Energy performance evaluation and prediction for an institution building

The building sector is responsible for almost a quarter of the total carbon dioxide emissions. The urgency to reduce the emissions is reflected in the stricter regulations and guidelines which have been implemented in various countries. They are two effective ways to reduce the building sector's emissions, namely constructing new energy efficient buildings or retrofitting existing buildings. Due to the life expectancy of existing building stock the greatest reduction in emissions before 2030 could be achieved through retrofits. This paper evaluates the energy performance gap between the measured and simulated results of an institution building and discussed how the computational method is contributing to the prediction of energy usage after retrofits. The case study building is a medium rise institution block with classrooms, offices, library, computer labs and cafeteria facilities within a city campus in Melbourne, Australia. A thermal simulation model of the case study building was compared with the measured energy performance of the building. The various identified retrofits were then incorporated in the simulation model and compared with the predictions calculated using a mathematical model used by the retrofit project consultant company. The energy performance gaps between the two methods were analysed. The conclusions are that the simulation model is reflecting the actual energy use of the building well. The electricity use is reflected well both in the total annual use, approximately 4% gap compared to measured value, and the monthly variation over the year. The total natural gas use is under predicting the annual energy use, approximately 40% gap to the measured value, but shows a good correlation to the monthly variation.