The technical chapters in the draft proposal for the Ventilation Code differ from the existing one. The technical means for achieving acceptable indoor climate will be described in a new way. In order to secure acceptable quality also in practise (not only in design), new requirements are suggested for design and especially the documentation of design, for commissioning and for maintenance planning. The suggested minimum ventilation rate is 4 l/s per person in rooms where smoking is not allowed and 10 l/s per person if smoking is allowed.
The new proposal for ventilation requirements in the National Building Code of Finland is on public review. The structure of the proposal is different from the existing ventilation code. Minimum requirements for acceptable indoor climate will be given to a wider extent than before, eg new requirements for indoor air temperature and purity are proposed. Also the quality of outdoor air should be taken into account in design of ventilation. Health aspects are also considered, based on today's international knowledge of indoor air quality and human health.
Good indoor air quality and thermal comfort and good energy-efficiency can be achieved simultaneously only if the amount of ventilation can be demand-controlled. Two approaches are discussed in the article: CO2- control and use of so-called air quality sensors. The first experiments have been promising but further development of equipment is still needed, in order to improve the reliability and economy of demand-controlled ventilation.
Ventilation systems perform a number of tasks. They must remove contamination/pollution, they act as heat/cold transporters and they must create a satisfactory room climate without causing draughts. States that users must be aware of the limitations of ventilation systems and that ventilation systems are not able to carry out all tasks completely satisfactorily. Compares the efficiencies of displacement and mixing systems and gives guide values for temperature differences between room air and supply air for office and industrial applications.
There is no patent solution. Discusses duties of ventilation system: to create a satisfactory indoor climate in a cost-effective manner while considering the demands of three intimately associated factors - well-being, health, working efficiency, risk. Notes the various criteria to be complied with to provide satisfactory ventilation: thermal requirements, air quality requirements, noise/safety, flexibility and economy.
Gives a history of the development of air conditioning, and displacement ventilation in particular. Discusses the constant problem of working environments - contamination, and the 'side effects' of economy measures resulting from the 1974 oil crisis. Refers to collaboration between HVAC engineers and the health authorities. Recommends the use of displacement ventilation because of its improvement in air quality. Considers the problems caused by the use of floor coverings and filled carpets in particular.
Discusses two main methods of fan-assisted air supply to a room - mixing ventilation and displacement ventilation. Gives a detailed account of the effects which furniture and the opening of doors have on a room and discussses factors such as vertical temperature variations, air velocity at floor level. Illustrates these effects in diagram form. Notes difficulty in translating older comfort criteria for use in displacement ventilation.
Discusses 11 strategies where methods and guidelines should be applied now by the building services engineer in designing new ventilation systems or retrofitting existing systems.
Treats major design and construction actions that can be taken in houses to limit conduction losses, increase heating performance, reduce energy losses through windows and provide adequate ventilation air - super insulation, high performance furnace or boiler, high performance windows and controlled ventilation. Discusses in some detail how controlling indoor air pollutants at source is the preferred approach to maintaining indoor air quality. Illustrates diagrammatically and explains how a house functions under natural ventilation conditions.
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