National calculation tool for epbd energy performance certification

Paper is focused on description of Czech national methodology and tool for energy performance calculation according to EPBD (Energy performance building directive 91/2002). Energy performance calculation is expressed by total annual energy consumption, including heating, cooling, ventilation, auxiliary and other energy required for building operation. There is a simplified multizone model, loaded by typical day for each month in hourly time step. Climate data are synthetic data for 4 climate zones according to standards, used for building physics calculation.

Heating energy penalties of cool roofs: the effect of snow accumulation on roof

Utilizing a cool roof is an efficient way to reduce the cooling energy use of a building. Cool roofs, however, may increase heating energy use in winter. In cold climates, during the winter the sun angle is lower, days are shorter, sky is cloudy, and most heating occur during early morning or evening hours when the solar intensity is low. In addition, the roof may be covered with snow for most of the heating season. All these lead to a lower (than what is commonly thought) winter time heating penalties for cool roofs.