidity levels in 16 humidity-controlled mechanically ventilated apartments in conjunction with another 16 identical apartments (as a control group) with constant ventilation. Interestingly, the humidity-controlled apartments were found to use less energy for heating than the control group, but still met humidity requirements. Furthermore, Donald McIntyre (EA Technology, UK) presented survey results (conducted during a winter period) of humidity and dust mites in 20 houses with MVHR and 20 other houses, from which he concluded that the majority of the MVHR houses had humidity levels sufficiently low to reduce dust mite numbers. This contrasted with a minority of the other houses. Sarah Palin, also from EA Technology, made a comparison of the energy consumption and resultant indoor humidity levels with each of PSV, MVHR, and mechanical extract fans (MEF) in a single family test house. Nigel Oseland (BRE , UK) found that the results of a postal survey of occupants of UK dwellings with either PSV or MEF showed, in general, that those with PSV in their homes seemed to have least problems with condensation or mould.

Radon

Paul Welsh (BRE , UK) and Fan Wang (University of Sheffield, UK) have been independently examining techniques for reducing radon concentration in UK single family dwellings. Their results presented at the Conference, indicated that extract ventilation (depressurisation) of the underfloor space produced the greatest reduction in radon levels in the living area. Pirjo Korhonen (University of Kuopio, Finland) found that radon levels in various workplaces in Finland depended mainly on the type of foundation and the magnitude of depressurisation of the work space. Richard Grot (Lagus Applied Technology, USA) explained how, using SF6 as a tracer gas in tunnels in a uranium mine, the transport of radon through the overlying soil and into the cellars of 15 different buildings above had been investigated.

Calculation Techniques

An important mechanism for implementing research results is the production of calculation methods. Iain Walker (LBNL , USA) explained his simplified procedure for the calculation of attic ventilation rates. Willem de Gids (TNO , The Netherlands) stated that TNO now has an algorithm for the calculation of building surface wind pressure coefficients, which has been designed to take into account surrounding shielding. An integrated approach to predicting building air flows by combining network models, CFD, and thermal simulation was reported by Jan Hensen (University of Strathclyde , UK) together with the 'onions' and 'ping-pong' alternative methods of coupling heat and air flow solvers. Both Muriel Regard (ENTPE , France) and Martin Simons (Coventry University , UK) presented their work on using CFD for ventilation effectiveness calculations. Prompted by ASHRAE Standard 62-1989, Milton Meckler (The Meckler Group, USA) demonstrated dynamic IAQ models of ventilation system response to emissions.

Measurement Techniques

A crucial aspect of ventilation research is having good measurement techniques. Stephen Flanders (US Army Cold Regions Research and Engineering Laboratory , USA) pointed out the uncertainties associated with fan pressurisation measurement, in particular, if ISO , CGSB and ASTM protocols are followed. Michael Cui (University of Illinois at Urbana-Champaign , USA) has been using particle-imaging velocimetry to produce whole room air velocity profiles. Peter Wouters (BBRI, Belgium) proposed that acceptable results can be achieved for the investigation of airborne moisture transport if accurate humidity measurements are made and tracer gas studies are used to find air flow rates.

Conference Awards and Banquet

Miriam Byrne, Imperial College, UK received the Best Paper award for her presentation entitled "Particulate Deposition on Indoor Surfaces - its Role, with Ventilation, in Indoor Air Quality Prediction". The Best Poster was awarded to Richard Diamond and Helmut Feustel of LBNL , USA for their poster entitled "Air Flow Distribution in a Mechanically Ventilated High-Rise Residential Building". Both these awards were presented by the Guest Speaker, John Millhone, Senior Fellow, Advanced International Studies, Battelle Pacific Northwest Laboratories (on assignment from the US Department of Energy ). After the awards, John Millhone delivered an address entitled "AIVC - Looking to the Next 16 Years" in which he stressed the importance of the AIVC grasping the new opportunities created by the growing international recognition of the importance of energy efficiency. He said that changes are occurring in Central and Eastern Europe, as countries in this area emerge from a centrally controlled to a free-market economy which exposes their profligate energy use and artificially low prices. He also saw AIVC playing an expanded role in the growing concern over the damage to the earth's climate being caused by greenhouse gases. He elaborated by saying that as the dominant greenhouse gas emission is carbon dioxide which is produced primarily by the burning of fossil fuels for energy, then it follows that energy efficiency programs are the fastest, cheapest and largest option available for containing this problem. He went on to say that the AIVC must expand their mission to provide information and services, designed for the air infiltration and ventilation problems of the emerging free-market countries, if necessary at a discounted cost or even funded through a third party. In this way, he sees it as a low-cost method of buying a world-class technology transfer service and the unique and significant findings of the researchers in these new participating countries would enrich the body of knowledge of the AIVC and give it an expanded relevance to major energy efficiency and environmental problems of the next 16 years. Just before the close of the Conference, the Summing-Up was given by Martin Liddament, Head of the AIVC, who reviewed how this field has progressed over the last 16 years.

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