Since 1 march 2020 we provide Meteodata of 8,948 weatherstations worldwide. Every day approximately 5,300 of these weatherstations carry out multiple meteorological measurements which we can collect. The most of them each hour (22%), followed by each half hour (12%) and each 20 minutes (24%). For the remaining 52% of the weatherstations, the number of measurements varies from 1 (29 weatherstations once per 24 hours) to around 600 (1 weatherstation every 2 minutes). With meteodata.xlsx we have developed an easy-to-use instrument to look up meteorological data and (cooling) degreedays. 

Degreedays were introduced by a Dutch oil company early in the sixties of the former century with the purpose to calculate the expected use of fuel in buildings of their clients. Later on degreedays (and cooling degreedays) were used to analyse the energyperformance of buildings, to predict plant and animal development rates (growing degreedays) or to predict when mosquitoes and black fly emerge and cease.

Most-perfect magic squares have due to their extreme symmetries excellent qualities to consider the use in encrypting and creating keys. A most-perfect magic square is a magic square were amongst other symmetries also 2x2 subsquares sums to a magic constant. 

eExplorer is a monitoring instrument for commodities (energy, water and chemicals). With prices one can focus on costs and savings. Cost cutting measures due to optimizing HVAC machines can easly be monitored.