outdoor air

HVAC system outdoor airflow rates are usually measured and set at the air-handling unit. The effectiveness of an HVAC system at delivering the outdoor air to the occupied spaces of a building is varied and often disputed. To investigate the delivery of outdoor air to the occupied spaces of a variable-air-volume system, ASHRAE Technical Committee 9.1, Large Building Air Conditioning Systems, funded Project 687- TRP, Minimum Ventilation Airflow Rates with VAV Systems. This article presents some of the information collected during that project.

The ventilation air intake (louver) is the first line of defence against an unfavourable outdoor climate. Unfortunately, the importance of this component is often an underestimated issue in the design process of many heating, ventilation and air conditioning (HVAC) systems. Field studies and inspections of a representative number of HVAC plants carried out between 1995 and 1998 in and around the city of Trondheim revealed that snow, and in several cases rain, easily passes through the air intake louver. Such intrusion of humidity can lead to unwanted microbial growth in the HVAC system.

Within an International Energy Agency (IEA) project (Annex 27) experts from 8 countries(Canada, France, Italy, Japan, The Netherlands, Sweden, UK, and USA) have developed toolsfor evaluating domestic ventilation systems during the heating season. Building and useraspects, thermal comfort, noise, energy, life cycle cost, reliability, and indoor air quality(IAQ) tools were developed.

Parametric studies have often been used for sensitivity analyses in the field of the pharmaceuticaland agricultural sector. All such studies aims at bringing some kind of order out of complicatedrelationships between influencing factors and some response parameter(s). With experimentaldesigns and statistical analysis methods, it is possible to trace and quantify influencesof individual as well as combinations of input factors on the response parameter. Thisprocedure has so far very seldom been used within the building sector.

This paper describes a European project to produce comprehensive design guidance on urban layout to ensure good access to solar gain, daylighting and passive cooling. The project involves:

Three buildings are investigated to study the indoor air quality and the impact of the outdoorair pollution. These buildings, a swimming pool, a school and a nursery are located in anurban area. So, during experimental studies, typical outdoor and indoor pollutants such ascarbon monoxyde, nitrogen dioxyde, carbon dioxyde, and total volatile organic compoundsare monitored. Also, the relative humidity and the temperature are carried out. The analysisallows us to reveal several points.

The main purpose of buildings is to provide a comfortable living environment for their occupants. This includes, among others, thermal, visual and acoustic comfort as well as indoor air quality. Except during the fifties and sixties, it has always been considered important that an excess use of energy should be avoided in the construction and the management of a building, sometimes even at the cost of user comfort. Energy saving is however not the main purpose of the building.

 In 1984 the municipality of Frederikshavn in northern Jutland, Denmark initiated a project for the climatic design of a new housing area. The site is particularly exposed to strong winds all the year round and one of the major tasks was to design the overall building site and the buildings so that major improvements in the exterior wind environment were achieved. Furthermore the design brief from the municipality called for an overall climatic design, where low-energy solutions were combined with consideration of the exterior environment near the buildings.