Proposal of retrofit of historic buildings as cafes in Korea: Recycling biomaterials to improve building energy and acoustic performance

While the preservation of historic buildings is important, they must remain usable. The comfort of occupants using the historic building must be considered due to the change of use. In this study, a 100-year-old building in Korea, protected as a cultural heritage site, is retrofitted. Buildings currently in continuous use as cafes require improvement of low building performance due to aging materials. The energy performance and sound environment of the target building were improved by recycling café generated coffee waste. Recycled coffee waste uses a phase change material, increasing its latent heat. DesignBuilder simulation, a building energy performance analysis software, analyzed energy consumption and room temperature before and after retrofit. C10 containing 10% of the phase change material of coffee waste board showed high efficiency, saving heating energy after retrofit. After retrofit according to the material sound absorption coefficient, ODEON simulation confirmed improvement of the indoor sound environment. The measured sound pressure level was 73.95 and 75.15 dB in the 500 and 1,000 Hz frequency bands, respectively; however, after implementing improvements, the sound pressure level decreased by up to 7.39%. Reverberation time was observed as high as 1.47 s and 1.83 s for the 500 and 1000 Hz frequency bands, respectively, and decreased by up to 66.67%. Therefore, application of coffee waste board to the retrofit of historic buildings is effective in improving indoor environment.