This paper presents a simple method for predicting snow density by use of weather data. Six hundred and eight snow density (bulk weight density) measurements from the period 1967-1986 are used in a multiple regression analysis. The measurements are performed at 105 sites in theÅs area situated in Akershus County in southeast Norway. The area has a relatively stable winter climate. Weather data from an observing station with three registrations a day are used in the analyses. The distance between the measurement sites and the meteorological station varied between 0.6 and 14 km. A clear correlation is found between the observed climate and the measured snow density. A multiple regression equation is developed with a coefficient of determination equal to 70% and a standard deviation equal to 24 kgm −3 . Snow density values suggested in the Norwegian code NS 3491-3 is in most cases overestimated. Expressions given in an annex to the international regulations for snow loading on roofs (ISO 4355) are less applicable to prescribing snow density for climate studied in this investigation. Still, they can be used as simple and rough estimates.

Vacuum insulation panels (VIPs) are regarded as one of the most promising existing high performance thermal insulation solutions on the market today as their thermal performance typically range 5 to 10 times better than traditional insulation materials. However, the VIPs have several disadvantages such as risk of puncturing by penetration of nails and that they cannot be cut or fitted at the construction site. Furthermore, thermal bridging due to the panel envelope and loadbearing elements may have a large effect on the overall thermal performance. Finally, degradation of thermal performance due to moisture and air diffusion through the panel envelope is also a crucial issue for VIPs. In this work, laboratory investigations have been carried out by hot box measurements. These experimental results have been compared with numerical simulations of several wall structure arrangements of vacuum insulation panels. Various VIP edge and overlap effects have been studied. Measured U-values from hot box VIP large scale experiments correspond well with numerical calculated U-values when actual values of the various parameters are used as input values in the numerical simulations.

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