Adaptive Envelopes for Better Energy Efficiency and Enhanced Indoor Thermal Comfort

Abstract

The increased use of renewable energy in the built environment is a key objective for sustainable development. While being a key priority for the future of energy use, renewable power generation is affected by local resource fluctuations, such as the amount of incoming solar radiation. Energy storage and increased energy efficiency will continue to gain importance in this context. In cold and moderate climates, heating has traditionally accounted for the predominant part of energy use in buildings. In many parts of the world, heating remains fossil-fuel based to a significant extent. Due to a number of issues, including climate change, the proportion of heating energy has been steadily decreasing, while cooling loads have been on the rise. The use of electricity for heating and cooling has been increasing, partly related to an increased use of different types of heat pump technologies. Growing electricity use for cooling is increasingly seen in highly-insulated, low-infiltration, high energy-performance buildings, but also in other parts of the building stock. High levels of insulation efficiently decrease heat losses during the heating season, but they also impair the removal of excess heat. This study explores how adaptive envelopes can be used to optimize the use of solar radiation during the heating season and enhance the removal of excess heat during the warm part of the year, depending on parameters including outdoor and indoor temperatures and the desired levels of thermal comfort. The IDA-ICE energy and indoor-climate simulation tool is used for exploring different adaptive envelope scenarios. It allows the calculation of heat flows through the walls, currently however without considering the impact of radiation on external walls. To compensate for this, a new approach is presented to simulating heat flows through different types of adaptive envelopes and wall constructions. This allows for a more detailed understanding of how adaptive envelopes allow incoming solar radiation in summer to be stored before it is transmitted to the main wall structure. Conversely, a more detailed analysis becomes possible of how accumulated heat can be released during the night by removing insulating layers of the wall, thus cooling the indoor environment.