This research shows the study and analysis of sunspaces behaviour as passive elements of architecture during the summer, taking into account that they are fundamentally passive solar heating elements for winter. This study is carried out through monitoring and energy simulation of six case studies, applying it to summer 2011-2012 which was extremely hot for the climate zone in which it is located. These results are useful for the study of residential buildings with the forecasts of climate change for Pamplona, especially for an architectural element as sensitive to overheating as is an attached sunspace. The research concludes that attached sunspaces also have a good thermal behavior in summer, even in extreme conditions, as long as they are designed and used properly, and therefore no active cooling system is necessary. This research also explores the energy efficiency and optimized design of the sunspaces for different climate zones in Spain, selected attending mainly to the severity of summer although with different winter conditions. (C) 2015 Elsevier B.V. All rights reserved.