Achieving mid-rise NZEB offices in Brazilian urban centres: A control strategy with desk fans and extension of set point temperature

Positive energy buildings (PEB) are foreseen to help achieving global emissions reduction targets and decarbonisation. However, for vertical office spaces in urban centres the photovoltaic (PV) production area is restricted, so innovative strategies are needed. For cooling-dominated climates the extension of set point temperature associated to local control of air movement has the potential to increase the use of natural ventilation and generate a great amount energy savings.. Therefore, this study aims to identify to what extent adopting a mixed-mode operation with desk fans could help mid-rise office buildings to become NZEBs in warm climates. To verify the impact of this strategy, computer simulations were carried out with three building heights in four Brazilian cities. Results show this strategy can generate 20-40% energy savings and the set point could be extended up to 28 degrees C or 30 degrees C depending on the climate, without jeopardizing occupants' thermal comfort. Thus, in warm climate cities, the strategy allows lower buildings to become PEBs and mid-rise buildings to become NZEBs. In addition, the demand for extra PV area is expressively reduced, increasing the viability of mid-rise PEBs. This study adds innovative knowledge for achieving PEB targets under suboptimal conditions and highlights multiple aspects that should be considered for applying this strategy. (C) 2022 Elsevier B.V. All rights reserved.