The Role of Solar Gains in Net-Zero Energy Buildings: Evaluating and Optimising the Design of Shading Elements as Passive Cooling Strategies in Single-Family Buildings in Colombia

Net zero-energy buildings have become one of the flagships in the path towards the decarbonisation of cities. Even though heating systems, especially in existing buildings, are currently the main consumer in many areas of the world, cooling needs are gaining relevance in several countries, and this is expected to be kept in the focus in the context of increasing temperatures, according to the climate projections identified by the IPCC. This has also additional implications on thermal comfort conditions (and, indirectly, on the derived health issues) in areas where no cooling systems are installed in residential buildings. This research work aims to evaluate the design of shading elements as a design strategy in the path towards net-zero residential buildings in diverse Colombian climates. A parametric analysis is developed, considering a combination of different shading solutions applied in residential buildings. Their effectiveness is evaluated in different climate zones in Colombia considering both the current climate data and future climate data expected according to the projections proposed by the IPCC. A reference building in Bucaramanga (Colombia) was selected for detailed monitoring, and the collected data were used to validate a simulation model developed in DesignBuilder. Almost 1000 alternative scenarios were established and parametrically evaluated, resulting from the combination of different shadings solutions, orientations and climate conditions. The results are evaluated considering two different approaches: cooling demand assuming a standard indoor temperature profile and indoor comfort when no cooling devices are used in the building, showing that some strategies, such as overhangs, involve significant improvements in terms of indoor thermal comfort and a reduction in cooling demand (reaching in some cases savings up to 30%) in the different climate conditions considered; as well, their effectiveness remains similar when future climate projections are considered.