Use of sunspaces to obtain energy savings by preheating the intake air of the ventilation system: Analysis of its main characteristics in the different Spanish climate zones

Abstract

Novel solutions need to be further developed to continue to improve the energy efficiency of buildings achieved over the last few decades. One of these innovative systems is the use of sunspaces to preheat the ventilation intake air and reduce heating consumption. The main goal of this research is to determine the optimal configuration of these sunspaces. For that purpose, a prototype was built to calibrate a simulation model. Once validated, the model was used to calculate the energy savings obtained with 96 sunspace configurations in the different Spanish climate zones. Different key factors were analyzed and the optimal configurations were established in each zone. The results show that, although these systems are based on solar gains, a low thermal transmittance of the glazing has a higher impact on the energy savings than a high solar heat gain coefficient. In addition, introducing inertia tanks is not convenient when the ventilation includes a heat recovery system. While combining sunspaces with heat recovery ventilation is not interesting in warmer climates; in cold climates, heat recovery becomes a determining factor to reduce energy consumption. The use of sunspaces is more efficient as the winter severity increases: while in the warmest Spanish climate zone, only 2.51 kWh·m −2 ·year −1 savings are achieved; in the coldest zone, 39.54 kWh·m −2 ·year −1 savings are obtained, which represents important energy savings of 60%. This research contributes to evaluating and quantifying the impact of key variables on the design, configuration, and operation of sunspaces to improve the energy efficiency of buildings. • Sunspaces to heat ventilation air entail great energy savings if properly designed. • A energy simulation model for sunspaces was validated with experimental results. • Savings of 96 sunspace configurations were quantified for different climatic zones. • Optimal sunspace configurations for maximum energy savings have been established. • In the coldest Spanish climatic zone savings of 60% in heating were achieved.