German

Discusses acceptable levels of CO2 contamination in occupied rooms. Describes measurements in a classroom over 3 days using an infra-red analyser with natural ventilation via the windows. Illustrates curves for CO2 concentrations in 8 graphs for closed windows. Notes that limiting value of 0.1% by volume CO2 (1000ppm) is reached in from 5 to 15 minutes. Repeated sudden ventilation by opening windows is not practicable. Evaluates air change rate. Concludes energy saving for ventilation in heavily populated rooms is only attainable by mechanical ventilation with heat recovery.

Steeply sloping ventilated roofs are preferred for single and two-family houses in West Germany. Notes lack of any scientifically substantiated notions concerning physical laws governing air exchange between ventilated zones and outside air. Describes air flow and heat transfer investigations in a 48 deg. sloping roof. Gives details of roof constructions. Illustrates roof space and distribution of thermocouples and arrangement for injecting tracer gas. Describes experimental procedure. Provides some measurement results. Compares theoretical bases with experimental results.

Treats drawbacks of current methods used in East Germany of calculating vapour barriers used to protect building elements from condensation. Notes building materials for which moisture absorbed in winter is sufficient to cause condensation damage before it has diffused in summer. Develops method based on calculation model of determining direct relation between any period of condensation and requisite vapour barriers. In addition amount of wateraccumulated during condensation period can also be determined.

Discusses standards and guidelines used for calculating the heat demand over a heating season. Notes inadequacy of current methods, in particular the inadequate account taken of certain environmental conditions and of particular window constructions. Proposes improved sizing procedure to take into account heat loss due to infiltrating air. Discusses simplifying assumptions. Gives expressions for critical heat output and for the quantity of air infiltrating a room.

Considers the characteristics of flow through small gaps. Discusses relation between wind tunnel measurements and actual wind pressure on buildings and the effect of building shape on ventilation. Derives equations for flow rate through a gap for different temperature and pressure differences and sizes of gap. The equations consider the pressure as a function of time thus modelling the effects of a turbulent wind incident on a gap.

Improved levels of thermal insulation for dwellings in W.Germany have substantially reduced thermal transmission losses, so that ventilation heat loss has become much more important component of total building heat demand. Amount of heat appears important enough to justify considering heat recovery from ventilation air residential buildings. Describes 3 examples of exhaust air recovery from flats in an apartment building. Provides details of air change rates.

The wind pressures on a building can be decreased by a shelter hedge. Gives results of wind tunnel tests which show how this shelter effect depends on the distance between hedge and house, and on the wind direction.

Gives theoretical calculation of the amount of air which moves from one room to another due to a temperature difference between the two rooms. Suggests the possibility of reducing the heating or cooling load by allowing an overpressure in one of the two rooms.

Gives results of a survey carried out in December 1978 on heating and ventilating of dwellings. 2000 men and women were questioned throughout the federal republic. Gives range of dwellings, desired and actual room temperatures, types of windows, frequency and duration-of window opening and the existence of draughts.< Concludes inter alia that heat loss through ventilation is greater than commonly assumed. In particular this heat loss is through leaky windows and ventilated bedrooms.

Reports tests of air leakage of windows, made in a wind tunnel. Six different windows were tested, five were of the same design with different manufacturers and materials;two steel, one wood, one aluminium and one cast iron. Gives expression for the airflow through a window. Discusses pressure distribution on buildings and stack effect.