window

Discusses some problems of providing weathertight joints between window and wall. Mentions sealing failures, condensation, frame defects and poor dpc detailing as important reasons for water penetration around windows. Refers to some principles of weather protection. Makes recommendations for the design of window-to-wall joints.

This is a short guide to the choice of a type of window, considering its position and exposure to wind. Defines exposure grades for windows. Gives recommendations for choice of windows considering air permeability, water tightness and wind resistance. The catagories of windows are as defined in standard N F P 20 302.

Describes test apparatus and method of testing windows for air leakage. This standard has been adopted by the following countries :- Austria, Belgium, Denmark, France, Italy, Netherlands, Spain, Switzerland and United Kingdom. It is available in English, French or German.

Reports tests using a natural exposure rig on a number of designs of horizontal and vertical joints employing labyrinths to separate the air and water entering the joint. Results obtained under a limited range of conditions show that it is possible, with suitable designs, to prevent penetration of water without necessarily making a joint airtight. Puts forward a number of potential applications, including a prototype window.

Describes standard tests for air leakage, water-tightness and mechanical tests to be carried out on windows. Describes apparatus and test method. Defines normal resistance to air leakage as air penetration of 12 to 60 m3/h/m2 of the surface at a pressure of 10mm. of water. At air penetration of less than 12 m|3/h/m|2 the windows have improved resistance to air penetration.

Briefly reviews air leakage around windows. Discusses heat loss through windows, dependence of leakage on pressure difference across windows, effect of leakage on condensation. States that tight windows can save heating and cooling costs but weatherstripping is necessary for tightness.

Presents results of measurements of ventilation rate and window air leakage made in blocks of flats in Sweden. Describes measurement of ventilation rate using nitrous oxide as a tracer gas and pressurization tests on windows. Gives graphical results of tests. Finds that the majority of windows do not satisfy 1975swedish building code. Reports measurements of air leakage of windows before and after renewal of draught excluders. Concludes that old windows can be made relatively draught-free and that this is not expensive or time consuming.

Reports a project to assess the value of weatherstripping windows and doors in a 30-year old home. Describes house and retrofitting technique using stainless steel weatherstrips. Air infiltration rates before and after retrofit were measured using three independent methods, tracer gas dilution using SF6,pressurization/depressurization for the whole house and depressurization of individual windows. Finds that air-change-rate for the whole house was reduced by 10-14.7%giving a predicted reduction of 15.5% for a complete retrofit which would result in an energy saving of 4-6%.

Weatherstrip for windows and doors were studied by full-scale tests with regard to airtightness, closing force and ageing properties. Tubular strips provided the highest degree of airtightness in both windows and doors, while angle strips were only slightly inferior in performance. The leakage of air was found to be considerably greater for strips of expanded and foam plastics and fibre strips. For tubular strips of small material thickness and for angle strips, the closing force in doors was low.

This draft gives provisional recommendations for performance requirements for windows. Gives grades of exposure, speed correction factors for ground roughness and height above ground level. Suggests values for wind loading and limits for air infiltration, water penetration and security.