Dynamic insulation : Analysis and field measurements

A nonlinear least squares method for continuous measurement ofthe air flow in a 'dynamic insulation' was presented. The methodis called the gradient method to indicate that the temperature gradientsin the insulation are used. The method includes one dimensionaltransient and steady state calculations ofthe heat transfer inthe insulation. The model was verified by analytical and numericalsimulations. With the use of this method the air flow through aninsulation was continually measured in a single storey one familyhouse with a living area of 116 m2 during one year (1993). The housewas built at Dalby, Sweden which has a yearly average temperatureof 7.8 C. The exhaust ventilation was about 53 l/s. The air flowthrough the dynamic insulation as measured by the gradient methodwas 21 l/s or 4O % of t]ne total inlet air. The measurements showed aslightly higher air flow during the spring that during the autumn.This result corresponds well with laboratory measurements performedby Roots (1994) where 50 % of the inlet air passed throughthe insulation