German

Discusses the principles involved in measuring air change rates using tracers and gives the theory. Outlines the preparation of the tracer and the test procedure in stables. Finds that satisfactory results can be obtained when the concentration of krypton-85 is only one tenth of the maximum allowable. Lists the advantages of the method.

Points out that increased levels of thermal insulation in dwellings make ventilation heat loss an increasingly significant proportion of total dwelling heat loss and of great significance for sizing heating installations and selecting their control equipment. Treats attempts to reduce ventilation loss by specifying greater tightness of building structures, especially windows.

Compares the new draft standard with the 1959 original. More sophisticated mathematical methods and meteorological data processing has necessitated the revision. The new standard incorporates SI units, uses resistance calculations and develops computer compatible stationery

A study made to confirm the values given in german standard DIN 4701. considers theoretical natures of air permeability and the k-value as they concern windows. Finds that infiltration through windows without weather-stripping depends to such an extent on the quality of manufacture and fitting that essential differences between single-glazed, double-glazed and double windows scarcely exist. Finds no real difference between woodenand metal frames when new, but after normal wear and tear an average value of 3m(3)/h for each metre of gap at 1mm pressure difference is acceptable.

According to TGL standard 112-0319, the demand of heat required for ventilating a building essentially depends on the passage of air through its window and door joints. This varies to a great extent. The losses of thermal energy can be reduced substantially by tolerance specifications for joint dimensions. Such tolerances will result in permissible resistance coefficients for different types of windows. Depending on thehygienic requirements suitable selection is then possible within a narrow margin of error.

States heat load on buildings due to wind is dependent on the shape of building, wind direction and wind speed. Gives theoretical calculation for the heat loss due to wind based ongerman standard DIN 4701. Discusses fundamentals of fluid dynamics and the practicalities of wind tunnel tests. Recounts tests made of a block of flats in Munich. Pressure distribution due to wind was determined by a wind tunnel test on a model, giving c-profiles for different wind directions.

For simplicity's sake the determination method outlined in previous issues of this article did not include the air infiltration through cracks. The graphical method is again demonstrated when allowing for air infiltration as specified in German standard DIN 4701 and examples are given.

Gives the results of measurements of wind and driving rain carried out over a 1-year period on an 18-storey block of flats, and compares these results with calculated and model scale data. The in-situ measurements indicate that the pressure differences between various locations on a facade, exposed to rain are much smaller than the calculated values, and also pressure differences due to wind at a window between the inside and outside are much lower than the theoretical values.

Derives mathematical relationships for the connection between pressure loss and volume flowrate using simple crack models and applying known laws of similarity for flow in pipes or gaps. Demonstrates how these relationships permit more exact determination of the permeability of cracks in normal building structural components than has been possible hitherto with the use of a few approximate average values for crack permeability coefficients and pressure exponents.

Describes a diagram from which heat losses due to infiltration according to German standard DIN 4701 can be obtained, as well as rate of air infiltration per unit length of crack. By considering several factors the method can be generalised for the case of several windows and doors of varying quality of fit. The method is therefore useful for both the approximate and the accurate calculation of infiltration heat losses.