Potential of attached sunspaces in winter season comparing different technological choices in Central and Southern Europe

The present study focuses on the potential applicability of attached sunspaces in Southern and Cen- tral Europe (winter season). Sunspace is a diffuse passive solution which reduces winter thermal losses and increases solar gains. This article analyses the geo-climatic applicability of this technology follow- ing a two-step study: 1) a climate based pre-evaluation of sunspace potential for 50 selected locations representing different climatic situations; 2) a calculation of sunspace potential in reducing energy con- sumption for heating using energy dynamic simulations on a sample building by comparing different technological choices. Step 1 examines heating demand (Heating Degree Days - HDD) and total solar radiation on a horizon- tal plane for each location. HDD was assumed as an indicator of the heating demand at different base temperatures (20 ± 2 ◦ C), while total winter solar radiation is considered as a general indicator of the “virtual” heating potential of attached sunspaces. Both calculations are based on a typical meteorologi- cal year (TMY). Step 2 is based on energy dynamic simulations of a sample building in order to analyse heating energy reduction caused by an attached sunspace on a monthly basis. Different technological choices were taken into account for both sunspaces and building envelopes in order to identify the best local solutions for passive heating as regards energy consumption in a set of 50 selected locations. Con- siderations and potential maps are reported to help designers optimise the applicability of sunspaces according to local climatic conditions and building technologies. Finally, the summer performances and the potential cooling demand reduction by shading and natural ventilation of sunspaces are analysed.