Comparative assessment of environmental and post- occupancy evaluation of green buildings vs conventional buildings

Due to increasing office space demand and rising rental rates, stakeholders seek cost-effective alternatives that align with sustainability goals. Therefore, green building offers an extensive solution particularly in growing office building rental rates and the need for cost-effective options that are consistent with environmentally conscious goals. Using the IPCC standard, the study assessed emissions across Scope 1 (refrigerant fugitive emissions) and Scope 1 emission from (Wastewater treatment system), Scope 2 (energy consumption emissions), and Scope 3 (emissions from water consumption, and waste generation). Scope 1 emissions are found to vary due to the usage of water-based fire-retardant systems, but they remain restricted across all buildings. Additionally, the Post-Occupancy Evaluation (POE) aspect evaluates tenant satisfaction and rental rate assessment survey. Total Scope 1 Direct Fugitive emission accounted for 61,600 kgCO2eq for Green Building 3, 144,147.89 kgCO2eq for Conventional Building 2 and 3. Apart from the wastewater treatment system, the number of building users and occupants’ consumption behaviors had direct effects on the high generation of Scope 1 emission (wastewater treatment system), in which, Green buildings emitted an average of 13.46 x 104 kg CO2e/year, compared to 20.6 x 104 kg CO2e/year for Conventional buildings. The impact of the COVID-19 pandemic on energy consumption was profound, with all facilities experiencing decreased energy usage during lockdowns. Moreover, there was little significant relationship was found between seasonal changes and energy consumption for all buildings. Green buildings used less Energy Use Intensity (EUI), average EUI range for Green Buildings were from 5.6 kWh/m2 to 11.6 kWh/m2, however, EUI value range of Conventional Buildings were higher compared to Green Buildings, which accounted from 6.9 kWh/m2 to 38.8 kWh/m2. The findings found that GHG emissions from Scope 2 emission (energy consumption) were the highest across all buildings, accounting for 62.2 to 98.2 percent of total GHG emissions. Scope 2 emission (Energy Consumption) for Green buildings averaged approximately 6.74 x 106 kgCO2e/year, while Conventional buildings averaged around 7.43 x 106 kgCO2e/year. However, there was no clear relationship between certification level of Green Building and actual energy consumption. Green buildings emitted fewer Scope 2 emission (water consumption) than conventional buildings, with an average value of 7.44 x 104 kgCO2e/year for Green buildings and 9.01 x 104 kgCO2e/year for conventional buildings. For Scope 3 (solid waste generation), even though all the buildings have waste segregation systems, the waste generation data for all the buildings are mixed and there was also lack of waste records in some buildings. Therefore, Scope 3 emission (Waste generation) of Green Building 1 accounted for 629,510.5 kgCO2e in 2022, and for Green Building 3 remain, the emission was substantial, with 9.9x105 kgCO2e in 2021 and 8.9x105 kgCO2e in 2022, respectively. According to survey results, environmental concerns have major influences on tenant choices, with a strong preference for “Lower operational costs” and “Energy efficiency”. However, the factors that influence tenants’ satisfaction on current buildings differed, with “Location and transportation” ranked first, followed by environmental issues such as “Energy efficiency” and “Water conservation”. Moreover, Green buildings were more likely to be preferred by respondents who had knowledge of green building principles. Long-term cost savings, a better indoor environment, and the presence of a green building certification were all associated with willingness to pay more.