Heat recovery ventilation solutions for school building renovation

case study

Abstract

School building ventilation solutions have been mainly natural ventilation. Only in a few decades has the renovation of ventilation systems in school buildings started. However, there are still many buildings in Estonia that have natural ventilation or mechanical extract ventilation without heat recovery. Last solution can ensure indoor climate requirements in favourable climate conditions if well designed. However, this can lead to excessive heating energy use resulting in not adequate energy performance. Therefore, there is a need of ventilation system renovation to improve both IAQ and energy performance. Two solutions with different cost are studied in this paper: classroom air handling unit (AHU), and central AHU. The aim of this study is to determine which solution is better in energy efficiency if there is demand to renovate ventilation system in school building. The calculations have been done in standard and real use and climate. Study will show the cost-optimality of these solutions in school buildings. Two school building models were composed and building performance simulations (BPS) with the test reference year climate file were conducted to calculate the building energy use based on EN 16798-1:2019 and real use (where the building model was calibrated with monthly measured real energy consumption from year 2014). Previous studies show, that natural ventilation is an electricity saving solution, but not good for indoor climate. This study found that classroom-based solution is easier to build and the initial cost is lower. However, the energy saving for central ventilation solution will exceed the classroom solution of 29 kWh/m2. Considering energy and cost calculations, the centralized mechanical ventilation with heat exchange will be slightly more cost-optimal solution in this case study as it gained 4 €/m2 lower global cost than classroom-based solution.