Natural ventilation rates in bedrooms at night have been measured in retrofitted apartments. The measurements indicate clearly that air quality in bedrooms may be unacceptable in dwellings with an energy-efficient minimal ventilation rate. The air supply rates may be as low as 1 l/s/person in themedian case of bedroom size, ventilation rate and two occupants. The carbon dioxide concentration will reach a level of 4000-4500 ppm in the morning depending on the length of sleeping time in a closed room.
The performance of whole-house mechanical ventilation systems was explored in an full-scale indoor test house (volume 176 m³ ) . A range of parameters were monitored: * The pressure distribution * The inflow of outdoor air to each room, the mean age of air in each room and the air-exchange effectiveness * The spread of a 'contaminant' released respectively in the kitchen and in the bedroom. The tests were undertaken both with the internal doors closed and with the internal doors open. Both mechanical extract system and balanced (combined) systems were tested.
A Compact Equipment for Survey of Air Renewal (CESAR) was developed at the Ecole Polytechnique Federale de Lausanne in Switzerland. Controlled by a microcomputer, this apparatus uses tracer gas methods ( decay, continuous flow or constant concentration). Up to ten different locations in inhabited rooms can be monitored simultaneously over extended periods of time, using mainly the "constant concentration" technique. Several air renewal surveys were carried out on different inhabited buildings.
Knowledge of the air change in dwellings under conditions of use is a prerequisite for the calculation of energy consumption and for evaluation of a dwelling's indoor climate. Air change was measured in a total of 25 occupied dwellings over a
Various ventilation systems have been examined in unoccupied test houses under natural climatic conditions. Two identical test houses were used to enable comparison of the effects of different ventilating systems on the air change rate and heat consumption. The systems examined were natural ventilating devices placed in the window area and centralized and decentralized mechanical systems. With the decentralized systems, draughts were generally unavoidable. Heat recovery from exhaust air at an air change rate of 1.0 h-1 gave a measured heat consumption saving of about 16 per cent.
Over a one-year period, measurements were taken of air temperature, air humidity, ventilation rate, concentration of organic gases and vapours, formaldehyde and odour intensity in a small unfurnished bedroom in each of 6 new unoccupied low energy houses. The indoor climate was on average characterized by an air temperature of 24.7 plus or minus 3 degrees C, and an air humidity of 5.9 plus or minus 2.0 g/kg. Ventilation in each room was between 0.79 and 2.92 air changes per hour. On average 14 different compounds were identified in the samples, a total of 23 compounds being identified.
Summarizes the main results of the seminar: 1 interdisciplinary collaboration is necessary, 2 a direct and intensive publicity campaign is needed to influence occupant behaviour, 3 an air change rate between 0.5 and 1 per hour (in relation to the total volume of the living quarters) should comply with normal requirements, 4 a method for measuring the airtightness or air change rate for individual buildings should be developed ready for application, 5 mechanical ventilation offers the best solution, 6 there exists a need for simple ventilation fittings which can be installed in existing buil
Discusses levels of radon commonly found, the limits fixed by Sweden for buildings, and the health effects of these levels. The three main sources of radon are domestic water, building materials and the ground, with the ground being the most important element. Radon values for different soils in Sweden are given as illustration. COSTIC is planning to study the most susceptible zones of France, and to follow this with recommendations, including minimumair change rates.
The installation of much tighter windows has led to reduced rates of natural ventilation in German dwellings. This has resulted in increased indoor air humidity and condensation formation on the inner surfaces of external building elements with thermal bridges. Notes the areas most at risk from condensation and mould, in particular corners of outside walls and along the ceiling angle.
Errors resulting from treating a house as an enclosure surrounding a single, well-mixed volume of air are explored in detail for a ranch house with abasement. A fairly typical ventilation pattern is assumed and three quantities, the air exchange rate, the indoor pollutant concentration from a given emission, and the energy required to heat infiltrating air, are calculated and compared using both the one and two zone models for this house.In general, the errors were around 10-20% if the basement was included in the one zone models and 30-40% if the basement was neglected.
Login