Evaluates results of the 'Ventilation in Residential Buildings' research programme of the German Federal Ministry for Research and Technology. It was found that conventional ventilation methods based on infiltration and window opening cannot secure proper air quality and at the same time provide energy conservation and user comfort, nor can intelligent ventilation habits be expected of the average user, for subjective and objective reasons. All ventilation systems evaluated had shortcomings.
In new buildings, the requirements for indoor air quality and energy efficiency cannot be met with natural ventilation. In renovations of existing buildings it is, however, often difficult or uneconomic to install a mechanical system. What is often forgotten is that the conditions for natural ventilation will have changed, even if no alterations are made to the ventilation system.
Describes a new ventilation strategy for retrofitted buildings. The system consists of two units including heat recovery, fan, filter, etc, which are installed in the window openings. They are operated in opposite directions which are periodically reversed. When desired, the unit is stopped and used as an airing panel. In laboratory tests the specified values were achieved. The heat recovery proved so efficient that no air heating was needed even at the lowest temperatures. Some noise and freezing problems were reported.
Some of the problems for designing ventilation systems for retrofitted buildings are presented. Measurements were taken in two public buildings in Helsinki with three ventilation systems of different types. In these two buildings only a balanced mechanical ventilation system seemed to fulfill therequirements for a satisfactory and healthy indoor environment.
Displacement flow has been found to be the best flow principle for ventilation, with ventilating air being supplied to the occupied zone. The design procedure should, amongst other things, contain an analysis of contaminant source in order to design the ventilating system to create the most favourable flow pattern for the contaminants. This paper deals with design principles and problems related to displacement ventilating systems.
A short description of a second generation low-energy house built at Hjortekaer in 1984, with a calculated annual heat demand of 3500 kWh (excluding domestic hot water), is given. The house is superinsulated and very airtight. The roof and walls are insulated with 400 and 300 mm of high quality mineral wool respectively, with infinitesimal thermal bridges, and the floor is a slab-on-grade construction insulated with 200 mm polystyrene. Most of the windows are south facing and fitted with a new type of lightweight external insulating shutter.
Examines the design of two houses, built in 1982, which integrate an exhaust air heat pump and a warm air heating system into a very well insulated structure. Monitored during 1983-84, they consumed 50% less energy than a typical Swedish house. Apart from occasional (avoidable) high temperatures, the warm air heating system led to a comfortable indoor climate. The performance of the houses could be improved by installing energy conservation appliances. The house of the future should be tight, well-insulated and mechanically ventilated.
The air exchange rate and total heat loss were measured in 11 detached dwellings to find the relationship between measured and calculated transmission heat loss factors based on standard Norwegian calculation methods. For 9 houses the measurements were done under stable climatic conditions. Air change rate varied between 0.2 and 0.7 ach with an average value of 0.45 ach. These measurements, together with several others, confirm that the Norwegian Standard (NS3031) for calculation of the transmission heat losses is reasonably correct.
Much research work has been carried out on modelling ventilation air currents. The authors propose that the currents be divided into specific zones, the air parameters of each zone being determined by different conditions. The formula is then derived by the addition of an infinite number of elementary currents flowing from a multitude of point sources. From this, a general formula is proposed to calculate the velocity, temperature and admixture concentration along the whole flow of the current.
Body odour emitted by 16 occupants at three activity levels (1, 4 and 6 met) was evaluated by 30 male and female judges. The judges assessed, when entering the occupied room, the intensity and acceptability of the body odour. CO2 concentration and air change rate were measured. For the same CO2 concentration, the body odour intensity was of the same magnitude whether the occupants were sedentary or engaged in physical activity up to 6 met. But odour caused by physical activity was less acceptable than odour from sedentary occupants.
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