A Comparison of Feasible Energy-Saving Retrofit Alternatives for Office Buildings in Urban Cities

The major portion of the world population lives in cities and consumes around 73% of world total energy. Due to rapid rise in population, improved standard of living, urbanization and major time spend indoor, the energy consumption in buildings has skyrocketed during the past few decades. The primary portion of building's energy consumption is utilized by HVAC system. Energy crisis is worsening day by day, especially in underdeveloped countries like Pakistan. In this research work, a SketchUp model of a single zone building is created, and it is subsequently loaded into the Energy plus program to simulate the model and ascertain the trends in energy use for the chosen cities in various scenarios for five major cities of Pakistan. Without insulation the zone temperature can reach upto 45.2 °C, 49.9 °C, 48.6 °C, 46 °C and 41.7 °C for Karachi, Lahore, Peshawar, Islamabad and Quetta respectively which is reduced by 22 – 28 % by applying insulation. For Peshawar, Karachi, Quetta and Islamabad highest energy consumption was reported in the month of July, May, July and June respectively. The energy saving is increased by 5 – 26 % by replacing conventional air conditioner with VRF AC without insulation and by 32 – 70 % by applying insulation with VRF AC as compared to VRF AC without insulation. The payback period ranges between 28 – 60, 19 – 42, 16 – 35, 18 – 39 and 21 – 45 months for Quetta, Karachi, Lahore, Peshawar and Islamabad respectively. The longest PBP of 92 months is reported for Quetta at 5% tariff and 60% investment cost increase with VRF air conditioner, while the lowest PBP of 16 months is recorded for Lahore at 15% tariff and 20% investment cost increase with combined installation of insulation and VRF air conditioner.